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.

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.

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.

Role of Blade Passage Flow Structurs in Axial Compressor Rotating Stall Inception

1999 ◽  
Vol 121 (4) ◽  
pp. 735-742 ◽  
Author(s):  
D. A. Hoying ◽  
C. S. Tan ◽  
Huu Duc Vo ◽  
E. M. Greitzer
Keyword(s):  
Leading Edge ◽  
Rotating Stall ◽  
Short Length ◽  
Tip Clearance ◽  
Length Scale ◽  
Central Feature ◽  
Local Flow ◽  
Stall Inception ◽  
Blade Passage ◽  
Tip Clearance Vortex

The influence of three-dimensional flow structures within a compressor blade passage has been examined computationally to determine their role in rotating stall inception. The computations displayed a short length-scale (or spike) type of stall inception similar to that seen in experiments; to the authors’ knowledge this is the first time such a feature has been simulated. A central feature observed during the rotating stall inception was the tip clearance vortex moving forward of the blade row leading edge. Vortex kinematic arguments are used to provide a physical explanation of this motion as well as to motivate the conditions for its occurrence. The resulting criterion for this type of stall inception (the movement of the tip clearance vortex forward of the leading edge) depends upon local flow phenomena related to the tip clearance with the implication that for this and possibly other stall mechanisms the flow structure within the blade passages must be addressed to explain the stability of an axial compression system that exhibits such short length-scale disturbances.

Performance and Short Length-Scale Disturbance Generation in an Axial Compressor With Non-Uniform Tip Clearance

2008 ◽  
Author(s):  
Scott C. Morris ◽  
Joshua D. Cameron ◽  
Matthew A. Bennington ◽  
G. Scott McNulty ◽  
Aspi Wadia
Keyword(s):  
Flow Field ◽  
Mass Flow ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Short Length ◽  
Tip Clearance ◽  
Length Scale ◽  
Stagnation Temperature ◽  
Local Flow ◽  
Stall Inception

The performance, efficiency, and stall inception of an axial compressor was investigated experimentally with small levels of rotor centerline offset. The measurements were acquired using a high-speed, single-stage compressor. The rotor was levitated magnetically during operation which allowed precise positioning of the rotor centerline within the circular casing. The offset magnitude used in this study was 0.23% of the rotor tip chord, equivalent to approximately 24% of the nominal gap value. The resulting asymmetry in the tip gap resulted in circumferential and radial variations in the measured stagnation pressure and stagnation temperature downstream of the stage. However, the spatially averaged performance of the compressor was not measurably different from that obtained with a concentric rotor. An array of unsteady (Kulite) pressure transducers was used to investigate the flow field during stall inception. These measurements were recorded during transient throttle movements which quickly decreased the mass flow in the compressor until the onset of rotating stall. A second set of measurements was acquired during quasi-transient throttling starting from a mass flow about 1% larger than the stalling mass flow. In both the symmetric and offset cases the flow breakdown was consistent with spike type inception. The measurements with offset indicated that the asymmetries in the local compressor flow field produced significant changes in the number of short-length scale rotating disturbances observed during throttling to stall. These disturbances appeared in the region of the annulus where the local flow coefficient was lowest and usually decayed upon rotating to the higher flow region. In this way, the addition of very small amounts of rotor offset tended to fix the disturbance generation location in the stationary reference frame. This was in contrast to the symmetric tip clearance case where the location of spike generation appeared stochastic.

scholarly journals Role of Blade Passage Flow Structures in Axial Compressor Rotating Stall Inception

1998 ◽  
Author(s):  
Donald A. Hoying ◽  
Choon S. Tan ◽  
Huu Duc Vo ◽  
Edward M. Greitzer
Keyword(s):  
Leading Edge ◽  
Rotating Stall ◽  
Short Length ◽  
Tip Clearance ◽  
Flow Structures ◽  
Length Scale ◽  
Central Feature ◽  
Local Flow ◽  
Stall Inception ◽  
Blade Passage

The influence of three-dimensional flow structures within a compressor blade passage has been examined computationally to determine their role in rotating stall inception. The computations displayed a short length-scale (or spike) type of stall inception similar to that seen in experiments; to the authors’ knowledge this is the first time such a feature has been simulated. A central feature observed during the rotating stall inception was the tip clearance vortex moving forward of the blade row leading edge. Vortex kinematic arguments are used to provide a physical explanation of this motion as well as to motivate the conditions for its occurrence. The resulting criterion for this type of stall inception (which appears generic for axial compressors with tip-critical flow fields) depends upon local flow phenomena related to the tip clearance and it is thus concluded that the flow structure within the blade passages must be addressed to explain the stability of an axial compression system which exhibits such short length-scale disturbances.

Criteria for Spike Initiated Rotating Stall

2005 ◽  
Author(s):  
Huu Duc Vo ◽  
Choon S. Tan ◽  
Edward M. Greitzer
Keyword(s):  
Computational Study ◽  
Axial Compressor ◽  
Leading Edge ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Length Scale ◽  
Stall Inception ◽  
Tip Clearance Flow ◽  
Clearance Flow ◽  
Circumferential Extent

A computational study to define the phenomena that lead to the onset of short length-scale (spike) rotating stall disturbances has been carried out. Unsteady simulations show 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 length scale circumferential extent of spike disturbances. The scenario developed is consistent with numerical simulations as well as with 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.

Effects of Steady Tip Clearance Asymmetry and Rotor Whirl on Stall Inception in an Axial Compressor

2007 ◽  
Author(s):  
Joshua D. Cameron ◽  
Matthew A. Bennington ◽  
Mark H. Ross ◽  
Scott C. Morris ◽  
Thomas C. Corke
Keyword(s):  
Mass Flow ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Rotating Stall ◽  
Short Length ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Correlation Technique ◽  
Length Scale ◽  
Stall Inception

Effects of rotor centerline offset and whirl on the pre-stall and stall inception behavior of a high-speed tip-critical axial compressor were investigated. The observations were made using a circumferential array of unsteady pressure transducers. The maximum amount of rotor offset and whirl used in this investigation was 26% and 13% of the design axisymmetric tip clearance respectively. Measurements were conducted using transient throttle movements which quickly decreased the mass flow in the compressor until the onset of rotating stall. A second set of measurements used quasi-transient throttling starting from a mass flow about 0.5% larger than the stalling mass flow. These data were analyzed with the traveling wave energy method, visual inspection of the filtered pressure traces, and a two-point spatial correlation technique. For the uniform tip clearance case rotating stall occurred while the slope of the pressure rise characteristic was negative. As expected, the flow breakdown exhibited “spike” inception with no observable rotating disturbances in the pre-stall time period. The introduction of small levels of steady and unsteady tip clearance asymmetry did not significantly alter the time average performance of the stage; circumferential variations in pressure rise and flow coefficient were minimal and the stalling flow coefficient remained unchanged. However, significant short length-scale rotating disturbances were observed in both of these cases prior to stall inception. As in the symmetric tip clearance case, short length-scale disturbances initiated rotating stall in the non-uniform tip clearance experiments. The location of the generation of the incipient stall cells with respect to the non-uniform tip clearance was strongly effected by the rotor offset/whirl.

Control of Short Length-Scale Rotating Stall Inception on a High-Speed Axial Compressor With Plasma Actuation

2008 ◽  
Author(s):  
Huu Duc Vo ◽  
Joshua D. Cameron ◽  
Scott C. Morris
Keyword(s):  
Axial Compressor ◽  
Rotating Stall ◽  
Short Length ◽  
Tip Clearance ◽  
Length Scale ◽  
Practical Consideration ◽  
Stall Inception ◽  
Plasma Actuation ◽  
Compressor Performance ◽  
The Impact

This paper presents a computational assessment of the use of Single Dielectric Barrier Discharge (SDBD), or plasma, actuators for the suppression of short-length scale (spike) stall inception in a transonic axial compressor. Casing plasma actuation has the potential to provide a robust and effective stall suppression device without compromising compressor performance. The objective of this work is to determine the optimum actuator location and actuation strength needed to suppress spike stall inception at transonic speeds without imposing a penalty on compressor performance. This is done through the implementation of an actuator model in a turbomachinery CFD code for simulations of a transonic research compressor rotor passage to measure the effectiveness of casing plasma actuation in delaying the tip clearance flow criteria that are believed to lead to the formation of spike disturbances. Results show that the casing plasma actuator should be positioned near the rotor leading edge so as to optimize the impact on the interface between the incoming and tip clearance flows as well as for practical consideration. Simulations also indicate that the required actuator strength is higher than that of typical SDBD actuators while still remaining within practical achievable limits. These results will form the basis for experimental validation of the concept in the corresponding research compressor rig in the near future.

Dynamic Characterization and Identification of Flow in a Blade Passage in Near-Stall Conditions of Axial Compressor Systems

2019 ◽  
Author(s):  
Eighdi Aung ◽  
Marco P. Schoen ◽  
Jichao Li
Keyword(s):  
Correlation Coefficient ◽  
Active Flow Control ◽  
Axial Compressor ◽  
Leading Edge ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Sensor Data ◽  
Detection Methods ◽  
Operating Point ◽  
Stall Inception

Abstract Axial compressor systems are susceptible to unstable conditions near their optimal operating point. In particular, rotating stall and surge are conditions that need to be avoided during the operation of an axial compressor. In extreme cases these conditions may cause damage to the compressor. The onset of either condition is rather rapid, and usually does not allow for remedial control action based on the limited time available. Hence, research efforts have been focusing on the development of new detection methods that allow for more time to take corrective measures. This paper explores and compares various existing and proposed methods to identify and detect those precursors. The methods detailed in this work are tested at different operating conditions and locations. The methods investigated include the sequentially computed correlation coefficient of pressure sensor data, correlation coefficient, the Generalized Extreme Studentized Deviate Test (ESD) for outlier detection, spectral entropy, and Autoregressive (AR) models. The primary goal of evaluating these methods is based on their suitability for employment as pre-processors for dynamic system identification. By using the dynamics of the identified model rather than a static precursor, it is stipulated that the onset of stall and surge can be managed with a control concept. For this work, the extracted models are investigated for suitability to serve as precursors, and the potential as predictive models. This work may serve for future work to achieve active flow control by direct air injection at the leading edge of the blades. For this work, a one-stage compressor system with a blade geometry that allows for spike inception is utilized. Spike stall inception is a precursor to fully developed rotating stall. The subsonic compressor has 60 blades, and its operating point is controlled by a throttle and constant speed control of the rotor. The pressure data is collected with 10 Kulite™ sensors which are placed along the blade cord length on the outer casing of the compressor. The results of the tabulated performance of the various methods and resulting models indicate that an ARESD combination yields the earliest indication for spike stall inception.

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