Rotating Stall Observations in a High Speed Compressor—Part I: Experimental Study

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
J. Dodds ◽  
M. Vahdati
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Low Frequency ◽  
Axial Flow ◽  
Rotating Stall ◽  
Strain Gages ◽  
Spectral Content ◽  
Pressure Transducers ◽  
Unsteady Rans ◽  
Variable Stator

In this two-part paper, the phenomenon of part span rotating stall is studied. The objective is to improve understanding of the physics by which stable and persistent rotating stall occurs within high speed axial flow compressors. This phenomenon is studied both experimentally (Part I) and through the use of unsteady RANS simulations (Part II). In this paper, the behavior of an eight stage high speed compressor is studied during slow acceleration maneuvres along a fixed working line. Casing mounted pressure transducers and rotor mounted strain gages are used to examine the spectral content of any unsteadiness in the flow and its behavior across the operating range. By deliberate aerodynamic mismatching of the front stages through adjustment of three rows of variable stator vanes (VSVs), stable rotating stall is initiated. The observed behavior falls into two “families” of high and low frequency when tracked on the instrumentation. Further analysis based on the Doppler shift between the static and rotating measurements confirms that these respective phenomena are due to rotating stall of high and low cell count. Acoustic modes resulting from stall/rotor interaction are also identified. Strong correlation of the stall intensity with simple 1D meanline predicted loading parameters suggests that these families of behavior are independently linked to the stalling of different regions within the compressor.

Rotating Stall Observations in a High Speed Compressor: Part 1 — Experimental Study

2014 ◽  
Author(s):  
J. Dodds ◽  
M. Vahdati
Keyword(s):  
High Speed ◽  
Low Frequency ◽  
Axial Flow ◽  
Rotating Stall ◽  
Strain Gauges ◽  
Spectral Content ◽  
Pressure Transducers ◽  
Unsteady Rans ◽  
Observed Behaviour ◽  
Variable Stator

In this two part paper the phenomenon of part span rotating stall is studied. The objective is to improve understanding of the physics by which stable and persistent rotating stall occurs within high speed axial flow compressors. This phenomenon is studied both experimentally (part 1) and through the use of unsteady RANS simulations (part 2). In this paper, the behaviour of an 8 stage high speed compressor is studied during slow acceleration manoeuvres along a fixed working line. Casing mounted pressure transducers and rotor mounted strain gauges are used to examine the spectral content of any unsteadiness in the flow and its behaviour across the operating range. By deliberate aerodynamic mismatching of the front stages through adjustment of three rows of variable stator vanes, stable rotating stall is initiated. The observed behaviour falls into two ‘families’ of high and low frequency when tracked on the instrumentation. Further analysis based on the Doppler shift between the static and rotating measurements confirms that these respective phenomena are due to rotating stall of high and low cell count. Acoustic modes resulting from stall/rotor interaction are also identified. Strong correlation of the stall intensity with simple 1D meanline predicted loading parameters suggests that these families of behaviour are independently linked to the stalling of different regions within the compressor.

Rotating Stall Observations in a High Speed Compressor—Part II: Numerical Study

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
J. Dodds ◽  
M. Vahdati
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Axial Flow ◽  
Leading Edge ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Numerical Predictions ◽  
Stage 1 ◽  
Variable Stator

In this two-part paper the phenomenon of part span rotating stall is studied. The objective is to improve understanding of the physics by which stable and persistent rotating stall occurs within high speed axial flow compressors. This phenomenon is studied both experimentally (Part I) and numerically (Part II). The experimental observations reported in Part I are now explored through the use of 3D unsteady Reynolds-averaged Navier–Stokes (RANS) simulation. The objective is to both validate the computational model and, where possible, explore some physical aspects of the phenomena. Unsteady simulations are presented, performed at a fixed speed with the three rows of variable stator vanes adjusted to deliberately mismatch the front stages and provoke stall. Two families of rotating stall are identified by the model, consistent with experimental observations from Part I. The first family of rotating stall originates from hub corner separations developing on the stage 1 stator vanes. These gradually coalesce into a multicell rotating stall pattern confined to the hub region of the stator and its downstream rotor. The second family originates from regions of blockage associated with tip clearance flow over the stage 1 rotor blade. These also coalesce into a multicell rotating stall pattern of shorter length scale confined to the leading edge tip region. Some features of each of these two patterns are then explored as the variable stator vanes (VSVs) are mismatched further, pushing each region deeper into stall. The numerical predictions show a credible match with the experimental findings of Part I. This suggests that a RANS modeling approach is sufficient to capture some important aspects of part span rotating stall behavior.

Rotating Stall Observations in a High Speed Compressor: Part 2 — Numerical Study

2014 ◽  
Author(s):  
J. Dodds ◽  
M. Vahdati
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Axial Flow ◽  
Leading Edge ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Numerical Predictions ◽  
Stage 1 ◽  
Variable Stator

In this two part paper the phenomenon of part span rotating stall is studied. The objective is to improve understanding of the physics by which stable and persistent rotating stall occurs within high speed axial flow compressors. This phenomenon is studied both experimentally (part 1) and numerically (part 2). The experimental observations reported in Part 1 are now explored through the use of 3D unsteady RANS simulation. The objective is to both to validate the computational model and, where possible, explore some physical aspects of the phenomena. Unsteady simulations are presented, performed at a fixed speed with the three rows of variable stator stagger vanes adjusted to deliberately mismatch the front stages and provoke stall. Two families of rotating stall are identified by the model, consistent with experimental observations from Part 1. The first family of rotating stall originates from hub corner separations developing on the stage 1 stator vanes. These gradually coalesce into a multi-cell rotating stall pattern confined to the hub region of the stator and its downstream rotor. The second family originates from regions of blockage associated with tip clearance flow over the stage 1 rotor blade. These also coalesce into a multi-cell rotating stall pattern of shorter length scale confined to the leading edge tip region. Some features of each of these two patterns are then explored as the variable stator vanes are mismatched further, pushing each region deeper into stall. The numerical predictions show a credible match with the experimental findings of Part 1. This suggests that a RANS modelling approach is sufficient to capture some important aspects of part span rotating stall behavior.

Stall Inception in a High Speed Centrifugal Compressor During Speed Transients

2017 ◽  
Author(s):  
Fangyuan Lou ◽  
John C. Fabian ◽  
Nicole L. Key
Keyword(s):  
Heat Transfer ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Flow Instability ◽  
Leading Edge ◽  
Fast Response ◽  
Rotating Stall ◽  
Transient Performance ◽  
Stall Inception ◽  
Pressure Transducers

The inception and evolution of rotating stall in a high-speed centrifugal compressor are characterized during speed transients. Experiments were performed in the Single Stage Centrifugal Compressor (SSCC) facility at Purdue University and include speed transients from sub-idle to full speed at different throttle settings while collecting transient performance data. Results show a substantial difference in the compressor transient performance for accelerations versus decelerations. This difference is associated with the heat transfer between the flow and the hardware. The heat transfer from the hardware to the flow during the decelerations locates the compressor operating condition closer to the surge line and results in a significant reduction in surge margin during decelerations. Additionally, data were acquired from fast-response pressure transducers along the impeller shroud, in the vaneless space, and along the diffuser passages. Two different patterns of flow instabilities, including mild surge and short-length-scale rotating stall, are observed during the decelerations. The instability starts with a small pressure perturbation at the impeller leading edge and quickly develops into a single-lobe rotating stall burst. The stall cell propagates in the direction opposite of impeller rotation at approximately one third of the rotor speed. The rotating stall bursts are observed in both the impeller and diffuser, with the largest magnitudes near the diffuser throat. Furthermore, the flow instability develops into a continuous high frequency stall and remains in the fully developed stall condition.

scholarly journals An Investigation of Surge in a High-Speed Centrifugal Compressor Using Digital PIV

2000 ◽  
Vol 123 (2) ◽  
pp. 418-428 ◽  
Author(s):  
Mark P. Wernet ◽  
Michelle M. Bright ◽  
Gary J. Skoch
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Transient Flow ◽  
Dynamic Pressure ◽  
Rotating Stall ◽  
Transient Pressure ◽  
Pressure Transducers ◽  
Stable Operating ◽  
Particle Imaging

Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a loss of engine power, large pressure transients in the inlet/nacelle, and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to control these events successfully. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to capture transient velocity and pressure measurements simultaneously in the nonstationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique that is ideally suited for studying transient flow phenomena in high-speed turbomachinery and has been used previously to map the stable operating point flow field in the diffuser of a high-speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

Experimental investigations on instability evolution in a transonic compressor at different rotor speeds

2015 ◽  
Vol 229 (18) ◽  
pp. 3378-3391 ◽  
Author(s):  
Qiushi Li ◽  
Tianyu Pan ◽  
Tailu Sun ◽  
Zhiping Li ◽  
Yifang Gong
Keyword(s):  
Low Frequency ◽  
Axial Flow ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Rotor Speed ◽  
Axial Flow Compressor ◽  
Transonic Compressor ◽  
New Type ◽  
Flow Compressor

Experimental investigations are conducted to study the instability evolution in a transonic axial flow compressor at four specific rotor speeds covering both subsonic and transonic operating conditions. Two routes of evolution to final instability are observed in the test compressor: at low rotor speeds, a disturbance in the rotor tip region occurs and then leads to rotating stall, while at high rotor speeds, a low-frequency disturbance in the hub region leads the compressor into instability. Different from stall and surge, this new type of compressor instability at high rotor speed is initiated through the development of a low-frequency axisymmetric disturbance at the hub, and we name it “partial surge”. The frequency of this low-frequency disturbance is approximately the Helmholtz frequency of the system and remains constant during instability inception. Finally, a possible mechanism for the occurrence of different instability evolutions and the formation of partial surge are also discussed.

An Experimental and Numerical Investigation Into the Mechanisms of Rotating Instability

2001 ◽  
Author(s):  
Joachim März ◽  
Chunill Hah ◽  
Wolfgang Neise
Keyword(s):  
Experimental Study ◽  
Numerical Investigation ◽  
Axial Flow ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Stable Mode ◽  
Tip Clearance Flow ◽  
Double Phase ◽  
Clearance Flow ◽  
Rotating Instability

This paper reports on an experimental and numerical investigation aimed at understanding the mechanisms of rotating instabilities in a low speed axial flow compressor. The phenomena of rotating instabilities in the current compressor were first identified with an experimental study. Then, an unsteady numerical method was applied to confirm the phenomena and to interrogate the physical mechanisms behind them. The experimental study was conducted with high-resolution pressure measurements at different clearances, employing a double phase-averaging technique. The numerical investigation was performed with an unsteady 3-D Navier-Stokes method that solves for the entire blade row. The current study reveals that a vortex structure forms near the leading edge plane. This vortex is the result of interactions among the classical tip-clearance flow, axially reversed endwall flow, and the incoming flow. The vortex travels from the suction side to the pressure side of the passage at roughly half of the rotor speed. The formation and movement of this vortex seem to be the main causes of unsteadiness when rotating instability develops. Due to the nature of this vortex, the classical tip-clearance flow does not spill over into the following blade passage. This behavior of the tip-clearance flow is why the compressor operates in a stable mode even with the rotating instability, unlike traditional rotating stall phenomena.

Stall Inception and Development in an Axial Flow Aeroengine

1994 ◽  
Vol 116 (2) ◽  
pp. 216-225 ◽  
Author(s):  
A. G. Wilson ◽  
C. Freeman
Keyword(s):  
High Speed ◽  
Engine Speed ◽  
Static Pressure ◽  
Flow Instability ◽  
Axial Flow ◽  
Fast Response ◽  
Rotating Stall ◽  
Flow Disturbance ◽  
Stall Inception ◽  
Small Flow

This paper describes the phenomenon of stall and surge in an axial flow aeroengine using fast response static pressure measurements from the compressor of a Rolls-Royce VIPER engine. It details the growth of flow instability at various speeds, from a small zone of stalled fluid involving only a few blades into the violent surge motion of the entire machine. Various observations from earlier theoretical and compressor rig results are confirmed by these new engine measurements. The main findings are as follows: (1) The point of stall inception moves rearward as engine speed increases, and is shown to be simply related to the axial matching of the compressor. (2) The final unstable operation of the machine can be divided into rotating stall at low speed and surge or multiple surge at high speed. (3) The inception process is independent of whether the final unstable operation is rotating stall or multiple surge. (4) Stall/surge always starts as a circumferentially small flow disturbance, rotating around the annulus at some fraction of rotor speed.

An adaptive logarithmic threshold framelet analysis of the partial surge initiated instability in a transonic axial flow compressor

2016 ◽  
Vol 231 (17) ◽  
pp. 3202-3213 ◽  
Author(s):  
Tianyu Pan ◽  
Haihui Wang ◽  
Qiushi Li
Keyword(s):  
Low Frequency ◽  
Axial Flow ◽  
Rotating Stall ◽  
Single Frequency ◽  
New Findings ◽  
New Type ◽  
General Data ◽  
Stall Cells ◽  
Flow Compressor ◽  
Data Processing Methods

Partial surge is a new type of instability inception in transonic axial flow compressors and occurs in the form of axisymmetric low-frequency disturbances localized in the hub region. The frequency of partial surge is about 12.5 Hz at 88% of the design rotor speed, while the frequency of developed rotating stall cells in the final phase of the evolution is around 190 Hz. As there are two different frequencies in the instability evolution of partial surge, it is difficult to well denoise the experimental data by general data processing methods that are focused on one single frequency. Considering the unique feature of the partial surge initiated instability, an adaptive logarithmic threshold framelet method has been built. By this method, the well-denoised results can be obtained. Based on the results, the instability evolution of partial surge is clearly shown. At the same time, several new findings about partial surge have been presented: (1) the propagating procedure of one partial surge disturbance: the amplitude of disturbance is increasing until one partial surge disturbance is developed; (2) the occurrence of rotating stall cells is related to the partial surge disturbance; (3) the propagating procedure of one rotating stall cell is presented; (4) the partial surge disturbance is well proved to be axisymmetric. Finally, the capability of this denoise method is also discussed.

A Distinction Between Different Types of Stall in a Centrifugal Compressor Stage

1986 ◽  
Vol 108 (1) ◽  
pp. 83-92 ◽  
Author(s):  
N. Ka¨mmer ◽  
M. Rautenberg
Keyword(s):  
Energy Transfer ◽  
Centrifugal Compressor ◽  
High Frequency ◽  
Low Frequency ◽  
Rotating Stall ◽  
Compressor Stage ◽  
Vaneless Diffuser ◽  
Pressure Transducers ◽  
Different Types ◽  
Probe Measurements

The flow at the stall line of a centrifugal compressor with vaneless diffuser was investigated at different speeds. A distinction between three kinds of stall phenomena could be made. One type of stall with regurgitation of fluid at the impeller inlet was of a nonperiodic character, whereas two different types of periodic stall appeared at higher speeds. The rotating nature of these two types of stall was verified from a comparison of signals of peripherally spaced pressure transducers. The low-frequency rotating stall exhibited features of diffuser generated stall and a lobe number of three was measured. From a detailed investigation of the high-frequency rotating stall, which included unsteady probe measurements upstream and downstream of the impeller, it can be shown that this type of rotating stall is generated in the impeller by a periodic breakdown of energy transfer from the rotor to the flow. This conclusion is supported by the distribution of shroud static pressures.

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