scholarly journals An Experimental Investigation of Rotating Stall Flow in a Centrifugal Compressor

1982 ◽  
Author(s):  
N. Kämmer ◽  
M. Rautenberg
Keyword(s):  
Centrifugal Compressor ◽  
Reverse Flow ◽  
Rotating Stall ◽  
Vaneless Diffuser ◽  
Flow Distortion ◽  
Inlet Velocity ◽  
Pressure Transducers ◽  
Compressor Impeller ◽  
Flow Through ◽  
Compressor Map

The flow through a centrifugal compressor impeller and a vaneless diffuser was investigated using unsteady pressure transducers and stationary probes when the compressor operated in the rotating stall region of the compressor map. The inlet velocity profile of the impeller was measured with traversing probes and was found to be significantly different from the profiles measured in an unthrottled condition. A zone of reverse flow was detected close to the suction duct wall as well as a strong swirl induced by the impeller. Circumferentially and meridionally spaced transducers made it possible to determine the stall frequency and the number of stall cells. The amplitude of the flow distortion as a function of meridional position was calculated from meridionally spaced transducers.

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.

Stall Inception Behavior in a Centrifugal Compressor

1994 ◽  
Author(s):  
J. Chen ◽  
H. Hasemann ◽  
Li Shi ◽  
M. Rautenberg
Keyword(s):  
Centrifugal Compressor ◽  
Reverse Flow ◽  
Low Frequency ◽  
Rotating Stall ◽  
Time Range ◽  
Stall Inception ◽  
Pressure Transducers ◽  
Axial Compressors ◽  
The Third ◽  
Speed Range

In studying the stall inception process, while most results were reported for axial compressors, the present paper investigates the stall inception behavior typified in a centrifugal compressor. The test was conducted with a radially-bladed impeller and in a speed range of 8000–14000 rpm. Extensive pressure transducers were used to study the frequency characteristics of emerging stall waves. As a result, stall precursors were detected, all with clear mode seen from frequency analysis, but very much different by the behavior of their onset, existence and development. The first type, called the stable-amplitude precursor, exists in a time range of about 20–90 impeller revolutions, with unpredictable and different frequencies from the fully developed stall. Such perturbation, once appeared, may grow to the full stall straightly, or may appear for several times intermittently before finally reaching the full stall, thus acting as a pre-precursor in the whole stall inception process. The second type is the progressive-amplitude precursor when the perturbation emerges as long as 270 impeller revolutions prior to and progressively develops into the full amplitude stall with no change of frequency during this process. The third type, which has been detected for the rotating stall with evident reverse flow symptom, is the precursive pressure increase accompanied with the stable- or progressive-amplitude perturbation, before the full stall establishes. The inception process is also examined for surge during the test of the same compressor, in which the existence of rotating stall in front of every surge cycle and the low frequency precursive wave before surge cycles is demonstrated. Finally, the blade passage frequencies for precursor pressure signals are further analysed to address the monitoring strategy during stall inception process.

Effect of Diffuser Contraction for a Centrifugal Compressor

2010 ◽  
Author(s):  
Kyung-Jun Kang ◽  
You-Hwan Shin ◽  
Kwang-Ho Kim ◽  
Yoon-Pyo Lee
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Pressure Fluctuation ◽  
Reverse Flow ◽  
Water Reservoir ◽  
Side Wall ◽  
Rotating Stall ◽  
Low Flow ◽  
Vaneless Diffuser ◽  
Flow Zone

This study will be described details on influence of movable diffuser such as local reverse flow patterns and pressure fluctuation in a vaneless diffuser during unstable operation of a centrifugal compressor. The experimental study is carried out in centrifugal compressor immersed into a water reservoir. Particle Image Velocity (PIV) is used to observe a secondary flow pattern and pressure transducer is used for investigating the onset and development of rotating stall inside vaneless diffuser. The reverse flow zone observes near hub wall of impeller exit at relatively low flow rate. This reverse flow on hub side wall brings about the rotating stall. This paper be simultaneously discussed on the effects of diffuser contraction to remove local reverse flow zone near hub wall, which are including variation of flow field in a vaneless diffuser and the influence on the pressure fluctuation. A contraction due to movable diffuser three cases (40%, 53% and 86% of diffuser width) was inserted into vaneless diffuser from a shroud wall. According to the results, the rotating stall involving single and two cells is enveloped by the outer lobe of the Rossby wave. Under the rotating stall onset, the stall propagation rate is 1.25Hz, 25% of the impeller speed in the same direction as the impeller in case of no contraction. In case of 40% contraction, onset of rotating stall is not delayed. In contrast of that, onset of rotating stall is delayed in case of 53%, 87% contraction. There exist several secondary vortices inside vaneless diffuser under onset of rotating stall. The size and location of them vary as flow rate decreases.

Pressure and Velocity Fluctuations in the Diffuser for Rotating Stall Period

2012 ◽  
Author(s):  
Youhwan Shin ◽  
Ji-In Yoon ◽  
Yoon Pyo Lee
Keyword(s):  
Measurement Technique ◽  
Reverse Flow ◽  
Tangential Velocity ◽  
Ccd Camera ◽  
Rotating Stall ◽  
Vaneless Diffuser ◽  
Velocity Fluctuations ◽  
Pressure Transducers ◽  
Piv Measurement ◽  
Velocity Images

This study describes details on local reverse flow patterns in a vaneless diffuser by experiments through PIV measurement technique in the water bath during the unstable operation of a compressor with radial impeller. In order to do these measurements, the pressure transducers were installed on the hub wall with several diffuser radius ratios and they were synchronized with the velocity images of CCD camera. Especially we tried to make them synchronize with time during rotating stall period. For relatively high and low pressure instants, we observed and discussed how the radial and tangential velocity components fluctuated.

Sensitivity analysis and optimization of a CO2 centrifugal compressor impeller with a vaneless diffuser

2021 ◽  
Author(s):  
Leandro Oliveira Salviano ◽  
Elóy Esteves Gasparin ◽  
Vitor Cesar N. Mattos ◽  
Bruno Barbizan ◽  
Fábio Saltara ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Centrifugal Compressor ◽  
Vaneless Diffuser ◽  
Compressor Impeller

Effects of Non-Axisymmetric Volute on Rotating Stall in the Vaneless Diffuser of a Centrifugal Compressor

2020 ◽  
Author(s):  
Zitian Niu ◽  
Zhenzhong Sun ◽  
Baotong Wang ◽  
Xinqian Zheng
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Centrifugal Compressor ◽  
Stability Boundary ◽  
Rotating Stall ◽  
Evolution Process ◽  
Vaneless Diffuser ◽  
Unstable Flow ◽  
Centrifugal Compressors ◽  
Specific Location

Abstract Rotating stall is an important unstable flow phenomenon that leads to performance degradation and limits the stability boundary in centrifugal compressors. The volute is one of the sources to induce the non-axisymmetric flow in a centrifugal compressor, which has an important effect on the performance of compressors. However, the influence of volute on rotating stall is not clear. Therefore, the effects of volute on rotating stall by experimental and numerical simulation have been explored in this paper. It’s shown that one rotating stall cell generates in a specific location and disappears in another specific location of the vaneless diffuser as a result of the distorted flow field caused by the volute. Also, the cells cannot stably rotate in a whole circle. The frequency related to rotating stall captured in the experiment is 43.9% of the impeller passing frequency (IPF), while it is 44.7% of IPF captured by three-dimensional unsteady numerical simulation, which proves the accuracy of the numerical method in this study. The numerical simulation further reveals that the stall cell initialized in a specific location can be split into several cells during the evolution process. The reason for this is that the blockage in the vaneless diffuser induced by rotating stall is weakened by the mainstream from the impeller exit to make one initialized cell disperse into several ones. The volute has an important influence on the generation and evolution process of the rotating stall cells of compressors. By optimizing volute geometry to reduce the distortion of the flow field, it is expected that rotating stall can be weakened or suppressed, which is helpful to widen the operating range of centrifugal compressors.

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.

Investigation on Effect of Curvilinear Element Blades on Centrifugal Impeller Performance

2017 ◽  
Author(s):  
Kiyotaka Hiradate ◽  
Hiromi Kobayashi ◽  
Takahiro Nishioka
Keyword(s):  
Centrifugal Compressor ◽  
Performance Test ◽  
Design Guidelines ◽  
Secondary Flows ◽  
Flow Coefficient ◽  
Numerical Calculations ◽  
Centrifugal Impeller ◽  
Compressor Stage ◽  
Vaneless Diffuser ◽  
Compressor Impeller

This study experimentally and numerically investigates the effect of application of curvilinear element blades to fully-shrouded centrifugal compressor impeller on the performance of centrifugal compressor stage. Design suction flow coefficient of compressor stage investigated in this study is 0.125. The design guidelines for the curvilinear element blades which had been previously developed was applied to line element blades of a reference conventional impeller and a new centrifugal compressor impeller with curvilinear element blades was designed. Numerical calculations and performance tests of two centrifugal compressor stages with the conventional impeller and the new one were conducted to investigate the effectiveness of application of the curvilinear element blades and compare the inner flowfield in details. Despite 0.5% deterioration of the impeller efficiency, it was confirmed from the performance test results that the compressor stage with the new impeller achieved 1.7% higher stage efficiency at the design point than that with the conventional one. Moreover, it was confirmed that the compressor stage with the new impeller achieved almost the same off-design performance as that of the conventional stage. From results of the numerical calculations and the experiments, it is considered that this efficiency improvement of the new stage was achieved by suppression of the secondary flows in the impeller due to application of negative tangential lean. The suppression of the secondary flows in the impeller achieved uniformalized flow distribution at the impeller outlet and increased the static pressure recovery coefficient in the vaneless diffuser. As a result, it is thought that the total pressure loss was reduced downstream of the vaneless diffuser outlet in the new stage.

Flow Behavior of a Centrifugal Compressor With Vaneless Diffuser at Design and Off Design Conditions

2012 ◽  
Author(s):  
Chuang Gao ◽  
Weiguang Huang ◽  
Haiqing Liu ◽  
Hongwu Zhang ◽  
Jundang Shi
Keyword(s):  
Centrifugal Compressor ◽  
Flow Behavior ◽  
Travelling Waves ◽  
Leading Edge ◽  
Pressure Oscillation ◽  
Rotating Stall ◽  
Vaneless Diffuser ◽  
Unstable Flow ◽  
Flow Recirculation ◽  
Static Performance

This paper concerns with the numerical and experimental aspects of both steady and unsteady flow behavior in a centrifugal compressor with vaneless diffuser and downstream collector. Specifically, the appearance of flow instabilities i.e., rotating stall and surge is investigated in great detail. As the first step, the static performance of both stage and component was analyzed and possible root cause of system surge was put forward based on the classic stability theory. Then the unsteady pressure data was utilized to find rotating stall and surge in frequency domain which could be classified as mild surge and deep surge. With the circumferentially installed transducers at impeller inlet, backward travelling waves during stall ramp could be observed. The modes of stall waves could be clearly identified which is caused by impeller leading edge flow recirculation at Mu = 0.96. However, for the unstable flow at Mu = 1.08, the system instability seems to be caused by reversal flow in vaneless diffuser where the pressure oscillation was strongest. Thus steady numerical simulation were performed and validated with the experimental performance data. With the help of numerical analysis, the conjectures are proved.

scholarly journals Rotating Stall in Centrifugal Compressor Vaneless Diffuser: Experimental Analysis of Geometrical Parameters Influence on Phenomenon Evolution

2004 ◽  
Vol 10 (6) ◽  
pp. 433-442 ◽  
Author(s):  
Giovanni Ferrara ◽  
Lorenzo Ferrari ◽  
Leonardo Baldassarre
Keyword(s):  
Centrifugal Compressor ◽  
Dynamic Pressure ◽  
Pressure Sensors ◽  
Experimental Tests ◽  
Fast Response ◽  
Rotating Stall ◽  
Geometrical Parameters ◽  
Vaneless Diffuser ◽  
Response Dynamic ◽  
Frequency Domains

The rotating stall is a key problem for achieving a good working range of a centrifugal compressor and a detailed understanding of the phenomenon is very important to anticipate and avoid it. Many experimental tests have been planned by the authors to investigate the influence on stall behavior of different geometrical configurations. A stage with a backward channel upstream, a 2-D impeller with a vaneless diffuser and a constant cross-section volute downstream, constitute the basic configuration. Several diffuser types with different widths, pinch shapes, and diffusion ratios were tested. The stage was instrumented with many fast response dynamic pressure sensors so as to characterize inception and evolution of the rotating stall. This kind of analysis was carried out both in time and in frequency domains. The methodology used and the results on phenomenon evolution will be presented and discussed in this article.

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