Effect of Blade Geometry and Foreign Object Kinetic Energy on Blades Damage

2010 ◽  
Author(s):  
Mickhail S. Nikhamkin ◽  
Leonid V. Voronov ◽  
Irina V. Semenova
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Kinetic Energy ◽  
Leading Edge ◽  
Material Behavior ◽  
Plastic Strain Rate ◽  
Problem Solution ◽  
Foreign Object ◽  
The Impact ◽  
Blade Leading Edge

One of the main reasons of engine failure is foreign object damage (FOD) of compressor blades. Engine manufactures are constantly searching for blade endurance increasing methods. The problem solution requires investigation in the field of the structural factor effects on the blade damageability. The paper describes numerical analysis method of the damage process. Based on “the typical damage case” concept, this method can simulate typical blade damages: dents, tears, notches. The numerical analysis is performed by the finite element method (FEM). Material behavior is described with an elastic-plastic strain rate dependent model. Blade damage numerical model is thoroughly verified by the results of special experiments. To implement the experimental modeling, actual blades were damaged, a special experimental setup based on a pneumatic gun being used. The foreign object kinematic parameters before and after the impact, a blade leading edge displacements and residual deformation fields registered in the experiment are used as verification criteria for the numerical model. The blade leading edge thickness and a foreign object energy effect on the blade damageability is investigated. The research showed there are some foreign object kinetic energy critical values at which the damage mechanism and type are changed.

scholarly journals Influence of the Cyclic Hardening Model on the Results of the Numerical Analysis of Fatigue Life on Example of the Compressor Blade

2019 ◽  
Vol 26 (2) ◽  
pp. 7-14
Author(s):  
Arkadiusz Bednarz
Keyword(s):  
Numerical Analysis ◽  
Leading Edge ◽  
Experimental Tests ◽  
Cyclic Hardening ◽  
Load Cycle ◽  
Geometrical Model ◽  
Fatigue Tests ◽  
Compressor Blade ◽  
Hardening Model ◽  
The Impact

Abstract The main goal of the presented work is to determine the impact of the cyclic hardening model on the numerical results of the ε-N fatigue test. As an object of study, compressor blade (from PZL-10W helicopter engine) was used. The examined blade was made of EI-961 alloy. In numerical analysis, a geometrical model of the blade with a preliminary defect was created. Geometrical defect – V-notch was created on the leading edge. This defect was introduced in order to weaken the structure of the element and the possibility of observing the crack initiation process (in experimental tests). Material data to ε-N analysis, based on Manson-Coffin-Basquin equation, were estimated for Mitchell’s model. This model was built based on strength data provided by the steel producer. Based on three different models of cyclic hardening (Manson, Fatemi, and Xianxin), a number of load cycles were calculated. Load cycle during numerical analysis was represented as resonance bending with an amplitude of displacement equal to A = 1.8 mm. Obtained results were compared with experimental data. Additionally, the analytical model of ε-N fatigue (depending on the cyclic hardening) was prepared. All the work carried out has been summarized by a comprehensive comparative analysis of the results. Obtained results and dependencies can be used in the selection of an appropriate model of cyclic hardening in further fatigue tests of many aerospace elements.

Flow Field Analysis and Nearfield Acoustic Signature Reduction of a Stationary Fan Blade Array

2020 ◽  
Author(s):  
Syed Qasim Zaheer ◽  
Peter Disimile
Keyword(s):  
Flow Field ◽  
Vortex Shedding ◽  
Leading Edge ◽  
Pressure Side ◽  
Validation Data ◽  
Array Configuration ◽  
Blade Cascade ◽  
Fan Blade ◽  
The Impact ◽  
Blade Leading Edge

Abstract A highly cambered and loaded stationary fan blade cascade of an in-service centrifugal fan is analyzed in this research work at flow conditions corresponding to design point operation of subject fan. The configuration of enclosed blade cascade includes upstream and downstream ducts. A preliminary analysis of flow variables and nearfield acoustic spectra is carried out experimentally which then provided boundary conditions and validation data for an extensive numerical analysis using Embedded Large Eddy Simulation turbulence model in ANSYS Fluent 19.0 ® environment. The comprehensive analysis of flow field and nearfield aeroacoustics of blade array configuration reveals vortex shedding from blade leading edge and its interaction with pressure side surface of adjacent blade becomes one of major source in the aeroacoustics signature of blade array. The vortex shedding frequency and the frequency of upstream turbulence interaction with blade leading edge are identified. A novel method of placing rectangular cavity on pressure side of blade array to suppress the impact of impingement of leading-edge vortex via cavity acoustic wave is explored. The numerical results reveal a reduction in noise by 6dB encouraging the efficacy of this method as a passive technique to reduce aeroacoustics signature of researched blade array configuration.

Impact of Main and Splitter Blade Leading Edge Contour on the Performance of High Pressure Ratio Centrifugal Compressors

2014 ◽  
Author(s):  
Rodrigo R. Erdmenger ◽  
Vittorio Michelassi
Keyword(s):  
High Pressure ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Centrifugal Compressors ◽  
Operating Range ◽  
High Pressure Ratio ◽  
The Impact ◽  
Blade Leading Edge

The impact of leading edge sweep in an attempt to reduce shock losses and extend the stall margin on axial compressors has been extensively studied, however only a few studies have looked at understanding the impact of leading edge contouring on the performance of centrifugal compressors. The present work studies the impact of forward and aft sweep on the main and splitter blade leading edge of a generic high flow coefficient and high pressure ratio centrifugal compressor design and the impact on its overall peak efficiency, pressure ratio and operating range. The usage of aft sweep on the main blade led to an increase of the pressure ratio and efficiency, however it also led to a reduction of the stable operating range of the impeller analyzed. The forward sweep cases analyzed where the tip leading edge was displaced axially forward showed a slight increase in pressure ratio, and a significant increase on operating range. The impact of leading edge sweep on the sensitivity of the impeller performance to tip clearance was also studied. The impeller efficiency was found to be less sensitive to an increase of tip clearance for both aft and forward sweep cases studied. The forward sweep cases studied also showed a reduced sensitivity from operating range to tip clearance. The studies conducted on the splitter leading edge profile indicate that aft sweep may help to increase the operating range of the impeller analyzed by up to 16% while maintaining similar pressure ratio and efficiency characteristics of the impeller. The improvement of operating range obtained with the leading edge forward sweep and splitter aft sweep was caused by a reduction of the interaction of the tip vortex of the main blade with the splitter tip, and a reduction of the blockage caused by this interaction.

Viscoplastic Effects Occurring in Impacts of Aluminum and Steel Bodies and Their Influence on the Coefficient of Restitution

2010 ◽  
Vol 77 (4) ◽  
Author(s):  
Robert Seifried ◽  
Hirofumi Minamoto ◽  
Peter Eberhard
Keyword(s):  
Kinetic Energy ◽  
Strain Rate ◽  
Yield Stress ◽  
Split Hopkinson Pressure Bar ◽  
Material Model ◽  
Coefficient Of Restitution ◽  
Material Behavior ◽  
Steel Sphere ◽  
Elastic Plastic ◽  
The Impact

Generally speaking, impacts are events of very short duration and a common problem in machine dynamics. During impact, kinetic energy is lost due to plastic deformation near the contact area and excitation of waves. Macromechanically, these kinetic energy losses are often summarized and expressed by a coefficient of restitution, which is then used for impact treatment in the analysis of the overall motion of machines. Traditionally, the coefficient of restitution has to be roughly estimated or measured by experiments. However, more recently finite element (FE) simulations have been used for its evaluation. Thereby, the micromechanical plastic effects and wave propagation effects must be understood in detail and included in the simulations. The plastic flow, and thus the yield stress of a material, might be independent or dependent of the strain-rate. The first material type is called elastic-plastic and the second type is called elastic-viscoplastic. In this paper, the influence of viscoplasticity of aluminum and steel on the impact process and the consequences for the coefficient of restitution is analyzed. Therefore, longitudinal impacts of an elastic, hardened steel sphere on aluminum AL6060 rods and steel S235 rods are investigated numerically and experimentally. The dynamic material behavior of the specimens is evaluated by split Hopkinson pressure bar tests and a Perzyna-like material model is identified. Then, FE impact simulations and impact experiments with laser-doppler-vibrometers are performed. From these investigations it is shown that strain-rate effects of the yield stress are extremely small for impacts on aluminum but are significant in impacts on steel. In addition, it is demonstrated that it is possible to evaluate for both impact systems the coefficient of restitution numerically, whereas for the aluminum body a simple elastic-plastic material model is sufficient. However, for the steel body an elastic-viscoplastic material model must be included.

The Effect of Blade Leading Edge Platform Shape on Upstream Disk Cavity to Mainstream Flow Interaction of a High-Pressure Turbine Stage

2007 ◽  
Author(s):  
Remo Marini ◽  
Sami Girgis
Keyword(s):  
Leading Edge ◽  
Cavity Flow ◽  
Flow Interaction ◽  
Passage Vortex ◽  
Mainstream Flow ◽  
Transient Simulations ◽  
The Impact ◽  
Stage Efficiency ◽  
Engine Condition ◽  
Blade Leading Edge

This paper presents a CFD study of a transonic highpressure 1-stage turbine that includes the blade upstream disk cavity. The emphasis of the analysis was to understand and quantify the impact of the blade leading edge platform shape on the flow interaction between the upstream disk cavity flow and the gaspath mainstream flow. Two blade platform shapes were analyzed: a recessed and a raised leading edge shape. The results presented include steadystate and transient simulations in order to describe the flow interaction and quantify the impact on stage efficiency. A sensitivity analysis on the amount of cavity flow was performed to investigate the impact on secondary losses (interpreted by entropy generation) and stage efficiency. It was found that the blade leading edge platform shape and cavity flow amount affected the blade hub passage vortex structure and location. At the nominal engine condition, the raised leading edge platform shape showed an improvement in stage efficiency. It also showed a reduced sensitivity of stage efficiency due to cavity flow amount.

Effect of Anti-Wear Tape on Behavior of Flexible Risers

2014 ◽  
Author(s):  
Chongyao Zhou ◽  
Naiquan Ye ◽  
Svein Sævik
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Cross Section ◽  
Bending Moment ◽  
Laboratory Measurements ◽  
Flexible Riser ◽  
Bending Loads ◽  
Flexible Risers ◽  
Bending Behavior ◽  
The Impact

The service life of a flexible riser is often dominated by the metallic layers under cyclic bending loads, particularly the tensile armor layers. The effect of the anti-wear tapes is normally omitted during cross section modelling, where a plane-remain-plane assumption is usually used for stick condition. Significant differences have been observed between numerical analysis assuming plane surfaces remain plane and laboratory measurements studying the bending moment versus curvature for a flexible riser which has anti-wear tapes between the two tensile armor layers. A new shear interaction algorithm has been developed in the numerical model to improve the modeling of the anti-wear tapes by taking the thickness and shear modulus of the anti-wear material into account. The impact of these parameters on the bending behavior of the flexible riser is demonstrated by comparing the numerical analysis results with the laboratory measurements.

Foreign Objects Damage on the Leading Edge of the Blade with Centrifugal Preload

2011 ◽  
Vol 148-149 ◽  
pp. 958-962
Author(s):  
Dong Mei Yin ◽  
Zhen Xiao Li
Keyword(s):  
Leading Edge ◽  
Relaxation Method ◽  
Foreign Object ◽  
Nonlinear Dynamic Model ◽  
Foreign Object Damage ◽  
Foreign Objects ◽  
Dynamic Relaxation Method ◽  
The Moment ◽  
In The Beginning ◽  
The Impact

The influence of centrifugal prestress on the foreign object damage of engine blades was analyzed by numerical simulation. A nonlinear dynamic model for foreign object damage of blade with centrifugal prestress was established. And the dynamic relaxation method was used to obtain the initial stress and displacement field of blade in the beginning of the dynamic analysis of impact. Numerical simulations of foreign objects impacting on the leading edges of the blades under different centrifugal preloads were carried out. The results indicate that the local plastic deformation on the impact location of blade with centrifugal preload, which is produced at the moment of impact, is decreasing with the increase of the preload. The growth of crack produced on the lead edge of blade is accelerated with the preload increasing.

scholarly journals Numerical Investigations of Film Cooling and Particle Impact on the Blade Leading Edge

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1102
Author(s):  
Ke Tian ◽  
Zicheng Tang ◽  
Jin Wang ◽  
Milan Vujanović ◽  
Min Zeng ◽  
...  
Keyword(s):  
Particle Size ◽  
Film Cooling ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Leading Edge ◽  
Turbine Engines ◽  
Small Particles ◽  
The Impact ◽  
First Time ◽  
Blade Leading Edge

As a vital power propulsion device, gas turbines have been widely applied in aircraft. However, fly ash is easily ingested by turbine engines, causing blade abrasion or even film hole blockage. In this study, a three-dimensional turbine cascade model is conducted to analyze particle trajectories at the blade leading edge, under a film-cooled protection. A deposition mechanism, based on the particle sticking model and the particle detachment model, was numerically investigated in this research. Additionally, the invasion efficiency of the AGTB-B1 turbine blade cascade was investigated for the first time. The results indicate that the majority of the impact region is located at the leading edge and on the pressure side. In addition, small particles (1 μm and 5 μm) hardly impact the blade’s surface, and most of the impacted particles are captured by the blade. With particle size increasing, the impact efficiency increases rapidly, and this value exceeds 400% when the particle size is 50 μm. Invasion efficiencies of small particles (1 μm and 5 μm) are almost zero, and the invasion efficiency approaches 12% when the particle size is 50 μm.

Impact of Tip Clearance Size and Rotation Speed on the Surge Onset in a High Pressure Centrifugal Compressor

2012 ◽  
Author(s):  
Nicolas Buffaz ◽  
Isabelle Trébinjac
Keyword(s):  
Centrifugal Compressor ◽  
Rotation Speed ◽  
Pressure Sensors ◽  
Leading Edge ◽  
Suction Side ◽  
Boundary Layer Separation ◽  
Tip Clearance ◽  
Vaned Diffuser ◽  
The Impact ◽  
Blade Leading Edge

The results presented in the paper aim at investigating the impact of tip clearance size and rotation speed on the surge onset in a transonic single-stage centrifugal compressor composed of a backswept splittered unshrouded impeller and a vaned diffuser. For that purpose, various slow throttle ramps into surge were conducted from 100% to 60% design speed of the compressor and two different tip clearance heights were investigated. The 1MW LMFA-ECL test rig was used to carry out the tests in the compressor stage. Unsteady pressure measurements up to 150 KHz were carried out in the inducer (i.e. the entry zone of the impeller between the main blade leading edge and the splitter blade leading edge) and in the diffuser thanks to nine and fifteen static pressure sensors respectively. At cruise rotation speed (92.7% of the nominal rotation speed), the surge is triggered by a boundary layer separation on the diffuser vane suction side whatever the tip clearance height may be. No precursor of surge or pre-surge activity has been recorded in the diffuser or in the impeller. The surge reveals a spike-type inception and the tip clearance increase does not change the path into instability. At lower rotation speeds high frequency disturbances (nearly half the BPF) have been recorded in the inducer before surge. These disturbances can be understood as “tip clearance rotating disturbances” because they are generated at the leading edge of the main blades and move along the tip clearance trajectory. These disturbances reveal a very unstable behavior while the compressor runs into a stable operating point even if the flow at the tip of impeller is dramatically affected by these disturbances. But these disturbances do not trigger the surge which always originates in the diffuser.

scholarly journals Foreign Object Damage characteristics and their effects on high cycle fatigue property of Ni-based superalloy GH4169

2021 ◽  
Author(s):  
Xu Jia ◽  
Zi-wen Zhang ◽  
Chen Ling ◽  
Xu-ping Lu ◽  
Rong Jiang ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Numerical Analysis ◽  
High Speed ◽  
High Cycle Fatigue ◽  
Shear Bands ◽  
Leading Edge ◽  
Fatigue Property ◽  
Foreign Object ◽  
Cycle Fatigue ◽  
Gh4169 Alloy

In this study, high-speed ballistic impact tests were conducted on GH4169 alloy samples with the aeroengine compressor blade leading edge feature to simulate the notch-type foreign object damages (FOD). Macroscopic and microscopic characterization of FOD and high cycle fatigue tests were performed to investigate the effect of FOD depth on GH4169 alloy fatigue strength along with numerical analysis using Kitagawa-Takahashi diagram. Results show the incident side of notch-type FOD is relatively smooth, whereas the exit side is rugged. The FOD depth ranges from 0.18mm to 1.33mm, and the fatigue strength of damaged samples is 37.93%~97.04% of the undamaged samples. As FOD depth increases, damage length, material losses and stress concentration coefficient of the FOD increase significantly along with the increasing adiabatic shear bands, micro voids and cracks, resulting in fatigue strength reduction. Numerical analysis indicates that the Kitagawa-Takahashi diagram can provide a basic model for the design of FOD tolerance.

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