1997 Best Paper Award—Turbomachinery Committee: A Study of Spike and Modal Stall Phenomena in a Low-Speed Axial Compressor

1998 ◽  
Vol 120 (3) ◽  
pp. 393-401 ◽  
Author(s):  
T. R. Camp ◽  
I. J. Day
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Short Length ◽  
Operating Conditions ◽  
Length Scale ◽  
Stall Inception ◽  
Low Speed ◽  
The Stability ◽  
Dimensional Instability

This paper presents a study of stall inception mechanisms in a low-speed axial compressor. Previous work has identified two common flow breakdown sequences, the first associated with a short length-scale disturbance known as a “spike,” and the second with a longer length-scale disturbance known as a “modal oscillation.” In this paper the physical differences between these two mechanisms are illustrated with detailed measurements. Experimental results are also presented that relate the occurrence of the two stalling mechanisms to the operating conditions of the compressor. It is shown that the stability criteria for the two disturbances are different: Long length-scale disturbances are related to a two-dimensional instability of the whole compression system, while short length-scale disturbances indicate a three-dimensional breakdown of the flow-field associated with high rotor incidence angles. Based on the experimental measurements, a simple model is proposed that explains the type of stall inception pattern observed in a particular compressor. Measurements from a single-stage low-speed compressor and from a multistage high-speed compressor are presented in support of the model.

A Study of Spike and Modal Stall Phenomena in a Low-Speed Axial Compressor

1997 ◽  
Author(s):  
T. R. Camp ◽  
I. J. Day
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Stability Criteria ◽  
Stall Inception ◽  
Low Speed ◽  
The Stability ◽  
Dimensional Instability

This paper presents a study of stall inception mechanisms a in low-speed axial compressor. Previous work has identified two common flow breakdown sequences, the first associated with a short lengthscale disturbance known as a ‘spike’, and the second with a longer lengthscale disturbance known as a ‘modal oscillation’. In this paper the physical differences between these two mechanisms are illustrated with detailed measurements. Experimental results are also presented which relate the occurrence of the two stalling mechanisms to the operating conditions of the compressor. It is shown that the stability criteria for the two disturbances are different: long lengthscale disturbances are related to a two-dimensional instability of the whole compression system, while short lengthscale disturbances indicate a three-dimensional breakdown of the flow-field associated with high rotor incidence angles. Based on the experimental measurements, a simple model is proposed which explains the type of stall inception pattern observed in a particular compressor. Measurements from a single stage low-speed compressor and from a multistage high-speed compressor are presented in support of the model.

Propagation of Multiple Short-Length-Scale Stall Cells in an Axial Compressor Rotor

1999 ◽  
Vol 122 (1) ◽  
pp. 45-54 ◽  
Author(s):  
M. Inoue ◽  
M. Kuroumaru ◽  
T. Tanino ◽  
M. Furukawa
Keyword(s):  
Cell Structure ◽  
Three Dimensional ◽  
Stable State ◽  
Axial Compressor ◽  
Large Cell ◽  
Short Length ◽  
Length Scale ◽  
Compressor Rotor ◽  
Double Phase ◽  
Stall Cells

Evolution and structure of multiple stall cells with short-length-scale in an axial compressor rotor have been investigated experimentally. In a low-speed research compressor rotor tested, a short-length-scale stall cell appeared at first, but did not grow rapidly in size, unlike a so-called “spike-type stall inception” observed in many multistage compressors. Alternatively, the number of cells increased to a certain stable state (a mild stall state) under a fixed throttle condition. In the mild stall state the multiple stall cells, the size of which was on the same order of the inception cell (a few blade spacings), were rotating at 72 percent of rotor speed and at intervals of 4.8 blade spacings. With further throttling, a long-length-scale wave appeared overlapping the multiple short-length-scale waves, then developed to a deep stall state with a large cell. In order to capture the short-length-scale cells in the mild stall state, a so-called “double phase-locked averaging technique” has been developed, by which the flow field can be measured phase locked to both the rotor and the stall cell rotation. Then, time-dependent ensemble averages of the three-dimensional velocity components upstream and downstream of the rotor have been obtained with a slanted hot-wire, and the pressure distributions on the casing wall with high-response pressure transducers. By a physically plausible explanation for the experimental results, a model for the flow mechanism of the short-length-scale stall cell has been presented. The distinctive feature of the stall cell structure is on the separation vortex bubble with a leg traveling ahead of the rotor, with changing the blade in turn on which the vortex leg stands. [S0889-504X(00)00701-7]

Effect of Tip Clearance on Stall Evolution Process in a Low-Speed Axial Compressor Stage

2004 ◽  
Author(s):  
Masahiro Inoue ◽  
Motoo Kuroumaru ◽  
Shinichi Yoshida ◽  
Takahiro Minami ◽  
Kazutoyo Yamada ◽  
...  
Keyword(s):  
Spectral Power ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Rotating Stall ◽  
Short Length ◽  
Tip Clearance ◽  
Evolution Process ◽  
Length Scale ◽  
Compressor Stage ◽  
Low Speed

Effect of the tip clearance on the transient process of rotating stall evolution has been studied experimentally in a low-speed axial compressor stage with various stator-rotor gaps. In the previous authors’ experiments for the small tip clearance, the stall evolution process of the rotor was sensitive to the gaps between the blade rows. For the large tip clearance, however, little difference is observed in the evolution processes independently of the blade row gap. In the first half process, it is characterized by gradual reduction of overall pressure-rise with flow rate decreasing, and the number of short length-scale disturbances is increasing with their amplitude increasing. In the latter half a long length-scale disturbance develops rapidly to result in deep stall. Just before the stall inception the spectral power density of the casing wall pressure reveals the existence of rotating disturbances with broadband high frequency near a quarter of the blade passing frequency. This is caused by the short length-scale disturbances occurring intermittently. A flow model is presented to explain mechanisms of the rotating short length-scale disturbance, which includes a tornado-like separation vortex and tip-leakage vortex breakdown. The model is supported by a result of a numerical unsteady flow simulation.

scholarly journals Experimental Investigation of Stall Inception Mechanisms of Low Speed Contra Rotating Axial Flow Fan Stage

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Tegegn Dejene Toge ◽  
A. M. Pradeep
Keyword(s):  
Mass Flow ◽  
Wavelet Transforms ◽  
Axial Flow ◽  
Short Length ◽  
Length Scale ◽  
Pressure Data ◽  
Flow Conditions ◽  
Axial Flow Fan ◽  
Stall Inception ◽  
Low Speed

The present paper is an attempt in understanding the stall inception mechanism in a low speed, contra rotating axial flow fan stage, using wavelet transforms. The rotors used in this study have relatively large tip gap (about 3% of the blade span) and aspect ratio of 3. The study was carried out near stall and at stall mass flow conditions for different speed ratios of rotor-2 to rotor-1. Unsteady pressure data from the casing wall mounted sensors are used to understand the stall inception mechanism. The wavelet transform clearly indicates that stall inception occurs mainly through long length scale disturbances for both rotors. It also reveals that short length disturbances occur simultaneously or intermittently in the case of rotor-1. The analysis shows the presence of a strong modal disturbance with 25–80% of the rotor frequency in the case of rotor-1 at the stall mass flow for all the speed combinations studied. The most interesting thing observed in the present study is that the frequency amplitude of the disturbance level is very small for both rotors.

Long-to-Short Length Scale Transition: A Stall Inception Phenomenon in an Axial Compressor With Inlet Distortion

2005 ◽  
Author(s):  
Feng Lin ◽  
Meilin Li ◽  
Jingyi Chen
Keyword(s):  
Axial Compressor ◽  
Axial Flow ◽  
Short Length ◽  
Scale Model ◽  
Future Research ◽  
Length Scale ◽  
Stall Inception ◽  
Inlet Distortion ◽  
Scale Transition ◽  
Asymmetric Flows

A theoretical and experimental study of stall inception processes in a three-stage low-speed axial flow compressor with inlet distortion is presented in this paper. Since inlet distortion provides asymmetric flows imposing onto the compressor, the main goal of this research is to unveil the mechanism of how such flows initiate long and/or short length-scale disturbances and how the compression system reacts to those disturbances. It is found that the initial disturbances are always triggered by the distorted flows, yet the growth of such disturbances depends on system dynamics. While in many cases the stall precursors were the short length scale spikes, there were some cases where the compressor instability was triggered after the disturbances going through a long-to-short length scale transition. A Moore-Greitzer based (system scale) model was proposed to qualitatively explain this phenomenon. It was found that when the compressor operated in a region where the nonlinearity of the characteristics dominated, long length-scale disturbances induced by the inlet distortion would evolve into short length-scale disturbances before they disappeared or triggered stall. However, the model was not able to predict the fact that many disturbances that were triggered by the distorted sector(s) were completely damped out in the undistorted sector(s). It is thus suggested that in future research of compressor instability, one should consider the flows in blade passage scale, the dynamics in system scale and their interaction simultaneously.

Short and Long Length-Scale Disturbances Leading to Rotating Stall in an Axial Compressor Stage With Different Stator/Rotor Gaps

2001 ◽  
Author(s):  
M. Inoue ◽  
M. Kuroumaru ◽  
S. Yoshida ◽  
M. Furukawa
Keyword(s):  
High Frequency ◽  
Wavelet Transforms ◽  
Wave Length ◽  
Axial Compressor ◽  
Leading Edge ◽  
Rotating Stall ◽  
Short Length ◽  
Length Scale ◽  
Compressor Stage ◽  
Stall Inception

The transient processes of rotating stall evolution have been investigated experimentally in a low-speed axial compressor stage with three stator-rotor gaps. The pressure traces at 8 circumferential locations on the casing wall near the rotor leading edge have been analyzed by the wavelet transforms. With the appropriate mother wavelets, the evolution of short and long length-scale disturbances leading to the stall can be captured clearly. Behavior of these disturbances is different depending on the stator-rotor gap. For the large and middle gap, the stall inception is detected by a spiky short length-scale disturbance, and the number of spiky waves increases to generate the high frequency waves. They becomes the short length-scale part-span stall cells at the mild stall for the large gap, while they turn into a big stall cell with growth of a long length-scale disturbance for the middle gap. In the latter case, therefore, the stalling process was identified with ‘high frequency stall inception’. For the small stator-rotor gap, the stalling process is identified with ‘long wave-length stall inception’, and supported the recent computational model for the short wave-length stall inception by showing that closing the rotor-stator gaps suppressed the growth of short length-scale disturbances. From the measurement of the pressure field traces on the casing wall, a hypothesis has been built up that the short length-scale disturbance should result from a separation vortex from a blade surface to reduce circulation. The processes of the stall evolution are discussed on this hypothesis.

Criteria for Spike Initiated Rotating Stall

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Huu Duc Vo ◽  
Choon S. Tan ◽  
Edward M. Greitzer
Keyword(s):  
Computational Study ◽  
Axial Compressor ◽  
Leading Edge ◽  
Rotating Stall ◽  
Short Length ◽  
Tip Clearance ◽  
Length Scale ◽  
Stall Inception ◽  
Tip Clearance Flow ◽  
Clearance Flow

A computational study to define the phenomena that lead to the onset of short length-scale (spike) rotating stall disturbances has been carried out. Based on unsteady simulations, we hypothesize there are two conditions necessary for the formation of spike disturbances, both of which are linked to the tip clearance flow. One is that the interface between the tip clearance and oncoming flows becomes parallel to the leading-edge plane. The second is the initiation of backflow, stemming from the fluid in adjacent passages, at the trailing-edge plane. The two criteria also imply a circumferential length scale for spike disturbances. The hypothesis and scenario developed are consistent with numerical simulations and experimental observations of axial compressor stall inception. A comparison of calculations for multiple blades with those for single passages also allows statements to be made about the utility of single passage computations as a descriptor of compressor stall.

Examination of Rotating Stall Inception in a Small High Speed Axial Compressor

2009 ◽  
Author(s):  
L. G. N. Bennett ◽  
W. D. E. Allan
Keyword(s):  
High Speed ◽  
Gasoline Engine ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Pressure Measurements ◽  
Operating Life ◽  
Fourier Decomposition ◽  
Stall Inception ◽  
Prediction And Prevention

Rotating stall is an internal aerodynamic disturbance that limits the performance and operating life of a compressor. It has been studied with the aim of developing techniques for its prediction and prevention. To further the understanding of rotating stall inception, a test rig was constructed with the axial stages of a Rolls Royce Model 250-C20B small, high speed axial compressor as the test article. A gasoline engine was used to power the compressor and airflow was throttled through a pneumatically controlled valve. Simultaneous static pressure measurements were taken with seven high speed transducers arranged in two configurations: distributed both axially and circumferentially around the compressor casing. The compressor characteristic was mapped and detailed pressure measurements were taken between normal and surge operating conditions. Previous studies of high speed multi-stage compressors have shown both modal and spike type stall inception at different compressor stages. Other examinations of the Model 250 compressor have shown stall inception occurring at the first stage of the compressor. Similar results were observed in this study and an analysis was conducted using a variety of signal processing techniques including pressure trace inspection and discrete spatial Fourier decomposition.

Short and Long Length-Scale Disturbances Leading to Rotating Stall in an Axial Compressor Stage With Different Stator/Rotor Gaps

2002 ◽  
Vol 124 (3) ◽  
pp. 376-384 ◽  
Author(s):  
M. Inoue ◽  
M. Kuroumaru ◽  
S. Yoshida ◽  
M. Furukawa
Keyword(s):  
High Frequency ◽  
Wavelet Transforms ◽  
Axial Compressor ◽  
Leading Edge ◽  
Rotating Stall ◽  
Short Length ◽  
Length Scale ◽  
Compressor Stage ◽  
Stall Inception ◽  
High Frequency Waves

The transient processes of rotating stall evolution have been investigated experimentally in a low-speed axial compressor stage with three stator-rotor gaps. The pressure traces at eight circumferential locations on the casing wall near the rotor leading edge have been analyzed by the wavelet transforms. With the appropriate mother wavelets, the evolution of short and long length-scale disturbances leading to the stall can be captured clearly. Behavior of these disturbances is different depending on the stator-rotor gap. For the large and middle gap, the stall inception is detected by a spiky short length-scale disturbance, and the number of spiky waves increases to generate the high frequency waves. They become the short length-scale part-span stall cells at the mild stall for the large gap, while they turn into a big stall cell with growth of a long length-scale disturbance for the middle gap. In the latter case, therefore, the stalling process was identified with “high-frequency stall inception.” For the small stator-rotor gap, the stalling process is identified with “long wavelength stall inception” and supported the recent computational model for the short wavelength stall inception by showing that closing the rotor-stator gaps suppressed the growth of short length-scale disturbances. From the measurement of the pressure field traces on the casing wall, a hypothesis has been developed that the short length-scale disturbance should result from a separation vortex from a blade surface to reduce circulation. The processes of the stall evolution are discussed on this hypothesis.

Stall Inception Measurements in a High-Speed Multi-Stage Compressor

1995 ◽  
Author(s):  
J. F. Escuret ◽  
V. Garnier
Keyword(s):  
High Speed ◽  
Fast Response ◽  
Finite Amplitude ◽  
Short Length ◽  
Length Scale ◽  
Stall Inception ◽  
Pressure Transducers ◽  
Multi Stage ◽  
Flow Phenomena ◽  
Response Pressure

This paper presents unsteady measurements taken in a high-speed four-stage aero-engine compressor prior to the onset of aerodynamic flow instabilities. In this experiment, forty fast-response pressure transducers have been located at various axial and circumferential positions throughout the machine in order to give a very detailed picture of stall inception. At all the compressor speeds investigated, the stall pattern observed is initiated by a very short length-scale finite-amplitude disturbance which propagates at a fast rate around the annulus. This initial stall cell leads to a large-amplitude system instability in less than five rotor revolutions. Varying the IGV setting angle is found to have a strong influence on the axial location of the first disturbance detected. In particular, transferring the aerodynamic loading from front to downstream stages moves the first disturbance detected from the first to the last stage of the compressor. Other repeatable features of the stall inception pattern in this compressor have been identified using a simple analysis technique particularly appropriate to the study of short length-scale disturbances. It is found that the origins of instabilities are tied to particular tangential positions in both the stationary and rotating frames of reference. These measurements lead to the conclusion that the stall inception process in high-speed multi-stage compressors can be characterised by some very local and organised flow phenomena. Moreover, there is no evidence of pre-stall waves in this compressor.

Sign in / Sign up

Export Citation Format

Share Document