scholarly journals Experimental Investigation of the Flow Field of Deep Rotating Stall in a Centrifugal Compressor

1994 ◽  
Author(s):  
Y. N. Chen ◽  
U. Seidel ◽  
J. Chen ◽  
U. Haupt ◽  
M. Rautenberg
Keyword(s):  
Rossby Wave ◽  
Centrifugal Compressor ◽  
Reverse Flow ◽  
Baroclinic Instability ◽  
Wave Theory ◽  
Polar Front ◽  
Rotating Stall ◽  
Squall Line ◽  
Two Dimensional ◽  
Pressure Pattern

The pressure field of deep rotating stall of a centrifugal compressor with two stall cells is analysed by means of the two-dimensional pressure pattern in the impeller determined by Chen et al. (1993). These authors transferred the pressure pattern measured on the shroud surface (i.e. in the absolute frame) to that related to the rotating blade channels. The transferred pressure pattern is thus a two-dimensional one. The existence of the low and high pressure vortices according to the Rossby wave theory is confirmed by this experiment. The development stages of the two vortices, in combination with the Rossby wave that steers the rotating stall, can be evaluated very well. The vortex low is developed from the front between the reverse flow (with high temperature and entropy) and the forward flow (with low temperature and entropy) due to baroclinic instability. Its center is situated within the channel of the splitter blade. This front is accompanied by a squall line of small-scaled eddies. This is the same phenomenon as can be observed on the meteorological polar front. The vortex high is induced by the vortex low. Its embryo starts on the pressure surface. Its center is situated behind the inlet edge of the splitter blade. It can be further verified that the stall cell is caused by the backflows of the induction fields of the two vortices (low and high).

Blade Excitation by Broad-Band Pressure Fluctuations in a Centrifugal Compressor

1988 ◽  
Vol 110 (1) ◽  
pp. 129-137 ◽  
Author(s):  
U. Haupt ◽  
M. Rautenberg ◽  
A. N. Abdel-Hamid
Keyword(s):  
Centrifugal Compressor ◽  
Reverse Flow ◽  
Pressure Ratio ◽  
Pressure Fluctuations ◽  
Broad Band ◽  
Rotating Stall ◽  
High Mass ◽  
Blade Vibration ◽  
Flow Angle ◽  
Unsteady Pressure

The mechanism of blade excitation during the operation of a high-mass-flow, high-pressure-ratio centrifugal compressor has been investigated. This was carried out in the compressor operating range below 60 percent of design speed and in the zone of unsteady flow occurrence, where considerable blade vibration has been measured but no periodic unsteady pressure pattern such as rotating stall could be identified. Experiments conducted to study the mechanism of interactions between flow and blades were accomplished using several measuring methods simultaneously, such as measurements of blade vibration, flow angle at impeller inlet, unsteady pressure at different meridional and peripheral locations, as well as flow visualization by means of oil pattern. Analysis of the measurements showed typical broad-band characteristics of the unsteady pressure field and also for the blade vibration behavior. Results of flow angle investigations at the impeller inlet together with the analysis of oil pattern show that the broad-band pressure fluctuations and blade excitation can be attributed to a strong reverse flow near the suction side of the radial blade in the shroud zone. This reverse flow has its source downstream of the impeller and is extending back up to a location ahead of the impeller inlet. Similar results were obtained when the compressor was operated with vaneless and vaned diffuser configurations.

Casing Modification for Increasing the Surge Margin of a Centrifugal Compressor in an Automotive Turbine Engine

1975 ◽  
Vol 97 (3) ◽  
pp. 329-335 ◽  
Author(s):  
C. A. Amann ◽  
G. E. Nordenson ◽  
G. D. Skellenger
Keyword(s):  
Gas Turbine ◽  
Analytical Model ◽  
Centrifugal Compressor ◽  
Rotating Stall ◽  
Flow Instabilities ◽  
Two Dimensional ◽  
Turbine Engine ◽  
The Third ◽  
Surge Margin ◽  
Third Dimension

The significance of broadening the flow range of the compressor in an automotive gas turbine engine by lowering its surge-limited flow is cited. Following a review of flow instabilities observed in the centrifugal compressor, data are presented from a particular machine. Review of these data suggest that surge is associated with the conditions inducing rotating stall, and that the rotating stall occurs initially in the diffuser. Employing a simplified two-dimensional analytical model of the flow at the rotor-diffuser interface, it is found that flow relief in the third dimension should delay the onset of surge. Incorporating such relief in the shroud casing is shown experimentally to reduce surge flow.

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.

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.

Evolution of Reverse Flow in a Transonic Centrifugal Compressor at Near-Surge

2017 ◽  
Author(s):  
Kazutoyo Yamada ◽  
Masato Furukawa ◽  
Hiromitsu Arai ◽  
Dai Kanzaki
Keyword(s):  
Centrifugal Compressor ◽  
Reverse Flow ◽  
High Reliability ◽  
Pressure Rise ◽  
Flow Region ◽  
Flow Fields ◽  
Rotating Stall ◽  
Centrifugal Compressors ◽  
Transonic Centrifugal Compressor ◽  
Flow Phenomena

In process centrifugal compressors used in various types of plants, the compressor is the heart of a plant, and it requires high reliability. Therefore, prediction of the surge is important for centrifugal compressors. There have been numerous researches on the surge: study on improvement of surge margin, and study on the rotating stall, which is recognized as a precursor to surge, in impeller or diffuser of the compressor. However, the researches have not focused on the surge inception flow phenomena, namely detailed flow mechanism leading to the surge, although understanding of such flow phenomena is important for prediction of the surge. The paper describes in detail unsteady flow fields in a transonic centrifugal compressor at near-surge conditions. The flow fields have been investigated by detached eddy simulations (DES) using 400 million grid points. The simulation results show that the huge reverse flow region occupies the flow field near the shroud in the impeller at off-design condition, triggered by the blade stall at the tip of impeller full-blade, and it drastically develops at near-surge. It is also found that the rotating disturbance with reversed flow appears in the diffuser near the endwall at around peak pressure-rise point, and it eventually evolves into the rotating stall cell with a large reverse flow, blocking the flow inside the diffuser at near-surge.

scholarly journals PARAMETRIC STUDY OF THE ROSSBY WAVE INSTABILITY IN A TWO-DIMENSIONAL BAROTROPIC DISK

2016 ◽  
Vol 823 (2) ◽  
pp. 84 ◽  
Author(s):  
Tomohiro Ono ◽  
Takayuki Muto ◽  
Taku Takeuchi ◽  
Hideko Nomura
Keyword(s):  
Rossby Wave ◽  
Parametric Study ◽  
Two Dimensional ◽  
Wave Instability

Roles of vanes in diffuser on stability of centrifugal compressor

2019 ◽  
Vol 233 (14) ◽  
pp. 5380-5392
Author(s):  
Wangzhi Zou ◽  
Xiao He ◽  
Wenchao Zhang ◽  
Zitian Niu ◽  
Xinqian Zheng
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Dynamic Pressure ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Rotating Stall ◽  
Centrifugal Compressors ◽  
Compression System ◽  
The Stability ◽  
Rotating Instability

The stability considerations of centrifugal compressors become increasingly severe with the high pressure ratios, especially in aero-engines. Diffuser is the major subcomponent of centrifugal compressor, and its performance greatly influences the stability of compressor. This paper experimentally investigates the roles of vanes in diffuser on component instability and compression system instability. High pressure ratio centrifugal compressors with and without vanes in diffuser are tested and analyzed. Rig tests are carried out to obtain the compressor performance map. Dynamic pressure measurements and relevant Fourier analysis are performed to identify complex instability phenomena in the time domain and frequency domain, including rotating instability, stall, and surge. For component instability, vanes in diffuser are capable of suppressing the emergence of rotating stall in the diffuser at full speeds, but barely affect the characteristics of rotating instability in the impeller at low and middle speeds. For compression system instability, it is shown that the use of vanes in diffuser can effectively postpone the occurrence of compression system surge at full speeds. According to the experimental results and the one-dimensional flow theory, vanes in diffuser turn the diffuser pressure rise slope more negative and thus improve the stability of compressor stage, which means lower surge mass flow rate.

Backward Traveling Rotating Stall Waves in Centrifugal Compressors

2002 ◽  
Author(s):  
Z. S. Spakovsky
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
First Principles ◽  
Rotating Stall ◽  
Air Injection ◽  
System Stability ◽  
Centrifugal Compressors ◽  
Injection Scheme ◽  
Surge Margin ◽  
Low Order

Rotating stall waves that travel against the direction of rotor rotation are reported for the first time and a new, low-order analytical approach to model centrifugal compressor stability is introduced. The model is capable of dealing with unsteady radially swirling flows and the dynamic effects of impeller-diffuser component interaction as it occurs in centrifugal compression systems. A simple coupling criterion is developed from first principles to explain the interaction mechanism important for system stability. The model findings together with experimental data explain the mechanism for first-ever observed backward traveling rotating stall in centrifugal compressors with vaned diffusers. Based on the low-order model predictions, an air injection scheme between the impeller and the vaned diffuser is designed for the NASA Glenn CC3 high-speed centrifugal compressor. The steady air injection experiments show an increase of 25% in surge-margin with an injection mass flow of 0.5% of the compressor mass flow. In addition, it is experimentally demonstrated that this injection scheme is robust to impeller tip-clearance effects and that a reduced number of injectors can be applied for similar gains in surge-margin. The results presented in this paper firmly establish the connection between the experimentally observed dynamic phenomena in the NASA CC3 centrifugal compressor and a first principles based coupling criterion. In addition, guidelines are given for the design of centrifugal compressors with enhanced stability.

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