scholarly journals Comparative Rotating Stall and Surge Characteristic of a Centrifugal Compressor With Three Different Types of Diffusers

1997 ◽  
Author(s):  
Abraham Engeda
Keyword(s):  
Centrifugal Compressor ◽  
Rotating Stall ◽  
Straight Channel ◽  
Vaneless Diffuser ◽  
Curved Channel ◽  
Vaned Diffuser ◽  
Channel Geometry ◽  
Different Types ◽  
Specific Geometry ◽  
Tip Radius

The diffuser system of a centrifugal compressor comes basically in two general categories either as vaneless or vaned diffuser. Vaned diffusers can further be subdivided into two depending on channel geometry as straight channel or curved channel, or depending on solidity. Three different diffuser types: a vaneless, conventional vaned and a low solidity vaned were tested in the present study. All diffusers were tested downstream of the same impeller. All the diffusers had the same diffuser exit radius to impeller tip radius ratio. The influence of each type of diffuser on the performance and stall characteristics of the inducer and impeller as a whole was studied. In addition, diffuser stall characteristics of each type diffuser were also studied. The type of diffuser had no significant effect on inducer and impeller stall. The inducer was more stable with the conventional vaned diffuser configuration. Rotating Stall was detected with the vaneless diffuser configuration at the onset of surge. Four stall cells rotated in the same direction as the impeller at 122 Hz. Numerous works have been documented on rotating stall and surge for centrifugal compressors. Prediction of the inception of rotating stall and surge for a specific geometry and operation is not yet fully possible. Therefore, experimental results and correlations are still of great importance.

Design and Investigation of Four Low Solidity Vaned Diffusers to Assess the Effect of Solidity and Vane Number

1998 ◽  
Author(s):  
Abraham Engeda
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Compressor Stage ◽  
Straight Channel ◽  
Vaneless Diffuser ◽  
Curved Channel ◽  
Vaned Diffuser ◽  
Channel Geometry ◽  
And Performance ◽  
The Individual

As part of a continued effort to understand the design and performance of Low Solidity Vaned Diffusers (LSVD), four new LSVDs have been designed and tested. A centrifugal compressor stage usually consists of the inlet, impeller, diffuser and collector systems. Even though the individual components of the compressor are capable of achieving high efficiency, it is the efficiency of the whole stage that is of great importance. The diffuser system of a centrifugal compressor comes basically in two general categories either as vaneless or vaned diffuser (excluding pipe diffusers). Vaned diffusers can further be subdivided into two depending on channel geometry as straight channel or curved channel, or depending on solidity. It is currently believed that the LSVD offers a compromise between a vaned and a vaneless diffuser by possessing the virtues of each. This paper discusses the design and experimental investigation of the new four LSVDs. The diffusers had a solidity of 0.9, 0.8, 0.7 and 0.6. These newly designed LSVDs are known as LSVD#5 to LSVD#8.

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.

Numerical Investigation of a Centrifugal Compressor With a Single Circumferential Groove in Different Types of Diffusers

2017 ◽  
Author(s):  
Xuefei Chen ◽  
Zijian Ai ◽  
Yunfeng Ji ◽  
Guoliang Qin
Keyword(s):  
Centrifugal Compressor ◽  
Stable Operation ◽  
Stable Range ◽  
Vaneless Diffuser ◽  
Vaned Diffuser ◽  
Effective Measure ◽  
Stall Margin ◽  
Casing Treatment ◽  
Circumferential Groove ◽  
Different Types

Enhancing compressor stall and surge has a great importance for the development of turbo compressors. The application of casing treatment is an effective measure to expand the stall margin and stable operation range. Numerical investigations were conducted to predict the performance of a low flow rate centrifugal compressor with circumferential groove casing treatment in diffuser. Numerical cases with different radial location, radial width and axial depth of a circumferential single groove in different types of diffusers (vaned diffuser, half-vaned diffuser, vaneless diffuser) were carried out to compare the results. The computational fluid dynamics analyses results show that the centrifugal compressor with circumferential groove in vaned diffuser can extend stable range by about 9.1% while the efficiency over the whole operating range decreases by 0.2 to 1.7%; the results with half-vaned diffuser and vaneless diffuser can improve stable range less and the efficiency decreases more. Efforts were made to study blade level flow mechanisms to determine how the circumferential groove impacts the compressor’s stall margin and performance. The flow structures in the passage, the tip gap, and the grooves as well as their mutual interactions were plotted and analyzed. The flow transport across the tip gap in the smooth wall and the circumferential grooves were compared.

Distinction Between Different Types of Impeller and Diffuser Rotating Stall in a Centrifugal Compressor With Vaneless Diffuser

1984 ◽  
Vol 106 (2) ◽  
pp. 468-474 ◽  
Author(s):  
P. Frigne ◽  
R. Van Den Braembussche
Keyword(s):  
Experimental Data ◽  
Experimental Investigation ◽  
Centrifugal Compressor ◽  
Rotating Stall ◽  
Rotating Flow ◽  
Hot Wire ◽  
Vaneless Diffuser ◽  
Velocity Fluctuations ◽  
Different Types ◽  
Induced Velocity

This paper describes the results of an experimental investigation of the sub-synchronous rotating flow patterns in a centrifugal compressor with vaneless diffuser. Several compressor configurations have been examined by means of hot wire anemometry, Fourier analysis allowed one to distinguish between the different modes of unstable operation. For both impeller and diffuser rotating stall, comparison is made between the amplitude, frequency, and periodicity of the induced velocity fluctuations. The results are further cross-checked with other experimental data.

The Influence of a Diffuser Width on the Unsteady Performance of a Centrifugal Compressor Stage

2002 ◽  
Author(s):  
Abraham Engeda
Keyword(s):  
Centrifugal Compressor ◽  
Time Domain ◽  
Rotating Stall ◽  
Compressor Stage ◽  
Relative Speed ◽  
Vaneless Diffuser ◽  
Flow Rates ◽  
Centrifugal Compressor Stage ◽  
Different Types ◽  
Unsteady Performance

An experimental investigation was conducted to determine the effect of the vaneless diffuser width on the unsteady flow performance of a centrifugal compressor stage. Two compressor configurations with different vaneless diffuser width were investigated at four different impeller speeds and compared in the frequency and time domain. Only one diffuser rotating stall but different types of impeller rotating stalls were detected. The experiments show that the diffuser has a strong influence on the flow in the impeller including in areas way upstream. Analysis of the results indicated: • With increasing diffuser width the onset of impeller rotating stall was shifted to lower flow rates. • With increasing diffuser width the frequencies of the rotating stalls decreased. • There is a common tendency in most of the experiments to lower numbers of rotating cells with increasing relative speed. The impeller rotating stalls can be subdivided in a slow pattern with a relative speed to the impeller of 0.21 to 0.29 and a fast pattern with a relative speed of 0.50 to 0.56. This occurrence of two rotating pressure patterns confirms analytical results presented in previous investigations.

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.

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.

scholarly journals Estimation of the Aerodynamic Force Induced by Vaneless Diffuser Rotating Stall in Centrifugal Compressor Stages

2016 ◽  
Vol 101 ◽  
pp. 734-741 ◽  
Author(s):  
Michele Marconcini ◽  
Alessandro Bianchini ◽  
Matteo Checcucci ◽  
Davide Biliotti ◽  
Marco Giachi ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Aerodynamic Force ◽  
Rotating Stall ◽  
Vaneless Diffuser

Effects of Inlet Flow Field Conditions on the Stall Onset of Centrifugal Compressor Vaned Diffusers

2003 ◽  
Author(s):  
Sabri Deniz
Keyword(s):  
Flow Field ◽  
Axial Flow ◽  
Rotating Stall ◽  
Field Conditions ◽  
Test Facility ◽  
Straight Channel ◽  
Inlet Flow ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Operating Range

This paper considers the performance and operating range of vaned diffusers for use in high performance centrifugal compressors. An experimental and numerical investigation is performed to determine the effects of inlet flow field conditions on pressure recovery and stall onset of different type vaned diffusers, such as discrete-passage and straight-channel diffusers. Diffuser inlet flow conditions examined include Mach number, flow angle, blockage, and axial flow non-uniformity. The investigation was carried out in a specially built test facility, designed to provide a controlled inlet flow field to the test diffusers. Unsteady pressure measurements showed the operating range of a compressor stage was limited by the onset of rotating stall, triggered by the loss of stability in the vaned diffuser, independent of the impeller operating point. For both diffusers investigated, loss of flow stability in the diffuser occurred at a critical value of the momentum-averaged flow angle into the diffuser. To provide additional information on diffuser flow development and to complement previous experimental work performed on straight-channel type diffuser, a computational investigation has been undertaken and important results are presented.

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