The Operational Stability of a Centrifugal Compressor and Its Dependence on the Characteristics of the Subcomponents

1994 ◽  
Vol 116 (2) ◽  
pp. 250-259 ◽  
Author(s):  
R. Hunziker ◽  
G. Gyarmathy
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Pressure Field ◽  
Dynamic Instability ◽  
Pressure Rise ◽  
Stability Limit ◽  
Maximum Pressure ◽  
Pressure Measurements ◽  
The Stability ◽  
Inlet Angle

A centrifugal compressor was tested with three different diffusers with circular-arc vanes. The vane inlet angle was varied from 15 to 30 deg. Detailed static wall pressure measurements show that the pressure field in the diffuser inlet is very sensitive to flow rate. The stability limit regularly occurred at the flow rate giving the maximum pressure rise for the overall stage. Mild surge arises as a dynamic instability of the compression system. The analysis of the pressure rise characteristic of each individual subcomponent (impeller, diffuser inlet, diffuser channel,...) reveals their contribution to the overall pressure rise. The diffuser channels play an inherently destabilizing role while the impeller and the diffuser inlet are typically stabilizing. The stability limit was mainly determined by a change in the characteristic of the diffuser inlet. Further, the stability limit was found to be independent of the development of inducer-tip recirculation.

scholarly journals The Operational Stability of a Centrifugal Compressor and its Dependence on the Characteristics of the Subcomponents

1993 ◽  
Author(s):  
René Hunziker ◽  
Georg Gyarmathy
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Pressure Field ◽  
Dynamic Instability ◽  
Pressure Rise ◽  
Stability Limit ◽  
Maximum Pressure ◽  
Pressure Measurements ◽  
The Stability ◽  
Inlet Angle

A centrifugal compressor was tested with three different diffusers with circular-arc vanes. The vane inlet angle was varied from 15° to 30°. Detailed static wall pressure measurements show that the pressure field in the diffuser inlet is very sensitive to flow rate. The stability limit regularly occurred at the flow rate giving the maximum pressure rise for the overall stage. Mild surge arises as a dynamic instability of the compression system. The analysis of the pressure rise characteristic of each individual subcomponent (impeller, diffuser inlet, diffuser channel,…) reveals their contribution to the overall pressure rise. The diffuser channels play an inherent destabilizing role while the impeller and the diffuser inlet are typically stabilizing. The stability limit was mainly determined by a change in the characteristic of the diffuser inlet. Further, the stability limit was found to be independent of the development of inducer-tip recirculation.

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.

Investigation of Self-Recycling-Casing-Treatment (SRCT) Influence on Stability of High Pressure Ratio Centrifugal Compressor With a Volute

2011 ◽  
Author(s):  
Mingyang Yang ◽  
Ricardo Martinez-Botas ◽  
Yangjun Zhang ◽  
Xinqian Zheng ◽  
Takahiro Bamba ◽  
...  
Keyword(s):  
High Pressure ◽  
Numerical Method ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Flow Distortion ◽  
Casing Treatment ◽  
High Pressure Ratio ◽  
The Stability

Large feasible operation range is a challenge for high pressure ratio centrifugal compressor of turbocharger in vehicle engine. Self-Recycling-Casing-Treatment (SRCT) is a widely used flow control method to enlarge the range for this kind of compressor. This paper investigates the influence of symmetrical/asymmetrical SRCT (ASRCT) on the stability of a high pressure ratio centrifugal compressor by experimental testing and numerical simulation. Firstly, the performance of the compressor with/without SRCT is tested is measured investigate the influence of flow distortion on the stability of compressor as well as the numerical method validation. Then detailed flow field investigation is conducted by experimental measurement and the numerical method to unveil the reasons for stability enhancement by symmetrical/asymmetrical SRCT. Results show that static pressure distortion at impeller outlet caused by the volute can make passages be confronted with flow distortion less stable than others because of their larger positive slope of T-S pressure ratio performance at small flow rate. SRCT can depress the flow distortion and reduce the slope by non-uniform recycling flow rate at impeller inlet. Moreover, ASRCT can redistribute the recycling flow in circumferential direction according to the asymmetric geometries. When the largest recycling flow rate is imposed on the passage near the distorted static pressure, the slope will be the most effectively reduced. Therefore, the stability is effectively enhanced by the optimized recycling flow device.

Operating Limits of Spark-Assisted Compression Ignition Combustion Under Boosted Ultra-EGR Dilute Conditions in a Negative Valve Overlap Engine

2019 ◽  
Author(s):  
Vassilis Triantopoulos ◽  
Jason B. Martz ◽  
Jeff Sterniak ◽  
George Lavoie ◽  
Dennis N. Assanis ◽  
...  
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Engine Speed ◽  
Pressure Rise ◽  
Stability Limit ◽  
Maximum Pressure ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Temperature Combustion ◽  
Operating Limits

Abstract Spark-assisted compression ignition (SACI) is a low temperature combustion mode that can offer thermal efficiency improvements and lower nitrogen oxide emissions compared to conventional spark-ignited combustion. However, the SACI operating range is often limited due to excessive pressure rise rates driven by rapid heat release rates. Well-controlled experiments were performed to investigate the SACI operating limits under previously unexplored boosted, stoichiometric, EGR dilute conditions, where low temperature combustion engines promise high thermodynamic efficiencies. At higher intake boost, the SACI high load limit shifted towards lower fuel-to-charge equivalence ratio mixtures, creating a larger gap between the conventional spark-ignition EGR dilution limit and the boosted SACI operating limits. Combustion phasing retard was very effective at reducing maximum pressure rise rate levels until the stability limit, primarily due to slower end-gas burn rates. Gross fuel conversion efficiency improvements up to 10% were observed by using intake boost for either load expansion or dilution extension. Changes in engine speed necessitated changes in unburned gas temperature to match autoignition timing, but were shown to have negligible impact on the heat release profile on a crank angle basis. Lower engine speeds were favorable for load expansion, as time-based peak pressure rise rates scaled with engine speed.

scholarly journals Study on Two Types of Stall Patterns in a Centrifugal Compressor with a Wide Vaneless Diffuser

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1251
Author(s):  
Qian Zhang ◽  
Liang Zhang ◽  
Qiuhong Huo ◽  
Lei Zhang
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Propagation Speed ◽  
Radius Ratio ◽  
Vaneless Diffuser ◽  
Vaneless Diffusers ◽  
Stall Cells ◽  
The Stability ◽  
The One

Two types of stall patterns in the centrifugal compressor with a wide vaneless diffuser were numerically studied in this paper. We carried out kinds of three-dimensional numerical simulations of the instability process in wide vaneless diffusers with different radius ratios. The results show that there are two kinds of stall patterns in wide vaneless diffusers with different radius ratios. For a short diffuser with a radius ratio of 1.5, the speed of the propagation of stalled cells is relatively high, and the propagation speed and frequency of stall cells do not change with the decrease in the flow rate. For a long diffuser with a radius ratio of 1.8, the propagation velocity of stall cells is smaller to the one in the short diffuser, and increases with the decrease in flow rate. For wide vaneless diffusers with different radius ratios, the main factor causing stall is the outlet reflux. Reducing the radius ratio of the wide vaneless diffuser has an important influence on the stability of the centrifugal compressor.

Characterization of the stability indices of a methanol induced partially premixed diesel dual fuel operation under varying split injection profiles: An experimental endeavour

2021 ◽  
pp. 1-16
Author(s):  
Dipankar Kakati ◽  
Sumit Roy ◽  
Rahul Banerjee
Keyword(s):  
Peak Pressure ◽  
Single Injection ◽  
Pressure Rise ◽  
Dual Fuel ◽  
Maximum Pressure ◽  
Effective Pressure ◽  
Split Injection ◽  
Indicated Mean Effective Pressure ◽  
Rise Rate ◽  
The Stability

Abstract The present investigation attempts to explore the prospects of the engine operational stability of a methanol induced partially premixed dual fuel operation under split injection strategy operating on a conventional single cylinder diesel engine coupled with a dedicated CRDI. The operation of such LTC regimes often deals with the stability concerns which are primarily characterized as the harshness of the operations and the non-repeatability of the combustion cycles. These two markers of operational stability have been mapped in this study through a comprehensive set of metrics of maximum pressure rise rate (ROPRmax) and Coefficient of Variation of Indicated Mean Effective Pressure (COVIMEP), Peak Pressure (COVPP) and Crank Angle of 50% mass fraction burn (COVCA50). The parametric investigation has been carried out at three different injection timings and pilot mass percentages at predefined methanol injection durations. The results have shown tremendous reductions in the non-repeatability of the combustion cycles and the harshness of the engine operation under split injection strategy, indicated by the lower scores of the stability indicators in comparison to the baseline single injection operation. Subsequently, the lowest scores of the maximum pressure rise rate and the Coefficient of Variation of indicated mean effective pressure, peak pressure and CA50 for the entire scope of investigation were registered as 0.62bar/CA, 0.75%, 0.48% and 1%, which were apparently observed as 65.5%, 86.36%, 94% and 53% lower than the corresponding scores registered in the baseline single injection operation.

Prediction and Validation of the Transient Pressure Field in a Centrifugal Compressor With Vaned Diffuser for the Application in High Cycle Fatigue Stress Estimations

2021 ◽  
Author(s):  
Gökay Bacakci ◽  
Friedrich Fröhlig ◽  
Lukas Stuhldreier ◽  
Johannes Deutsch ◽  
Peter Jeschke
Keyword(s):  
Centrifugal Compressor ◽  
High Cycle Fatigue ◽  
Pressure Field ◽  
Transient Flow ◽  
Pressure Fluctuations ◽  
Fast Response ◽  
Pressure Measurements ◽  
Cycle Fatigue ◽  
Transient Pressure ◽  
Response Pressure

Abstract In this paper, the transient pressure field in a centrifugal compressor is predicted by the Nonlinear Harmonic (NLH) method, as well as the unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations and validated by transient pressure measurements. The accurate prediction of these pressure fluctuations is crucial, because they have a significant influence on the High-Cycle-Fatigue (HCF) behavior in turbomachinery applications. As the first step, excited and non-excited rotational speeds, caused by rotor-stator interactions, are identified by modal analysis performed on a single segment impeller assembly. In order to eliminate any additional pressure fluctuations caused by blade vibrations, three non-excited operating points at different rotational speed levels are selected for the transient flow simulations. The transient pressure fields predicted by these methods are validated by transient pressure measurements at three circumferentially different locations on the impeller shroud. A study of the modeling of these fast-response pressure probes in numerical calculations also falls within the scope of this work in order to identify its effect on the transient pressure amplitudes. The results of the numerical calculations and measurements are compared in the frequency domain by performing Fast-Fourier Transformations (FFT) and Short-Time Fourier Transformations (STFT) on the numerical and experimental data respectively. It is shown that the transient pressure field in a single staged centrifugal compressor is calculated accurately by both of the numerical methods in comparison to the transient flow measurements. This paper demonstrates that the numerical modeling of the fast-response pressure sensors has a significant impact on the unsteady pressure amplitudes, which needs to be taken into account for a reliable experimental validation process.

The Experimental Study of Matching Between Centrifugal Compressor Impellers and Vaneless Diffusers for Turbochargers

2007 ◽  
Author(s):  
Hideaki Tamaki ◽  
Satoshi Yamaguchi
Keyword(s):  
Flow Rate ◽  
Peak Pressure ◽  
Pressure Rise ◽  
Positive Slope ◽  
Vaneless Diffuser ◽  
Effective Measure ◽  
New Correlation ◽  
Design Changes ◽  
Physical Effects ◽  
The Stability

The operating range of centrifugal compressors for turbochargers using vaneless diffuser is considered from measurements of the separate pressure rise of the impeller and the diffuser. In some cases, the peak pressure rise of the stage corresponds to the peak pressure rise of the impeller (which is considered to correspond to inducer stall). From these measurements a new correlation for the onset of inducer stall is proposed. In other cases the stability of the vaneless diffuser (defined as positive slope of the pressure rise versus flow characteristic) determines the stability of the stage. A 1D analysis of the pressure rise versus flow rate in a vaneless diffuser captures the main physical effects due to friction and provides a guide to the effect of design changes for increasing the range. Subsequent tests confirm that reduction of diffuser height is the most effective measure for reducing the surge flow rate.

Inducer Stall in a Centrifugal Compressor With Inlet Distortion

1987 ◽  
Vol 109 (1) ◽  
pp. 27-35 ◽  
Author(s):  
I. Ariga ◽  
S. Masuda ◽  
A. Ookita
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Stability Margin ◽  
Rotating Stall ◽  
Characteristic Parameters ◽  
Inlet Distortion ◽  
Rate Region ◽  
Compressor Performance ◽  
The Stability ◽  
Lower Flow Rate

The effects of inlet distortion on the inducer stall in a centrifugal compressor are investigated. Cases of both radial and circumferential distortion are investigated. It is shown that the rotating stall onset is amplified by radial distortions, and restrained by circumferential distortions. These results are compared with calculations based on the small disturbance theory. The authors find that the stall onset is governed by the characteristic parameters related to the lower flow rate region for radial distortions, but affected by those of the higher flow rate region for circumferential distortion. It is shown that the process of stall is different for each distortion pattern. Existence of inlet distortion reduces compressor performance characteristics and strongly influences the stability margin.

Assessment of Steady and Unsteady Model Predictions for a Subsonic Centrifugal Compressor Stage

2012 ◽  
Author(s):  
Y. Bousquet ◽  
X. Carbonneau ◽  
I. Trebinjac
Keyword(s):  
Centrifugal Compressor ◽  
Industrial Development ◽  
Pressure Ratio ◽  
Stability Limit ◽  
Compressor Stage ◽  
Common Procedure ◽  
Centrifugal Compressor Stage ◽  
Steady Simulation ◽  
The Stability ◽  
High Level

The most common procedure to obtain the performance of a centrifugal compressor in an industrial development process is based on the use of a steady RANS model with the mixing-plane approach. However some phenomena such as the flow interaction between the impeller and the diffuser can be the source of unsteady effects which can affect the steady model prediction. This paper investigates the ability of a steady simulation to predict the overall performance and the flow structures in a subsonic centrifugal compressor stage by comparison with time-dependent results. Simulations are performed considering three operating points: peak efficiency, close to the stability limit and close to the blockage. The results show that the steady model is accurate enough to predict the stage static-to-total pressure ratio. However, in location where high level of fluctuation is expected, the steady model shows some weakness to predict the time-averaged quantities of the flow structure.

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