Estimation of Centrifugal Compressor Stability With Diffuser Loss-Range System

1977 ◽  
Vol 99 (1) ◽  
pp. 76-81
Author(s):  
G. B. Reeves
Keyword(s):  
Centrifugal Compressor ◽  
Flow Characteristic ◽  
Pressure Ratio ◽  
Maximum Flow ◽  
Experimental Results ◽  
Constant Speed ◽  
Maximum Efficiency ◽  
Range Data ◽  
Loss Range ◽  
Estimate Flow

A method has been developed by which centrifugal compressor flow range and the nature of the pressure ratio characteristic approaching surge can be predicted by use of fundamental impeller exit conditions and diffuser entrance geometry in a system where minimum to maximum flow range is determined by the diffuser. Experimental results from compressor tests demonstrate the influence of these basic variables on flow range. Data from pipe type diffuser configurations designed under the assumptions of the loss-range method verify the capability to estimate flow range. Results of tests confirm the use of the method to predict the shape of the pressure ratio/weight flow characteristic and the location of maximum efficiency at constant speed.

scholarly journals Genetic Algorithm Optimization of the Volute Shape of a Centrifugal Compressor

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Martin Heinrich ◽  
Rüdiger Schwarze
Keyword(s):  
Numerical Model ◽  
Centrifugal Compressor ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Maximum Efficiency ◽  
Algorithm Optimization ◽  
Cross Sectional ◽  
Design Variables ◽  
Design Speed

A numerical model for the genetic optimization of the volute of a centrifugal compressor for light commercial vehicles is presented. The volute cross-sectional shape is represented by cubic B-splines and its control points are used as design variables. The goal of the global optimization is to maximize the average compressor isentropic efficiency and total pressure ratio at design speed and four operating points. The numerical model consists of a density-based solver in combination with the SSTk-ωturbulence model with rotation/curvature correction and the multiple reference frame approach. The initial validation shows a good agreement between the numerical model and test bench measurements. As a result of the optimization, the average total pressure rise and efficiency are increased by over1.0%compared to the initial designs of the optimization, while the maximum efficiency rise is nearly 2.5% atm˙corr=0.19 kg/s.

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.

Effect of Vaned Diffuser on a Modified Turbocharger Centrifugal Compressor Performance

2014 ◽  
Vol 663 ◽  
pp. 347-353
Author(s):  
Layth H. Jawad ◽  
Shahrir Abdullah ◽  
Zulkifli R. ◽  
Wan Mohd Faizal Wan Mahmood
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Width Ratio ◽  
Outlet Section ◽  
Suction Surface ◽  
Vaned Diffuser ◽  
Minimum Width

A numerical study that was made in a three-dimensional flow, carried out in a modified centrifugal compressor, having vaned diffuser stage, used as an automotive turbo charger. In order to study the influence of vaned diffuser meridional outlet section with a different width ratio of the modified centrifugal compressor. Moreover, the performance of the centrifugal compressor was dependent on the proper matching between the compressor impeller along the vaned diffuser. The aerodynamic characteristics were compared under different meridional width ratio. In addition, the velocity vectors in diffuser flow passages, and the secondary flow in cross-section near the outlet of diffuser were analysed in detail under different meridional width ratio. Another aim of this research was to study and simulate the effect of vaned diffuser on the performance of a centrifugal compressor. The simulation was undertaken using commercial software so-called ANSYS CFX, to predict numerically the performance charachteristics. The results were generated from CFD and were analysed for better understanding of the fluid flow through centrifugal compressor stage and as a result of the minimum width ratio the flow in diffuser passage tends to be uniformity. Moreover, the backflow and vortex near the pressure surface disappear, and the vortex and detachment near the suction surface decrease. Conclusively, it was observed that the efficiency was increased and both the total pressure ratio and static pressure for minimum width ratio are increased.

Effect of Recirculation Device With Counter Swirl Vane on Performance of High Pressure Ratio Centrifugal Compressor

2011 ◽  
Author(s):  
Hideaki Tamaki
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Negative Slope ◽  
Tip Leakage Flow ◽  
Recirculation Flow ◽  
Operating Range ◽  
High Pressure Ratio

Centrifugal compressors used for turbochargers need to achieve a wide operating range. The author has developed a high pressure ratio centrifugal compressor with pressure ratio 5.7 for a marine use turbocharger. In order to enhance operating range, two different types of recirculation devices were applied. One is a conventional recirculation device. The other is a new one. The conventional recirculation device consists of an upstream slot, bleed slot and the annular cavity which connects both slots. The new recirculation device has vanes installed in the cavity. These vanes were designed to provide recirculation flow with negative preswirl at the impeller inlet, a swirl counterwise to the impeller rotational direction. The benefits of the application of both of the recirculation devices were ensured. The new device in particular, shifted surge line to a lower flow rate compared to the conventional device. This paper discusses how the new recirculation device affects the flow field in the above transonic centrifugal compressor by using steady 3-D calculations. Since the conventional recirculation device injects the flow with positive preswirl at the impeller inlet, the major difference between the conventional and new recirculation device is the direction of preswirl that the recirculation flow brings to the impeller inlet. This study focuses on two effects which preswirl of the recirculation flow will generate. (1) Additional work transfer from impeller to fluid. (2) Increase or decrease of relative Mach number. Negative preswirl increases work transfer from the impeller to fluid as the flow rate reduces. It increases negative slope on pressure ratio characteristics. Hence the recirculation flow with negative preswirl will contribute to stability of the compressor. Negative preswirl also increases the relative Mach number at the impeller inlet. It moves shock downstream compared to the conventional recirculation device. It leads to the suppression of the extension of blockage due to the interaction of shock with tip leakage flow.

The influence of the trailing edge angle of the micro centrifugal impeller on the performance of the centrifugal compressor

2021 ◽  
pp. 1-15
Author(s):  
Xu Yu-dong ◽  
Li Cong ◽  
Lv Qiong-ying ◽  
Zhang Xin-ming ◽  
Mu Guo-zhen
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Centrifugal Impeller ◽  
Centrifugal Compressors ◽  
Trailing Edge ◽  
Sweep Angle ◽  
Impeller Blade ◽  
Bending Angle ◽  
Edge Angle ◽  
Isentropic Efficiency

In order to study the effect of the trailing edge sweep angle of the centrifugal impeller on the aerodynamic performance of the centrifugal compressor, 6 groups of centrifugal impellers with different bending angles and 5 groups of different inclination angles were designed to achieve different impeller blade trailing edge angle. The computational fluid dynamics (CFD) method was used to simulate and analyze the flow field of centrifugal compressors with different blade shapes under design conditions. The research results show that for transonic micro centrifugal compressors, changing the blade trailing edge sweep angle can improve the compressor’s isentropic efficiency and pressure ratio. The pressure ratio of the compressor shows a trend of increasing first and then decreasing with the increase of the blade bending angle. When the blade bending angle is 45°, the pressure ratio of the centrifugal compressor reaches a maximum of 1.69, and the isentropic efficiency is 67.3%. But changing the inclination angle of the blade trailing edge has little effect on the isentropic efficiency and pressure ratio. The sweep angle of blade trailing edge is an effective method to improve its isentropic efficiency and pressure ratio. This analysis method provides a reference for the rational selection of the blade trailing edge angle, and provides a reference for the design of micro centrifugal compressors under high Reynolds numbers.

Effect of Different Geometrical Inlet Pipes on a High Speed Centrifugal Compressor

2013 ◽  
Author(s):  
Ce Yang ◽  
Ben Zhao ◽  
C. C. Ma ◽  
Dazhong Lao ◽  
Mi Zhou
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Ratio ◽  
Inlet Pipe ◽  
Unsteady Pressure ◽  
Bent Pipe ◽  
Low Mass ◽  
Compressor Performance ◽  
Spectral Frequency ◽  
The One

Two different inlet configurations, including a straight pipe and a bent pipe, were experimentally tested and numerically simulated using a high-speed, low-mass flow centrifugal compressor. The pressure ratios of the compressor with the two inlet configurations were tested and then compared to illustrate the effect of the bent inlet pipe on the compressor. Furthermore, different circumferential positions of the bent inlet pipe relative to the volute are discussed for two purposes. One purpose is to describe the changes in the compressor performance that result from altering the circumferential position of the bent inlet pipe relative to the volute. This change in performance may be the so-called clocking effect, and its mechanism is different from the one in multistage turbomachinery. The other purpose is to investigate the unsteady flow for different matching states of the bent inlet pipe and volute. Thus, the frequency spectrum of unsteady pressure fluctuation was applied to analyze the aerodynamic response. Compared with the straight inlet pipe, the experimental results show that the pressure ratio is modulated and that the choke point is shifted in the bent inlet pipe. Similarly, the pressure ratio can be influenced by altering the circumferential position of the bent inlet pipe relative to the volute, which may have an effect on the unsteady pressure in the rotor section. Therefore, the magnitude of interest spectral frequency is significantly changed by clocking the bent inlet pipe.

Numerical Analysis of Deposits and Corrosion Influence on a Centrifugal Compressor Performance

2012 ◽  
Author(s):  
Mohammad R. Aligoodarz ◽  
Mohammad Reza Soleimani Tehrani ◽  
Hadi Karrabi ◽  
Mohammad R. Roshani
Keyword(s):  
Numerical Modeling ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Mechanical Damage ◽  
3D Numerical Modeling ◽  
Compressor Blades ◽  
Turbine Performance ◽  
Common Causes ◽  
Sst Turbulence Model ◽  
Compressor Performance

Turbo machineries including compressors performance degrades over the period of operation and deviates from design levels due to causes including dust entrance into the compressor, blades mechanical damage, erosion and corrosion. These lead to reduction in compressor performance, efficiency and pressure ratio. Subsequently gas turbine performance is affected since their operation sate is correlated. In this study the numerical investigation of common causes that determine geometric characteristics of a 2-stage centrifugal compressor running in a gas station, including blades fouling and corrosion is performed. 3D Numerical modeling is implemented along with utilization of Shear Stress Transport (SST) turbulence model and independency from the grids is verified.

Development of a High Specific Speed Centrifugal Compressor

1996 ◽  
Author(s):  
C. Rodgers
Keyword(s):  
Centrifugal Compressor ◽  
Test Performance ◽  
Pressure Ratio ◽  
High Volume ◽  
Limited Information ◽  
Component Test ◽  
Booster Compressor ◽  
Specific Speed ◽  
Stage Efficiency ◽  
Very High

This paper describes the development of a subscale single stage centrifugal compressor with a dimensionless specific speed (Ns) of 1.8, originally designed for full size appllcatioa as a high volume flow, low pressure ratio, gas booster compressor. The specific stage is noteworthy in that it provides a benchmark representing the performance potential of very high specific speed compressors of which limited information is found in open literature. Stage & component test performance characteristics are presented together with traverse results at the impeller exit. Traverse test results were compared with recent CFD computational predictions, for a exploratory analytical callbration of a very high specific speed impeller geometry. The tested subscale (0.583) compressor essentially satisfied design performance expectations with an overall stage efficiency of 74% incinding, excessive exit casing losses. It was estimated that stage efficiency could be increased to 81% with exit casing losses halved.

Flow With Shock Waves in a Transonic Centrifugal Compressor With a Low-Solidity Cascade Diffuser Using PIV

2004 ◽  
Author(s):  
Hiroshi Hayami ◽  
Masahiro Hojo ◽  
Norifumi Hirata ◽  
Shinichiro Aramaki
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Centrifugal Compressor ◽  
Gas Flow ◽  
Pressure Ratio ◽  
Transonic Centrifugal Compressor ◽  
Image Velocimetry ◽  
Rotor Stator Interaction ◽  
Rotating Impeller ◽  
Low Solidity Cascade Diffuser

A single-stage transonic centrifugal compressor with a pressure ratio greater than six was tested in a closed loop with HFC134a gas. Flow at the inducer of a rotating impeller as well as flow in a stationary low-solidity cascade diffuser was measured using a double-pulse and double-frame particle image velocimetry (PIV). Shock waves in both flows were clearly observed. The effect of flow rate on a 3D configuration of shock wave at the inducer and a so-called rotor-stator interaction between a rotating impeller and a stationary cascade were discussed based on a phase-averaged measurement technique. Furthermore, the unsteadiness of inducer shock wave and the flow in a cascade diffuser during surge were discussed based on instantaneous velocity vector maps.

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