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1
Gribin, Vladimir, Ilya Gavrilov, Aleksandr Tishchenko, Victor Tishchenko, Vitaliy Popov, Sergey Khomyakov, and Roman Alexeev. "Features of liquid phase movement in the inter-blade channel of nozzle blade cascade." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 5 (September 13, 2017): 452–60. http://dx.doi.org/10.1177/0957650917730947.
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The experimental results of wet steam flow in the blade channel of flat nozzle blade cascade have been considered in the paper. The aim of this work is to study the motion of liquid droplets inside the inter-blade channel. Experimental studies were performed on installation circuit of wet steam. In order to obtain velocity fields of droplets in investigated channel, the laser diagnostics system was used. It carries out the cross-correlation method—particle tracking velocimetry. Numerical simulation of wet steam flow in studied channel was performed. According to the obtained data, the main features of the droplets motion in the blade channel have been revealed. Basic droplets streams and the sources of their appearance have been determined. The process of deposition and breakdown of the droplets on the surface of the blades have been studied. It is shown that reflected region of droplets (“fountain”) is formed around the leading edge. The experimental data were compared with the results of numerical simulation of the droplets motion in the flat nozzle blade cascade.
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Zhang, Jinfeng, Guidong Li, Jieyun Mao, Shouqi Yuan, Yefei Qu, and Jing Jia. "Effects of the outlet position of splitter blade on the flow characteristics in low-specific-speed centrifugal pump." Advances in Mechanical Engineering 10, no. 7 (July 2018): 168781401878952. http://dx.doi.org/10.1177/1687814018789525.
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To elucidate the influences of the outlet position of splitter blades on the performance of a low-specific-speed centrifugal pump, two different splitter blade schemes were proposed: one located in the middle of the channel and the other having a deviation angle at the trailing edge of splitter blade toward the suction side of the main blade. Experiments on the model pump with different splitter blade schemes were conducted, and numerical simulations on internal flow characteristics in the impellers were studied by means of the shear stress transport k- ω turbulence model. The results suggest that there is a good agreement between the experimental and numerical results. The splitter blade schemes can effectively optimize the structure of the jet-wake pattern and improve the internal flow states in the impeller channel. In addition, the secondary flow and inlet circulation on the pressure surface of main blade, the flow separation on the suction side of splitter blade, the pressure coefficient distributions on blade surface can achieve an evident amelioration when the trailing edge of splitter blade toward the suction side of the main blade is mounted at an appropriate position.
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Zhao, Wenbin, Jianbin Hu, and Kai Wang. "Influence of Channel-Diffuser Blades on Energy Performance of a Three-Stage Centrifugal Pump." Symmetry 13, no. 2 (February 5, 2021): 277. http://dx.doi.org/10.3390/sym13020277.
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In order to improve hydraulic efficiency, influence of inlet angle, outlet angle, wrap angle, inlet shape and outer edge camber lines of channel-diffuser blades on the energy performance of a three-stage centrifugal pump were studied and the pressure distributions on the blade of the first-stage channel-diffuser were particularly analyzed. The result shows that the efficiency of the pump is maximal when the blade inlet angle is 12°. The pressure variation in the model with the inlet angle of 12° was small and the amplitude of fluctuation was also not large. When the outlet angle was 90°, the pressure distribution in the outlet of the blades that are symmetrically distributed along the center of the diffuser shell was significantly better than that with other outlet angles. The effect of the blade wrap angle of the channel-diffuser on the energy performance of the pump was relatively small. The internal flow in the diffuser with the diffusion inlet shapes was steady for both the convex surface and concave surface. The diffusion inlet of the channel-diffuser blade corresponded to the outlet region of the impeller blade, which reflected a good matching. The fluctuation amplitude and the distribution range of the models with a uniform transition were smaller than those with non-uniform transition. In order to verify the effectiveness of the research results, an experimental test was carried out on the pump. The results show that when the flow rate is 850 m3/h, the head of the pump is 138.67 m and the efficiency of pump is 69.48%.
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Суббота, Анатолий Максимович, and Виталий Георгиевич Джулгаков. "ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ВЕТРОЭНЕРГЕТИЧЕСКОЙ УСТАНОВКИ С ВЕРТИКАЛЬНОЙ ОСЬЮ ВРАЩЕНИЯ." RADIOELECTRONIC AND COMPUTER SYSTEMS, no. 1 (February 23, 2018): 77–86. http://dx.doi.org/10.32620/reks.218.1.10.
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The questions connected with increase of efficiency of functioning of a wind power plant with a vertical axis of rotation are considered.Such plants convert the energy of the wind flow into rotational energy of the generator shaft, pump or other actuators. An overview of the design options for wind turbines of this type is presented. For vertically-axial wind power plants, in comparison with horizontally-propeller ones, it is possible to increase their efficiency by providing insensitivity to wind direction change. This is possible provided that the angular position of the blades with respect to the wind flow is continuously and purposefully changed as the wind turbine rotates. The principle of increasing the efficiency of the wind power plant is proposed due to the synchronous control of the position of the blades, depending on the direction and speed of the wind flow. The implementation of this principle is considered in detail for a four-bladed wind turbine. Depending on the direction and magnitude of the wind flow, as well as the angular velocity of rotation of the turbine, the value of the angle of the initial installation of the blades was analytically obtained, which ensures the maximum efficiency of using the wind plant. The functional scheme of the control system of the orientation of the four blades is formed. This system uses information about the current power of the generator, the rotation speed of the wind turbine, the direction and speed of the wind flow, obtained from the respective sensors. A detailed functional diagram of one channel of the control system has been constructed taking into account the initial exposure of the blade, which additionally uses information about the current angular position of the blade and the speed of its turn. Each such channel contains a proportional-differential controller or fuzzy logic controller. The proposed fuzzy controller has two inputs of linguistic variables - the angle of rotation of the blade and the speed of its rotation. As a kind of membership functions, a triangular distribution is chosen. A system of rules for adjusting the fuzzy controller has been developed. The computer simulation of the channel functioning of the control system with two types of regulators for the mode of initial setting of the blades with a change in wind direction was performed. Comparison of the quality of the control system with a proportional-differential and fuzzy controller is performed
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Wang, Peng, Xinyu Zhu, and Yi Li. "Analysis of Flow and Wear Characteristics of Solid–Liquid Two-Phase Flow in Rotating Flow Channel." Processes 8, no. 11 (November 21, 2020): 1512. http://dx.doi.org/10.3390/pr8111512.
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To study the flow characteristics and the wear distribution of pumps at different rotation speeds, a rotating disc with three blades was designed for experiments. Numerical simulations were conducted using a computational fluid dynamics-discrete phase model (CFD–DPM) approach. The experimental and numerical results were compared, and the flow characteristics and wear behaviors were determined. As the speed increased, the particles at the blade working surface aggregated. The particle velocity gradually increased at the outlet of the channel. The severe wear areas were all located in the outlet area of the blade working surface, and the wear area extended toward the inlet area of the blade with increasing speed. The wear rate of the blade surface increased as the speed increased, and an area with a steady wear rate appeared at the outlet area of the blade. When the concentration was more than 8%, the severe wear areas were unchanged at the same speed. When the speed increased, the severe wear areas of the blade produced wear ripples, and the area of the ripples increased with increasing speed. The height difference between the ripples along the flow direction on the blade became larger as the speed increased.
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Fan, Hong-Zhou, Shang-Jin Wang, Guang Xi, and Yan-Long Cao. "A novel tool-path generation method for five-axis flank machining of centrifugal impeller with arbitrary surface blades." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 231, no. 1 (August 8, 2016): 155–66. http://dx.doi.org/10.1177/0954405415599943.
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The centrifugal impeller with arbitrary surface blades is a very important component in automobile, ships, and aircraft industry, and it is one of the most difficult parts to process. Focusing on the machining efficiency improvement, combining the geometric advantages of ruled surface and arbitrary surface, and utilizing the efficient and accurate advantages of flank machining and point machining, this article presents a novel and targeted tool-path generation method and algorithm for five-axis flank machining of centrifugal impeller with arbitrary surface blades. In light of specific characters of different surfaces, the analyses of two different impeller blades are proposed first, the more characteristic and complex geometrical structures of the arbitrary blade are achieved. In rough machining, an approximate ruled surface blade is obtained, and a simple channel is achieved; the flank milling of the centrifugal impeller with ruled surface blades is achieved relative to the point milling of the centrifugal impeller with arbitrary surface blades; and the triangle tool path planning method is added in this process to save the machining time and cost collectively. Furthermore, in semi-finish machining, the approximate sub-ruled blade surfaces are calculated, and a new flank milling method of the sub-ruled blade surfaces is achieved; a new solution for tool interference is achieved in this process and the generation of non-interference tool paths becomes easy. Machining experiments of two different impellers are presented as a test of the proposed methods.
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Abdullah, Bestoon, Vadim Varsegov, and Adolf Limansky. "CENTRIFUGAL COMPRESSOR HEAD CHARACTERISTIC OF A MICRO TURBOJET ENGINE BASED ON NUMERICAL SIMULATION." Perm National Research Polytechnic University Aerospace Engineering Bulletin, no. 62 (2020): 5–11. http://dx.doi.org/10.15593/2224-9982/2020.62.01.
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Shown the possibility of using the standard ANSYS CFX hydrodynamic software package for calculating the gasdynamic characteristics of the centrifugal compressor impeller of micro turbojet engines with different options for profiling blades which based on physical and numerical modeling. Presented a methodology for designing the impeller of a centrifugal compressor based on solving the inverse problem of gas dynamics. As a result of a numerical study, the head coefficient of various forms of the impeller was obtained and presented the dependences of the head coefficient and efficiency on the blade back sweep angle 2 β . b The article discusses the effect of the blade back sweep angle 2 β b on the compressor efficiency and the head characteristic for three different values of the blade back sweep angle 2 β b for example, the impeller with the back sweep angle 2 β b and with the radial blades 2 β 90 b and with blades bent forward 2 β b The centrifugal compressor was designed using Vista CCD programs in one-dimensional computing and Fluid flow CFX in three-dimensional computing. For blade profiling, the BladeGend program was used with different profiling options in order to improve compressor efficiency. The computational grid and the construction of a structured hexahedral mesh for the impeller was carried out in Ansys Turbogrid and the SST model of turbulence was selected in the calculation, which, with sufficient grinding of the mesh at the walls, adequately simulates separated flows at the channel walls, as well as the flow in the flow core. When constructing a grid along the walls between the channel blades, the parameter y + was controlled, which should not exceed 2. It is permissible to use a coarser grid in the flow core compared to the grid near the walls. The design grid of the impeller consists of 350000 elements.
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Luxa, Martin. "The Sonic Surface in the Inter-Blade Channel of the Last Stage Rotor Wheel in the Steam Turbine of Large Output." MATEC Web of Conferences 168 (2018): 02006. http://dx.doi.org/10.1051/matecconf/201816802006.
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The paper deals with sonic surface in a modern turbine wheel consisting of non-prismatic ultra long blades. The whole inter-blade channel is choked. Different positions and shapes of the sonic line in particular cross-sections along the span are observed. The sensitivity of sonic line formation to small changes of effective shape of the inter-blade channel in the root section and the influence of inlet angle, stagger angle and pitch/chord ratio in the tip section are discussed. The problematic of sonic line development in the case of supersonic inlet flow filed is also described. The presented work is based on results of theoretical, experimental and numerical approaches.
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Zhang, Delong, Yu Wang, Junjie Sha, and Yuguang He. "Performance Prediction of a Turbodrill Based on the Properties of the Drilling Fluid." Machines 9, no. 4 (March 31, 2021): 76. http://dx.doi.org/10.3390/machines9040076.
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High-temperature geothermal well resource exploration faces high-temperature and high-pressure environments at the bottom of the hole. The all-metal turbodrill has the advantages of high-temperature resistance and corrosion resistance and has good application prospects. Multistage hydraulic components, consisting of stators and rotors, are the key to the turbodrill. The purpose of this paper is to provide a basis for designing turbodrill blades with high-density drilling fluid under high-temperature conditions. Based on the basic equation of pseudo-fluid two-phase flow and the modified Bernoulli equation, a mathematical model for the coupling of two-phase viscous fluid flow with the turbodrill blade is established. A single-stage blade performance prediction model is proposed and extended to multi-stage blades. A Computational Fluid Dynamics (CFD) model of a 100-stage turbodrill blade channel is established, and the multi-stage blade simulation results for different fluid properties are given. The analysis confirms the influence of fluid viscosity and fluid density on the output performance of the turbodrill. The research results show that compared with the condition of clear water, the high-viscosity and high-density conditions (viscosity 16 mPa∙s, density 1.4 g/cm3) will increase the braking torque of the turbodrill by 24.2%, the peak power by 19.8%, and the pressure drop by 52.1%. The results will be beneficial to the modification of the geometry model of the blade and guide the on-site application of the turbodrill to improve drilling efficiency.
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Zhang, Bo, Quan Hong, Yuanyuan Dou, Honghu Ji, and Rui Chen. "Experimental investigation of flow and heat transfer characteristics on matrix ribbed channel." Thermal Science 24, no. 3 Part A (2020): 1593–600. http://dx.doi.org/10.2298/tsci190702026z.
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The effect of the rib width to height ratio t/e and width to pitch ratio t/p on the local heat transfer distribution in a rectangular matrix ribbed channel with two opposite in line 45? ribs are experimentally investigated for Reynolds numbers from 54000 to 150000. The rib height to channel height ratio e/H is 0.5, t/p and t/e both varies in range of 0.3-0.5. To simulate the actually situation in turbine blades, and provide useful direct results for turbine blade designers, the parameters are same with the blade. The experiments results show that, in comparison to fully developed flow in a smooth pipe of equivalent hydraulic diameter, the Nusselt number inside the matrix-ribbed rectangular channel is increased up to 5 to 9 times higher, while total pressure drop is enlarged by up to significant magnitude. The Nusselt number ratio increases with t/p and t/e increased. Semi-empirical heat transfer is developed for designing of cooling channel.
11
Potapov, V. A., and A. A. Sanko. "Performance simulation of multi-stage axial-flow compressor of turbo-shaft engine with account for erosive wear nonlinearity of its blades." Civil Aviation High Technologies 23, no. 5 (October 28, 2020): 39–53. http://dx.doi.org/10.26467/2079-0619-2020-23-5-39-53.
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The construction and useful practice of gas-turbine engine diagnosis systems depend largely on the availability of the engine mathematical models and its certain components in their structure. Utilization of multi-stage axial flow compressor performance with account for erosive wear of its parts during the operation fundamentally raises possibilities of such systems as erosive wear of flow channel, blade rings of impellers and vane rings of multi-stage compressor is a common cause of preschedule gas-turbine engine detaching from an aircraft. As evidenced by various contributions presented in the article, special emphasis on abrasive wear impact assessment on axial flow compressor performance is placed upon rotor-wing turbo-shaft engine due to their particular operating conditions. One of the main tasks in the process of mathematic simulation of an axial flow compressor blade ring is consideration of its wear type that again has a nonlinear distribution along the level of the blade. In addition, wear rate at entry and exit blade edges often have different principles. Detecting of these principles and their consideration when constructing the compressor mathematical model is a crucial task in diagnostic assessment and integrity monitoring of rotor-wing turbo-shaft engine in operation. The article represents a concept to an estimate nonlinear erosive wear effect of axial flow compressor blades on its performance based on the three-dimensional flow approach in the gas-air flow duct of compressor with a formulation of the blade rings. This approach renders possible to take into account the nonlinearity of the compressor blades wear during their operation. Through the example of the inlet compressor stage of a rotor-wing aircraft gas-turbine engine, the engine pump properties predictions with different kind of rotor blade wear have been presented.
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Tao, Ran, and Zhengwei Wang. "Comparative modeling and analysis of the flow asymmetricity in a centrifugal pump impeller at partial load." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, no. 2 (May 29, 2019): 237–47. http://dx.doi.org/10.1177/0957650919851921.
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Undesirable flow regime occurs at partial-load conditions of the centrifugal pump. Flow separates at the leading edge and pulses in the blade channel with complex stall cell transfer law. The passing capability of the blade channel becomes important when rotating stall happens. In this study, the blade channel number influence on the flow stability in a centrifugal pump impeller was studied by unsteady flow simulations after numerical-experimental verification. The 5-, 6-, and 7-blade impellers were discussed under the same partial-load flow rate condition and the same rotating speed. Results show that the internal flow pattern was strongly influenced by the blade channel number. Periodic half-blockage was observed in the 5-blade impeller. Alternating stall with three stalled and three well-behaved channels existed in the 6-blade impeller. Complex aperiodic flow pattern occurred in the 7-blade impeller with the well-behaved, half-blocked, and fully stalled passages were all observed with stall cell transfer. The different flow regime caused different pressure pulsations. In the 5-blade impeller, the inter-channel flow frequencies, which were induced by the fluid extruded from blocked channels flowed into other channels, dominated. In the 6-blade impeller, the pressure pulsations performed low-in-amplitude and high-in-frequency. The flow regime was stable even under the rotating stall. In the 7-blade impeller, the rotating stall frequency dominated. The inter-channel flow frequencies were also obvious. The stable rotating stall pattern does not strongly influence the pressure pulsation and impeller axial and radial forces. The transferring stall cell induces extra mild pressure pulsation and impeller forces. The inter-channel flow adds strong pressure pulsation and impeller forces. When centrifugal pumps are operating at partial-load conditions, the flow characters especially the inter-channel flow caused by half-channel-blockage should be checked to avoid operation instability and security.
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Dumitrache, Constantin, Ioan Calimanescu, and Corneliu Comandar. "Naval Centrifugal Compressor Design Using CAD Solutions." Applied Mechanics and Materials 658 (October 2014): 59–64. http://dx.doi.org/10.4028/www.scientific.net/amm.658.59.
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Centrifugal compressors of turbochargersoperate in a wide range of rotational speeds, which depends on the load of the supercharged engine. Current designs of turbocharger compressors exhibit high efficiencies accompanied by high flow capacities [1]. Consequences of aerodynamic optimization are high mean stress values in the blades due to centrifugal loading as well as dynamic stresses due to blade vibrations. Blade vibrations in a turbocharger compressor are assumed to be predominantly excited by unsteady aerodynamic forces [2]. These forces are caused by a variety of sources influencing the flow. Examples include the geometry of the flow channel, elbows, the diffuser vanes or struts. Therefore, an understanding of FSI is essential for further design optimizations.
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McMillin, R. D., and S. C. Lau. "Effect of Trailing-Edge Ejection on Local Heat (Mass) Transfer in Pin Fin Cooling Channels in Turbine Blades." Journal of Turbomachinery 116, no. 1 (January 1, 1994): 159–68. http://dx.doi.org/10.1115/1.2928271.
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Experiments are conducted to study the local heat transfer distribution and pressure drop in a pin fin channel that models the cooling passages in modern gas turbine blades. The detailed heat/mass transfer distribution is determined via the naphthalene sublimation technique for flow through a channel with a 16-row, staggered 3 × 2 array of short pin fins (with a height-to-diameter ratio of 1.0, and streamwise and spanwise spacing-to-diameter ratios of 2.5) and with flow ejection through holes in one of the side walls and at the straight flow exit (to simulate ejection through holes along the trailing edges and through tip bleed holes of turbine blades). The pin fin heat/mass transfer and the channel wall heat/mass transfer are obtained for the straight-flow-only and the ejection-flow cases. The results show that the regional pin heat/mass transfer coefficients are generally higher than the corresponding regional wall heat/mass transfer coefficients in both cases. When there is side wall flow ejection, a portion of the flow turns to exit through the ejection holes and the rate of heat/mass transfer decreases in the straight flow direction as a result of the reducing mass flow rate along the channel. The rate of cooling air flow through a pin fin channel in a gas turbine blade must be increased to compensate for the “loss” of the cooling air through trailing edge ejection holes, so that the blade tip is cooled sufficiently.
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Bouregba, Fatima, Mustapha Belkadi, Mohammed Aounallah, and Lahouari Adjlout. "Effect of the blade number on the marine propeller performance." EPJ Web of Conferences 213 (2019): 02007. http://dx.doi.org/10.1051/epjconf/201921302007.
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This paper deals with numerical simulation of stationary flow around a marine propeller. The aim is to reproduce the hydrodynamic turbulent flow around the Wageningen B serie propellers in open water using the ANSYS FLUENT code and the RANS approach. The computational domain consists of an inter-blade channel with periodic boundaries, meshed with tetrahedral cells. The turbulence is modeled with the k-ω. The obtained results provide good agreement with the available experimental data and show that the blades number affects considerably the marine propellers performances. It is interesting to notice that the six blades propeller is the best adapted one for the open water flows.
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Prasad Rao, Jubilee, and Francisco Diez. "Novel Cyclic Blade Pitching Mechanism for Wind and Tidal Energy Turbine Applications." Energies 11, no. 12 (November 29, 2018): 3328. http://dx.doi.org/10.3390/en11123328.
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A vertical axis drag-based turbine is proposed that allows for an improved performance by feathering its blades during recovery strokes to eliminate adverse blade forces. The turbine blades resemble flat plates and pitch by 90 ∘ between the two turbine strokes using a novel dual-cam mechanism. This passive mechanism orients the blades vertically during the drive stroke for maximum effective area and horizontally for minimum effective area during the recovery stroke. This allows maximizing the positive drive stroke force and minimizing the recovery stroke losses, in turn maximizing the net energy capture and the turbine performance. It is called the cyclic pitch turbine, and a mathematical model is developed that predicts the turbine performance. It shows that the turbine is self-starting for all orientations and has a higher and more uniform static torque coefficient than the popular Savonius turbine. The dynamic analysis also indicates a higher performance, and the predicted values for torque and power coefficients match very closely with those from water channel and wind tunnel experiments on a prototype. Results of testing several blade shapes indicate that airfoil section blades with long and narrow continuous shapes that have less area towards the blade’s tip result in higher performance.
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Khalatov, A. A., A. S. Kovalenko, and S. B. Reznik. "FEATURES OF ORGANIZATION OF FILM COOLING OF HIGH TEMPERATURE GAS TURBINES BLADES." Industrial Heat Engineering 39, no. 4 (March 24, 2017): 11–20. http://dx.doi.org/10.31472/ihe.4.2017.02.
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The features of the release of the cooling air in the interscapular channel high temperature gas turbines at the film cooling are considered. Possibilities of its local distribution on contour of an entrance edge of the perforated blades are investigated. The presented calculations show that the substantial increase in the cooling efficiency can be attained due to channels of small dimension in the blade wall.
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Ben-Mansour, R., and L. Al-Hadhrami. "Effect of Reynolds Number and Property Variation on Fluid Flow and Heat Transfer in the Entrance Region of a Turbine Blade Internal-Cooling Channel." International Journal of Rotating Machinery 2005, no. 1 (2005): 36–44. http://dx.doi.org/10.1155/ijrm.2005.36.
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Internal cooling is one of the effective techniques to cool turbine blades from inside. This internal cooling is achieved by pumping a relatively cold fluid through the internal-cooling channels. These channels are fed through short channels placed at the root of the turbine blade, usually called entrance region channels. The entrance region at the root of the turbine blade usually has a different geometry than the internal-cooling channel of the blade. This study investigates numerically the fluid flow and heat transfer in one-pass smooth isothermally heated channel using the RNGk−εmodel. The effect of Reynolds number on the flow and heat transfer characteristics has been studied for two mass flow rate ratios (1/1and1/2) for the same cooling channel. The Reynolds number was varied between10 000and50 000. The study has shown that the cooling channel goes through hydrodynamic and thermal development which necessitates a detailed flow and heat transfer study to evaluate the pressure drop and heat transfer rates. For the case of unbalanced mass flow rate ratio, a maximum difference of8.9% in the heat transfer rate between the top and bottom surfaces occurs atRe=10 000while the total heat transfer rate from both surfaces is the same for the balanced mass flow rate case. The effect of temperature-dependent property variation showed a small change in the heat transfer rates when all properties were allowed to vary with temperature. However, individual effects can be significant such as the effect of density variation, which resulted in as much as9.6% reduction in the heat transfer rate.
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Zhang, Fan, Martin Böhle, and Shouqi Yuan. "Experimental investigation on the performance of a side channel pump under gas–liquid two-phase flow operating condition." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 231, no. 7 (June 2, 2017): 645–53. http://dx.doi.org/10.1177/0957650917713090.
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Side channel pump is a kind of small volume vane pump with low flow rate but high head and most side channel pumps can transport gas–liquid two-phase flow. In order to investigate the performance of this type of pump depending on the blade suction angle under gas–liquid two-phase flow operating condition, an experimental study has been carried out. The head and efficiency curves, and the influence of blade suction angle changes on these curves for different inlet gas volume fraction states are analyzed in detail. Moreover, the gas transporting capability of the impeller with three different blade suction angles (10°, 20°, 30°) are also compared. The results show that the head and efficiency performances of the three impellers decrease a large value when the side channel pump operates with a little gas inside, and the operating range narrows as well. With the increasing of inlet gas volume fraction, the performance of the side channel pump worsens. The head and efficiency performances in the single-phase state improve by increasing the blade suction angle, but decrease by increasing the blade suction angle in the gas–liquid two-phase flow state. The maximum gas transporting capability of the impeller with a small blade suction angle is better than a large blade suction angle. Analysis on the measured data allows a better understanding of the effect of inlet gas quantity on the performance of the side channel pump with different blade suction angles, and it could supply the design reference for two-phase flow side channel pumps.
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Miyauchi, Sunao, Hironori Horiguchi, Jun-ichirou Fukutomi, and Akihiro Takahashi. "Optimization of Meridional Flow Channel Design of Pump Impeller." International Journal of Rotating Machinery 10, no. 2 (2004): 115–19. http://dx.doi.org/10.1155/s1023621x04000120.
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The meridional flow channel design of a pump impeller affects its performance. However, since so many design parameters exist, a new design method is proposed in which a meridional and blade-to-blade flow channel is designed by the parallel use of the circulation distribution provided by the designer. Thus, an optimization method was used to design an axis-symmetrical meridional flow channel from the circulation distribution. In addition, the inverse design method proposed by Zangeneh et al. (1996) was employed to design a three-dimensional blade-to-blade flow channel from the circulation distribution and the optimized meridional shape. In this article, a few design examples and these Computational Fluid Dynamics (CFD) validations are also given.
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Vasudevan, B., A. Prabhu, and R. Narasimha. "Blade manipulators in turbulent channel flow." Experiments in Fluids 12, no. 3 (January 1992): 200–208. http://dx.doi.org/10.1007/bf00188259.
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Zhou, Lingjiu, Meng Liu, Zhengwei Wang, Demin Liu, and Yongzhi Zhao. "Numerical simulation of the blade channel vortices in a Francis turbine runner." Engineering Computations 34, no. 2 (April 18, 2017): 364–76. http://dx.doi.org/10.1108/ec-10-2015-0302.
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Purpose This study analyzes the blade channel vortices inside Francis runner with a particular focus on the identification of different types of vortices and their causes. Design/methodology/approach A single-flow passage of the Francis runner with refined mesh and periodic boundary conditions was used for the numerical simulation to reduce the computational resource. The steady-state Reynolds-averaged Navier–Stokes equations closed with the k-ω shear–stress transport (SST) turbulence model were solved by ANSYS CFX to determine the flow field. The vortices were identified by the second largest eigenvalue of velocity. Findings Four types of vortices were identified inside the runner. Three types were related to the inlet flow. The last one (Type 4) was caused by the reversed flow near the runner crown and had the lowest pressure inside the core near the runner outlet. Thus, in the blade channel vortex inception line, Type 4 vortex would appear earlier than the other three ones. Besides, the Type 4 vortex emerged from the crown and shed toward the blade-trailing edge. And its location moved from near the crown down to near the band when the unit speed increased or unit discharge decreased. Research limitations/implications Although the refined mesh was used and the main vortices in the Francis runner were well predicted, the current mesh is not enough to accurately predict the lowest pressure in the channel vortex core. Practical/implications This knowledge is instructive in the runner blade design and troubleshooting related to the channel vortex. Originality/value This study gives an overview of the main observed blade channel vortices and their causes, and points out the important role the reversed flow plays in the formation of blade channel vortices. This knowledge is instructive in the runner blade design and troubleshooting related to blade channel vortices.
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Zhang, Hong Ming, and Li Xiang Zhang. "Numerical Simulation of Blade Channel Vortex in a Low Head Francis Turbine." Applied Mechanics and Materials 291-294 (February 2013): 1958–62. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.1958.
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The paper presents numerical simulation of blade channel vortex in a low head Francis turbine using OpenFoam code. A mixture assumption and a finite rate mass transfer model were introduced to analyze blade channel vortex. The finite volume method is used to solve the governing equations of the mixture model and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results have shown that using cavitation model to analyze blade channel vortex is very effective.
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Münsterjohann, Sven, and Stefan Becker. "Wall Pressure and Blade Surface Pressure in a Side Channel Blower." International Journal of Rotating Machinery 2018 (June 3, 2018): 1–17. http://dx.doi.org/10.1155/2018/2308759.
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In side channel blowers, the pressure field is the result of complex, inner flow mechanisms. While there are already experimental investigations on the wall pressure distributions, little is known about the pressure in the rotating system, i.e., on the blade surface. In this work, we present an experimental setup for measuring the unsteady blade surface pressure in several positions. The acquired data will be complemented by and compared to the additionally measured wall pressure on the side channel housing. Miniature pressure sensors are integrated into the impeller. It is modified to ensure flush mounted membranes of the sensors and to avoid impacting on the flow field. A telemetric system is used for a wireless transfer of the data from the rotating system to the data recorder. As a result, we show the time-resolved pressure distribution as well as its phase-locked ensemble average. The variations of the pressure field are related to the integral pressure difference across the turbomachine and to its rotational speed. Due to the high temporal resolution of the measurement data, an exact spatial localization of crucial flow phenomena is achieved. Low integral pressure differences show a nearly linear increase of the pressure in circumferential direction, while greater integral pressure differences evolve exponentially over the azimuth. The results confirm the circulatory flow theory. Different rotational speeds elicit a comparable behavior. The stripper is a dominant source for pressure fluctuations. Its individual geometric discontinuities are correlated to the flow field. Our results provide a deeper understanding of the flow phenomena in side channel blowers and the theory of pressure generation. Although the measurements were performed for only one type of side channel blower with a double-flow configuration and open blades, the energy transfer mechanism is the same for other modifications like single flow or closed blade versions.
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Li, Chao, Huo-Xing Liu, and Zhi-Hong Zhou. "Experimental Research about Shock Wave in a 1+1/2 Counter-Rotating Turbine." MATEC Web of Conferences 151 (2018): 02005. http://dx.doi.org/10.1051/matecconf/201815102005.
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To investigate the internal distribution regularities of shock wave structure in 1+1/2 counter-rotating turbine, numerical simulation and experimental research about the shock wave structure were conducted by using the schlieren apparatus under different working conditions.From the point of the unsteady results, the unsteady effect has few influence on the flow field of high pressure guide vane, but the wake of the high pressure guide leaves periodically sweeps through the front edge of the high pressure blade and there presents strong unsteady effect on flow field of high pressure rotor. Because of periodic influence of external wake and shock wave, the unsteadiness of flow in low pressure rotor is still strong but not that drastic compared to the high pressure rotor. 50% height section of the blade of the three types of blades are extracted respectively to make plane cascades which are conducted blowing experiments in supersonic wind tunnel. The final photograph were analyzed by comparing with the CFD results. Results show that with the increase of expansion ratio, the wave structures in blade channel move toward the exit and the caudal interference between the outer tail wave and is strengthened gradually.
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Carsten, Degendorfer, Reza S. Abhari, Klemens Vogel, and René Hunziker. "Experimental and numerical investigation of blade resonance in a centrifugal compressor for varying gas properties." Journal of the Global Power and Propulsion Society 2 (September 20, 2018): Q15CRP. http://dx.doi.org/10.22261/jgpps.q15crp.
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The blades of centrifugal compressors are exposed to unsteady forces during operation which can result in resonance response conditions and failures due to high cycle fatigue. A typical source of excitation is the unsteady fluid structure interaction between the impeller blades and the downstream vaned diffuser. Centrifugal compressors are operated with various working fluids with a wide range of applications in the power and process industry. Understanding the excitation mechanisms for different working fluids will help to design aerodynamically efficient compressors, while ensuring mechanical integrity and reducing the number of experimental design validations. A variation in working fluid properties allows investigation of the contribution of blade forcing and damping while the modal response remains unchanged. Experiments have been conducted at ETH Zurich’s radial compressor facility with a state of the art industrial compressor design. Dynamic strain gauge measurements on the impeller blades were used to determine the amplitude response, damping properties and forcing at a defined resonance condition. Two working fluids have been investigated to vary compressor flow settings while the modal response remains unchanged. Unsteady flow simulations and harmonic FSI simulations were used to complement the experiments and to investigate the local blade forcing distribution, which then were linked to flow effects. Experiments showed a change in resonance amplitude up to a factor of 4 due to a change in the applied working fluid. Estimation of the damping ratio with a single degree of freedom model found the exciting force to be the main contributor to the differences in resonant response. The unsteady flow simulations were able to identify the locations on the blade surface which are responsible for the change in forcing. It was found that the forcing depends on wave propagation effects in the flow channel and on how the pressure field matches the mode shape.
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Ji, Chunjun, Chunyang Li, Junyi Fang, and Qi Sun. "Loss Mechanism of Static Interstage Components of Multistage Centrifugal Compressors for Integrated Blade Design." Mathematical Problems in Engineering 2018 (December 5, 2018): 1–16. http://dx.doi.org/10.1155/2018/9025650.
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Although centrifugal compressors are widely used in construction, they consume a large amount of energy; in existing multistage centrifugal compressors, there is a serious pressure loss of ~15.13% when gas flows through the diffuser, bend, and return channel. In this study, we analyze the loss mechanisms of these stages in detail, using computational fluid dynamics. Based on this analysis, we present a new type of integrated blade, connecting the diffuser, bend, and return channels, which can eliminate the airflow stall phenomenon. Through effective control of the airflow spreading process, we minimized losses in the component, which improved its efficiency by 4.39% and increased the pressure ratio by 2.86% relative to a compressor without the newly-designed integrated blade. The concepts used in the creation of this component can provide a reference for the future design of blades for flow through parts of multistage compressors.
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Siddiqui, A. M., A. Imran, M. Zeb, and M. A. Rana. "Magnetohydrodynamic flow of Newtonian fluid in a scraped surface heat exchanger." Canadian Journal of Physics 93, no. 10 (October 2015): 1088–99. http://dx.doi.org/10.1139/cjp-2014-0195.
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This paper aims to study a mathematical model of electrically conducting incompressible Newtonian fluid flow in a scraped surface heat exchanger in the presence of a transverse magnetic field. In our case the gap between the blades and the device wall is narrow so lubrication theory approximations work for the flow. Steady isothermal flow of an electrically conducting Newtonian fluid is considered around a periodic array of pivoted scraper blade in a channel in which the lower wall is moving and the upper wall is at rest. Two-dimensional flow in the transverse section of a scraped surface heat exchanger is taken. Details of the flow properties, including the possible presence of regions of reversed flow under the blades, the forces on the blades and walls, and the fluxes of fluid above and below the blades are calculated. Graphic representation for involved flow parameters is also given.
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Frąckowiak, Andrzej, Aleksander Olejnik, Agnieszka Wróblewska, and Michał Ciałkowski. "Application of the Protective Coating for Blade’s Thermal Protection." Energies 14, no. 1 (December 24, 2020): 50. http://dx.doi.org/10.3390/en14010050.
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This paper presents an algorithm applied for determining temperature distribution inside the gas turbine blade in which the external surface is coated with a protective layer. Inside the cooling channel, there is a porous material enabling heat to be transferred from the entire volume of the channel. This algorithm solves the nonlinear problem of heat conduction with the known: heat transfer coefficient on the external side of the blade surface, the temperature of gas surrounding the blade, coefficients of heat conduction of the protective coating and of the material the blade is made of as well as of the porous material inside the channel, the volumetric heat transfer coefficient for the porous material and the temperature of the air flowing through the porous material. Based on these data, the distribution of material porosity is determined in such a way that the temperature on the boundary between the protective coating and the material the blade is made of is equal to the assumed distribution To. This paper includes results of calculations for various thicknesses of the protective coating and the given constant values of temperature on the boundary between the protective coating and the material the blade is made of.
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Kumar, Micha, N. Alagumurthi, and K. Palaniradja. "Conjugated heat transfer analysis of gas turbine vanes using MacCormack's technique." Thermal Science 12, no. 3 (2008): 65–73. http://dx.doi.org/10.2298/tsci0803065k.
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It is well known that turbine engine efficiency can be improved by increasing the turbine inlet gas temperature. This causes an increase of heat load to the turbine components. Current inlet temperature level in advanced gas turbine is far above the melting point of the vane material. Therefore, along with high temperature material development, sophisticated cooling scheme must be developed for continuous safe operation of gas turbine with high performance. Gas turbine blades are cooled internally and externally. Internal cooling is achieved by passing the coolant through passages inside the blade and extracting the heat from outside of the blade. This paper focuses on turbine vanes internal cooling. The effect of arrangement of rib and parabolic fin turbulator in the internal cooling channel and numerical investigation of temperature distribution along the vane material has been presented. The formulations for the internal cooling for the turbine vane have been done and these formulated equations are solved by MacCormack's technique.
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Редин, И. И., and М. А. Шевченко. "УЛУЧШЕНИЕ ТОПЛИВНОЙ ЭФФЕКТИВНОСТИ ГАЗОТУРБИННОГО ДВИГАТЕЛЯ УСТАНОВКОЙ В КОМПРЕССОРЕ НАДРОТОРНОГО УСТРОЙСТВА." Open Information and Computer Integrated Technologies, no. 81 (November 16, 2018): 72–85. http://dx.doi.org/10.32620/oikit.2018.81.08.
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The analysis of the influence of annular grooves on the flow in the compressor rotor air gas channel and the axial compressor characteristics as well as on the fuel efficiency of the gas turbine engine is presented. The hypothetical mechanism of the flow effect in the cavity of the annular groove on the main flow in the tip end of the blade air-foil of the axial compressor stage is outlined. The effectiveness of the casing treatment in the form of single annular groove, width is 20% of the axial projection of the chord of the tip end section of the blade is shown experimentally in a single-stage and multi-stage axial compressor system. The increase of the compressor efficiency with ten single annular grooves installed above the leading edges of the blades of each stage, has reduced the specific fuel consumption of the serial GTE in its main operating modes.
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Tang, Fei, and Li Jia Wen. "Characterization of Rotating Cavitation in a High Speed Inducer of Liquid Rocket Engine." Advanced Materials Research 320 (August 2011): 196–201. http://dx.doi.org/10.4028/www.scientific.net/amr.320.196.
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Rotating cavitation is one of the most important problems in the development of modern high performance rocket pump inducers. In this paper, a numerical simulation of rotating cavitation phenomenon in a 2D blade cascade of liquid rocket engine inducer was carried out using a mixture model based on Rayleigh-Plesset equation. The purpose is to investigate the characterization of rotating cavitation in a high speed inducer. The results show that when sub-synchronous rotating cavitation occurs, the speed for the length of the blade surface cavitation is lower than the speed frequency of rotation shaft with the same direction. The external aspect is that the pressure at the upstream of blades changes synchronous. Thus, the generation of sub-synchronous rotating cavitation is closely related to the changes of flow angel which caused by the flow fluctuations. Hence, elimination of the flow rate redistribution among the flow channel can effectively suppress the occurrence of this phenomenon.
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Karpik, Anna. "ESTIMATION OF THE STRESS-STRAIN STATE OF THE BLADE BASED ON INTERPROGRAM INTERACTION OF PROGRAM COMPLEXES." Vibrations in engineering and technology, no. 2(93) (May 31, 2019): 30–36. http://dx.doi.org/10.37128/2306-8744-2019-2-5.
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Basis of numerical simulation of turbulent viscous gas flow, using the Navier-Stokes equations averaged the Reynolds (RANS-model), a static analysis of the gas turbine compressor blade was performed. The simulation of flow parameters in three-dimensional formulation was carried out. For the solution of system of the equations the iterative differential scheme was built. The initial equations are integrated numerically by use of the iterative explicit and implicit differential scheme with a second order approximation. The differential two-parametrical SST Menter's model is used as a model of turbulence. As a result, distributed pressure and velocities in the blades channel were obtained and unfavorable flow zones were identified. At the second stage, was developed algorithm by which the interrelation of the gas-dynamic and mechanical calculation program was established. As a result, distributed pressure was applied to the finite-element model of the blade and a static analysis was performed. Static calculation makes it possible to calculate the stress-strain state of the construction.
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Li, Zhehong, Xinxue Ye, and Yikun Wei. "Investigation on Vortex Characteristics of a Multi-Blade Centrifugal Fan near Volute Outlet Region." Processes 8, no. 10 (October 2, 2020): 1240. http://dx.doi.org/10.3390/pr8101240.
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The origins and effects of the complex vortex structure near the volute outlet of a multi-blade centrifugal fan are investigated in this paper. Due to the wide blade and short blade channel, the airflow maintains a large radial velocity during the blade channel. This continuous radial partial velocity causes vortices to be generated at the region of volute outlet. Then, the secondary flow close to the impeller generate from the center to the sides in volute. It is obtained that the streamlines are divided into two parts (backflow and outflow) at volute outlet. Although the vortices near volute outlet region are complex, the main features of flow behavior caused by the vortex are understandable.
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Dibelius, G. H., and E. Ahlers. "Influence of Periodically Unsteady Wake Flow on the Flow Separation in Blade Channels." Journal of Turbomachinery 114, no. 1 (January 1, 1992): 108–13. http://dx.doi.org/10.1115/1.2927973.
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The influence of periodically unsteady perturbations on the turbulent flow along the suction side of turbine blades is investigated in a test rig. The blade suction side is represented by a flat plate 550 mm in length. The pressure profile typically encountered in a turbine blade channel is generated by a curved wall opposite to the flat plate. The angle of the divergent part of the test channel and hence the pressure can be increased to induce flow separation on the flat plate. For simulation of the wakes from the upstream blade row, the incoming flow is periodically disturbed by a wake generator consisting of five flat profiles arranged in front and parallel to the plate rotating with adjustable speed and phase angle. An LDV with high spatial resolution is used to measure averaged and fluctuating components of the velocity inside the boundary layer flow down to a distance of y = 0.05 mm from the plate surface, determining the boundary layer parameters as well as the wall shear stress. By Fourier analysis of the measured time-related velocity distributions, the stochastic and periodic parts of the overall turbulence are identified. With a periodic wake flow the separation is shifted downstream as compared to the steady flow situation. This is due to the energization of the boundary layer flow associated with the conversion of periodic in stochastic parts of the turbulence. Conclusions resulting from the experimental findings for the theoretical understanding of the flow turbine cascades are discussed in particular with respect to turbulence modeling.
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Boldyrev, Aleksei V., Sergei V. Boldyrev, and Dmitrii L. Karelin. "THE EFFECT OF BLADE PROFILE ON THE PERFORMANCE OF A SIDE CHANNEL PUMP." Tyumen State University Herald. Physical and Mathematical Modeling. Oil, Gas, Energy 6, no. 3 (2020): 23–37. http://dx.doi.org/10.21684/2411-7978-2020-6-3-23-37.
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This article presents the results of a numerical modeling of a steady turbulent flow of an incompressible fluid in an open-type vortex pump with an open side channel, comparing the generalized simulation results with the existing experimental data. The mathematical model is based on the Reynolds-averaged Navier — Stokes and continuity equations, as well as on the equations of the two-layer Realizable k-ε turbulence model that accounts for the curvature of streamlines. The authors have estimated the grid independence of the solution and studied the influence of 14 blade profiles on the head and efficiency of the vortex pump. The solution of the model equations was achieved by the finite volume method using a sequential algorithm in three calculation areas (“feeder channel”, “blade wheel”, “open hull side channel and diverter channel”) with the evaluation of grid independence of the solution. The result of the solution between the calculated areas was transmitted at the corresponding points of the interface surfaces. The authors have studied the influence of 14 profiles of a blade on pressure and efficiency of the vortex pump: the initial profile of the blade with the installation in the wheel coaxial shaft of the ring plate of different width, the initial profile of the blade with a bevel on the discharge side, a profile in the form of an isosceles triangle, a profile in the form of a quadrangle, the initial profile with a rounded blade on the suction side, and a profile in the form of a rectangular triangle with a rounded blade on the suction side, among others. The simulation results have aided in proposing the blade profiles: in the form of a rectangle with a convex rounding of the blade on the suction side with a 10 mm radius and a right-angled triangle with a concave rounding of the blade on the suction side with a 52 mm radius and without rounding, giving a significant increase in pressure — more than 20%. Nevertheless, none of the considered cases have revealed any significant increase in the vortex pump hydraulic efficiency.
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Carstens, Volker, and Joachim Belz. "Numerical Investigation of Nonlinear Fluid-Structure Interaction in Vibrating Compressor Blades." Journal of Turbomachinery 123, no. 2 (February 1, 2000): 402–8. http://dx.doi.org/10.1115/1.1354138.
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The aeroelastic behavior of vibrating blade assemblies is usually investigated in the frequency domain where the determination of aeroelastic stability boundaries is separated from the computation of linearized unsteady aerodynamic forces. However, nonlinear fluid-structure interaction caused by oscillating shocks or strong flow separation may significantly influence the aerodynamic damping and hence effect a shift of stability boundaries. In order to investigate such aeroelastic phenomena, the governing equations of structural and fluid motion have to be simultaneously integrated in time. In this paper a technique is presented which analyzes the aeroelastic behavior of an oscillating compressor cascade in the time domain. The structural part of the governing aeroelastic equations is time-integrated according to the algorithm of Newmark, while the unsteady airloads are computed at every time step by an Euler upwind code. The link between the two time integrations is an automatic grid generation in which the used mesh is dynamically deformed as such that it conforms with the deflected blades at every time step. The computed time series of the aeroelastic simulation of an assembly of twenty compressor blades performing torsional vibrations in transonic flow are presented. For subsonic flow, the differences between time domain and frequency domain results are of negligible order. For transonic flow, however, where vibrating shocks and a temporarily choked flow in the blade channel dominate the unsteady flow, the energy transfer between fluid and structure is no longer comparable to that of a linear system. It is demonstrated that the application of the time domain method leads to a significantly different aeroelastic behavior of the blade assembly including a shift of the stability boundary.
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Ding, Bi-Rong, Yuan-long Chen, Ji Zhou, and Pei-xuan Chen. "Research on Key Process Technology for Profile Electrolytic Finishing of Large Marine Propeller Impeller." Polish Maritime Research 25, s2 (August 1, 2018): 158–63. http://dx.doi.org/10.2478/pomr-2018-0087.
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Abstract An electrolysis process method for free-form blade surface finishing is proposed for a free-form surface impeller, and a stepwise method is used to process the inter-blade channel of the overall impeller. The forming cathode is then used to finish the blade to meet the blade processing requirements. In the design, the forming cathode structure was improved by using motion simulation software, and the flow field simulation software was used to simulate and analyze the cathode flow channel. The cathode shape and the electrolyte flow rate between the electrodes meet the processing requirements. In the process of processing experiments, the motion path of the cathode was analyzed and optimized. The effect of the feed direction on the uneven distribution of the blade machining gap was reduced through optimization, and high-frequency pulse power processing was used to reduce the machining gap and improve the machining accuracy of the blade. The experimental results show that the process scheme is feasible and the precision of the processed impeller free-form surface is significantly improved. The material is a monolithic turbine disk of high-temperature alloys, and its large twisted blade processing has always been a problem in the manufacturing industry.
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Xu, Liang, Qingyun Shen, Qicheng Ruan, Lei Xi, Jianmin Gao, and Yunlong Li. "Optimization Design of Lattice Structures in Internal Cooling Channel of Turbine Blade." Applied Sciences 11, no. 13 (June 23, 2021): 5838. http://dx.doi.org/10.3390/app11135838.
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Recently, the inlet temperatures in gas turbine units have been drastically increased, which extremely affects the lifespan of gas turbine blades. Traditional cooling structures greatly improve the high temperature resistance of the blade; however, these structures scarcely concern both heat transfer and mechanical performances. Lattice structure (LS) can realize these requirements because of its characteristics of light weight, high strength, and porosity. Although the topology of LS is complex, it can be manufactured with the 3D metal printing technology. In this study, an integral optimization method of lattice cooling structure, used at the trailing edge of turbine blades, concerned with heat transfer and mechanical performance, was presented. Firstly, functions between the first-order natural frequency (freq1), elasticity modulus (E), relative density (ρ¯), and Nusselt number (Nu), and the geometric variables of pyramid type LS (PLS) and X-type LS (XLS) were established, and the reliability of these functions was verified. Then, a mathematical optimization model was developed based on these functions which contained two selected optimization problems. Finally, relations among objectives were analyzed; influence law of geometric variables to objectives were discussed, and the accuracy of the optimal LS was proved by experiment and numerical simulation. The optimization results suggest that, compared to the initial LS, Nu increases by 24.1% and ρ¯ decreases by 31% in the optimal LS of the first selected problem, and the Nu increases by 28.8% while freq1 and ρ¯ are almost unchanged in the optimal LS of the second selected problem compared to the initial LS. This study may provide a guidance for functions integration design of lattice cooling structures used at turbine blades based on 3D printing.
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Chen, Naixing, Fengxian Zhang, and Weihong Li. "An Inverse (Design) Problem Solution Method for the Blade Cascade Flow on Streamsurface of Revolution." Journal of Turbomachinery 108, no. 2 (October 1, 1986): 194–99. http://dx.doi.org/10.1115/1.3262037.
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On the basis of the fundamental equations of aerothermodynamics a method for solving the inverse (design) problem of blade cascade flow on the blade-to-blade streamsurface of revolution is suggested in the present paper. For this kind of inverse problem the inlet and outlet flow angles, the aerothermodynamic parameters at the inlet, and the other constraint conditions are given. Two approaches are proposed in the present paper: the suction-pressure-surface alternative calculation method (SSAC) and the prescribed streamline method (PSLM). In the first method the metric tensor (blade channel width) is obtained by alternately fixing either the suction or pressure side and by revising the geometric form of the other side from one iteration to the next. The first step of the second method is to give the geometric form of one of the streamlines. The velocity distribution or the mass flow rate per unit area on that given streamline is estimated approximately by satisfying the blade thickness distribution requirement. The stream function in the blade cascade channel is calculated by assuming initial suction and pressure surfaces and solving the governing differential equations. Then, the distribution of metric tensor on the given streamline is specified by the stream function definition. It is evident that the square root of the metric tensor is a circumferential width of the blade cascade channel for the special nonorthogonal coordinate system adopted in the present paper. The iteration procedure for calculating the stream function is repeated until the convergence criterion of the metric tensor is reached. A comparison between the solutions with and without consideration of viscous effects is also made in the present paper.
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Song, J. W., M. Raheel, and A. Engeda. "A compressible flow theory for regenerative compressors with aerofoil blades." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 217, no. 11 (November 1, 2003): 1241–57. http://dx.doi.org/10.1243/095440603771665269.
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Regenerative flow compressors (RFCs) are rotodynamic machines capable of producing high heads at very low flowrates. They have very low specific speed and share some of the characteristics of positive displacement machines such as a roots blower, but without the problems of lubrication and wear. They can produce heads equivalent to that of several centrifugal stages from a single rotor with comparable tip speed. The compression process is usually not regarded as efficient. Typically they produce efficiency of less than 50 per cent but still they have found many applications because they allow the use of fluid dynamic compressors in place of positive displacement compressors for duties requiring high heads at low flowrates. There are very few mathematical models in the literature that explain the behaviour of regenerative turbomachines and predict the performance. Most of these models assumed incompressible flow, thus limiting their use to only pumps and blowers. Moreover, they needed extensive experimental support for performance prediction. Hence, it is very interesting from an industrial point of view to find efficient theoretical means that are able to forecast regenerative compressor performances, using easy to find geometric and fluid dynamic parameters. A compressible flow theory is thus presented for the first time in this paper to describe complex three-dimensional corkscrew flow patterns in regenerative compressors. Conventional RFC were designed with radial, non-radial or semicircular impeller blades. In the present investigation, the authors have discussed RFCs with aerofoil blades and an annular flow channel containing a core to direct circulating flow to the blades with a minimum amount of losses. The effects of various geometric elements on the performance of RFCs are studied. All the major sources of losses in blade and channel region are identified. Governing equations for the flow in the compressor are derived and a performance prediction code based on governing equations and loss models is developed. Theoretical performance results are compared with published test data on aerofoil blade RFCs. Based on sensitivity analysis from the code, design changes are suggested for performance improvement.
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Kalinkevych, M., V. Ihnatenko, O. Bolotnikova, and O. Obukhov. "Design of high efficiency centrifugal compressors stages." Refrigeration Engineering and Technology 54, no. 5 (October 31, 2018): 4–9. http://dx.doi.org/10.15673/ret.v54i5.1239.
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The modern trend in compressor industry is an extension of the use of multi-shaft centrifugal compressors. Multi-shaft compressors have a number of advantages over single-shaft. The design of such compressors gives opportunity to use an axial inlet for all stages and select the optimum rotational speed for each pair of impellers, which, along with the cooling of the gas after each stage, makes possible to achieve high levels of efficiency. The design of high-efficiency centrifugal compressor stages can be performed on the basis of highly effective stage elements. Such elements are: impellers with spatial blades, vaned and channel diffusers with given velocity distribution. In this paper, impellers with axial-radial blades are considered. The blade profile is determined by the specified pressure distribution along the blade. Such design improves the structure of the gas flow in the interblade channels of the impeller, which leads to an increase in its efficiency. Characteristics of loss coefficients from attack angles for impellers were obtained experimentally. Vaned and channel diffusers, the characteristics of which are given in this article, are designed with the given velocity distribution along the vane. Compared to the classic type of diffuser, such diffusers have lower losses and a wider range of economical operation. For diffusers as well as for impellers, characteristics of loss coefficients from attack angles were obtained. High efficient impellers and diffusers and obtained gas-dynamic characteristics were used in the design of a multi-shaft compressor unit for the production of liquefied natural gas. The initial pressure of the unit is 3bar. The obtained characteristics of loss coefficients from attack angles for the considered impellers and diffusers make it possible to calculate the gas-dynamic characteristics of high-efficient centrifugal compressors stages. The high-efficient centrifugal compressors stages can be designed using high-efficient elements, such as: impeller with spatial blades and vaned diffuser with given velocity distribution.
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Кухтин, Юрий Петрович, and Руслан Юрьевич Шакало. "СНИЖЕНИЕ ВИБРОНАПРЯЖЕННОСТИ ПОПАРНО БАНДАЖИРОВАННЫХ РАБОЧИХ ЛОПАТОК ТУРБИНЫ." Aerospace technic and technology, no. 7 (August 31, 2020): 52–58. http://dx.doi.org/10.32620/aktt.2020.7.08.
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To reduce the vibration stresses arising in the working blades of turbines during resonant excitations caused by the frequency of passage of the blades of the nozzle apparatus, it is necessary to control the level of aerodynamic exciting forces. One of the ways to reduce dynamic stresses in rotor blades under operating conditions close to resonant, in addition to structural damping, maybe to reduce external exciting forces. To weaken the intensity of the exciting forces, it is possible to use a nozzle apparatus with multi-step gratings, as well as with non-radially mounted blades of the nozzle apparatus.This article presents the results of numerical calculations of exciting aerodynamic forces, as well as the results of experimental measurements of stresses arising in pairwise bandaged working blades with a frequency zCA ⋅ fn, where fn – is the rotor speed, zCA – is the number of nozzle blades. The object of research was the high-pressure turbine stage of a gas turbine engine. Two variants of a turbine stage were investigated: with the initial geometry of the nozzle apparatus having the same geometric neck area in each interscapular channel and with the geometry of the nozzle apparatus obtained by alternating two types of sectors with a reduced and initial throat area.The presented results are obtained on the basis of numerical simulation of a viscous unsteady gas flow in a transonic turbine stage using the SUnFlow home code, which implements a numerical solution of the Reynolds-averaged Navier-Stokes equations. Discontinuity of a torrent running on rotor blades is aggravated with heat drops between an ardent flow core and cold jets from film cooling of a blade and escapes on clock surfaces. Therefore, at simulation have been allowed all blowngs cooling air and drain on junctions of shelves the impeller.As a result of the replacement of the nozzle apparatus with a constant passage area by a nozzle apparatus with a variable area, a decrease in aerodynamic driving force by 12.5 % was obtained. The experimentally measured stresses arising in a pairwise bandaged blade under the action of this force decreased on average by 26 %.
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Zhou, Xin, Yongxue Zhang, Zhongli Ji, and Hucan Hou. "The Optimal Hydraulic Design of Centrifugal Impeller Using Genetic Algorithm with BVF." International Journal of Rotating Machinery 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/845302.
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Derived from idea of combining the advantages of two-dimensional hydraulic design theory, genetic algorithm, and boundary vorticity flux diagnosis, an optimal hydraulic design method of centrifugal pump impeller was developed. Given design parameters, the desired optimal centrifugal impeller can be obtained after several iterations by this method. Another 5 impellers with the same parameters were also designed by using single arc, double arcs, triple arcs, logarithmic spiral, and linear-variable angle spiral as blade profiles to make comparisons. Using Reynolds averaged N-S equations with a RNGk-εtwo-equation turbulence model and log-law wall function to solve 3D turbulent flow field in the flow channel between blades of 6 designed impellers by CFD code FLUENT, the investigation on velocity distributions, pressure distributions, boundary vorticity flux distributions on blade surfaces, and hydraulic performance of impellers was presented and the comparisons of impellers by different design methods were demonstrated. The results showed that the hydraulic performance of impeller designed by this method is much better than the other 5 impellers under design operation condition with almost the same head, higher efficiency, and lower rotating torque, which implied less hydraulic loss and energy consumption.
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Maulana, Muhammad Ilham, Ahmad Syuhada, and Fiqih Almas. "Computational Fluid Dynamic Predictions on Effects of Screw Number on Performance of Single Blade Archimedes Screw Turbine." E3S Web of Conferences 67 (2018): 04027. http://dx.doi.org/10.1051/e3sconf/20186704027.
Full textAbstract:
One of the alternative solutions to reduce the impact of electricity crisis in Aceh and other isolated areas in Indonesia is by the construction of small-scale hydro power plants that can work efficiently on the heads lower than 10 meters. One suitable type of turbine applied to the head below 10 meters is the Archimedes screw turbine. Due to the lack of information about the application of low head power plants, resulting in applications of this type of turbine is still less in Indonesia. This paper examined the appropriate turbine model. Before experimental turbine testing, turbines were designed theoretically first and then analyzed numerically. The flow velocity and pressure patterns within the turbine were analyzed using ANSYS CFD (Computational Fluid Dynamic) software under design conditions for 7, 9 and 11 screw numbers for single blade turbine. Based on the results of pressure analysis, speed and turbulent kinetic energy, it found that turbine performance using 11 blades is better among the three turbines. However, the highest average speed was obtained on the turbine using 7 screws, which maximum pressure obtained on a turbine 7 screws of 1406 Pa, on 9 screws on plane 1301 Pa and at 11 screws of 1175 Pa. Based on the results of the analysis, it showed that the smaller the distance between the channel and turbine blades, the results were more efficient due to the absence of wasted streams. Therefore, the flow pressure in the inlet position all directly leaded to the tip off the blade to produce a momentum.
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WU, HUACHUN, GAO GONG, ZHIQIANG WANG, YEFA HU, and CHUNSHENG SONG. "STRUCTURAL DESIGN AND NUMERICAL SIMULATION OF THE DIFFUSER FOR MAGLEV AXIAL BLOOD PUMP." Journal of Mechanics in Medicine and Biology 14, no. 03 (March 13, 2014): 1450045. http://dx.doi.org/10.1142/s0219519414500456.
Full textAbstract:
Hydraulic performance is an especially important factor for maglev axial blood pumps that have been used in patients with heart disease. Most maglev axial blood pumps basically consist of a straightener, an impeller and a diffuser. The diffuser plays a key role in the performance of the maglev axial blood pump to provide an adequate pressure head and increase the hydraulic efficiency. Maglev axial blood pumps with various structural diffusers exhibit different hydraulic performance. In this study, computational fluid dynamics (CFD) analysis was performed to quantify hydrodynamic in a maglev axial blood pump with a flow rate of 6 L/min against a pressure head of 100 mmHg to optimize the diffuser structure. First, we design the prototype of diffuser structure based on traditional design method, establish blood flow channel models using commercial software ANSYS FLUENT. Specifically, compare the performance of pump with the diffusers of different parameters, such as the leading edge blade angle, blade-thickness and blade-number. The results show that the diffuser structures with the thickening blade by arc airfoil law, blade-number of 6, leading edge blade angle of 24°, and trailing edge blade angle of 90° exhibited the best hydraulic performance which could be utilized in the optimization design of maglev axial blood pumps.
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Taslim, M. E., L. A. Bondi, and D. M. Kercher. "An Experimental Investigation of Heat Transfer in an Orthogonally Rotating Channel Roughened With 45 deg Criss-Cross Ribs on Two Opposite Walls." Journal of Turbomachinery 113, no. 3 (July 1, 1991): 346–53. http://dx.doi.org/10.1115/1.2927882.
Full textAbstract:
Turbine blade cooling is imperative in advanced aircraft engines. The extremely hot gases that operate within the turbine section require turbine blades to be cooled by a complex cooling circuit. This cooling arrangement increases engine efficiency and ensures blade materials a longer creep life. One principle aspect of the circuit involves serpentine internal cooling passes throughout the core of the blade. Roughening the inside surfaces of these cooling passages with turbulence promoters provides enhanced heat transfer rates from the surface. The purpose of this investigation was to study the effect of rotation, aspect ratio, and turbulator roughness on heat transfer in these rib-roughened passages. The investigation was performed in an orthogonally rotating setup to simulate the actual rotation of the cooling passages. Single-pass channels, roughened on two opposite walls, with turbulators positioned at 45 deg angle to the flow, in a criss-cross arrangement, were studied throughout this experiment. The ribs were arranged such that their pitch-to-height ratio remained at a constant value of 10. An aspect ratio of unity was investigated under three different rib blockage ratios (turbulator height/channel hydraulic diameter) of 0.1333, 0.25, and 0.3333. A channel with an aspect ratio of 2 was also investigated for a blockage ratio of 0.25. Air was flown radially outward over a Reynolds number range of 15,000 to 50,000. The rotation number was varied from 0 to 0.3. Stationary and rotating cases of identical geometries were compared. Results indicated that rotational effects are more pronounced in turbulated passages of high aspect and low blockage ratios for which a steady increase in heat transfer coefficient is observed on the trailing side as rotation number increases while the heat transfer coefficient on the leading side shows a steady decrease with rotation number. However, the all-smooth-wall classical pattern of heat transfer coefficient variation on the leading and trailing sides is not followed for smaller aspect ratios and high blockage ratios when the relative artificial roughness is high.
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Wei, Zhicong, Wei Yang, and Ruofu Xiao. "Pressure Fluctuation and Flow Characteristics in a Two-Stage Double-Suction Centrifugal Pump." Symmetry 11, no. 1 (January 8, 2019): 65. http://dx.doi.org/10.3390/sym11010065.
Full textAbstract:
Pressure fluctuation is the primary factor that affects the stability of turbomachines. The goal of the present work is to explore the propagation of pressure fluctuations in a two-stage double-suction centrifugal pump. The pressure fluctuation characteristics of each component of a two-stage double-suction centrifugal pump are simulated under four typical flow rates based on the SST k-ω turbulence model. It is shown that the pressure fluctuation frequency at blade passing frequency and its first harmonic is the same at the suction chamber, the leading edge, and the middle of the first-stage impeller, which is different from the rotor–stator interaction. Moreover, the uneven impeller inlet flow distribution will produce fluctuations with rotation frequency and its harmonics at the leading edge of the impellers in both stages. Finally, broadband frequency is found at the trailing edge of the impellers in both stages associated with the first harmonic of the rotation frequency, especially under the part load condition. The large size backflow vortex appears in the blade flow channel leading to the low-pressure zone between the impeller, the tongue, and the start of the partition. That is why the pressure drops significantly twice in one rotation period when the blades pass through the tongue and the start of the partition.
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Badshah, Mujahid, Saeed Badshah, James VanZwieten, Sakhi Jan, Muhammad Amir, and Suheel Abdullah Malik. "Coupled Fluid-Structure Interaction Modelling of Loads Variation and Fatigue Life of a Full-Scale Tidal Turbine under the Effect of Velocity Profile." Energies 12, no. 11 (June 11, 2019): 2217. http://dx.doi.org/10.3390/en12112217.
Full textAbstract:
Velocity profiles in tidal channels cause cyclic oscillations in hydrodynamic loads due to the dependence of relative velocity on angular position, which can lead to fatigue damage. Therefore, the effect of velocity profile on the load variation and fatigue life of large-scale tidal turbines is quantified here. This is accomplished using Fluid Structure Interaction (FSI) simulations created using the ANSYS Workbench software, which couples the fluid solver ANSYS CFX to the structural solver ANSYS transient structural. While these load oscillations only minimally impact power and thrust fluctuation for rotors, they can significantly impact the load variations on individual rotor blades. To evaluate these loadings, a tidal turbine within a channel with a representative flow that follows a 1/7th power velocity profile and an onset turbulence intensity of 5% is simulated. This velocity profile increases the thrust coefficient variation from mean cycle value of an individual blade from 2.8% to 9% and the variation in flap wise bending moment coefficient is increased from 4.9% to 19%. Similarly, the variation from the mean cycle value for blade deformation and stress of 2.5% and 2.8% increased to 9.8% and 10.3%, respectively. Due to the effect of velocity profile, the mean stress is decreased, whereas, the range and variation of stress are considerably increased.
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Kim, Y. W., and D. E. Metzger. "Heat Transfer and Effectiveness on Film Cooled Turbine Blade Tip Models." Journal of Turbomachinery 117, no. 1 (January 1, 1995): 12–21. http://dx.doi.org/10.1115/1.2835630.
Full textAbstract:
In unshrouded axial turbine stages, a small but generally unavoidable clearance between the blade tips and the stationary outer seal allows a clearance gap leakage flow to be driven across the blade tip by the pressure-to-suction side pressure difference. In modern high-temperature machines, the turbine blade tips are often a region prone to early failure because of the presence of hot gases in the gap and the resultant added convection heating that must be counteracted by active blade cooling. The blade tip region, particularly near the trailing edge, is often very difficult to cool adequately with blade internal coolant flow, and film cooling injection directly onto the blade tip region can be used in an attempt to reduce the heat transfer rates directly from the hot clearance flow to the blade tip. An experimental program has been designed and conducted to model and measure the effects of film coolant injection on convection heat transfer to turbine blade tips. The modeling approach follows earlier work that found the leakage flow to be mainly a pressure-driven flow related strongly to the airfoil pressure loading distribution and only weakly, if at all, to the relative motion between blade tip and shroud. In the present work the clearance gap and blade tip region is thus modeled in stationary form with primary flow supplied to a narrow channel simulating the clearance gap above a plane blade tip. Secondary film flow is supplied to the tip surface through a line array of discrete normal injection holes near the upstream or pressure side. Both heat transfer and effectiveness are determined locally over the test surface downstream of injection through the use of thin liquid crystal coatings and a computer vision system over an extensive test matrix of clearance heights, clearance flow Reynolds numbers, and film flow rates. The results of the study indicate that film injection near the pressure-side corner on plane turbine blade tips can provide significant protection from convection heat transfer to the tip from the hot clearance gap leakage flow.