Experimental Investigation and Characterization of the Rotating Stall in a High Pressure Centrifugal Compressor: Part IV — Impeller Influence on Diffuser Stability

2003 ◽  
Author(s):  
A. Cellai ◽  
G. Ferrara ◽  
L. Ferrari ◽  
C. P. Mengoni ◽  
L. Baldassarre
Keyword(s):  
Experimental Investigation ◽  
High Pressure ◽  
Centrifugal Compressor ◽  
Rotating Stall ◽  
Radius Ratio ◽  
Vaneless Diffuser ◽  
Stall Inception ◽  
Last Stage ◽  
And Diffusion

Vaneless diffuser rotating stall is a major problem for centrifugal compressors since it is a limit to their working range. In particular the last stage seems to be the most critical. In the literature some good correlations for predicting stall inception can be found but they do not adequately cover the case of the last stage configuration, especially for very low blade-outlet-width-to-impeller-radius-ratio impellers typically used in high-pressure applications. Extensive research has been performed to define diffuser stall limits for this family of stages: three impellers characterized by different blade-outlet-width-to-impeller-radius-ratios are tested with different diffuser configurations (different pinch shapes, diffuser widths and diffusion ratios). Part I and II report the results of these geometry modifications on diffuser stability for the first impeller. Part III, those for the second impeller. In this part the comparison of these results in terms of impeller influence on diffuser stability is reported.

Experimental Characterization of Vaneless Diffuser Rotating Stall: Part VI — Reduction of Three Impeller Results

2006 ◽  
Author(s):  
E. A. Carnevale ◽  
G. Ferrara ◽  
L. Ferrari ◽  
L. Baldassarre
Keyword(s):  
Rotating Stall ◽  
Radius Ratio ◽  
Vaneless Diffuser ◽  
Cross Sectional ◽  
Stall Inception ◽  
Return Channel ◽  
Geometrical Scale ◽  
And Diffusion ◽  
Basic Configuration

Vaneless diffuser rotating stall is a major problem for centrifugal compressors since it is a limit to their working range. In the literature some good correlations for predicting stall inception can be found but they do not adequately cover the case of the last stage configuration, especially for very low blade-outlet-width-to-impeller-radius-ratio impellers typically used in high-pressure applications. Extensive research has been performed to define diffuser stall limits for this family of stages: three impellers characterized by different blade-outlet-width-to-impeller-radius-ratios have been tested with different diffuser configurations (different pinch shapes, diffuser widths and diffusion ratios). The basic configuration comprises a 1:1 geometrical scale stage with a return channel upstream, a 2D impeller with a vaneless diffuser and a volute with a constant cross sectional area downstream. Several diffuser types with different widths and diffusion ratios were tested. Detailed experimental results have been reported in previous works [1, 2, 3 and 4]. In this paper experimental data are reviewed in order to analyze impeller influence on diffuser stability and to develop some summarizing consideration on stall behavior of vaneless diffuser for impeller with low blade-outlet-width-to-impeller-radius-ratio.

Experimental Investigation and Characterization of the Rotating Stall in a High Pressure Centrifugal Compressor: Part I — Influence of Diffuser Geometry on Stall Inception

2002 ◽  
Author(s):  
G. Ferrara ◽  
L. Ferrari ◽  
C. P. Mengoni ◽  
M. De Lucia ◽  
L. Baldassarre
Keyword(s):  
Centrifugal Compressor ◽  
Experimental Tests ◽  
Rotating Stall ◽  
Main Task ◽  
Test Results ◽  
Vaneless Diffuser ◽  
Stall Inception ◽  
Last Stage ◽  
Prediction Criteria

Extensive research on centrifugal compressors has been planned to define diffuser stall limits for a group of stages characterized by low blade-outlet-width-to-impeller-radius-ratio. Very little data is available on this centrifugal compressor family, especially for the last stage configuration. In addition, the most important stall diffuser prediction criteria barely cover this machine type. Many experimental tests have been planned to investigate several geometry variations. A simulated stage with a backward channel upstream, a 2D impeller with a vaneless diffuser and a constant cross section volute downstream constitute the basic geometry. Several diffuser geometries with different widths, pinch shapes, diffusion ratios were tested. Test results and conclusions are shown in the paper in terms of critical diffuser inlet flow angles, flow coefficients at stall inception and stage working ranges. The main task of the present work is to increase the knowledge and the amount of available data to characterize rotating stall phenomena, in particular for very narrow stages.

Experimental Investigation and Characterization of the Rotating Stall in a High Pressure Centrifugal Compressor: Part III — Influence of Diffuser Geometry on Stall Inception and Performance (2nd Impeller Tested)

2003 ◽  
Author(s):  
A. Cellai ◽  
G. Ferrara ◽  
L. Ferrari ◽  
C. P. Mengoni ◽  
L. Baldassarre
Keyword(s):  
High Pressure ◽  
Rotating Stall ◽  
Point Of View ◽  
Vaneless Diffuser ◽  
Cross Sectional ◽  
Stall Inception ◽  
Last Stage ◽  
Return Channel ◽  
And Performance ◽  
Geometrical Scale

Vaneless diffuser rotating stall is a serious problem for centrifugal compressors since it limits their working range. In particular the last stage seems to be the most critical from this point of view. In the literature some good correlations can be found for predicting stall inception but they hardly cover the case of last stage configuration, especially for very low blade-outlet-width-to-impeller-radius-ratio impellers typically used in high-pressure applications. Extensive research has been planned to define diffuser stall limits for this family of stages: three impellers characterized by different blade-outlet-width-to-impeller-radius-ratios are tested. The basic configuration comprises a 1:1 geometrical scale stage with a return channel upstream, a 2D impeller with a vaneless diffuser and a volute with a constant cross sectional area downstream. Several diffuser types with different widths, pinch shapes and diffusion ratios were tested. The results for the first impeller have already been reported in part I and II. In this part the effects of the above mentioned geometric parameter changes on stage stability and performance are presented with respect to the second impeller.

Application of Low Solidity Vaned Diffusers to Prevent Rotating Stall in Centrifugal Compressors: Experimental Investigation

2003 ◽  
Author(s):  
A. Cellai ◽  
M. De Lucia ◽  
G. Ferrara ◽  
L. Ferrari ◽  
C. P. Mengoni ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
High Pressure ◽  
Rotating Stall ◽  
Geometrical Parameters ◽  
Vaneless Diffuser ◽  
Centrifugal Compressors ◽  
Vaned Diffuser ◽  
Stall Inception ◽  
And Performance

Rotating stall is a key problem in centrifugal compressors especially for high-pressure applications. Among the several solutions proposed to prevent this problem, low solidity vaned diffusers (LSDs) have been successfully applied. The aim of this research is to find an optimized LSD configuration in terms of stall inception and performance for the tested compressor. The influence of the vane leading and trailing edge radii, maintaining the same solidity and null deflection were investigated. The geometrical parameters of tested configurations were methodically chosen in order to achieve a design of experiment (DOE) analysis. In view of the above, a series of tests on five low solidity vaned diffuser configurations were carried out. Tests allowed determination of 2 different LSDs that showed the best behavior in terms of working range and performance. These LSDs were then compared with the standard and the reduced-width vaneless diffuser to better understand the best solution to the stall problem.

Stall Inception in a Vaneless Diffuser of a Centrifugal Compressor

2003 ◽  
Author(s):  
Jeong-Seek Kang ◽  
Shin-Hyoung Kang
Keyword(s):  
Fourier Coefficient ◽  
Centrifugal Compressor ◽  
Wave Energy ◽  
Traveling Wave ◽  
Analytical Investigation ◽  
Rotating Stall ◽  
Vaneless Diffuser ◽  
Stall Inception ◽  
Cell Structures ◽  
Warning Time

This paper presents an experimental and analytical investigation of a rotating stall inception in a vaneless diffuser of a centrifugal compressor. Eight fast-response pressure transducers are equally spaced around the circumference at the inlet and exit of a parallel vaneless diffuser. Instantaneous pressure data is measured near the stall inception point and characteristics of a rotating stall, a stall-initiating mechanism, a stall precursor and its warning schemes are discussed. It is found that one-cell, two-cell and three-cell structures of small amplitude wave grow and decay repeatedly before they are fully developed to a rotating stall, which is named as “pre-cell.” When it appears, the phase of spatial Fourier coefficient increases linearly and the traveling wave energy increases. The pre-cell travels at, or slightly lower than, the speed of the fully developed rotating stall. Its growing-decaying life span is about several decades of the impeller revolution. Pre-cells of one-cell, two-cell, and three-cell structures are found to interact frequently with their growing and decaying mechanism through transferring energy from one structure to another. Two stall warning schemes are used for the stall in the vaneless diffuser. The first scheme is to detect the linear increase region in the phase of the spatial Fourier coefficient from where the according warning time is about 0.3∼1.4 sec. (300∼700 impeller revs.) The second scheme is to detect the increase of traveling wave energy from where the according warning time is about 0.2∼2.3 sec. (200∼1200 impeller revs.) These warning schemes are useful because their warning time is long enough to be applied in active control of a compressor stall.

Experimental Characterization of Vaneless Diffuser Rotating Stall: Part V — Influence of Diffuser Geometry on Stall Inception and Performance (3rd Impeller Tested)

2006 ◽  
Author(s):  
G. Ferrara ◽  
L. Ferrari ◽  
L. Baldassarre
Keyword(s):  
Rotating Stall ◽  
Radius Ratio ◽  
Vaneless Diffuser ◽  
Cross Sectional ◽  
Stall Inception ◽  
Wide Range ◽  
Return Channel ◽  
And Performance ◽  
Geometrical Scale ◽  
Performance Results

Vaneless diffuser rotating stall is a serious problem for centrifugal compressors, since it limits their working range. In the literature some good correlations can be found for predicting stall inception but they have limited coverage of last stage configuration case, especially for very low blade-outlet-width-to-impeller-radius-ratio impellers typically used in high-pressure applications. In addition, stall inception is strictly bounded to diffuser geometry (for example, diffuser width and diffusion ratio). As a part of a wide range activity on rotating stall, a stage with a blade-outlet-width-to-impeller-radius-ratio of 0.1 has been tested. The stage configuration is made up by a 1:1 geometrical scale stage with a return channel upstream, a 2D impeller with a vaneless diffuser and a volute with a constant cross sectional area downstream. Diffusers with three different widths and two diffusion ratios were tested in order to find their influence on stage stability and performance. Results obtained for impellers with lower blade-outlet-width-to-impeller-radius-ratios have been published in previous papers. The purpose of this paper is to comment the obtained results and increase the amount of experimental data available on vaneless diffuser rotating stall behaviour.

Experimental Investigation of Rotating Instabilities in a Two-Stage Centrifugal Compressor With Vaneless Diffuser

2001 ◽  
Author(s):  
Vladimir V. Golubev
Keyword(s):  
Experimental Investigation ◽  
Centrifugal Compressor ◽  
Pressure Fluctuations ◽  
Rotating Stall ◽  
Sensitive Area ◽  
Flow Conditions ◽  
Vaneless Diffuser ◽  
Unstable Flow ◽  
Two Stage ◽  
Multi Stage

Abstract This paper examines unsteady response of an experimental two-stage centrifugal compressor with vaneless diffusers. A thorough investigation of pressure fluctuations along the compressor channel is carried out in order to examine the onset of unstable flow conditions. Rotating stall structures are localized, with special attention paid to identifying the most sensitive area of the multi-stage compressor channel which may serve as a precursor to unstable compressor operation. It is shown that both stages may develop rotating stall structures simultaneously, however the 2nd stage tends to destabilize first and reveals higher magnitudes of the unsteady response.

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.

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.

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.

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