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1
Park, Juhyeon, Hoyong Lee, Gyejo Jung, and Jinyi Lee. "Nondestructive testing of turbine disk roots using solid-state GMR sensor arrays and an axial directional scanning system." International Journal of Applied Electromagnetics and Mechanics 64, no. 1-4 (December 10, 2020): 525–31. http://dx.doi.org/10.3233/jae-209360.
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A nondestructive testing device, consisting of a scanner and signal processing circuits was developed to detect cracks in turbine disk roots. The scanner consists of a longitudinal feeder and a fir-tree-shaped sensor probe. The feeder inserted the sensor probe along the grooves of the turbine blade attachment. Meanwhile, permanent magnets were placed in opposite direction, to generate a closed magnetic field between the magnetic sensors located on the crests of the sensor probe. The fatigue crack in the turbine disk root occurred in the circumferential direction of the turbine. As a result, magnetic flux leakage was caused by disturbing the flow of closed magnetic field by permanent magnets. The magnetic flux leakage was measured by a magnetic sensor. The effectiveness of the proposed device has been verified using artificial defects introduced into the turbine disk roots by electric discharge machining.
2
Jin, Guang Yuan, Hua Ouyang, and Zhao Hui Du. "An Experimental Study of Sweep Effect on 3D Flow Downstream of Axial Fans at Off-Design Conditions." Applied Mechanics and Materials 281 (January 2013): 335–42. http://dx.doi.org/10.4028/www.scientific.net/amm.281.335.
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The 3D flow characteristics in axial fans with circumferential skewed blades were investigated at off-design conditions using Hot-wire test, and the effect of sweep on controlling the aerodynamic limits was discussed. Two circumferential skewed fans, with the blade skew angles at 8.3° forward and backward, respectively, were investigated in this study. The 3D instantaneous velocity components in nearfield, downstream of the fans were measured using Hot-wire Anemometry (CTA) at off-design conditions. From the measured results, the structure of passage flow in circumferential skewed fans is analyzed according to flow rate. The boundary layer flow and its relation with circumferential skewed blades, to expand stall-free operation range of axial fans, were discussed. As flow rate decreases, the 3D flow structure in blade passage is controlled by the circumferential skewed blades, and the obvious suppression of decreasing passage flow near shroud and hub region; the main flow retains at mid blade span; the radial flow can’t be neglected; the forward-skewed blade is found to be effective in controlling low energy flow in the vicinity of shroud and hub to expand stall-free operation range; the effect of skewed blades on boundary layer is discussed by radial equilibrium equation; as the centrifugal force increases, the blade radial force Fr of the circumferential forward-skewed blade has an positive effect on pressure gradient, and seems to be efficient to control the style and velocity of boundary layer movement.
3
Li, H. D., and L. He. "Blade Count and Clocking Effects on Three-Bladerow Interaction in a Transonic Turbine." Journal of Turbomachinery 125, no. 4 (October 1, 2003): 632–40. http://dx.doi.org/10.1115/1.1622711.
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A computational study of the multirow interaction mechanisms has been carried out for a one-and-a-half stage (NGV-rotor-stator) transonic turbine. In addition to measurable subharmonic unsteadiness on the rotor blades induced by two fundamental stator passing frequencies, a significant aperiodic (“mistuned”) circumferential variation of unsteady forcing magnitude by about three times has been observed in the downstream stator blades. Further parametric studies with various stator blade counts illustrate that the circumferential variation pattern of the unsteady forcing is dictated by the NGV-stator blade count difference, while the local stator forcing magnitude is affected by its circumferential clocking position relative to the upstream NGV blades. The present work suggests that the circumferential clocking together with the choice of blade count should be considered as an aeromechanical design parameter. For cases with stator-stator (or rotor-rotor) blade counts resulting in a tuned (or nearly tuned) unsteady forcing pattern, the clocking position should be chosen to minimize the unsteady forcing. On the other hand, if the choice of blade counts leads to a significant aerodynamic aperiodicity (mistuning), the clocking-forcing analysis can be used to identify the most vulnerable blade that is subject to the maximum forcing.
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Chen, Yuxuan, Zhicheng Zhu, Xiao Li, Yanping Zhang, and Wei Gao. "Aerodynamic Optimization of a 10 kW Radial Inflow Turbine with Splitter Blades." Processes 9, no. 7 (July 20, 2021): 1256. http://dx.doi.org/10.3390/pr9071256.
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The application of splitter blades can improve passage obstructions and reduce flow loss of small-scale organic Rankine cycle (ORC) radial inflow turbines. In this study, taking R245fa as the working fluid, splitter blades are applied to design an impeller layout for a 10 kW ORC radial inflow turbine, and numerical simulation is conducted on different impeller schemes through Fluent 15.0. The influence of the meridian length and circumferential position of the splitter blade on the performance of the turbine impeller is studied. The results show that the meridian length and circumferential position of the splitter blade exert greater effects on the flow field distribution inside the impeller and the impeller performance. When the circumferential offset of the splitter blade is around 0.6 and the blade length is around 80% of the length of main blade, the ORC radial inflow turbine designed in this study reaches optimum performance, and its performance is better than the traditional impeller.
5
Zhao, Zhen Hong, Xiu Ming Jiang, Yu Hong Du, and M. Q. Ren. "Basic Equation of the Axial Flow Pump with Linear Distribution of Discharge Velocity and Simulate." Key Engineering Materials 426-427 (January 2010): 176–81. http://dx.doi.org/10.4028/www.scientific.net/kem.426-427.176.
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The basic equation of axial flow pump is derived from the assumption， which axial plane velocity and circumferential velocity distribute linearly along the blade radius. Based on the basic equation, the axial plane velocity and circumferential velocity gradient of discharge blade are calculated, and the flow field of pump is built. Using arc method of design blade, a design case is given. The standard K- epsilon turbulence model is applied to simulate the flow field of axial flow pump by FLUENT software. The simulation results indicate that pump efficiency reach 91%, there aren’t impact or vortex in pump, and the pressure distribution on the blade suction surface is even and high, the anti-cavitation performance is improved.
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Arnone, Andrea, Michele Marconcini, Alberto Scotti Del Greco, and Ennio Spano. "Numerical Investigation of Three-Dimensional Clocking Effects in a Low Pressure Turbine." Journal of Turbomachinery 126, no. 3 (July 1, 2004): 375–84. http://dx.doi.org/10.1115/1.1740780.
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One and a half stages of a low pressure turbine were investigated using a three-dimensional time-accurate viscous solver. Unsteady analyses were carried out by varying the circumferential relative position of consecutive vanes to study the effects of clocking on performance. Assuming that efficiency improvements by clocking are linked to the wake tangential position with respect to the successive blade, a certain circumferential shift in this position can be observed along the blade height due to blade twist and nonradial stacking, giving different contributions. In order to assess this phenomenon, results from three-dimensional computations were compared with a quasi-three-dimensional analysis at mid-span. The effects of clocking on wake interaction mechanisms and unsteady blade loadings are presented and discussed.
7
Zhang, L., GZ Tang, ZB Liao, and HC Shang. "Development and experimental research on circumferential impulse microturbine power generation system." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 2 (April 4, 2013): 378–87. http://dx.doi.org/10.1177/0954406213484874.
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Circumferential impulse microturbine is a key component of the micro-electro-mechanical system and provides power to the latter. An innovative concept of microturbine power generation system was presented, and prototype improved circumferential impulse microturbine power generation systems were developed, and their output performances were tested. It is validated that the system can operate at a high speed in a dynamic equilibrium state using rolling bearings, and it is found that the output power and rotational speed of a six-blade turbine hollow-cup coil structure is higher than the output power and rotational speed of a six-blade turbine iron-core coil structure. The maximum output power of the eight-blade turbine hollow-cup coil power generation system is 1.1 W, and the maximum turbine rotational speed is 55,000 r/min. The maximum output power of the eight-blade turbine hollow-cup coil system increases up to 25% when compared to the six-blade turbine hollow-cup coil system and increases up to 83% when compared to the six-blade turbine iron-core coil system.
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Jin, G. Y., H. Ouyang, Y. D. Wu, and Z. H. Du. "Experimental and numerical investigations of the tip leakage flow of axial fans with circumferential skewed blades under off-design conditions." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 224, no. 6 (June 1, 2010): 1203–16. http://dx.doi.org/10.1243/09544062jmes1813.
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Experimental and numerical investigations of tip leakage flow of circumferential skewed axial fans were conducted under off-design conditions. Two circumferential skewed fans, with the blade skew angles of 8.3° forward and backward, respectively, and a base fan were investigated in this study. Aerodynamic and aeroacoustic performances were measured. The Navier—Stokes flow simulations were validated experimentally and the key analysis of tip leakage flow was based on computational fluid dynamics results. The simulations show that with a decrease in flowrate, the start of the tip leakage vortex moves towards the leading edge in the chordwise direction and towards the hub in the spanwise direction. These movements are less significant for the forward-skewed blade than for the backward-skewed blade. The strength of the tip leakage vortex decreases along the vortex line. The vortex strength for the forward-skew blade is significantly less than that for the backward-skewed blade. The aeroacoustic source intensity in the tip clearance region is reduced by employing circumferential skewed blades and changes with a change in flowrate in the same manner as the measured sound pressure level. The forward-skewed blade is found to be effective in eliminating noise sources in the tip clearance region and in controlling tip leakage flow to expand the stall-free operation range under off-design conditions.
9
Davidson, David L. "Gas turbine disk-blade attachment crack." Journal of Failure Analysis and Prevention 5, no. 1 (February 2005): 55–71. http://dx.doi.org/10.1361/15477020522104.
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Liu, Zhibo, Fajie Duan, Guangyue Niu, Ling Ma, Jiajia Jiang, and Xiao Fu. "An Improved Circumferential Fourier Fit (CFF) Method for Blade Tip Timing Measurements." Applied Sciences 10, no. 11 (May 26, 2020): 3675. http://dx.doi.org/10.3390/app10113675.
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Rotating blade vibration measurements are very important for any turbomachinery research and development program. The blade tip timing (BTT) technique uses the time of arrival (ToA) of the blade tip passing the casing mounted probes to give the blade vibration. As a non-contact technique, BTT is necessary for rotating blade vibration measurements. The higher accuracy of amplitude and vibration frequency identification has been pursued since the development of BTT. An improved circumferential Fourier fit (ICFF) method is proposed. In this method, the ToA is not only dependent on the rotating speed and monitoring position, but also on blade vibration. Compared with the traditional circumferential Fourier fit (TCFF) method, this improvement is more consistent with reality. A 12-blade assembly simulator and experimental data were used to evaluate the ICFF performance. The simulated results showed that the ICFF performance is comparable to TCFF in terms of EO identification, except the lower PSR or more number probes that have a more negative effect on ICFF. Besides, the accuracy of amplitude identification is higher for ICFF than TCFF on all test conditions. Meanwhile, the higher accuracy of the reconstruction of ICFF was further verified in all measurement resonance analysis.
11
Jennions, I. K., and P. Stow. "The Importance of Circumferential Non-uniformities in a Passage-Averaged Quasi-Three-Dimensional Turbomachinery Design System." Journal of Engineering for Gas Turbines and Power 108, no. 2 (April 1, 1986): 240–45. http://dx.doi.org/10.1115/1.3239894.
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The purpose of this paper is to show, for both rotating and non-rotating blade rows, the importance of including circumferential non-uniform flow effects in a quasi-three-dimensional blade design system. The paper follows from previous publications on the system in which the mathematical analysis and computerized system are detailed. Results are presented for a different stack of the nozzle guide vane presented previously and for a turbine rotor. In the former case it is again found that the blade force represents a major contribution to the radial pressure gradient, while for the rotor the radial pressure gradient is dominated by centrifugal effects. In both examples the effects of circumferential non-uniformities are detailed and discussed.
12
Miner, S. M., R. J. Beaudoin, and R. D. Flack. "Laser Velocimeter Measurements in a Centrifugal Flow Pump." Journal of Turbomachinery 111, no. 3 (July 1, 1989): 205–12. http://dx.doi.org/10.1115/1.3262257.
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A laser velocimeter was used to measure velocities within the impeller and volute of a centrifugal pump. Measurements were made at four circumferential and eight radial positions. Flow rates ranged from 40 to 105 percent of design flow. Blade-to-blade profiles for the four circumferential positions indicate the flow is circumferentially asymmetric around the pump even at the design flow. Blade-to-blade profiles show normal blade loading for 90 percent of the impeller, with reverse and zero loading occurring in the outer 10 percent of the impeller for design flow. Reversed blade loading over greater portions of the impeller is seen at off-design flow. At 40 percent of design flow, recirculating flow within the impeller was found. Axial traverses across the impeller show the radial velocity profile skewed toward the hub surface at the inlet and away from the hub surface at the exit. The stagnation point on the tongue moved from the outside to the inside as the flow rate was increased from 40 to 105 percent of design. Values for slip range from 0.96 to 0.71 from the inlet to the exit.
13
Joslyn, H. D., J. J. Brasz, and R. P. Dring. "Centrifugal Compressor Impeller Aerodynamics: An Experimental Investigation." Journal of Turbomachinery 113, no. 4 (October 1, 1991): 660–69. http://dx.doi.org/10.1115/1.2929132.
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The ability to acquire blade loadings (surface pressure distributions) and surface flow visualization on an unshrouded centrifugal compressor impeller is demonstrated. Circumferential and streamwise static pressure distributions acquired on the stationary shroud are also presented. Data were acquired in a new facility designed for centrifugal compressor aerodynamic research. Blade loadings calculated with a blade-to-blade potential flow analysis are compared with the measured results. Surface flow visualization reveals some complex aspects of the flow on the surface of the impeller blading and hub.
14
Hah, C., D. C. Rabe, T. J. Sullivan, and A. R. Wadia. "Effects of Inlet Distortion on the Flow Field in a Transonic Compressor Rotor." Journal of Turbomachinery 120, no. 2 (April 1, 1998): 233–46. http://dx.doi.org/10.1115/1.2841398.
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The effects of circumferential distortions in inlet total pressure on the flow field in a low-aspect-ratio, high-speed, high-pressure-ratio, transonic compressor rotor are investigated in this paper. The flow field was studied experimentally and numerically with and without inlet total pressure distortion. Total pressure distortion was created by screens mounted upstream from the rotor inlet. Circumferential distortions of eight periods per revolution were investigated at two different rotor speeds. The unsteady blade surface pressures were measured with miniature pressure transducers mounted in the blade. The flow fields with and without inlet total pressure distortion were analyzed numerically by solving steady and unsteady forms of the Reynolds-averaged Navier–Stokes equations. Steady three-dimensional viscous flow calculations were performed for the flow without inlet distortion while unsteady three-dimensional viscous flow calculations were used for the flow with inlet distortion. For the time-accurate calculation, circumferential and radial variations of the inlet total pressure were used as a time-dependent inflow boundary condition. A second-order implicit scheme was used for the time integration. The experimental measurements and the numerical analysis are highly complementary for this study because of the extreme complexity of the flow field. The current investigation shows that inlet flow distortions travel through the rotor blade passage and are convected into the following stator. At a high rotor speed where the flow is transonic, the passage shock was found to oscillate by as much as 20 percent of the blade chord, and very strong interactions between the unsteady passage shock and the blade boundary layer were observed. This interaction increases the effective blockage of the passage, resulting in an increased aerodynamic loss and a reduced stall margin. The strong interaction between the passage shock and the blade boundary layer increases the peak aerodynamic loss by about one percent.
15
Cheng, Xiaorui, Boru Lv, Chenying Ji, Ningning Jia, and Dorah N. "Influence of Circumferential Placement Position of Guide Vanes on Performance and Dynamic Characteristics of Nuclear Reactor Coolant Pump." Mathematical Problems in Engineering 2020 (February 29, 2020): 1–12. http://dx.doi.org/10.1155/2020/3786745.
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In order to study the influence of the circumferential placement position of the guide vane on the flow field and stress-strain of a nuclear reactor coolant pump, the CAP1400 nuclear reactor coolant pump is taken as the research object. Based on numerical calculation and test results, the influence of circumferential placement position of the guide vane on the performance of the nuclear reactor coolant pump and stress-strain of guide vanes are analyzed by the unidirectional fluid-solid coupling method. The results show that the physical model and calculation method used in the study can accurately reflect the influence of the circumferential placement position of the guide vane on the nuclear reactor coolant pump. In the design condition, guide vane position has a great influence on the nuclear reactor coolant pump efficiency value, suction surface of the guide vane blade, and the maximum equivalent stress on the hub. However, it has a weak effect on the head value, pressure surface of the guide vane blade, and the maximum equivalent stress on the shroud. When the center line of the outlet diffuser channel of the case is located at the center of the outlet of flow channel of the guide vane, it is an optimal guide vane circumferential placement position, which can reduce the hydraulic loss of half of the case. Finally, it is found that the high stress concentration area is at the intersection of the exit edge of the vane blade and the front and rear cover, and the exit edge of the guide vane blade and its intersection with the front cover are areas where the strength damage is most likely to occur. This study provides a reference for nuclear reactor coolant pump installation, shock absorption design, and structural optimization.
16
Cheng, Xiaorui, Jiaheng Luo, Bo Xiong, and Yimeng Jiang. "Influence of the Balance Hole Circumferential Position on the Cavitation Performance of the Semiopen Impeller Centrifugal Pump." Mathematical Problems in Engineering 2021 (July 9, 2021): 1–14. http://dx.doi.org/10.1155/2021/4472433.
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In order to study the influence of the circumferential position of the balance hole on the cavitation performance of the semiopen impeller centrifugal pump, a low specific speed semiopen impeller centrifugal pump is taken as the object, and 4 kinds of circumferential positions of balance holes are designed. The SST k-ω turbulence model and the Rayleigh–Plesset cavitation bubble dynamics equation are used to calculate the full flow field of the centrifugal pump. Research shows that, under cavitation conditions, as the circumferential position of the balance hole is farther away from the blade working surface, the cavitation performance of the pump is reduced, and the larger θ (the angle of the balance hole and the leading edge of the blade in the direction of rotation) is, the easier the jet cavitation occurs near the balance hole. On the other hand, with the development of cavitation, the axial force of the impeller has also changed greatly. In contrast, the farther the balance hole is arranged in the circumferential direction (i.e., the greater θ), the more limited is the ability of the balance hole to balance the axial force.
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Wang, Rong Jie, and Hong Wei Chen. "Analysis and Improvement of Fan Blades Noise." Applied Mechanics and Materials 568-570 (June 2014): 1706–9. http://dx.doi.org/10.4028/www.scientific.net/amm.568-570.1706.
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Fan blades noise is mechanical noise and aerodynamic noise, and the aerodynamic noise is the main noise. Fan's speed, blade number, angle, radius of curvature is the main factor affecting the fan blades noise. Key of control fan noise, should be placed in fan design, Reduce the circumferential velocity, leaned blade, increase the radius of curvature is favorable measures of reducing the noise of the fan blade. Control of noise from the source, will achieve better results.
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Wang, Zhengming. "A Method for Aerodynamic Design of Blades in Quasi-Three-Dimensional Calculation of Turbomachines." Journal of Turbomachinery 110, no. 2 (April 1, 1988): 181–86. http://dx.doi.org/10.1115/1.3262178.
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A special inverse problem is formulated in which the shape of the mean streamline and the circumferential thickness distribution of the profile are given. On the basis of the series expansion method on a selected streamline, in quasi-three-dimensional aerodynamic design, the blade profile thickness is automatically fulfilled by computer. Six radial sections of a turbine blade are designed by this method.
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Tisserant, D., and F. A. E. Breugelmans. "Rotor Blade-to-Blade Measurements Using Particle Image Velocimetry." Journal of Turbomachinery 119, no. 2 (April 1, 1997): 176–81. http://dx.doi.org/10.1115/1.2841096.
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The study of turbomachinery flow fields requires detailed experimental data. The rotating parts of turbomachines greatly limit the measurement techniques that can be used. Particle Image Velocimetry (PIV) appears to be a suitable tool to investigate the blade-to-blade flow in a rotor. The facility is a subsonic axial-flow compressor. The experimental apparatus enables the recording of a double-exposed photograph in a circumferential plane located at 85 percent of the blade height. The illumination plane has an axial direction and is provided by a pulsed ruby laser. The tracers used are submicron glycerine oil droplets. Data are processed by Young’s fringes method. Measurements were performed at 3000, 4500, and 6000 rpm with velocities in the range of 30 to 70 m/s. Steady operating conditions are chosen in such a way that the effect of radial velocity on PIV measurements can be neglected. Experimental problems encountered included homogeneous seeding of the flow field and laser light scattering from blade surfaces. The uncertainty affecting the velocity determination corresponds to 2 percent of the measured value. For a given set of operating conditions, 10 PIV pictures are recorded. The periodic flow field is approximated by averaging the experimental data point by point. Upstream and downstream velocity triangles are confirmed by measurements obtained from pressure probes. PIV measurement results were found to be similar to those of a blade-to-blade potential-flow calculation.
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Arakere, Nagaraj K., and Gregory Swanson. "Fretting Stresses in Single Crystal Superalloy Turbine Blade Attachments." Journal of Tribology 123, no. 2 (June 27, 2000): 413–23. http://dx.doi.org/10.1115/1.1308032.
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Single crystal nickel base superalloy turbine blades are being utilized in rocket engine turbopumps and turbine engines because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. High cycle fatigue induced failures in aircraft gas turbine and rocket engine turbopump blades is a pervasive problem. Blade attachment regions are prone to fretting fatigue failures. Single crystal nickel base superalloy turbine blades are especially prone to fretting damage because the subsurface shear stresses induced by fretting action at the attachment regions can result in crystallographic initiation and crack growth along octahedral planes. This paper presents contact stress evaluation in the attachment region for single crystal turbine blades used in the NASA alternate advanced high pressure fuel turbo pump for the space shuttle main engine. Single crystal materials have highly anisotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. Blades and the attachment region are modeled using a large-scale three-dimensional finite element model capable of accounting for contact friction, material anisotropy, and variation in primary and secondary crystal orientation. Contact stress analysis in the blade attachment regions is presented as a function of coefficient of friction and primary and secondary crystal orientation. Fretting stresses at the attachment region are seen to vary significantly as a function of crystal orientation. The stress variation as a function of crystal orientation is a direct consequence of the elastic anisotropy of the material. Fatigue life calculations and fatigue failures are discussed for the airfoil and the blade attachment regions.
21
Taghavi Zenouz, Reza, Mehran Eshaghi Sir, and Mohammad Hosein Ababaf Behbahani. "Performance of a Low Speed Axial Compressor Rotor Blade Row under Different Inlet Distortions." Mechanical Sciences 8, no. 1 (May 31, 2017): 127–36. http://dx.doi.org/10.5194/ms-8-127-2017.
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Abstract. Responses of an axial compressor isolated rotor blade row to various inlet distortions have been investigated utilizing computational fluid dynamic technique. Distortions have been imposed by five screens of different geometries, but with the same blockage ratio. These screens were embedded upstream of the rotor blade row. Flow fields are simulated in detail for compressor design point and near stall conditions. Performance curves for distorted cases are extracted and compared to the undisturbed case. Flow simulations and consequent performance characteristics show that the worst cases belong to non-symmetric blockages, i.e., those of partial circumferential configurations. These cases produce the largest wakes which can disturb the flow, considerably. Superior performances correspond to the inner and outer continuous circumferential distortion screens. Since, they produce no significant disturbances to the main flow in comparison to the non-symmetric screens.
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Zhu, Ai Hua. "Simulation Analysis of Adjustable Movable Blade Axial Flow Fan." Advanced Materials Research 945-949 (June 2014): 236–41. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.236.
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This paper focuses on the study on the installation angle of the adjustable movable blade axial flow fan.At first, the airfoil and the corresponding series of fan is selected, and detailed calculation of the blade section is performed to obtain the chord length and the thickness of the fan airfoil at different circumferential surfaces, as well as the coordinate value of each section. Then, a three-dimensional solid modeling of the fan with different installation angles in Pro/E is used for mesh generation and boundary conditions arrangement in Gambit. Finally, an analogue simulation is carried out in fluent to analyze the velocity of the blade, the backpressure and turbulence generated by the airflow on the blade.
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Shuxian, Cheng, Li Zhigang, and Li Jun. "Effects of endwall profiling near the blade leading edge on the sealing effectiveness of turbine rim seal." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 233, no. 7 (March 27, 2019): 821–33. http://dx.doi.org/10.1177/0957650919839579.
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Endwall profiling designed to reduce secondary flow loss may change the local pressure distribution which has an impact on the sealing effectiveness of a rim seal. This paper presents a numerical comparison of the sealing effectiveness of the rim seal and the aerodynamic performance of the blade with five different endwall profiling near the blade leading edge. Three-dimensional unsteady Reynolds-averaged Navier-Stokes (URANS) equations coupled with a fully developed shear stress transport (SST) turbulent model are utilized to investigate the sealing effectiveness and the flow characteristics of turbine rim seal. The numerical method for the pressure field and sealing performance of turbine rim seal is validated on the basis of published experimental data. The total-to-static efficiency of the blade and the minimum sealing rates of the rim seal with five endwall profiling near blade leading edge are compared. The baseline, convex and concave cases are selected to investigate the transient variation of the sealing effectiveness and the flow field in the disc cavity. In comparison with baseline case, the convex endwall makes the high pressure area move forward, increases the mainstream circumferential pressure fluctuation, and reduces the sealing effectiveness. The concave endwall reduces the local pressure and the mainstream circumferential pressure fluctuation, and increases the sealing effectiveness. However, the concave endwall profiling enhances the vortex in the blade passage and increases the secondary flow loss. The flow field near the rim seal with different endwall profiling is illustrated and analyzed.
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Mantsha, Khathutshelo Kentridge, Dawood Ahmed Desai, and P. Stephan Heyns. "Development of a Modal-Based Turbomachine Blade-Disk Attachment Inspection Technique." International Journal of Engineering Research in Africa 54 (June 2021): 147–61. http://dx.doi.org/10.4028/www.scientific.net/jera.54.147.
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Turbine blade failures are among the leading causes of steam turbine failure. Failure types typically include cracking, rubbing, blade fouling, and foreign object damage. There is currently a range of non-destructive testing methods used to detect damage at the blade-disk attachment zone, all of which involve disassembling of the blade from the disk for periodic inspection. Evidence indicate that a method to detect damage at the blade-disk attachment zone using a non-contact, non-destructive in-situ off-line modal-based structural health monitoring technique could be useful under some circumstances. Such a technique would have the advantage of eliminating the necessity to disassemble blades during inspection. This would result in significant cost savings. Also, defects associated with the disassembly and reassembly of blades would be avoided. Thus, the aim of this study was to develop a modal-based turbomachinery blade disk attachment inspection technique. Modal parameters were acquired from a robust experimental modal analysis of freely supported low-pressure steam turbine blade-disk segment assemblies. Artificial single-location cracks were intentionally introduced into the turbine blades by cutting a 1 mm thickness notch at three probable damage locations, namely, at the upper pinhole on the leading-edge pressure side, above the root at the base of the aerofoil on the leading-edge and on the trailing-edge. In this work, a finite element analysis of the bladed disk segment assemblies was carried out with and without damage. To validate the reliability of the numerical models, the numerical results were correlated with the measured values, the results of which showed a strong correlation. Finally, a parametric study was conducted in which various healthy and damaged blade-disk cases were systematically investigated. This was done to examine the sensitivity of the blade natural frequency to damage. The artificial damage above the root was found to cause the largest changes in natural frequency. These changes were even more pronounced for assemblies with two blades. Receiver operating characteristic curves were used to assess the discriminatory ability of the results. Each damage case was found to be unique and therefore identifiable from its corresponding healthy case.
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Yu, Zheqin, Jianping Tan, and Shuai Wang. "Multi-parameter analysis of the effects on hydraulic performance and hemolysis of blood pump splitter blades." Advances in Mechanical Engineering 12, no. 5 (May 2020): 168781402092129. http://dx.doi.org/10.1177/1687814020921299.
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The splitter blade can effectively optimize pump performance, but there is still insufficient research in blood pumps that cover both hydraulic and hemolysis performance. Thus, the aim of this study was to investigate the effect of key factors related to splitter blade on the performance and flow field of axial flow blood pump. In this study, the number of splitter blades, the axial length, and the circumferential offset were chosen as three objects of study. An analysis of the flow field and performance of the pump by orthogonal array design using computational fluid mechanics was carried out. A set of hydraulic and particle image velocimetry experiments of the model pumps were performed. The result showed that the pump had greater hydraulic performance without sacrificing its hemolytic performance when it had two splitter blades, the axial length ratio was 0.6, and the circumferential offset was 15°. Based on these reference data, the splitter blade may contribute to greater hydraulic performance of the pump and cause no side effect on the velocity distribution of the flow field. This finding provides an effective method for the research, development, and application of structural improvement of the axial flow blood pump.
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Zhou, Qibin, Canxiang Liu, Xiaoyan Bian, Kwok L. Lo, and Dongdong Li. "Numerical analysis of lightning attachment to wind turbine blade." Renewable Energy 116 (February 2018): 584–93. http://dx.doi.org/10.1016/j.renene.2017.09.086.
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Pfau, A., M. Treiber, M. Sell, and G. Gyarmathy. "Flow Interaction From the Exit Cavity of an Axial Turbine Blade Row Labyrinth Seal." Journal of Turbomachinery 123, no. 2 (February 1, 2000): 342–52. http://dx.doi.org/10.1115/1.1368124.
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The structure of labyrinth cavity flow has been experimentally investigated in a three fin axial turbine labyrinth seal (four cavities). The geometry corresponds to a generic steam turbine rotor shroud. The relative wall motion has not been modeled. The measurements were made with specially developed low-blockage pneumatic probes and extensive wall pressure mapping. Instead of the classical picture of a circumferentially uniform leakage sheet exiting from the last labyrinth clearance, entering the channel, and uniformly spreading over the downstream channel wall, the results reveal uneven flow and the existence of high circumferential velocity within the entire exit cavity. The circumferential momentum is brought into the cavity by swirling fluid from the main channel. This fluid penetrates the cavity and breaks up the leakage sheet into individual jets spaced according to the blade passages. This gives rise to strong local cross flows that may also considerably disturb the performance of a downstream blade row.
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Song, Weimin, Yufei Zhang, and Haixin Chen. "Design and Optimization of Multiple Circumferential Casing Grooves Distribution Considering Sweep and Lean Variations on the Blade Tip." Energies 11, no. 9 (September 11, 2018): 2401. http://dx.doi.org/10.3390/en11092401.
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This paper focuses on the design and optimization of the axial distribution of the circumferential groove casing treatment (CGCT). Effects of the axial location of multiple casing grooves on the flow structures are numerically studied. Sweep and lean variations are then introduced to the blade tip, and their influences on the grooves are discussed. The results show that the ability of the CGCT to relieve the blockage varies with the distribution of grooves, and the three-dimensional blading affects the performance of both the blade and the CGCT. Accordingly, a multi-objective optimization combining the CGCT design with the sweep and lean design is conducted. Objectives, including the total pressure ratio and the adiabatic efficiency, are set at the design point; meanwhile, the choking mass flow and the near-stall performance are constrained. The coupling between the CGCT and the blade is improved, which contributes to an optimal design point performance and a sufficient stall margin. The sweep and lean in the tip redistribute the spanwise and chordwise loading, which enhances the ability of the CGCT to improve the blade’s performance. This work shows that the present CGCT-blade integrated optimization is a practical engineering strategy to develop the working capacity and efficiency of a compressor blade while achieving the stall margin extension.
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Molyakov, V. D., and B. A. Kunikeev. "Using the Similarity Theory in the Design of Gas Turbine Engines." Proceedings of Higher Educational Institutions. Маchine Building, no. 6 (735) (June 2021): 48–57. http://dx.doi.org/10.18698/0536-1044-2021-6-48-57.
Full textAbstract:
At present, in the promising development of gas turbine engines compared to at least the fourth generation products, there have been significant changes in the approaches to the design of engine. First of all, it is an increase in maximum values of temperature, gas pressure and circumferential flow speeds, an increase in power of the turbine stage, as well as improvement of the turbine manufacturing technology. All these factors lead to the fact that when designing the flow parts of the gas turbine, it is necessary at the fixed design flow rate of the working medium in the engine, i.e. at the fixed diameters, lengths of the nozzle and rotor blades forming the outline of the inter-blade channels, to increase the blade chords with the corresponding reduction of the number of blades in the row. The increase in turbine stage power associated with the increase in temperature, pressure (density), and circumferential velocity increases the bending stresses leading to the need to increase chords at a fixed blade length. Significant reduction of number of blades in stages, simplifies technology of blades manufacturing. A substantial increase in the maximum gas temperature, in the perspective of more than 2000 K, also leads to the need to increase the blade chords, due to the need to place cooling cavities in the blades. As a result, contradictions arise with the use of similarity theory in the design of stages of turbines of different purpose, as some of the main requirements of similarity are violated — geometric similarity of blade channels of the flow part and then the use of the generally accepted number Re by the chord of blades loses meaning. Therefore, it is necessary to carry out detailed investigations of all flow parameters in four stages of turbines with detection of influence of change of rotor blade chords at equal length of blades. And justify the effect of change of rotor blade chords on physical processes in flow parts of turbines in engines of various purpose.
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Arnone, Andrea, Michele Marconcini, Roberto Pacciani, Claudia Schipani, and Ennio Spano. "Numerical Investigation of Airfoil Clocking in a Three-Stage Low-Pressure Turbine." Journal of Turbomachinery 124, no. 1 (February 1, 2001): 61–68. http://dx.doi.org/10.1115/1.1425810.
Full textAbstract:
A quasi-three-dimensional, blade-to-blade, time-accurate, viscous solver was used for a three-stage LP turbine study. Due to the low Reynolds number, transitional computations were performed. Unsteady analyses were then carried out by varying the circumferential relative position of consecutive vanes and blade rows to study the effects of clocking on the turbine’s performance. A clocking strategy developed in order to limit the number of configurations to be analyzed is discussed. The optimum analytically-determined clocking position is illustrated for two different operating conditions, referred to as cruise and takeoff. The effects of clocking on wake interaction mechanisms and unsteady blade loadings is presented and discussed. For low Reynolds number turbine flows, the importance of taking transition into account in clocking analysis is demonstrated by a comparison with a fully turbulent approach.
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Adachi, Tsutomu, Naohiro Sugita, and Yousuke Yamada. "Study on the Performance of a Sirocco Fan (Flow Around the Runner Blade)." International Journal of Rotating Machinery 10, no. 5 (2004): 415–24. http://dx.doi.org/10.1155/s1023621x04000417.
Full textAbstract:
Initially in this research, effects of blade inlet and outlet angles on the performance were considered by measuring performances. Twelve impellers with various blade angles were used for the measurements. The most suitable inlet and outlet angles and the inclination angle were acquired. Then, measurements on the inlet and outlet flows and their axial and circumferential distributions were taken for various operating conditions at the various measuring positions. The turning angles through the blade were calculated from these measured results. The inlet and outlet flows of the sirocco fan are not uniform around the circumference. The distributions of the flow have some relations with the development of flow in the inlet part and in the casing. Discussions were made on the flow to have a improved performance.
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Zhao, Xiao-lu, Chun-lin Sun, and Chung-Hua Wu. "A Simple Method for Solving Three-Dimensional Inverse Problems of Turbomachine Flow and the Annular Constraint Condition." Journal of Engineering for Gas Turbines and Power 107, no. 2 (April 1, 1985): 293–300. http://dx.doi.org/10.1115/1.3239714.
Full textAbstract:
In 1950, Wu [1] suggested that the three-dimensional inverse (design) problem of turbomachine flow may be solved approximately by a Taylor series expansion in the circumferential direction based on the known flow variation over an S2 stream surface in the midchannel of the blade passage. This idea has been realized recently. A new coordinate transformation has been developed. The coordinate surfaces are coincident with the S2 stream surfaces. This transformation leads to a new method to calculate the aerodynamic equations of three-dimensional flow. By the use of this transformation, a high-order expansion is realized to determine the shape of the blade surfaces from the fluid state on the S2m stream surface directly. Computation in this manner soon leads to the discovery that theoretically the distribution of flow parameter (usually Vθr) on S2m prescribed by the designer should satisfy a constraint condition, which guarantees that the S1 stream surfaces along the hub and shroud obtained from circumferential extension of the S2m surface are surfaces of revolution. An approximate method is suggested to meet this condition.
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Yu, Zheqin, Jianping Tan, Shuai Wang, and Bin Guo. "Multiple parameters and target optimization of splitter blades for axial spiral blade blood pump using computational fluid mechanics, neural networks, and particle image velocimetry experiment." Science Progress 104, no. 3 (July 2021): 003685042110393. http://dx.doi.org/10.1177/00368504211039363.
Full textAbstract:
The blood pump is an implantable device with strict performance requirements. Any effective structural improvement will help to improve the treatment of patients. However, the research of blood pump structure improvement is a complex optimization problem with multiple parameters and objectives. This study takes the splitter blade as the object of structural improvement. Computational fluid mechanics and neural networks are combined in research and optimization. And hydraulic experiments and micro particle image velocimetry technology were used. In the optimization study, the number of blades, axial length and circumferential offset are optimization parameters, and hydraulic performance and hemolytic prediction index are optimization targets. The study analyzes the influence of each parameter on performance and completes the optimization of the parameters. In the results, the optimal parameters of number of blades, axial length ratio, and circumferential offset are 2.6° and 0.41°, respectively. Under optimized parameters, hydraulic performance can be significantly improved. And the results of hemolysis prediction and micro particle image velocimetry experiments reflect that there is no increase in the risk of hemolytic damage. The results of this study provide a method and ideas for improving the structure of the axial spiral blade blood pump. The established optimization method can be effectively applied to the design and research of axial spiral blade blood pumps with complex, high precision, and multiple parameters and targets.
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Prieto, Ruth, José María Pascual, Maria Rosdolsky, Inés Castro-Dufourny, Rodrigo Carrasco, Sewan Strauss, and Laura Barrios. "Craniopharyngioma adherence: a comprehensive topographical categorization and outcome-related risk stratification model based on the methodical examination of 500 tumors." Neurosurgical Focus 41, no. 6 (December 2016): E13. http://dx.doi.org/10.3171/2016.9.focus16304.
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OBJECTIVE Craniopharyngioma (CP) adherence strongly influences the potential for achieving a radical and safe surgical treatment. However, this factor remains poorly addressed in the scientific literature. This study provides a rational, comprehensive description of CP adherence that can be used for the prediction of surgical risks associated with the removal of these challenging lesions. METHODS This study retrospectively analyzes the evidence provided in pathological, neuroradiological, and surgical CP reports concerning 3 components of the CP attachment: 1) the intracranial structures attached to the tumor; 2) the morphology of the adhesion; and 3) the adhesion strength. From a total of 1781 CP reports published between 1857 and 2016, a collection of 500 CPs providing the best information about the type of CP attachment were investigated. This cohort includes autopsy studies (n = 254); surgical studies with a detailed description or pictorial evidence of CP adherence (n = 298); and surgical CP videos (n = 61) showing the technical steps for releasing the attachment. A predictive model of CP adherence in hierarchical severity levels correlated with surgical outcomes was generated by multivariate analysis. RESULTS The anatomical location of the CP attachment occurred predominantly at the third ventricle floor (TVF) (54%, n = 268), third ventricle walls (23%, n = 114), and pituitary stalk (19%, n = 94). The optic chiasm was involved in 56% (n = 281). Six morphological patterns of CP attachment were identified: 1) fibrovascular pedicle (5.4%); 2) sessile or patch-like (21%); 3) cap-like (over the CP top, 14%); 4) bowl-like (around the CP bottom, 13.5%); 5) ring-like (encircling central band, 19%); and 6) circumferential (enveloping the entire CP, 27%). Adhesion strength was classified in 4 grades: 1) loose (easily dissectible, 8%); 2) tight (requires sharp dissection, 32%); 3) fusion (no clear cleavage plane, 40%); and 4) replacement (loss of brain tissue integrity, 20%). The types of CP attachment associated with the worst surgical outcomes are the ring-like, bowl-like, and circumferential ones with fusion to the TVF or replacement of this structure (p < 0.001). The CP topography is the variable that best predicts the type of CP attachment (p < 0.001). Ring-like and circumferential attachments were observed for CPs invading the TVF (secondary intraventricular CPs) and CPs developing within the TVF itself (infundibulo-tuberal CPs). Brain invasion and peritumoral gliosis occurred predominantly in the ring-like and circumferential adherence patterns (p < 0.001). A multivariate model including the variables CP topography, tumor consistency, and the presence of hydrocephalus, infundibulo-tuberal syndrome, and/or hypothalamic dysfunction accurately predicts the severity of CP attachment in 87% of cases. CONCLUSIONS A comprehensive descriptive model of CP adherence in 5 hierarchical levels of increased severity—mild, moderate, serious, severe, and critical—was generated. This model, based on the location, morphology, and strength of the attachment can be used to anticipate the surgical risk of hypothalamic injury and to plan the degree of removal accordingly.
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Dawes, W. N. "Toward Improved Throughflow Capability: The Use of Three-Dimensional Viscous Flow Solvers in a Multistage Environment." Journal of Turbomachinery 114, no. 1 (January 1, 1992): 8–17. http://dx.doi.org/10.1115/1.2928002.
Full textAbstract:
A methodology is presented for simulating turbomachinery blade rows in a multistage environment by deploying a standard three-dimensional Navier–Stokes solver simultaneously on a number of blade rows. The principal assumptions are that the flow is steady relative to each blade row individually and that the rows can communicate via inter-row mixing planes. These mixing planes introduce circumferential averaging of flow properties but preserve quite general radial variations. Additionally, each blade can be simulated in three-dimensional or axisymmetrically (in the spirit of throughflow analysis) and a series of axisymmetric rows can be considered together with one three-dimensional row to provide, cheaply, a machine environment for that row. Two applications are presented: a transonic compressor rotor and a steam turbine nozzle guide vane simulated both isolated and as part of a stage. In both cases the behavior of the blade considered in isolation was different to when considered as part of a stage and in both cases was in much closer agreement with the experimental evidence.
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Padova, Corso, Jeffery Barton, Michael G. Dunn, and Steve Manwaring. "Experimental Results From Controlled Blade Tip/Shroud Rubs at Engine Speed." Journal of Turbomachinery 129, no. 4 (August 11, 2006): 713–23. http://dx.doi.org/10.1115/1.2720869.
Full textAbstract:
Experimental results obtained for an Inconel® compressor blade rubbing a steel casing at engine speed are described. Load cell, strain gauge, and accelerometer measurements are discussed and then applied to analyze the metal-on-metal interaction resulting from sudden incursions of varying severity, defined by incursion depths ranging from 13μm to 762μm (0.0005in. to 0.030in.). The results presented describe the transient dynamics of rotor and casing vibro-impact response at engine operational speed similar to those experienced in flight. Force components at the blade tip in axial and circumferential directions for a rub of moderate incursion depth (140μm) are compared to those for a severe rub (406μm). Similar general trends of variation during the metal-to-metal contact are observed. However, in the nearly threefold higher incursion the maximum incurred circumferential load increases significantly, while the maximum incurred axial load increases much less, demonstrating the non-linear nature of the rub phenomena. Concurrently, the stress magnification on the rubbing blade at root mid-chord, at tip leading edge, and at tip trailing edge is discussed. The results point to the possibility of failure occurring first at the airfoil trailing edge. Such a failure was in fact observed in the most severe rub obtained to date in the laboratory, consistent with field observations. Computational models to analyze the non-linear dynamic response of a rotating beam with periodic pulse loading at the free-end are currently under development and are noted.
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Zboinski, G. "Physical and Geometrical Non-Linearities in Contact Problems of Elastic Turbine Blade Attachments." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 209, no. 4 (July 1995): 273–86. http://dx.doi.org/10.1243/pime_proc_1995_209_154_02.
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The paper presents briefly the theoretical basis of linear and non-linear contact problems of linear elasticity as applied to the kinetostatic analysis of turbomachinery blade attachments. The physical and geometrical non-linearities of the problem are due to friction and unilateral constraints respectively. For three classes of contact problems finite element calculations of a real fir-tree turbine blade attachment with and without clearances within the contact surfaces are performed. The results for effective stresses of the root and disc hooks are thoroughly analysed and compared. Furthermore, the results for contact node status and nodal slips between the blade root and the disc sector are presented. The significance of the physical and geometrical non-linearities to the stress, displacement and contact states of the attachment is then discussed.
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Schulz, H. D., and H. D. Gallus. "Experimental Investigation of the Three-Dimensional Flow in an Annular Compressor Cascade." Journal of Turbomachinery 110, no. 4 (October 1, 1988): 467–78. http://dx.doi.org/10.1115/1.3262220.
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A detailed experimental investigation was carried out to examine the influence of blade loading on the three-dimensional flow in an annular compressor cascade. Data were acquired over a range of incidence angles. Included are airfoil and endwall flow visualization, measurement of the static pressure distribution on the flow passage surfaces, and radial-circumferential traverse measurements. The data indicate the formation of a strong vortex near the rear of the blade passage. This vortex transports low-momentum fluid close to the hub toward the blade suction side and seems to be partly responsible for the occurrence of a hub corner stall. The effect of increased loading on the growth of the hub corner stall and its impact on the passage blockage are discussed. Detailed mapping of the blade boundary layer was done to determine the loci of boundary layer transition and flow separation. The data have been compared with results from an integral boundary layer method.
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Wang, Biaobiao, Haoyang Zhang, Fanjie Deng, Chenguang Wang, and Qiaorui Si. "Effect of Short Blade Circumferential Position Arrangement on Gas-Liquid Two-Phase Flow Performance of Centrifugal Pump." Processes 8, no. 10 (October 20, 2020): 1317. http://dx.doi.org/10.3390/pr8101317.
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In order to study the internal flow characteristics of centrifugal pumps with a split impeller under gas-liquid mixed transportation conditions, this paper conducted a steady calculation of the flow field in the centrifugal pump under the conditions of different inlet gas volume fractions based on the Eulerian-Eulerian heterogeneous flow model, using air and water as the working media and the Schiller Nauman model for the interphase resistance. This paper takes a low specific speed centrifugal pump as the research object, through the controlling variables, using the same pump body structure and pump body geometric parameters and setting three different arrangements of long and short blades (each plan uses the same long and short blades) to explore the influence of the short blade arrangement on the low specific speed centrifugal pump performance under a gas-liquid two-phase flow. The research results show that, under pure water conditions, the reasonable arrangement of the short blade circumferential position can eliminate the hump of the centrifugal pump under low-flow conditions, can make the flow velocity in the impeller more uniform, and can optimize the performance of the pump. Under the design conditions and the gas-liquid two-phase inflow conditions, when the circumferential position of the short blades is close to the suction surface of the long blades, some of the bubbles on the suction surface of the long blade can be broken under the work of the pressure surface of the short blade and flow out of the impeller with the liquid, which improves the flow state of the flow field in the impeller.
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Gu, Yandong, Shouqi Yuan, Ji Pei, Jinfeng Zhang, Fan Zhang, and Xi Huang. "Effects of the impeller–volute tongue interaction on the internal flow in a low-specific-speed centrifugal pump with splitter blades." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 2 (July 3, 2017): 170–80. http://dx.doi.org/10.1177/0957650917718117.
Full textAbstract:
To investigate the effects of the main blades and splitter blades interacting with the volute tongue on the internal flow in a low-specific-speed centrifugal pump, the Reynolds-averaged Navier–Stokes equation, coupled with SST k-ω turbulence model, is employed to simulate the transient turbulent flow in the whole flow passage. The numerical simulation results have been verified with the experimental measurements by comparing the head and efficiency. The pressure fluctuation caused by impeller–volute tongue interaction, including time–history and frequency characteristics, is calculated and analyzed at five monitoring points adjoining the impeller outlet and tongue, as well as the torque of a single main blade and a single splitter blade. After that, both the energy loss and vorticity distributions on the middle section are discussed when the impeller rotates to four circumferential positions relative to the cutwater. The results show that the maximum pressures at the monitoring points occur before the blades reach the closest circumferential position with respect to the cutwater, and the peak pressure near the trailing edge of splitter blades is larger than main blades. There is only one torque peak of a single blade in one revolution when the angle between the monitoring blade and tongue is about 15°. Additionally, the torque peak arises before the torque valley, but the pressure valley at monitoring points in the impeller comes earlier than the pressure peak. Both the energy loss and vorticity are enlarged around the volute tongue evidently after the blades pass by the cutwater, and the splitter blades produce more unsteadiness and energy dissipation than main blades.
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Porro, Marco, Richard Jefferson-Loveday, and Ernesto Benini. "Axial Flow Compressor Stability Enhancement: Circumferential T-Shape Grooves Performance Investigation." Aerospace 8, no. 1 (January 4, 2021): 12. http://dx.doi.org/10.3390/aerospace8010012.
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This work focuses its attention on possibilities to enhance the stability of an axial compressor using a casing treatment technique. Circumferential grooves machined into the case are considered and their performances evaluated using three-dimensional steady state computational simulations. The effects of rectangular and new T-shape grooves on NASA Rotor 37 performances are investigated, resolving in detail the flow field near the blade tip in order to understand the stall inception delay mechanism produced by the casing treatment. First, a validation of the computational model was carried out analysing a smooth wall case without grooves. The comparisons of the total pressure ratio, total temperature ratio and adiabatic efficiency profiles with experimental data highlighted the accuracy and validity of the model. Then, the results for a rectangular groove chosen as the baseline case demonstrated that the groove interacts with the tip leakage flow, weakening the vortex breakdown and reducing the separation at the blade suction side. These effects delay stall inception, improving compressor stability. New T-shape grooves were designed keeping the volume as a constant parameter and their performances were evaluated in terms of stall margin improvement and efficiency variation. All the configurations showed a common efficiency loss near the peak condition and some of them revealed a stall margin improvement with respect to the baseline. Due to their reduced depth, these new configurations are interesting because they enable the use of a thinner light-weight compressor case as is desirable in aerospace applications.
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Rossikhin, Anton A. "Frequency-domain method for multistage turbomachine tone noise calculation." International Journal of Aeroacoustics 16, no. 6 (September 2017): 491–506. http://dx.doi.org/10.1177/1475472x17730458.
Full textAbstract:
A method of frequency-domain calculation of the multistage turbomachinery tone noise is presented. The method is based on the kinematic relations featuring dependence of flow fields in a turbomachine on time and circumferential angle. It solves the flow in several blade passages inside each row and can be used in conjunction with nonlinear equations. The method is developed at Central Institute of Aviation Motor and implemented in the Three Dimensional Acoustics Solver in-house solver. The multi-passage method is verified on two numerical problems. One is the tone noise generation by a 2D two stage turbine. The other is the problem of nonlinear interaction of circumferential modes in a 2D cylindrical channel.
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Tjokroaminata, W. D., C. S. Tan, and W. R. Hawthorne. "A Design Study of Radial Inflow Turbines With Splitter Blades in Three-Dimensional Flow." Journal of Turbomachinery 118, no. 2 (April 1, 1996): 353–61. http://dx.doi.org/10.1115/1.2836650.
Full textAbstract:
An inverse design technique to design turbomachinery blading with splitter blades in three-dimensional flow is developed. It is based on the use of Clebsch transformation, which allows the velocity field to be written as a potential part and a rotational part. It is shown that the rotational part can be expressed in terms of the mean swirl schedule (the circumferential average of the product of radius and tangential velocity) and the blade geometry that includes the main blade as well as the splitter blade. This results in an inverse design approach, in which both the main and the splitter blade geometry are determined from a specification of the swirl schedule. Previous design study of a heavily loaded radial inflow turbine, without splitter blades, for a rather wide variety of specified mean swirl schedules results in a blade shape with unacceptable nonradial blade filament; the resulting reduced static pressure distribution yields an “inviscid reverse flow region” covering almost the first half of the blade pressure surface. When the inverse design technique is applied to the design study of the turbine wheel with splitter blades, the results indicate that the use of splitter blades is an effective means for making the blade filament at an axial location more radial as well as a potential means for eliminating any “inviscid reverse flow” region that may exist on the pressure side of the blades.
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Tian, Da Ke, and Xu Yang Liu. "Research on Similarity Scaling of Structure for Compressor Disc." Advanced Materials Research 591-593 (November 2012): 144–47. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.144.
Full textAbstract:
To study the similarity scaling of structure for compressor disc, based on the basic rules of similarity scaling, physical speed of five linear scale factors (LSF) is determined, and the ratio of between centrifugal force and LSF is established, then the centrifugal force of single rotor blade and single rim flange with different LSF is obtained. Using the method of finite element numerical simulation, strength of four assessment projects including circumferential stress of disc heart, circumferential stress of cylindrical surface, radial stress of cylindrical surface and circumferential stress of meridian plane is analyzed. The results show that the maximum relative error among four assessment projects is only 2.60%, and stress level of disc corresponding to the different LSF is very close to each other. Then a conclusion can be got that the stress level of disc is little difference with itself geometry size, and the structure of disc can be designed pro rata scaling.
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Dhadwal, H. S., and A. P. Kurkov. "Dual-Laser Probe Measurement of Blade-Tip Clearance." Journal of Turbomachinery 121, no. 3 (July 1, 1999): 481–85. http://dx.doi.org/10.1115/1.2841340.
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This paper describes two dual-laser probe integrated fiber optic systems for measuring blade tip clearance in rotating turbomachinery. The probes are nearly flush with the casing inner lining, resulting in minimal flow disturbance. The two probes are closely spaced in a circumferential plane and are slanted at an angle relative to each other so that the blade tip traverse time of the space between the two laser beams varies with the tip radius, allowing determination of the tip clearance at the rotor operating conditions. The tip clearance can be obtained for all the blades in a rotor with a single system, provided there are no synchronous vibrations present at a particular operating condition. These probes were installed in two holders; one provided an included angle between the probes of 20 deg, and the other provided an included angle of 40 deg. The two configurations were calibrated in a vacuum spin rig facility that is capable of reproducing realistic blade tip speeds.
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Mailach, R., I. Lehmann, and K. Vogeler. "Rotating Instabilities in an Axial Compressor Originating From the Fluctuating Blade Tip Vortex." Journal of Turbomachinery 123, no. 3 (February 1, 2000): 453–60. http://dx.doi.org/10.1115/1.1370160.
Full textAbstract:
Rotating instabilities (RIs) have been observed in axial flow fans and centrifugal compressors as well as in low-speed and high-speed axial compressors. They are responsible for the excitation of high amplitude rotor blade vibrations and noise generation. This flow phenomenon moves relative to the rotor blades and causes periodic vortex separations at the blade tips and an axial reversed flow through the tip clearance of the rotor blades. The paper describes experimental investigations of RIs in the Dresden Low-Speed Research Compressor (LSRC). The objective is to show that the fluctuation of the blade tip vortex is responsible for the origination of this flow phenomenon. RIs have been found at operating points near the stability limit of the compressor with relatively large tip clearance of the rotor blades. The application of time-resolving sensors in both fixed and rotating frame of reference enables a detailed description of the circumferential structure and the spatial development of this unsteady flow phenomenon, which is limited to the blade tip region. Laser-Doppler-anemometry (LDA) within the rotor blade passages and within the tip clearance as well as unsteady pressure measurements on the rotor blades show the structure of the blade tip vortex. It will be shown that the periodical interaction of the blade tip vortex of one blade with the flow at the adjacent blade is responsible for the generation of a rotating structure with high mode orders, termed a rotating instability.
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Leishman, B. A., and N. A. Cumpsty. "Mechanism of the Interaction of a Ramped Bleed Slot With the Primary Flow." Journal of Turbomachinery 129, no. 4 (December 21, 2006): 669–78. http://dx.doi.org/10.1115/1.2752193.
Full textAbstract:
An experimental and computational study of the ramped bleed slot in a compressor cascade is presented. The geometry is a circumferential slot downstream of the stator blade trailing edge, with endwall ramps inside the blade passage, and the paper builds on work previously reported for different bleed off-take geometries (Leishman et al., 2007, ASME J. Turbomach., 129, pp. 645–658; Leishman et al., 2007, ASME J. Turbomach., 129, pp. 659–668). The strong interaction between any bleed slot and the primary flow through the cascade can be strong, thereby causing the levels of loss and blockage in the primary flow leaving the blade passage to be increased at some bleed flow rates. Radial flow into the bleed slot is highly nonuniform because the blade-to-blade pressure field causes flow to enter the bleed slot preferentially where the static pressure is high, and to spill out into the primary flow where the static pressure is low. The mechanism for the ramped bleed slot is different from that described in the earlier papers for other geometries. For the ramped bleed slot a static pressure field, with large variations of static pressure in the circumferential direction, is set up in the slot because the endwall flow entering the slot has higher stagnation pressure downstream of the pressure surface than downstream of the suction surface of the upstream blades. The flow entering the slot with high stagnation pressure is brought to rest in a stagnation point on the downstream surface of the slot, and the consequent variation in static pressure on the rear surface sets tangential and radial components of velocity which are a large fraction of the freestream velocity. As well as demonstrating the mechanism for the flow behavior, the paper presents results of experiments and calculations to demonstrate the behavior and gives guidance for the design of bleed slots by stressing the fundamental features of the flow.
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Arndt, N. "Blade Row Interaction in a Multistage Low-Pressure Turbine." Journal of Turbomachinery 115, no. 1 (January 1, 1993): 137–46. http://dx.doi.org/10.1115/1.2929198.
Full textAbstract:
The objective of this work was to enhance the understanding of unsteady flow phenomena in multistage low-pressure turbines. For this purpose, hot-film probe measurements were made downstream of every rotor blade row of a five-stage low-pressure turbine. Rotor–rotor interaction and stator–rotor interaction were observed to have a profound influence on the flow through the low-pressure turbine. Interaction of rotors of different turbine stages occurred owing to the influence of the wakes shed by one rotor blade row upon the flow through the next downstream rotor blade row. This wake-induced rotor–rotor interaction resulted in strongly amplitude-modulated periodic and turbulent velocity fluctuations downstream of every rotor blade row with the exception of the most upstream one. Significantly different wake depths and turbulence levels measured downstream of every rotor blade row at different circumferential positions evidenced the effect of the circumferentially nonuniform stator exit flow upon the next downstream rotor blade row. Stator-rotor interaction also strongly influenced the overturning and the under-turning of the rotor wakes, caused by the rotor secondary flows, in the rotor endwall regions. Low rotor wake overturning and underturning, i.e., reduced rotor secondary flow influence, were observed to correlate well with low rotor wake turbulence levels.
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Taghavi Zenouz, R., MH Ababaf Behbahani, F. Rousta, and A. Khoshnejad. "Experimental investigation on flow unsteadiness during spike stall suppression process in an axial compressor via air injection." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 14 (October 13, 2016): 2677–88. http://dx.doi.org/10.1177/0954410016673093.
Full textAbstract:
Stall recovery process for performance enhancement of an axial compressor has been experimentally carried out using air injection at its rotor blade row tip region. Twelve air injectors had been mounted evenly spaced around the compressor casing upstream the rotor blade row. Instantaneous flow velocities at various radial and circumferential positions were measured simultaneously utilizing hot wire anemometry. These unsteady results, separately presented in frequency and time domains, provided to distinguish stall inception process and consequent flow induced fluctuations. Time-dependent responses of the flow field properties within the compressor passage and progressive alleviation of stall cells are demonstrated during the tip injection process. Blade tip air injection worked effectively and enhanced the compressor stall margin about 9%. This attractive result occurred for the case where the total mass flow rate passing through the air injectors was as small as 0.8% of the compressor main flow rate. In addition, this augmentation in the stall margin was accompanied by increase in the compressor delivery total pressure. Air injection at the blade row tip region caused its beneficial effects to extend throughout the blade whole span, especially while working at the near-stall conditions.
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Pinarbasi, A., and M. W. Johnson. "Off-Design Flow Measurements in a Centrifugal Compressor Vaneless Diffuser." Journal of Turbomachinery 117, no. 4 (October 1, 1995): 602–8. http://dx.doi.org/10.1115/1.2836574.
Full textAbstract:
Detailed measurements have been taken of the three-dimensional velocity field within the vaneless diffuser of a backswept low speed centrifugal compressor using hot-wire anemometry. A 16 percent below and an 11 percent above design flow rate were used in the present study. Results at both flow rates show how the blade wake mixes out more rapidly than the passage wake. Strong secondary flows inherited from the impeller at the higher flow rate delay the mixing out of the circumferential velocity variations, but at both flow rates these circumferential variations are negligible at the last measurement station. The measured tangential/radial flow angle is used to recommend optimum values for the vaneless space and vane angle for design of a vaned diffuser.