Mechanisms and Key Parameters for Compressor Blade Stall Flutter

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Xiaowei Zhang ◽  
Yanrong Wang ◽  
Kening Xu
Keyword(s):  
Shock Wave ◽  
Numerical Method ◽  
Compressor Blade ◽  
Suction Surface ◽  
Structure Interaction ◽  
Compressor Rotor ◽  
Flutter Boundary ◽  
Stall Flutter ◽  
Interblade Phase Angle ◽  
Wave Properties

This paper describes a fluid-structure interaction (FSI) numerical method in frequency domain to improve the overall understanding of the mechanisms of compressor blade stall flutter and to identify the key flutter parameters. The numerical method, whose accuracy is verified by comparing the numerical predicted stall flutter boundary with that measured through engine rig tests in a compressor rotor, is applied to investigate the effects of blade mode, reduced velocity, and interblade phase angle (IBPA) on flutter stability, and to reveal the flutter mechanisms directly related to shock wave properties and flow separation effects. It is found that the shock wave on the suction surface and the separation area behind it are important flutter inducements.

scholarly journals Aerodynamic Response of Turbomachinery Blade Rows to Convecting Density Wakes

2002 ◽  
Vol 124 (2) ◽  
pp. 269-274 ◽  
Author(s):  
H. S. Wijesinghe ◽  
C. S. Tan ◽  
E. E. Covert
Keyword(s):  
Shock Wave ◽  
Computational Study ◽  
Separation Bubble ◽  
Compressor Blade ◽  
Density Parameter ◽  
Two Dimensional ◽  
Suction Surface ◽  
Blade Passage ◽  
Flow Simulations ◽  
Blade Row

A two-dimensional computational study was conducted to characterize the density wake induced force and moment fluctuations on a compressor blade row. The flow simulations indicate unsteady blade excitation generated by: (1) density wake fluid directed to the blade suction surface, (2) axial deflection of the blade passage shock wave position and (3) formation of a separation bubble on the blade suction surface. The blade force and moment fluctuation amplitudes are found to scale with the nondimensional density wake width w/c and a nondimensional density parameter ρ*.

Development of Hub Corner Stall and Its Influence on the Performance of Axial Compressor Blade Rows

1999 ◽  
Vol 121 (1) ◽  
pp. 67-77 ◽  
Author(s):  
C. Hah ◽  
J. Loellbach
Keyword(s):  
Numerical Solutions ◽  
Stokes Equations ◽  
Flow Direction ◽  
Three Dimensional ◽  
Suction Side ◽  
Compressor Blade ◽  
Suction Surface ◽  
Simple Diffusion ◽  
Transonic Compressor ◽  
Compressor Rotor

A detailed investigation has been performed to study hub corner stall phenomena in compressor blade rows. Three-dimensional flows in a subsonic annular compressor stator and in a transonic compressor rotor have been analyzed numerically by solving the Reynolds-averaged Navier–Stokes equations. The numerical results and the existing experimental data are interrogated to understand the mechanism of compressor hub corner stall. Both the measurements and the numerical solutions for the stator indicate that a strong twisterlike vortex is formed near the rear part of the blade suction surface. Low-momentum fluid inside the hub boundary layer is transported toward the suction side of the blade by this vortex. On the blade suction surface near the hub, this vortex forces fluid to move against the main flow direction and a limiting stream surface is formed near the hub. The formation of this vortex is the main mechanism of hub corner stall. When the aerodynamic loading is increased, the vortex initiates further upstream, which results in a larger corner stall region. For the transonic compressor rotor studied in this paper, the numerical solution indicates that a mild hub corner stall exists at 100 percent rotor speed. The hub corner stall, however, disappears at the reduced blade loading, which occurs at 60 percent rotor design speed. The present study demonstrates that hub corner stall is caused by a three-dimensional vortex system and that it does not seem to be correlated with a simple diffusion factor for the blade row.

The Behavior of Tip Clearance Flow at Near-Stall Condition in a Transonic Axial Compressor Rotor

2007 ◽  
Author(s):  
K. Yamada ◽  
K. Funazaki ◽  
M. Furukawa
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Axial Compressor ◽  
Boundary Layer Separation ◽  
Tip Clearance ◽  
Suction Surface ◽  
Tip Clearance Flow ◽  
Compressor Rotor ◽  
Clearance Flow ◽  
Transonic Axial Compressor

It is known that the tip clearance flow is dominant and very important flow phenomena in axial compressor aerodynamics because the tip clearance flow has a great influence on the stability as well as aerodynamic loss of compressors. Our goal is to clarify the behavior of tip clearance flow at near-stall condition in a transonic axial compressor rotor (NASA Rotor 37). In the present work, steady and unsteady RANS simulations were performed to investigate vortical flow structures and separated flow field near the tip for several different clearance cases. Boundary layer separation on the casing wall and blade suction surface was investigated in detail for near-stall and stall condition. In order to understand such complicated flow field, vortex cores were identified using the critical point theory and a topology of the three-dimensional separated and vortical flows was analyzed. In the nominal clearance case, the breakdown of tip leakage vortex has occurred at a near-stall operating condition because of the interaction of the vortex with the shock wave, leading to a large blockage and unsteadiness in the rotor tip. On the other hand, the calculation with no clearance suggested that the separation on the suction surface was different from that with the nominal clearance. Since the shock wave induced the boundary layer separation on the blade suction surface in the transonic axial compressor rotor, focal-type critical points appeared on the suction surface near the tip at near-stall condition.

Development of Hub Corner Stall and its Influence on the Performance of Axial Compressor Blade Rows

1997 ◽  
Author(s):  
Chunill Hah ◽  
James Loellbach
Keyword(s):  
Numerical Solutions ◽  
Stokes Equations ◽  
Flow Direction ◽  
Three Dimensional ◽  
Suction Side ◽  
Compressor Blade ◽  
Suction Surface ◽  
Simple Diffusion ◽  
Transonic Compressor ◽  
Compressor Rotor

A detailed investigation has been performed to study hub corner stall phenomena in compressor blade rows. Three-dimensional flows in a subsonic annular compressor stator and in a transonic compressor rotor have been analyzed numerically by solving the Reynolds-averaged Navier-Stokes equations. The numerical results and the existing experimental data are interrogated to understand the mechanism of compressor hub corner stall. Both the measurements and the numerical solutions indicate that a strong twister-like vortex is formed near the rear part of the blade suction surface. Low momentum fluid inside the hub boundary layer is transported toward the suction side of the blade by this vortex. On the blade suction surface near the hub, this vortex forces fluid to move against the main flow direction and a limiting stream surface is formed near the hub. The formation of this vortex is the main mechanism of hub corner stall. When the aerodynamic loading is increased, the vortex initiates further upstream, which results in a larger corner stall region. For the transonic compressor rotor studied in this paper, the numerical solution and the measured data indicate that a mild hub corner stall exists at 100 percent rotor speed. The hub corner stall, however, disappears at the reduced blade loading which occurs at 60 percent rotor design speed. The present study demonstrates that hub corner stall is caused by a three-dimensional vortex system and that it does not seem to be correlated with a simple diffusion factor for the blade row.

Numerical Simulation of Transonic Fan Flutter With 3D N-S CFD Code

2008 ◽  
Author(s):  
Mizuho Aotsuka ◽  
Naoki Tsuchiya ◽  
Yasuo Horiguchi ◽  
Osamu Nozaki ◽  
Kazuomi Yamamoto
Keyword(s):  
Shock Wave ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Suction Surface ◽  
Navier Stokes Equations ◽  
Blade Loading ◽  
Flow Solver ◽  
Flutter Boundary ◽  
Transonic Fan ◽  
Volume Method

This paper describes the calculation of transonic stall flutter of a fan. A new CFD code has been developed and validated. The code is an unsteady 3D multi-block flow solver. The Reynolds-Averaged Navier-Stokes equations are solved using a finite volume method with Spallart-Allmaras 1 equation turbulence model. A grid deforming system is applied, so the new code is capable of simulating an oscillating blade row. This grid deforming system produces less grid distortion and the code has robustness for a blade oscillating calculation. The code has validated on an IHI’s research transonic fan rig test, and the result was in good agreement with the test data in the prediction of the flutter boundary. In the rig test at part-speed condition, stall-side flutter was experienced. In that condition, the inlet relative Mach number in the tip region is about unity. The aerodynamic work by the CFD at the near flutter condition is positive, which means that the flutter characteristic is unstable, while at other conditions the aerodynamic work is negative. The aerodynamic work increases rapidly just before the zero damping point with the increase of the blade loading. From the detailed CFD result, the shock wave on the suction surface contributes to the excitement of the blade oscillation, and the aerodynamic work of the shock wave has large value at the flutter condition.

scholarly journals Structure Analysis of Marine Pipes under the Effect of Water Explosion Force (Wave)

2017 ◽  
Vol 3 (6) ◽  
pp. 442-449 ◽  
Author(s):  
Kamran Khalifehei
Keyword(s):  
Shock Wave ◽  
Numerical Modeling ◽  
Numerical Method ◽  
Structure Analysis ◽  
Underwater Explosion ◽  
Shock Wave Loading ◽  
Wave Loading ◽  
Structure Interaction ◽  
Shockwave Loading ◽  
Abaqus Software

Underwater explosion is a subject that has been paid attention to by many researchers. In this study the underwater explosion phenomena under shockwave loading is explored by numerical method. For this purpose, by modeling a marine pipe buried in the water by ABAQUS software, the effect of the shock wave and the damages were assessed. Then using the laboratorial results, the fluid-structure interaction and shock wave loading and its results were analysed. Finally, it was concluded from numerical modeling that the highest levels of strain on the pipe buried in the water under underwater explosion and shock wave loading occur in the ending parts of the pipe in both sides and away from explosion field.

scholarly journals Aerodynamic Response of Turbomachinery Blade Rows to Convecting Density Wakes

2000 ◽  
Author(s):  
H. S. Wijesinghe ◽  
C. S. Tan ◽  
E. E. Covert
Keyword(s):  
Shock Wave ◽  
Computational Study ◽  
Separation Bubble ◽  
Compressor Blade ◽  
Density Parameter ◽  
Two Dimensional ◽  
Suction Surface ◽  
Blade Passage ◽  
Flow Simulations ◽  
Blade Row

A two–dimensional computational study was conducted to characterize the density wake induced force and moment fluctuations on a compressor blade row. The flow simulations indicate unsteady blade excitation generated by: (1) density wake fluid directed to the blade suction surface, (2) axial deflection of the blade passage shock wave position and (3) formation of a separation bubble on the blade suction surface. The blade force and moment fluctuation amplitudes are found to scale with the nondimensional density wake width w/c and a non–dimensional density parameter ρ*.

scholarly journals Computational Modeling of Vortex Generators for Turbomachinery

2002 ◽  
Author(s):  
R. V. Chima
Keyword(s):  
Computational Models ◽  
Body Force ◽  
Secondary Flows ◽  
The Body ◽  
Vortex Generators ◽  
Force Model ◽  
Suction Surface ◽  
Near Surface ◽  
Compressor Rotor ◽  
Surface Particle

In this work computational models were developed and used to investigate applications of vortex generators (VGs) to turbomachinery. The work was aimed at increasing the efficiency of compressor components designed for the NASA Ultra Efficient Engine Technology (UEET) program. Initial calculations were used to investigate the physical behavior of VGs. A parametric study of the effects of VG height was done using 3-D calculations of isolated VGs. A body force model was developed to simulate the effects of VGs without requiring complicated grids. The model was calibrated using 2-D calculations of the VG vanes and was validated using the 3-D results. Then three applications of VGs to a compressor rotor and stator were investigated: 1. The results of the 3-D calculations were used to simulate the use of small casing VGs used to generate rotor preswirl or counterswirl. Computed performance maps were used to evaluate the effects of VGs. 2. The body force model was used to simulate large partspan splitters on the casing ahead of the stator. Computed loss buckets showed the effects of the VGs. 3. The body force model was also used to investigate the use of tiny VGs on the stator suction surface for controlling secondary flows. Near-surface particle traces and exit loss profiles were used to evaluate the effects of the VGs.

Normal shock-wave properties in imperfect air and nitrogen

AIAA Journal ◽  
1965 ◽  
Vol 3 (3) ◽  
pp. 554-556 ◽  
Author(s):  
CLARK H. LEWIS ◽  
E. G. BURGESS
Keyword(s):  
Shock Wave ◽  
Normal Shock ◽  
Normal Shock Wave ◽  
Wave Properties

Comment on ‘Propagation of solitary waves and shock wavelength in the pair plasma (J. Plasma Phys. 78, 525–529, 2012)’

2014 ◽  
Vol 80 (3) ◽  
pp. 513-516
Author(s):  
Frank Verheest
Keyword(s):  
Shock Wave ◽  
Solitary Wave ◽  
Solitary Waves ◽  
Plasma Phys ◽  
Theoretical Underpinning ◽  
Pair Plasma ◽  
Electrons And Positrons ◽  
Small Dissipation ◽  
Pseudopotential Approach ◽  
Wave Properties

In a recent paper ‘Propagation of solitary waves and shock wavelength in the pair plasma (J. Plasma Phys. 78, 525–529, 2012)’, Malekolkalami and Mohammadi investigate nonlinear electrostatic solitary waves in a plasma comprising adiabatic electrons and positrons, and a stationary ion background. The paper contains two parts: First, the solitary wave properties are discussed through a pseudopotential approach, and then the influence of a small dissipation is intuitively sketched without theoretical underpinning. Small dissipation is claimed to lead to a shock wave whose wavelength is determined by linear oscillator analysis. Unfortunately, there are errors and inconsistencies in both the parts, and their combination is incoherent.

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