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1
Etuk, E. M., A. E. Ikpe, and U. A. Adoh. "Design and analysis of displacement models for modular horizontal wind turbine blade structure." Nigerian Journal of Technology 39, no. 1 (April 3, 2020): 121–30. http://dx.doi.org/10.4314/njt.v39i1.13.
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This study examined the normal, radial, axial and tangential loading cycles undergone by wind turbine rotor blades and their effects on the displacement of the blade structure. The rotor blade was modelled using Q Blade finite element sub module, which evaluated the loading cycles in terms of the forces induced on the blade at various frequencies through several complete revolution cycles (360o each cycle). At frequencies of 5 HZ, 23 Hz, 60 Hz, 124 Hz and 200 Hz, maximum strain deformation of 0.004, 0.04, 0.08, 0.14 and 0.24 were obtained, and geometry of the deformed blades were characterized by twisting and bending configuration. Maximum deflections from tangential loading increased from -0.55-1.2 mm, -0.39-1.6 mm from axial loading, -0.28-1.8 mmfrom radial loading and -0.01-2.3 mm from normal loading. From these deflection values, normal loading cycle would cause the highest level of structural damage on the rotor blade followed by radial, axial and tangential loading. Moreover, the strain deformations and deflections of the blade structure increased as the cycles of frequency increased.
Keywords: Loading cycle, Wind turbine, Rotor blade, Frequency, Strain deformations, Deflections.
2
Hesse, Nicholas H., and J. H. G. Howard. "Experimental Investigation of Blade Loading Effects at Design Flow in Rotating Passages of Centrifugal Impellers." Journal of Fluids Engineering 121, no. 4 (December 1, 1999): 813–23. http://dx.doi.org/10.1115/1.2823542.
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Laser-Doppler Anemometry (LDA) was used to study the effect of blade loading on the relative velocity field in a rotating passage of a centrifugal-pump impeller. Two variations of the impeller, 8-bladed and 16-bladed, were investigated. The measured primary and secondary velocities and turbulence show that the effect of blade loading is not that previously predicted. The 16-blade impeller with high blade loading has a rapidly thickening suction side boundary layer, suggesting the onset of transient separation near the exit. However, for the 8-blade impeller with even higher blade loading, the onset of separation is not indicated at any measured location in the impeller. At the design flow, it is concluded that the stronger potential eddy and lower solidity associated with the very high blade loading caused a change in the secondary flow pattern, retarding the growth and the likelihood of transitory separation of the suction side boundary layer.
3
McNerney, G. M., C. P. van Dam, and D. T. Yen-Nakafuji. "Blade-Wake Interaction Noise for Turbines With Downwind Rotors." Journal of Solar Energy Engineering 125, no. 4 (November 1, 2003): 497–505. http://dx.doi.org/10.1115/1.1627830.
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The interaction between the rotor and the tower wake is an important source of noise for wind turbines with downwind rotors. The tower wake modifies the dynamic pressure and the local flow incidence angle as seen by the blades and, hence, modifies the aerodynamic loading of the blade during blade passage. The resulting n per revolution fluctuation in the blade loading (where n is the number of blades) is the source of low frequency but potentially high amplitude sound levels. The Wind Turbine Company (WTC) Proof of Concept 250 kW (POC) wind turbine has been observed by field personnel to produce low-frequency emissions at the National Wind Technology Center (NWTC) site during specific atmospheric conditions. Consequently, WTC is conducting a three-phase program to characterize the low frequency emissions of its two-bladed wind turbines and to develop noise mitigation techniques if needed. This paper summarizes the first phase of this program including recent low-frequency noise measurements conducted on the WTC POC250 kW wind turbine, a review of the wake characteristics of circular towers as they pertain to the blade-wake interaction problem, and techniques to attenuate the sound pressure levels caused by the blade-wake interaction.
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Tripp, Nicolás G., Aníbal E. Mirasso, and Sergio Preidikman. "Numerical analysis of the influence of inertial loading over morphing trailing edge devices." Journal of Intelligent Material Systems and Structures 29, no. 18 (June 28, 2018): 3533–49. http://dx.doi.org/10.1177/1045389x18783867.
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Larger and more flexible wind turbine blades are currently being manufactured. Those highly flexible blades suffer from loading of aeroelastic nature which increases the fatigue damage. Smart blade concepts are being developed to reduce the aerodynamic loading. The state of the art favors the discrete deformable trailing edge concept. Many authors have reported adequate performance of this type of actuators in reducing the blade vibrations. However, the question of whether the actuator can maintain its authority under strong external loading remains still answered. To solve this question, actuator models that include the loading produced by the blade vibration are required. In this article, a smart morphing trailing edge model is presented that includes the inertial forces produced by the blade dynamics. The model is applied to a commercial actuator and the influence of its parameters is analyzed. Finally, a simple estimation of the inertial loading produced by a 35-m wind turbine blade at the flutter instability condition is analyzed to understand the design requirements of this type of systems.
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Zalkind, Daniel S., Gavin K. Ananda, Mayank Chetan, Dana P. Martin, Christopher J. Bay, Kathryn E. Johnson, Eric Loth, D. Todd Griffith, Michael S. Selig, and Lucy Y. Pao. "System-level design studies for large rotors." Wind Energy Science 4, no. 4 (November 11, 2019): 595–618. http://dx.doi.org/10.5194/wes-4-595-2019.
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Abstract. We examine the effect of rotor design choices on the power capture and structural loading of each major wind turbine component. A harmonic model for structural loading is derived from simulations using the National Renewable Energy Laboratory (NREL) aeroelastic code FAST to reduce computational expense while evaluating design trade-offs for rotors with radii greater than 100 m. Design studies are performed, which focus on blade aerodynamic and structural parameters as well as different hub configurations and nacelle placements atop the tower. The effects of tower design and closed-loop control are also analyzed. Design loads are calculated according to the IEC design standards and used to create a mapping from the harmonic model of the loads and quantify the uncertainty of the transformation. Our design studies highlight both industry trends and innovative designs: we progress from a conventional, upwind, three-bladed rotor to a rotor with longer, more slender blades that is downwind and two-bladed. For a 13 MW design, we show that increasing the blade length by 25 m, while decreasing the induction factor of the rotor, increases annual energy capture by 11 % while constraining peak blade loads. A downwind, two-bladed rotor design is analyzed, with a focus on its ability to reduce peak blade loads by 10 % per 5∘ of cone angle and also reduce total blade mass. However, when compared to conventional, three-bladed, upwind designs, the peak main-bearing load of the upscaled, downwind, two-bladed rotor is increased by 280 %. Optimized teeter configurations and individual pitch control can reduce non-rotating damage equivalent loads by 45 % and 22 %, respectively, compared with fixed-hub designs.
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Leian, Zhang, Huang Xuemei, and Yuan Guangming. "Fatigue Life Evaluation For Wind Turbine Blade Based on Multistage Loading Accumulative Damage Theory." Open Mechanical Engineering Journal 9, no. 1 (June 26, 2015): 422–27. http://dx.doi.org/10.2174/1874155x01509010422.
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The fatigue life of MW wind turbine blade was assessed by applying theoretical calculation and test verification. Firstly, the fatigue characteristic curve of FRP material was obtained based on Palmgren-Miner damage theory. Furthermore, The fatigue life of Aeroblade1.5-40.3 wind turbine blade using multistage loading accumulative damage theory could be evaluated over 20 years accordingly. Then the coordinate system of wind turbine blade and its Bladed simulation model were set. By calculating fatigue loading, the moment distribution of fatigue test was obtained. Finally, the blade’s fatigue loading system driven by an eccentric mass was built and the multi-level amplitude resonant mode was adopted to carry on the test. Almost three months’ test results showed that the blade vibrating amplitude was constant, which illustrate the little variation of stiffness of loading point. The stable of stiffness could testify the fatigue life of blade was over 20 years. The results of in-site experiment were basically consistent with the theoretical calculation.
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Parry, A. B. "The effect of blade sweep on the reduction and enhancement of supersonic propeller noise." Journal of Fluid Mechanics 293 (June 25, 1995): 181–206. http://dx.doi.org/10.1017/s0022112095001686.
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An asymptotic frequency-domain approach is used to describe the radiation from a supersonic swept propeller within the framework of linear acoustics. With this approach the radiation of singularities, their points of origin on the blades, and their relation to blade geometry and loading are easily obtained. In particular, it is shown that a swept propeller with a completely subsonic leading edge can still radiate singularities, if the leading edge is blunt, due to a supersonic edge effect at the blade tips. In addition, the radiation from a family of ‘critical’ swept-blade designs is shown to be more singular than that from a straight-bladed design. Numerical and asymptotic results for such designs show that the peak radiation is, typically, increased by 5–10 dB.
8
Zhou, Fang, Hassan Mahfuz, Gabriel M. Alsenas, and Howard P. Hanson. "Static and Fatigue Analysis of Composite Turbine Blades Under Random Ocean Current Loading." Marine Technology Society Journal 47, no. 2 (March 1, 2013): 59–69. http://dx.doi.org/10.4031/mtsj.47.2.6.
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AbstractThe objective of this paper is to investigate how U.S. National Renewable Energy Laboratory (NREL)‐designed modeling tools commonly used for wind turbine blade design and analysis can be applied to the design of ocean current turbines (OCT). Design, static analysis, and fatigue life predictions of a horizontal-axis, ocean current turbine composite blade were investigated using NREL’s PreCom, BModes, AeroDyn, FAST with seawater conditions. PreComp was used to compute section properties of this OCT blade. BModes calculated mode shapes and frequencies of the blade. Loading on a turbine blade in the Gulf Stream at a South Florida location (26o4.3’N 79o50.5’W, 25-m depth) was calculated with AeroDyn. FAST was then used to obtain the dynamic response of the blade, including flap and edge bending moment distribution with respect to blade rotation. Static analysis was performed by using a combination of Sandia’s NuMAD and ANSYS. Palmgren-Miner’s cumulative fatigue damage model was employed with damage estimation based on the material fatigue property data in DOE/MSU Composite Material Fatigue Database. During service life, OCT blades are subjected to cyclic loads and random ocean current loading. Hence, the blades experience repeated and alternating stresses, which can lead to fatigue failure. These loads were weighted by rate of occurrence from a histogram analysis of in situ measurements conducted by the Southeast National Marine Renewable Energy Center (SNMREC).
9
Liu, Zheng, Xin Liu, Kan Wang, Zhongwei Liang, José A. F. O. Correia, and Abílio De Jesus. "GA-BP Neural Network-Based Strain Prediction in Full-Scale Static Testing of Wind Turbine Blades." Energies 12, no. 6 (March 15, 2019): 1026. http://dx.doi.org/10.3390/en12061026.
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This paper proposes a strain prediction method for wind turbine blades using genetic algorithm back propagation neural networks (GA-BPNNs) with applied loads, loading positions, and displacement as inputs, and the study can be used to provide more data for the wind turbine blades’ health assessment and life prediction. Among all parameters to be tested in full-scale static testing of wind turbine blades, strain is very important. The correlation between the blade strain and the applied loads, loading position, displacement, etc., is non-linear, and the number of input variables is too much, thus the calculation and prediction of the blade strain are very complex and difficult. Moreover, the number of measuring points on the blade is limited, so the full-scale blade static test cannot usually provide enough data and information for the improvement of the blade design. As a result of these concerns, this paper studies strain prediction methods for full-scale blade static testing by introducing GA-BPNN. The accuracy and usability of the GA-BPNN prediction model was verified by the comparison with BPNN model and the FEA results. The results show that BPNN can be effectively used to predict the strain of unmeasured points of wind turbine blades.
10
Sjolander, S. A., and K. K. Amrud. "Effects of Tip Clearance on Blade Loading in a Planar Cascade of Turbine Blades." Journal of Turbomachinery 109, no. 2 (April 1, 1987): 237–44. http://dx.doi.org/10.1115/1.3262090.
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The paper examines in detail the structure of the tip leakage flow and its effect on the blade loading in a large-scale planar cascade of turbine blades. The tip clearance was varied from 0.0 to 2.86 percent of the blade chord. One of the blades is instrumented with 14 rows of 73 static taps which allowed a very detailed picture of the loading near the tip to be obtained. In addition to the measurements, extensive flow visualization was conducted using both smoke and surface oil flow. A new feature found in the present experiment was the formation of multiple, discrete tip-leakage vortices as the clearance was increased. Their presence is clearly evident from the surface oil flow and they account for the multiple suction peaks found in the blade pressure distributions. Integration of the pressure distributions showed that for larger values of the clearance the blade loading increases as the tip is approached and only begins to decline very near the tip. The increase was found to occur primarily in the axial component of the force.
11
van Leeuwen, Hans, Don van Delft, John Heijdra, Henk Braam, Eric R. Jørgensen, Denja Lekou, and Pantelis Vionis. "Comparing Fatigue Strength From Full Scale Blade Tests With Coupon-Based Predictions." Journal of Solar Energy Engineering 124, no. 4 (November 1, 2002): 404–11. http://dx.doi.org/10.1115/1.1509463.
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In order to get a deeper understanding of the blade-to-blade variations and to determine the statistical distribution of the fatigue strength of rotor blades, 37 small rotor blades have been tested in static and fatigue loading. The blades are 3.4 m commercially available blades adapted to the needs of the project. In addition to these blade tests, coupons of the blade material have been tested. The tests have encompassed static flapwise bending tests, flapwise fatigue tests at two different sections of the blade, and edgewise fatigue tests. Since some blades could be re-used after a first test, a total number of 42 blade tests has been carried out in three different testing laboratories. The blades showed large deformation, development of creep and stiffness reduction. After correction for these phenomena, the fatigue strength of the blades was predicted very well by the classical Goodman relation using the well-known slope parameter of 10.
12
Pešek, Ludĕk, Ladislav Půst, Vítĕzslav Bula, and Jan Cibulka. "Application of Piezofilms for Excitation and Active Damping of Blade Flexural Vibration." Archives of Acoustics 40, no. 1 (March 1, 2015): 59–69. http://dx.doi.org/10.1515/aoa-2015-0008.
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Abstract The steam turbine blades of low pressure stages are endangerd by the high-cyclic fatigue due to the combined loading of dynamic stresses by the steam time-variant pressure and the pre-stress from centrifugal forces. Therefore, the importance of their experimental dynamic analysis in the design stage is critical. For laboratory tests of the blades, the piezo actuators placed on the blades, unlike electromagnets placed in the stationary space, give a possibility to excite the flexural vibration of the blades within the bladed disk by time continuous forces independently of the rotor revolutions. In addition, the piezo actuators can be also used to control the vibrations of the blade. Therefore, several dynamic experiments of the clamped model blade equipped with PVDF films were performed for the force description of the piezo foils and their behavior as actuators of the blade vibration. The numerical beam models were used for numerical analysis of the vibration suppression effects both by additional parametric excitation and by active damping. The optimal phase shift of piezo actuator voltage supply was ascertained both for amplitude amplification and suppression. The results contribute to the knowledge of the actuation and active damping of blade vibration by the piezo elements
13
Agnalt, Einar, Igor Iliev, Bjørn W. Solemslie, and Ole G. Dahlhaug. "On the Rotor Stator Interaction Effects of Low Specific Speed Francis Turbines." International Journal of Rotating Machinery 2019 (March 3, 2019): 1–11. http://dx.doi.org/10.1155/2019/5375149.
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The rotor stator interaction in a low specific speed Francis model turbine and a pump-turbine is analyzed utilizing pressure sensors in the vaneless space and in the guide vane cascade. The measurements are analyzed relative to the runner angular position by utilizing an absolute encoder mounted on the shaft end. From the literature, the pressure in the analyzed area is known to be a combination of two effects: the rotating runner pressure and the throttling of the guide vane channels. The measured pressure is fitted to a mathematical pressure model to separate the two effects for two different runners. One turbine with 15+15 splitter blades and full-length blades and one pump-turbine with six blades are investigated. The blade loading on the two runners is different, giving different input for the pressure model. The main findings show that the pressure fluctuations in the guide vane cascade are mainly controlled by throttling for the low blade loading case and the rotating runner pressure for the higher blade loading case.
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Jiang, J., and T. Dang. "Design Method for Turbomachine Blades With Finite Thickness by the Circulation Method." Journal of Turbomachinery 119, no. 3 (July 1, 1997): 539–43. http://dx.doi.org/10.1115/1.2841155.
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This paper presents a procedure to extend a recently developed three-dimensional inverse method for infinitely thin blades to handle blades with finite thickness. In this inverse method, the prescribed quantities are the blade pressure loading and the blade thickness distributions, and the calculated quantity is the blade mean camber line. The method is formulated in the fully inverse mode whereby the blade shape is determined iteratively using the flow-tangency condition along the blade surfaces. Design calculations are presented for an inlet guide vane, an impulse turbine blade, and a compressor blade in the two-dimensional inviscid- and incompressible-flow limit. Consistency checks are carried out for these design calculations using a panel analysis method and the analytical solution for the Gostelow profile.
15
Muyan, Can, and Demirkan Coker. "Finite element simulations for investigating the strength characteristics of a 5 m composite wind turbine blade." Wind Energy Science 5, no. 4 (October 20, 2020): 1339–58. http://dx.doi.org/10.5194/wes-5-1339-2020.
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Abstract. Full-scale structural tests enable us to monitor the mechanical response of the blades under various loading scenarios. Yet, these tests must be accompanied by numerical simulations so that the physical basis of the progressive damage development can be better interpreted and understood. In this work, finite element analysis is utilized to investigate the strength characteristics of an existing 5 m RÜZGEM composite wind turbine blade under extreme flapwise, edgewise and combined flapwise plus edgewise loading conditions. For this purpose, in addition to a linear buckling analysis, Puck's (2D) physically based phenomenological model is used for the progressive damage analysis of the blade. The 5 m RÜZGEM blade is found to exhibit sufficient resistance against buckling. However, Puck's damage model indicates that laminate failure plays a major role in the ultimate blade failure. Under extreme flapwise and combined load cases, the internal flange at the leading edge and the trailing edge are identified as the main damaged regions. Under edgewise loading, the leading edge close to the root is the failure region. When extreme load case is applied as a combination of edgewise and flapwise loading cases, less damage is observed compared to the pure flapwise loading case.
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Hu, Site, Chao Zhou, and Shiyi Chen. "Large Eddy Simulation of Secondary Flows in an Ultra-High Lift Low Pressure Turbine Cascade at Various Inlet Incidences." International Journal of Turbo & Jet-Engines 37, no. 2 (September 25, 2020): 195–207. http://dx.doi.org/10.1515/tjj-2017-0020.
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AbstractIncreasing the blade loading of a low pressure turbine blade decreases the number of blades, thus improving the aero-engine performance in terms of the weight and manufacture cost. Many studies focused on the blade-to-blade flow field of ultra-high lift low pressure turbines. The secondary flows of ultra-high lift low pressure turbines received much less attention. This paper investigates the secondary flows in an ultra-high lift low pressure turbine cascade T106C by large eddy simulation at a Reynolds number of 100,000. Both time-averaged and instantaneous flow fields of this ultra-high lift low pressure turbine are presented. To understand the effects of the inlet angle, five incidences of ‒10°, ‒5°, 0, +5° and +10° are investigated. The case at the design incidence is analyzed first. Detailed data is used to illustrate the how the fluids in boundary layers develops into secondary flows. Then, the cases with different inlet incidences are discussed. The aerodynamic performances are compared. The effect of blade loading on the vortex structures is investigated. The horseshoe vortex, passage vortex and the suction side corner vortex are very sensitive to the loading of the front part of the blade.
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Andrew, D. N. "The effect of Uniform Spanwise Vorticity on the Two-Dimensional Flow Through Cascades." Proceedings of the Institution of Mechanical Engineers, Part C: Mechanical Engineering Science 203, no. 6 (November 1989): 371–78. http://dx.doi.org/10.1243/pime_proc_1989_203_130_02.
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An inherent characteristic of the flow in regenerative turbomachines is the presence of a uniform vorticity in the blade-to-blade plane. Control volume arguments indicate that the effect of this spanwise component of vorticity is to modify the loading on the blades, and modified forms of the Zweifel aerodynamic loading coefficient and the Lieblein compressor diffusion factor are derived to account for this effect. A method for calculating two-dimensional flow through cascades with a uniform spanwise vorticity is described, and results are presented which illustrate the increase in loading and deviation due to the presence of the vorticity.
18
Doubrava, Karel, and Jiří Kuželka. "Turbine Blade Loading and Experimental Verification." Applied Mechanics and Materials 486 (December 2013): 273–76. http://dx.doi.org/10.4028/www.scientific.net/amm.486.273.
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The paper describes process of verification of FEM model of turbine rotor blade fatigue tests. Design of new turbine blade is tested on experimental stand, where load situation is similar to load of rotor blade of steam turbine during operation. Real load of blade and boundary condition on experimental stand was monitored by means of strain gauges set. Experimental data were compared with the computed results of several FEM models.
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Haldeman, C. W., M. L. Krumanaker, and M. G. Dunn. "Influence of Clocking and Vane/Blade Spacing on the Unsteady Surface Pressure Loading for a Modern Stage and One-Half Transonic Turbine." Journal of Turbomachinery 125, no. 4 (October 1, 2003): 743–53. http://dx.doi.org/10.1115/1.1625398.
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This paper describes pressure measurements obtained for a modern one and one-half stage turbine. As part of the experimental effort, the position of the high-pressure turbine (HPT) vane was clocked relative to the downstream low-pressure turbine (LPT) vane to determine the influence of vane clocking on both the steady and unsteady pressure loadings on the LPT vane and the HPT blade. In addition, the axial location of the HPT vane relative to the HPT blade was changed to investigate the combined influence of vane/blade spacing and clocking on the unsteady pressure loading. Time-averaged and time-accurate surface-pressure results are presented for several spanwise locations on the vanes and blade. Results were obtained at four different HPT vane-clocking positions and at two different vane/blade axial spacings for three (of the four) clocking positions. For time-averaged results, the effect of clocking is small on the HPT blade and vane. The influence of clocking on the transition ducts and the LPT vane is slightly greater (on the order of ±1%). Reduced HPT vane/blade spacing has a larger effect than clocking on the HPT vanes and blades ±3% depending upon the particular surface. Examining the data at blade passing and the first fundamental frequency, the effect of spacing does not produce a dramatic influence on the relative changes that occur between clocking positions. The results demonstrate that clocking and spacing effects on the surface pressure loading are very complex and may introduce problems if the results of measurements or analysis made at one span or location in the machine are extrapolated to other sections.
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Xuemei, Huang, Zhang Lei’an, Tao Liming, and Wei Xiuting. "RESEARCH ON THE SELF-SYNCHRONOUS VIBRATION OF FATIGUE LOADING TESTS FOR WIND TURBINE BLADES." Transactions of the Canadian Society for Mechanical Engineering 40, no. 5 (December 2016): 871–81. http://dx.doi.org/10.1139/tcsme-2016-0071.
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To carry on fatigue loading tests for wind turbine blades accurately, the self-synchronous vibration mechanism of loading system was investigated. Firstly, the mathematical model of vibration was deduced based on LaGrange Equation, thus the influence factors of self-synchronous vibration could be obtained. Then to study the influencing rules of the initial phase difference between loading equipment and blade, a simulating model was constructed to carry on the numerical simulation and it was found that when the driving frequency of the loading equipment was the same as the natural frequency of the blade, a different initial phase separation would generate different effect on self-synchronous vibration. Finally, an on-site fatigue test system was established to verify the accuracy of mathematical and simulation model mentioned above. It could be concluded that the test results were consistent with the simulating result. The research on the self-synchronous vibration performance of loading system for blade could supply a theory support for the sequent control of blade’s fatigue tests precisely.
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Kenyon, J. A., J. H. Griffin, and N. E. Kim. "Sensitivity of Tuned Bladed Disk Response to Frequency Veering." Journal of Engineering for Gas Turbines and Power 127, no. 4 (March 1, 2004): 835–42. http://dx.doi.org/10.1115/1.1924486.
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A continuous method is presented for representing the mode interaction that occurs in frequency veering in terms of the nominal sector modes of a cyclic symmetric bladed disk model constrained at a reference interblade phase angle. Using this method, the effect of frequency veering on the mode shapes can be considered in the context of the generalized forces exciting the system and the modal response of the bladed disk. It is shown that in a blade-dominated family of modes, the transfer of modal energy to the disk in the veering results in a lower generalized force exciting the mode as well as reduced response amplitude in the blade. For the disk-dominated modes, the sharing of modal energy with the blades can lead to the disk being excited by aerodynamic loading. These effects can have important implications for predicting and interpreting forced response in bladed disks. Numerical examples are provided to illustrate these concepts.
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Ghaly, W. S. "A Parametric Study of Radial Turbomachinery Blade Design in Three-Dimensional Subsonic Flow." Journal of Turbomachinery 112, no. 3 (July 1, 1990): 338–45. http://dx.doi.org/10.1115/1.2927665.
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An aerodynamic design method is described and used to implement a parametric study of radial turbomachinery blade design in three-dimensional subsonic flow. Given the impeller hub and shroud, the number of blades and their stacking position, the design method gives the detailed blade shape, flow, and pressure fields that would produce a prescribed tangentially averaged swirl schedule. The results from that study show that decreasing the number of blades increases the blade wrap, and that the blade loading is strongly affected by the rate of change of mean swirl along the mean streamlines. The results also show that the blade shape and the pressure field are rather sensitive to the prescribed mean swirl schedule, which suggests that, by carefully tailoring the swirl schedule, one might be able to control the blade shape and the pressure field and hence secondary flow.
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Cao, Zhiyuan, Bo Liu, Ting Zhang, and Yibing Xu. "Design strategies and numerical simulation of highly loaded aspirated compressor blades." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 4 (October 25, 2017): 315–36. http://dx.doi.org/10.1177/0957650917736921.
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Boundary layer suction can effectively eliminate flow separations and increase aerodynamic loading of axial compressors. The design methodology of highly loaded aspirated compressor blades was developed and illustrated in this study. In this work, Computational Fluid Dynamics (CFD) methods were first validated with existing data and then used to develop the design strategy of aspirated compressor blades. Design strategies for higher blade performances, including higher loading, larger stall margin and larger blade thickness near the suction slot of aspirated blades, were investigated through analyzing a series of highly loaded aspirated cascades with diffusion factors (DF) around 0.71. Results showed that the design methodology proposed in this paper was appropriate for designing highly loaded aspirated compressor blades. Under the condition of no boundary layer suction (BLS), severe flow separations of highly loaded blades were tailored at the aft part of suction surface by adopting the “ski-slope” velocity distribution, which almost remained unchanged within a large incidence range. The “ski-slope” velocity distribution was appropriate for removing flow separations and beneficial for obtaining thicker blade. High loading of aspirated blade was achieved by the postpositional suction peak and minimum velocity distribution on pressure surface. The stall margin of highly loaded aspirated cascades could be enlarged by designing the velocity distribution upstream of the suction slot and by selecting suction peak position and solidity. A three-dimensional (3D) highly loaded aspirated cascade was designed based on a two-dimensional (2D) cascade. Both the trailing edge separation and corner separation of the 3D highly loaded aspirated cascade were eliminated successfully with coupled suction surface and endwall suction.
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Bădărău, Rodica, Teodor Miloş, Ilare Bordeaşu, and Adrian Bej. "Corrective Solutions for the Shaft with Flange Used for Fixing the Blade on a 5 kW Wind Turbine to Withstand Extreme Weather Conditions." Advanced Materials Research 1029 (September 2014): 118–23. http://dx.doi.org/10.4028/www.scientific.net/amr.1029.118.
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The paper presents a case study on the original solution of a flange shaft as part of the root area of a 5 kW wind turbine blade. There were analyzed the causes that led to the shaft breakage under wind loadings in extreme weather conditions, and consequently technical solutions have been searched in order to improve the shaft design making it more reliable as mechanical strength at extreme wind loadings. The flange shaft is a welded subassembly that keeps the blades attached to the rotor hub. The first part of the paper consists in an analysis referring the loading status, the materials used for blade manufacturing, the identification of critical areas where the breaking was initiated and also the causes for which the materials assumed and specified in the technical design and manufacturing technology failed under loading at wind gusts of about 30 m/sec. Based on this preliminary analysis, the second part of the paper presents the technical solutions which were considered in reference to the materials and the improved design concept aiming to provide the right mechanical strength necessary to withstand specific wind loadings in extreme weather conditions.
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Liao, Gao Hua, Jian Zhong Wu, and Yong Jun Yu. "Study of Fatigue Test Loading Spectrum for Wind Turbine Blade." Advanced Materials Research 889-890 (February 2014): 221–24. http://dx.doi.org/10.4028/www.scientific.net/amr.889-890.221.
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According to the principle of equivalent, the approach to draw up the fatigue test loading spectrum of wind turbine blade is presented. Analysis of wind load characteristics, based on ARMA (Autoregressive Moving Average Model) for the simulation of wind speed, wind load simulation example is given. Using Bladed software, the wind speed-time history is converted to a moment-time history that is the equivalent of blade root.Using data compression technology and the rain flow counting algorithm, load represented by a 2D matrix examples is given.The one-dimensional symmetry loading spectrum draw up, the complexity can be simplified, and provides the necessary foundation for fatigue life analysis.
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Yang, Wei, Xiaoyu Lei, and Benqing Liu. "Three-Dimensional Inverse Design of Low Specific Speed Turbine for Energy Recovery in Cooling Tower System." Energies 11, no. 12 (November 30, 2018): 3348. http://dx.doi.org/10.3390/en11123348.
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A three-dimensional inverse design of a low specific speed turbine is studied, and a set of design criteria for low specific speed turbine runner is proposed, including blade loading distributions and blade lean angles. The characteristics of the loading parameters for low specific speed turbine runner are summarized by analyzing the suction performance of different loading positions, loading slopes and blade lean angles based on the orthogonal experiment design and range analysis. It is found that the blade loading distribution at the band plays a more important role than it does at the crown and it should be fore loaded for both band and crown. The blade lean angle at the blade leading edge should be negative. Then, the blade is optimized through the inverse method by fixing blade lean angle, based on the response surface method. After seeking the optimal value of the response surface function, the optimal result of the design parameters is obtained, which is in conformity with the design criteria and verifies the rationality of the established design criteria for low specific speed turbine.
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Hayami, H., Y. Senoo, Y. I. Hyun, and M. Yamaguchi. "Effects of Tip Clearance of Nozzle Vanes on Performance of Radial Turbine Rotor." Journal of Turbomachinery 112, no. 1 (January 1, 1990): 58–63. http://dx.doi.org/10.1115/1.2927421.
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In radial turbines with variable nozzles, the flow downstream of the nozzles could be distorted by the leakage flow through the tip clearance of the upstream nozzle vanes. To investigate the effects of flow distortion on the performance of turbine rotors, two rotors with different numbers of blades were tested for three types of distorted velocity distribution at the rotor inlet. In the case of the 20-blade rotor with moderate blade loading, the flow distortion at the rotor inlet had a negligible effect on the rotor characteristics, and the measured data on the turbine performances agreed well with prediction. Predictions were made with a conventional one-dimensional flow model applied to the rotor flow, while a two-layer flow model was applied to the flow in the nozzle with clearance. In the case of the 10-blade rotor with heavy blade loading, however, the rotor performance was found to be sensitive to the inlet flow distortion and was considerably lower than the prediction.
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Pullan, Graham, and Neil W. Harvey. "Influence of Sweep on Axial Flow Turbine Aerodynamics at Midspan." Journal of Turbomachinery 129, no. 3 (July 14, 2006): 591–98. http://dx.doi.org/10.1115/1.2472397.
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Sweep, when the stacking axis of the blade is not perpendicular to the axisymmetric streamsurface in the meridional view, is often an unavoidable feature of turbine design. Although a high aspect ratio swept blade can be designed to achieve the same pressure distribution as an unswept design, this paper shows that the swept blade will inevitably have a higher profile loss. A modified Zweifel loading parameter, taking sweep into account, is first derived. If this loading coefficient is held constant, it is shown that sweep reduces the required pitch-to-chord ratio and thus increases the wetted area of the blades. Assuming fully turbulent boundary layers and a constant dissipation coefficient, the effect of sweep on profile loss is then estimated. A combination of increased blade area and a raised pressure surface velocity means that the profile loss rises with increasing sweep. The theory is then validated using experimental results from two linear cascade tests of highly loaded blade profiles of the type found in low-pressure aeroengine turbines: one cascade is unswept, the other has 45deg of sweep. The swept cascade is designed to perform the same duty with the same loading coefficient and pressure distribution as the unswept case. The measurements show that the simple method used to estimate the change in profile loss due to sweep is sufficiently accurate to be a useful aid in turbine design.
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Liu, Xin, Zheng Liu, Zhongwei Liang, Shun-Peng Zhu, José A. F. O. Correia, and Abílio M. P. De Jesus. "PSO-BP Neural Network-Based Strain Prediction of Wind Turbine Blades." Materials 12, no. 12 (June 12, 2019): 1889. http://dx.doi.org/10.3390/ma12121889.
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The full-scale static testing of wind turbine blades is an effective means to verify the accuracy and rationality of the blade design, and it is an indispensable part in the blade certification process. In the full-scale static experiments, the strain of the wind turbine blade is related to the applied loads, loading positions, stiffness, deflection, and other factors. At present, researches focus on the analysis of blade failure causes, blade load-bearing capacity, and parameter measurement methods in addition to the correlation analysis between the strain and the applied loads primarily. However, they neglect the loading positions and blade displacements. The correlation among the strain and applied loads, loading positions, displacements, etc. is nonlinear; besides that, the number of design variables is numerous, and thus the calculation and prediction of the blade strain are quite complicated and difficult using traditional numerical methods. Moreover, in full-scale static testing, the number of measuring points and strain gauges are limited, so the test data have insufficient significance to the calibration of the blade design. This paper has performed a study on the new strain prediction method by introducing intelligent algorithms. Back propagation neural network (BPNN) improved by Particle Swarm Optimization (PSO) has significant advantages in dealing with non-linear fitting and multi-input parameters. Models based on BPNN improved by PSO (PSO-BPNN) have better robustness and accuracy. Based on the advantages of the neural network in dealing with complex problems, a strain-predictive PSO-BPNN model for full-scale static experiment of a certain wind turbine blade was established. In addition, the strain values for the unmeasured points were predicted. The accuracy of the PSO-BPNN prediction model was verified by comparing with the BPNN model and the simulation test. Both the applicability and usability of strain-predictive neural network models were verified by comparing the prediction results with simulation outcomes. The comparison results show that PSO-BPNN can be utilized to predict the strain of unmeasured points of wind turbine blades during static testing, and this provides more data for characteristic structural parameters calculation.
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Dervilis, Nikolaos, M. Choi, Ifigeneia Antoniadou, K. M. Farinholt, S. G. Taylor, Rob J. Barthorpe, G. Park, Charles R. Farrar, and Keith Worden. "Machine Learning Applications for a Wind Turbine Blade under Continuous Fatigue Loading." Key Engineering Materials 588 (October 2013): 166–74. http://dx.doi.org/10.4028/www.scientific.net/kem.588.166.
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Structural health monitoring (SHM) systems will be one of the leading factors in the successful establishment of wind turbines in the energy arena. Detection of damage at an early stage is a vital issue as blade failure would be a catastrophic result for the entire wind turbine. In this study the SHM analysis will be based on experimental measurements of vibration analysis, extracted of a 9m CX-100 blade under fatigue loading. For analysis, machine learning techniques utilised for failure detection of wind turbine blades will be applied, like non-linear Neural Networks, including Auto-Associative Neural Network (AANN) and Radial Basis Function (RBF) networks models.
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Wang, Yi Chun, Jian Zhong Wu, and Gao Hua Liao. "Design and Trial of MW-Scale Wind Turbine Blade Fatigue Loading Control System." Advanced Materials Research 945-949 (June 2014): 1123–28. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.1123.
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This study analyzed requirements of the wind turbine blade fatigue loading, and proposed a novel design method for blade fatigue loading control system. The hardware and software of the control system were designed. Frequency scanning, frequency control and amplitude tracking flow chart have been presented. A control system of the fatigue loading facility was built based on this investigation. The loading test of wind turbine blade has been completed. The data and curve acquired from the test prove that the control system could satisfy loading requirements.
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Yang, Li, Ouyang Hua, and Du Zhao-Hui. "Optimization Design and Experimental Study of Low-Pressure Axial Fan with Forward-Skewed Blades." International Journal of Rotating Machinery 2007 (2007): 1–10. http://dx.doi.org/10.1155/2007/85275.
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This paper presents an experimental study of the optimization of blade skew in low pressure axial fan. Using back propagation (BP) neural network and genetic algorithm (GA), the optimization was performed for a radial blade. An optimized blade is obtained through blade forward skew. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the optimized blade demonstrated improvements in efficiency, total pressure ratio, stable operating range, and aerodynamic noise. Detailed flow measurement was performed in outlet flow field for investigating the responsible flow mechanisms. The optimized blade can cause a spanwise redistribution of flow toward the blade midspan and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at midspan. In addition, the measured spectrums show that the broadband noise of the impeller is dominant.
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Garipova, Lyaysan Ildusovna, Andrei Sergeevich Batrakov, Alexander Nikolaevich Kusyumov, Sergey Anatolievich Mikhaylov, and George Barakos. "Aerodynamic and acoustic analysis of helicopter main rotor blade tips in hover." International Journal of Numerical Methods for Heat & Fluid Flow 26, no. 7 (September 5, 2016): 2101–18. http://dx.doi.org/10.1108/hff-08-2015-0348.
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Purpose The design of main rotor blade tips is of interest to helicopter manufactures since the tip details affect the performance and acoustics of the rotor. The paper aims to discuss this issue. Design/methodology/approach In this paper, computation fluid dynamics is used to simulate the flow around hovering helicopter blades with different tip designs. For each type of blade tip a parametric study on the shape is also conducted for comparison calculations were performed the constant rotor thrust condition. The collective pitch and the cone angles of the blades were determined by at an iterative trimming process. Findings Analysis of the distributed blade loads shows that the tip geometry has a significant influence on aerodynamics and aeroacoustics especially for stations where blade loading is high. Originality/value The aeroacoustic characteristics of the rotors were obtained using Ffowcs Williams-Hawkings equations.
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Wdowiński, Wojciech, Elżbieta Szymczyk, Jerzy Jachimowicz, and Grzegorz Moneta. "Design and Strength Analysis of Curved-Root Concept for Compressor Rotor Blade in Gas Turbine." Fatigue of Aircraft Structures 2017, no. 9 (December 1, 2017): 137–55. http://dx.doi.org/10.1515/fas-2017-0011.
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AbstractThe motivation of the article is fatigue and fretting issue of the compressor rotor blades and disks. These phenomena can be caused by high contact pressures leading to fretting occurring on contact faces in the lock (blade-disk connection, attachment of the blade to the disk). Additionally, geometrical notches and high cyclic loading can initiate cracks and lead to engine failures. The paper presents finite element static and modal analyses of the axial compressor 3rd rotor stage (disk and blades) of the K-15 turbine engine. The analyses were performed for the original trapezoidal/dovetail lock geometry and its two modifications (new lock concepts) to optimize the stress state of the disk-blade assembly. The cyclic symmetry formulation was used to reduce modelling and computational effort.
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Yeo, Hyeonsoo, and Wayne Johnson. "Investigation of Maximum Blade Loading Capability of Lift-Offset Rotors." Journal of the American Helicopter Society 59, no. 1 (January 1, 2014): 1–12. http://dx.doi.org/10.4050/jahs.59.012005.
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The maximum blade loading capability of a coaxial, lift-offset rotor is investigated using a rotorcraft configuration designed in the context of short-haul, medium-size civil and military missions. The aircraft was sized for a 6600-lb payload and a range of 300 nm. The rotor planform and twist were optimized for hover and cruise performance. For the present rotor performance calculations, the collective pitch angle is progressively increased up to and through stall with the shaft angle set to zero. The effects of lift offset on rotor lift, power, controls, and blade airloads and structural loads are examined. The maximum lift capability of the coaxial rotor increases as lift offset increases and extends well beyond the McHugh lift boundary as the lift potential of the advancing blades are fully realized. A parametric study is conducted to examine the differences between the present coaxial rotor and the McHugh rotor in terms of maximum lift capabilities and to identify important design parameters that define the maximum lift capability of the rotor. The effects of lift offset on rotor blade airloads and structural loads are also investigated. Flap bending moment increases substantially as lift offset increases to carry the hub roll moment even at low collective values. The magnitude of flap bending moment is dictated by the lift-offset value (hub roll moment) but is less sensitive to collective and speed.
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Manwaring, Steven R., and Sanford Fleeter. "Periodic rotor-blade aerodynamics including loading effects." Journal of Propulsion and Power 6, no. 5 (September 1990): 590–97. http://dx.doi.org/10.2514/3.23260.
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Andrews, S., P. Wild, and D. Strong. "An experimental assessment of lawnmower blade loading." Journal of Strain Analysis for Engineering Design 41, no. 2 (February 2006): 151–60. http://dx.doi.org/10.1243/03093247jsa99.
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HAYAMI, Hiroshi, Masayuki SAWAE, Takanori NAKAMURA, and Nobumasa KAWAGUCHI. "Blade Loading of Transonic Circular Cascade Diffuser." Transactions of the Japan Society of Mechanical Engineers Series B 58, no. 550 (1992): 1776–79. http://dx.doi.org/10.1299/kikaib.58.1776.
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Kodama, H., and M. Namba. "Unsteady Lifting Surface Theory for a Rotating Cascade of Swept Blades." Journal of Turbomachinery 112, no. 3 (July 1, 1990): 411–17. http://dx.doi.org/10.1115/1.2927675.
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A lifting surface theory is developed to predict the unsteady three-dimensional aerodynamic characteristics for a rotating subsonic annular cascade of swept blades. A discrete element method is used to solve the integral equation for the unsteady blade loading. Numerical examples are presented to demonstrate effects of the sweep on the blade flutter and on the acoustic field generated by interaction of rotating blades with a convected sinusoidal gust. It is found that increasing the sweep results in decrease of the aerodynamic work on vibrating blades and also remarkable reduction of the modal acoustic power of lower radial orders for both forward and backward sweeps.
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Wydro, Tomasz. "Impact of the Winding Angle of the Auger Blade on the Loading Process With Milling Auger Drums." New Trends in Production Engineering 3, no. 1 (August 1, 2020): 241–50. http://dx.doi.org/10.2478/ntpe-2020-0020.
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AbstractThis publication addresses the impact of selected design parameters of milling auger cutting drums on the loading process, and above all the winding angle of the auger blade. The loading process is often referred to as an auxiliary process because the milling process is considered to be the dominant throughout the work of the cutting drum. The correct determination of the relationship between the mining process and the loading process allows to understand how the individual design and kinematic parameters of the mining drums and the mining machine on which they are installed affect each other. The publication discusses the problem of loading with milling cutting drums and ways to increase its efficiency. The research results of the loading process have been presented, affecting the efficiency of this process in the aspect of various angles of inclination of the auger blades. Based on the tests, conclusions have been formulated that allow for the possible selection of an appropriate winding angle for the auger blade, depending on the granulation of spoil.
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Hoyniak, D., and S. Fleeter. "Forced Response Analysis of an Aerodynamically Detuned Supersonic Turbomachine Rotor." Journal of Vibration and Acoustics 108, no. 2 (April 1, 1986): 117–24. http://dx.doi.org/10.1115/1.3269311.
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High-performance aircraft engine fan and compressor blades are vulnerable to aerodynamically forced vibrations generated by inlet flow distortions due to wakes from upstream blade and vane rows, atmospheric gusts, and maldistributions in inlet ducts. In this paper, an analysis is developed to predict the flow-induced forced response behavior of an aerodynamically detuned rotor operating in a supersonic flow with a subsonic axial component. The aerodynamic detuning is achieved by alternating the circumferential spacing of adjacent rotor blades. The total unsteady aerodynamic loading acting on the blading, due to the convection of the transverse gust past the airfoil cascade and the resulting motion of the cascade, is developed in terms of influence coefficients. This analysis is then utilized to investigate the effect of aerodynamic detuning on the forced response characteristics of a 12-bladed rotor, with Verdon’s Cascade B flow geometry as a uniformly spaced baseline configuration. The results of this study indicate that for forward traveling wave gust excitations, aerodynamic detuning is generally very beneficial, resulting in significantly decreased maximum amplitude blade responses for many interblade phase angles.
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Полянский, Aleksandr Polyansky, Полянский, and Vladislav Polyansky. "Nozzle Diaphragms of Liquid Rocket Engines. Residual Life Estimation of the Blade with a Crack." NDT World 19, no. 3 (September 20, 2016): 54–58. http://dx.doi.org/10.12737/21167.
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Introduction. The results of multiple tests of liquid rocket engines indicate that the engine with cracks in blades can "safely" work within a few launchings. Therefore, the resource estimation of the nozzle blade with a crack becomes highly relevant, especially for reusable rocket engines. The objective of this work was to determine the residual life of nozzle diapgragm blades with cracks. Method. For reliable residual life estimation of the blade with a crack the comprehensive approach was used: fractographic and material science studies on the one hand and fracture mechanics propositions on the other hand. Results. Fractographic and material science studies have shown that blade destruction occurs through the countergrowth of fatigue surface cracks from the blade pressure side and the blade suction face, which interconnects to form a "main" crack, whose growth is controlled by growth of surface cracks from the blade pressure side. Using the fracture mechanics propositions and the results of finite element calculations of the stress-strain state of nozzle diaphragm blades under gas and thermal loads in elasto-plastic formulation, equations of crack growth in nozzle blades were obtained. Finally the scheme of blade unstable fracture is proposed; the blade guaranteed residual life under certain conditions is evaluated and the maximum tolerable crack length in the blade suction face is determined. Conclusion. The method offered in this work makes it possible to evaluate the blade residual life as the number of loading cycles while fatigue crack propagation and as the tolerable number of firing tests. The method also enables the maximum permissible crack lenth to be determined.
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Hale, A., and W. O’Brien. "1997 Best Paper Award—Education Committee: A Three-Dimensional Turbine Engine Analysis Compressor Code (TEACC) for Steady-State Inlet Distortion." Journal of Turbomachinery 120, no. 3 (July 1, 1998): 422–30. http://dx.doi.org/10.1115/1.2841733.
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The direct approach of modeling the flow between all blade passages for each blade row in the compressor is too computationally intensive for practical design and analysis investigations with inlet distortion. Therefore a new simulation tool called the Turbine Engine Analysis Compressor Code (TEACC) has been developed. TEACC solves the compressible, time-dependent, three-dimensional Euler equations modified to include turbomachinery source terms, which represent the effect of the blades. The source terms are calculated for each blade row by the application of a streamline curvature code. TEACC was validated against experimental data from the transonic NASA rotor, Rotor 1B, for a clean inlet and for an inlet distortion produced by a 90-deg, one-per-revolution distortion screen. TEACC revealed that strong swirl produced by the rotor caused the compressor to increase in loading in the direction of rotor rotation through the distorted region and decrease in loading circumferentially away from the distorted region.
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Sezen, Savas, and Sakir Bal. "A computational investigation of noise spectrum due to cavitating and non-cavitating propellers." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 234, no. 2 (December 19, 2019): 374–87. http://dx.doi.org/10.1177/1475090219892368.
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In this article, noise spectrum of marine propellers is investigated in uniform flow under non-cavitating and cavitating conditions. New results are presented for this research field. Hydrodynamic performance of both non-cavitating and cavitating marine propellers is first analyzed by viscous and potential based flow solvers. In viscous solver, sheet cavitation on propeller blades is simulated with Schnerr–Sauer cavitation model based on Rayleigh Plesset equation using volume of fluid approach. Numerical hydrodynamic results based on viscous solver is compared with potential solver and then validated with experimental data of benchmark David Taylor Model Basin 4119 model propeller. Later, noise spectrum of model propellers is predicted by a hybrid method which combines Reynolds-averaged Navier Stokes and Ffowcs Williams Hawkings equations. Computed noise spectrum is compared with other numerical studies in the literature for the selected model propeller. In addition, hydrodynamic and hydroacoustic pressures are compared in near field to show reliability of numerical solution. Effects of blade number on hydrodynamic performance and noise spectrum are also investigated. Numerical results indicated that as blade number increases, propeller noise level decreases for different loading conditions due to decreased blade loading (circulation) per blade. However, propeller efficiency increases as blade number decreases.
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Zhang, Lei An, Xue Mei Huang, and Xiu Ting Wei. "Research on Wind Turbine Blade Static Loading System and its Variable Traction Control Mode." Advanced Materials Research 588-589 (November 2012): 595–98. http://dx.doi.org/10.4028/www.scientific.net/amr.588-589.595.
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According to MW-class wind turbine blades loading system requirements, the load requirement of traction apparatus under the different operating conditions were discussed. At the same time, the variable traction feature of traction apparatus was analyzed. A multi-node hydraulic loading system based on CAN bus was designed in this paper. In order to improve the precision of traction and the following performance of loading system, opting for the “V-F” control mode, we proposed the variable proportional separate integral control algorithm with amplitude limit to enhance the system's adaptive capacity. Experiments show that this program has a good coordination feature in the variable traction control, and fully meets the requirements of blade loading test.
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Xiaolu, Zhao, and Qin Lisen. "An Approximate Three-Dimensional Aerodynamic Design Method for Centrifugal Impeller Blades." Journal of Turbomachinery 112, no. 1 (January 1, 1990): 44–49. http://dx.doi.org/10.1115/1.2927419.
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An aerodynamic design method, which is based on the Mean Stream Surface Method (MSSM), has been developed for designing centrifugal compressor impeller blades. As a component of a CAD system for centrifugal compressor, it is convenient to use the presented method for generating impeller blade geometry, taking care of manufacturing as well as aerodynamic aspects. The design procedure starts with an S2m indirect solution. Afterward from the specified S2m surface, by the use of Taylor series expansion, the blade geometry is generated by straight-line elements to meet the manufacturing requirements. Simultaneously, the fluid dynamic quantities across the blade passage can be determined directly. In terms of these results, the designer can revise the distribution of angular momentum along the shroud and hub, which are associated with blade loading, to get satisfactory velocities along the blade surfaces in order to avoid or delay flow separation.
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Zangeneh, M., M. Schleer, F. Pløger, S. S. Hong, C. Roduner, B. Ribi, and R. S. Abhari. "Investigation of an Inversely Designed Centrifugal Compressor Stage—Part I: Design and Numerical Verification." Journal of Turbomachinery 126, no. 1 (January 1, 2004): 73–81. http://dx.doi.org/10.1115/1.1645868.
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In this paper the three-dimensional inverse design code TURBOdesign-1 is applied to the design of the blade geometry of a centrifugal compressor impeller with splitter blades. In the design of conventional impellers the splitter blades normally have the same geometry as the full blades and are placed at mid-pitch location between the two full blades, which can usually result in a mismatch between the flow angle and blade angles at the splitter leading edge. In the inverse design method the splitter and full blade geometry is computed independently for a specified distribution of blade loading on the splitter and full blades. In this paper the basic design methodology is outlined and then the flow in the conventional and inverse designed impeller is compared in detail by using computational fluid dynamics (CFD) code TASCflow. The CFD results confirm that the inverse design impeller has a more uniform exit flow, better control of tip leakage flow and higher efficiency than the conventional impeller. The results also show that the shape of the trailing edge geometry has a very appreciable effect on the impeller Euler head and this must be accurately modeled in all CFD computations to ensure closer match between CFD and experimental results. Detailed measurements are presented in part II of the paper.
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Soltani Dehkharqani, Arash, Fredrik Engström, Jan-Olov Aidanpää, and Michel J. Cervantes. "Experimental Investigation of a 10 MW Prototype Kaplan Turbine during Start-Up Operation." Energies 12, no. 23 (December 2, 2019): 4582. http://dx.doi.org/10.3390/en12234582.
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An increase in the start/stop cycles of hydraulic turbines due to the penetration of intermittent renewable energy sources is important. Hydraulic instabilities that occur in hydraulic turbines during start/stops may cause structural issues in the turbine components. High-stress fluctuations on the runner blades are expected during start-ups due to the unsteady pressure loading on the runner blades. This paper presents experiments performed on a 10 MW prototype Kaplan turbine at the Porjus Hydropower Center during a start-up cycle. Synchronized unsteady pressure and strain measurements on a runner blade and axial, bending (in two directions) and torsion strain measurements on the shaft were performed. In addition, the general parameters of the turbine (e.g., rotational speed, guide vane opening and runner blade angle) were acquired. Low-frequency fluctuations (0–15 Hz) were observed in the pressure data on the runner blade after opening the guide vanes from the completely closed position. A higher strain value was observed on the strain gauges installed on the runner blade near the hub (200–500 μ m / m ) compared to the ones near the shroud at the leading and trailing edge. The strain fluctuation level on the shaft decreased after loading the generator by further opening the guide vanes. Higher fluctuations were observed in the torsion strain compared to axial and bending strain. In addition, the torsion strain peak-to-peak value reached 12 times its corresponding value at 61% guide vane opening.
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So̸rensen, Jens No̸rkær, and Wen Zhong Shen. "Numerical Modeling of Wind Turbine Wakes." Journal of Fluids Engineering 124, no. 2 (May 28, 2002): 393–99. http://dx.doi.org/10.1115/1.1471361.
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An aerodynamical model for studying three-dimensional flow fields about wind turbine rotors is presented. The developed algorithm combines a three-dimensional Navier-Stokes solver with a so-called actuator line technique in which the loading is distributed along lines representing the blade forces. The loading is determined iteratively using a blade-element approach and tabulated airfoil data. Computations are carried out for a 500 kW Nordtank wind turbine equipped with three LM19.1 blades. The computed power production is found to be in good agreement with measurements. The computations give detailed information about basic features of wind turbine wakes, including distributions of interference factors and vortex structures. The model serves in particular to analyze and verify the validity of the basic assumptions employed in the simple engineering models.
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Stern, F., H. T. Kim, V. C. Patel, and H. C. Chen. "Computation of Viscous Flow Around Propeller-Shaft Configurations." Journal of Ship Research 32, no. 04 (December 1, 1988): 263–84. http://dx.doi.org/10.5957/jsr.1988.32.4.263.
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A viscous-flow method for predicting propeller-hull interaction is validated by detailed comparisons with available experimental data for the relatively simple case of propeller-shaft configurations. The steady-flow results are in excellent agreement with the data and show that the present procedures are able to accurately predict many details of the flow field. The dependence of the flow field on propeller loading, including the formation of the hub vortex, is accurately simulated. Also, the robustness of the solution procedure is demonstrated by performing calculations for off-design (large-loading) conditions. The unsteady-flow calculations, which simulate the fanning action of a rotating finite-bladed propeller and which show reasonable agreement with certain general aspects of the experimental data, point out the difficulties of accurately resolving the complex blade-to-blade flow.