Visualization and Time-Resolved Particle Image Velocimetry Measurements of the Flow in the Tip Region of a Subsonic Compressor Rotor

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
David Tan ◽  
Yuanchao Li ◽  
Ian Wilkes ◽  
Rinaldo L. Miorini ◽  
Joseph Katz
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Axial Compressor ◽  
Time Resolved ◽  
Tip Leakage ◽  
Compressor Rotor ◽  
Direct Measurements ◽  
Image Velocimetry ◽  
The One ◽  
And Behavior

A new optically index matched facility has been constructed to investigate tip flows in compressor-like settings. The blades of the one and a half stage compressor have the same geometry, but lower aspect ratio as the inlet guide vanes (IGVs) and the first stage of the low-speed axial compressor (LSAC) facility at NASA Glenn. With transparent blades and casings, the new setup enables unobstructed velocity measurements at any point within the tip region and is designed to facilitate direct measurements of effects of casing treatments on the flow structure. We start with a smooth endwall casing. High speed movies of cavitation and time-resolved PIV measurements have been used to characterize the location, trajectory, and behavior of the tip leakage vortex (TLV) for two flow rates, the lower one representing prestall conditions. Results of both methods show consistent trends. As the flow rate is reduced, TLV rollup occurs further upstream, and its initial orientation becomes more circumferential. At prestall conditions, the TLV is initially aligned slightly upstream of the rotor passage, and subsequently forced downstream. Within the passage, the TLV breaks up into a large number of vortex fragments, which occupy a broad area. Consequently, the cavitation in the TLV core disappears. With decreasing flow rate, this phenomenon becomes more abrupt, occurs further upstream, and the fragments occupy a larger area.

Visualization and Time Resolved PIV Measurements of the Flow in the Tip Region of a Subsonic Compressor Rotor

2014 ◽  
Author(s):  
David Tan ◽  
Yuanchao Li ◽  
Ian Wilkes ◽  
Rinaldo L. Miorini ◽  
Joseph Katz
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Time Resolved ◽  
Piv Measurements ◽  
Tip Leakage ◽  
Compressor Rotor ◽  
Direct Measurements ◽  
The One ◽  
And Behavior ◽  
Casing Treatments

A new optically index matched facility has been constructed to investigate tip flows in compressor-like settings. The blades of the one and a half stage have the same geometry, but lower aspect ratio as the inlet guide vanes and the first stage of the LSAC facility at NASA Glenn. With transparent blades and casings, the new setup enables unobstructed velocity measurements at any point within the tip region, and is designed to facilitate direct measurements of effects of casing treatments on the flow structure. We start with a smooth endwall casing. High speed movies of cavitation and time-resolved PIV measurements have been used to characterize the location, trajectory, and behavior of the Tip Leakage Vortex (TLV) for two flow rates, the lower one representing pre-stall conditions. Results of both methods show consistent trends. As the flow rate is reduced, TLV rollup occurs further upstream, and its initial orientation becomes more circumferential. At pre-stall conditions, the TLV is initially aligned slightly upstream of the rotor passage, and subsequently forced downstream. Within the passage, the TLV breaks up into a large number of vortex fragments, which occupy a broad area. Consequently, the cavitation in the TLV core disappears. With decreasing flow rate, this phenomenon becomes more abrupt, occurs further upstream, and the fragments occupy a larger area.

Stall Inception and Development Process Due to Tip Leakage Flow in Axial Compressor Rotor Blades Row

2014 ◽  
Vol 30 (3) ◽  
pp. 307-313 ◽  
Author(s):  
R. Taghavi-Zenou ◽  
S. Abbasi ◽  
S. Eslami
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Leading Edge ◽  
Rotor Blades ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Compressor Rotor

ABSTRACTThis paper deals with tip leakage flow structure in subsonic axial compressor rotor blades row under different operating conditions. Analyses are based on flow simulation utilizing computational fluid dynamic technique. Three different circumstances at near stall condition are considered in this respect. Tip leakage flow frequency spectrum was studied through surveying instantaneous static pressure signals imposed on blades surfaces. Results at the highest flow rate, close to the stall condition, showed that the tip vortex flow fluctuates with a frequency close to the blade passing frequency. In addition, pressure signals remained unchanged with time. Moreover, equal pressure fluctuations at different passages guaranteed no peripheral disturbances. Tip leakage flow frequency decreased with reduction of the mass flow rate and its structure was changing with time. Spillage of the tip leakage flow from the blade leading edge occurred without any backflow in the trailing edge region. Consequently, various flow structures were observed within every passage between two adjacent blades. Further decrease in the mass flow rate provided conditions where the spilled flow ahead of the blade leading edge together with trailing edge backflow caused spike stall to occur. This latter phenomenon was accompanied by lower frequencies and higher amplitudes of the pressure signals. Further revolution of the rotor blade row caused the spike stall to eventuate to larger stall cells, which may be led to fully developed rotating stall.

Numerical Investigation of Active Flow Control Using Tip Synthetic Jet on the Performance of a High-Speed Axial Compressor Rotor

2020 ◽  
Author(s):  
Guang Wang ◽  
Wuli Chu
Keyword(s):  
Flow Control ◽  
High Speed ◽  
Active Flow Control ◽  
Axial Compressor ◽  
Synthetic Jet ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Compressor Rotor ◽  
The Stability ◽  
Active Flow

Abstract In order to weaken the negative effect of tip leakage flow and improve the tip flow condition, this paper introduces synthetic jet into the flow control field of axial compressor, and proposes a method of active flow control by arranging synthetic jet at the tip. A high-speed axial compressor rotor of the author’s research group is taken as the numerical simulation object. On the basis of keeping geometric parameters of the synthetic jet actuator unchanged, this paper studies the influence of applying tip synthetic jet on aerodynamic performance of the compressor rotor at three axial positions of −10%Ca, 0%Ca and 21.35%Ca respectively. The results show that when tip synthetic jet is in the above three positions, comprehensive stability margin of the compressor rotor increases by 2.62%, 3.77% and 12.46% respectively, and efficiency near stall point increases by 0.22%, 0.25 and 0.47% respectively. This shows that when tip synthetic jet is far away from blade, the aerodynamic performance improvement of the compressor rotor is limited, and when tip synthetic jet is just above the leading edge, the effect of expanding stability is the best and the efficiency is the most improved. The mechanism of tip synthetic jet can increase the stability of the compressor rotor is that when the actuator is in the blowing stage, it can blow the low-speed air flow of blade top to downstream, and when the actuator is in the suction stage, it can suck the low-speed air flow of blade top into slot, so as to alleviate the top blockage and realize the stability expansion. The mechanism of tip synthetic jet can improve the efficiency of compressor rotor is that the blowing and suction of actuator weaken the intensity of tip leakage flow, reduce the size of vortex core and also reduce the flow loss of the compressor rotor correspondingly.

Measurement of the Three-Dimensional Tip Region Flow Field in an Axial Compressor

1993 ◽  
Vol 115 (3) ◽  
pp. 468-476 ◽  
Author(s):  
R. C. Stauter
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Time Resolved ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Rotating Blade ◽  
Flow Phenomena ◽  
Component Velocity ◽  
And Behavior

A two-color, five-beam LDV system has been configured to make simultaneous three-component velocity measurements of the flow field in a two-stage axial compressor model. The system has been used to make time-resolved measurements both between compressor blade rows and within the rotating blade passages in an axial compressor. The data show the nature and behavior of the complex, three-dimensional flow phenomena present in the tip region of a compressor as they convect downstream. In particular, the nature of the tip leakage vortex is apparent, being manifested by high blockage as well as the expected vortical motion. The data indicate that the radial flows associated with the tip leakage vortex begin to decrease while within the rotor passage, and that they temporarily increase aft of the passage.

A Novel Stall Warning Indicator: Part I — Applications and Limitations

2019 ◽  
Author(s):  
Roland Rückert ◽  
Mario Eck ◽  
Dieter Peitsch ◽  
Marc Lehmann
Keyword(s):  
High Speed ◽  
Axial Compressor ◽  
Leading Edge ◽  
Experimental Tests ◽  
Axial Direction ◽  
Time Resolved ◽  
Compressor Rotor ◽  
Flight Operations ◽  
Stall Warning ◽  
The Impact

Abstract The present work is the first of two papers investigating the operation principle of stall warning quantities. It discusses the use and implementation of novel stall warning techniques based on experimental tests. Each of the addressed techniques is based upon integral statistical analysis of time-resolved wall pressures in close proximity to the leading edge of a compressor rotor. The experiments were conducted on a low speed axial compressor test rig at the Chair of Aeroengines at the Technische Universität Berlin. The compressor suffers from a specific type of pre-stall instability. The signature within the frequency spectrum of this semi-stable operating point is in itself unique and was observed by many within the scientific community on numerous occasions and various axial compressor types, both low and high speed. Strong evidence has been elaborated which indicate that each of those so called stall warning indicator’s functionality is based upon the existence of this prestall phenomena. The first of two indicators is time-dependent as it evaluates the as-is state against surrounding operating points during transient manoeuvres. Furthermore, the impact of varying geometrical boundary conditions, which are known to regularly arise in flight operations, were taken into account. The functionality of the indicator is assured if the instrumentation is adjusted accordingly. The second indicator is mainly a location-dependent quantity as it evaluates the pressure signature along the axial direction within the rotor passage at various aerodynamic loadings. The latter also gave rise to some fundamental and preliminary understanding of the physics behind so called prestall disturbances.

scholarly journals Measurement of the Three-Dimensional Tip Region Flowfield in an Axial Compressor

1992 ◽  
Author(s):  
R. C. Stauter
Keyword(s):  
Three Dimensional ◽  
Axial Compressor ◽  
Time Resolved ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Rotating Blade ◽  
Flow Phenomena ◽  
Component Velocity ◽  
Vortical Motion ◽  
And Behavior

A two-color, five-beam LDV system has been configured to make simultaneous three-component velocity measurements of the flow field in a two-stage axial compressor model. The system has been used to make time-resolved measurements both between compressor blade rows as well as within the rotating blade passages in an axial compressor. The data show the nature and behavior of the complex, three-dimensional flow phenomena present in the tip region of a compressor as they convect downstream. In particular, the nature of the tip leakage vortex is apparent, being manifested by high blockage as well as the expected vortical motion. The data indicate that the radial flows associated with the tip leakage vortex begin to decrease while within the rotor passage, and that they temporarily increase aft of the passage.

Study of the Standard k-ε Model for Tip Leakage Flow in an Axial Compressor Rotor

2016 ◽  
Vol 33 (4) ◽  
Author(s):  
Yanfei Gao ◽  
Yangwei Liu ◽  
Luyang Zhong ◽  
Jiexuan Hou ◽  
Lipeng Lu
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Turbulent Viscosity ◽  
Axial Compressor ◽  
Leakage Flow ◽  
Reynolds Stresses ◽  
Mean Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Compressor Rotor

AbstractThe standard k-ε model (SKE) and the Reynolds stress model (RSM) are employed to predict the tip leakage flow (TLF) in a low-speed large-scale axial compressor rotor. Then, a new research method is adopted to “freeze” the turbulent kinetic energy and dissipation rate of the flow field derived from the RSM, and obtain the turbulent viscosity using the Boussinesq hypothesis. The Reynolds stresses and mean flow field computed on the basis of the frozen viscosity are compared with the results of the SKE and the RSM. The flow field in the tip region based on the frozen viscosity is more similar to the results of the RSM than those of the SKE, although certain differences can be observed. This finding indicates that the non-equilibrium turbulence transport nature plays an important role in predicting the TLF, as well as the turbulence anisotropy.

Unveiling the Flow Behavior Inside GDI Engine Cylinder Using High-Speed Time-Resolved Particle Image Velocimetry and CFD Simulation

2021 ◽  
Author(s):  
Mohammed El Adawy ◽  
Morgan Heikal ◽  
bin Abd. Aziz Abd. Rashid
Keyword(s):  
Particle Image Velocimetry ◽  
High Speed ◽  
Particle Image ◽  
Cfd Simulation ◽  
Injection Pressure ◽  
Valve Lift ◽  
Fuel Spray ◽  
Time Resolved ◽  
Image Velocimetry ◽  
Spray Plume

Abstract RICARDO-VECTIS CFD simulation of the in-cylinder air flow was first validated with those of the experimental results from high-speed particle image velocimetry (PIV) measurements taking cognisant of the mid-cylinder tumble plane. Furthermore, high-speed fuel spray measurements were carried out simultaneously with the intake-generated tumble motion at high valve lift using high-speed time-resolved PIV to chronicle the spatial and time-based development of air/fuel mixture. The effect of injection pressure(32.5 and 35.0 MPa) and pressure variation across the air intake valves(150, 300 and 450 mmH2O) on the interaction process were investigated at valve lift 10 mm where the tumble vortex was fully developed and filled the whole cylinder under steady-state conditions. The PIV results illustrated that the intake generated-tumble motion had a substantial impact on the fuel spray distortion and dispersion inside the cylinder. During the onset of the injection process the tumble motion diverted the spray plume slightly towards the exhaust side before it followed completely the tumble vortex. The fuel spray plume required 7.2 ms, 6.2 ms and 5.9 ms to totally follow the in-cylinder air motion for pressure differences 150, 300 and 450 mmH2O, respectively. Despite, the spray momentum was the same for the same injection pressure, the magnitude of kinetic energy was different for different cases of pressure differences and subsequently the in-cylinder motion strength.

Spatio-Temporal Development of Supercavitation Over an Impulsively Launched Projectile

2006 ◽  
Author(s):  
C. J. Weiland ◽  
P. P. Vlachos
Keyword(s):  
High Speed ◽  
Temporal Development ◽  
Two Phase ◽  
Time Resolved ◽  
Gas Gun ◽  
Supercavitating Flow ◽  
Image Velocimetry ◽  
Spatio Temporal ◽  
Asymmetric Vortices ◽  
First Time

Supercavitation inception and formation was studied over blunt projectiles. The projectiles were fired using a gas gun method. In this method, projectiles are launched under the action of expanding detonation gases. Both qualitative and quantitative optical flow diagnostics using high speed digital imaging were used to analyze the spatio-temporal development of the supercavitating flow. For the first time, quantification of the supercavitation was achieved using Time Resolved Digital Particle Image Velocimetry (TRDPIV) detailing the two phase flow field surrounding the translating projectiles and the gas vapor bubble. Experimental results indicate that the supercavity forms at the aft end of the projectile and travels forward along the direction of projectile travel. The impulsive start of the projectile generates two asymmetric vortices which are shed from the blunt nose of the projectile. The vortices interact with the moving cavity and subsequently deform. This interaction is believed to directly contribute to the instabilities in the flight path.

Numerical Investigation of Relation Between Unsteady Behavior of Tip Leakage Vortex and Rotating Disturbance in a Transonic Axial Compressor Rotor

2008 ◽  
Author(s):  
K. Yamada ◽  
K. Funazaki ◽  
H. Sasaki
Keyword(s):  
Vortex Breakdown ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Tip Leakage Vortex ◽  
Tip Clearance Flow ◽  
Tip Leakage ◽  
Compressor Rotor ◽  
Clearance Flow ◽  
Transonic Axial Compressor ◽  
Rotating Instability

The purpose of this study is to have a better understanding of the unsteady behavior of tip clearance flow at near-stall condition from a multi-passage simulation and to clarify the relation between such unsteadiness and rotating disturbance. This study is motivated by the following concern. A single passage simulation has revealed the occurrence of the tip leakage vortex breakdown at near-stall condition in a transonic axial compressor rotor, leading to the unsteadiness of the tip clearance flow field in the rotor passage. These unsteady flow phenomena were similar to those in the rotating instability, which is classified in one of the rotating disturbances. In other words it is possible that the tip leakage vortex breakdown produces a rotating disturbance such as the rotating instability. Three-dimensional unsteady RANS calculation was conducted to simulate the rotating disturbance in a transonic axial compressor rotor (NASA Rotor 37). The four-passage simulation was performed so as to capture a short length scale disturbance like the rotating instability and the spike-type stall inception. The simulation demonstrated that the unsteadiness of tip leakage vortex, which was derived from the vortex breakdown at near-stall condition, invoked the rotating disturbance in the rotor, which is similar to the rotating instability.

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