A Study of a Single Stage Centrifugal Compressor

2006 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Design Method ◽  
Pressure Ratio ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Low Flow ◽  
High Pressure Ratio ◽  
Surge Margin ◽  
Low Flow Coefficient

A low flow coefficient unshrouded centrifugal compressor would give up clearance very large in relation to the span of the blades, because centrifugal compressors produce a sufficiently large pressure rise in fewer stages. This problem is more acute for a low flow high-pressure ratio impeller. The large tip clearance would cause flow separations, and as a result it would drop both the efficiency and surge margin. Thus a design of a high efficiency and wide operation range for a low flow coefficient centrifugal compressor is a great challenge. This paper describes a new development of high efficiency and large surge margin low flow coefficient (0.145) centrifugal compressor. A viscous turbomachinery optimal design method developed by the authors for axial flow machine was further extended and used in this centrifugal compressor design. The new compressor has three main parts: impeller, a low solidity diffuser and volute. The tip clearance is under a special consideration in this design to allow impeller insensitiveness to the clearance. A three-dimensional low solidity diffuser design method is proposed and applied to this design. This design is successful to extend the low solidarity diffusers to high-pressure ratio compressor. It is demonstrated that the design is in a great success. The design performance range of the total to static efficiency of the compressor is about 85% and stability range is over 35%. The experimental results showed that the test results are in good agreement with the design.

Development of a Low Flow Coefficient Single Stage Centrifugal Compressor

2005 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Design Method ◽  
Pressure Ratio ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Low Flow ◽  
High Pressure Ratio ◽  
Surge Margin ◽  
Low Flow Coefficient

A low flow coefficient unshrouded centrifugal compressor would give up clearance very large in relation to the span of the blades, because centrifugal compressors produce a sufficiently large pressure rise in fewer stages. This problem is more acute for a low flow high-pressure ratio impeller. The large tip clearance would cause flow separations, and as a result it would drop both the efficiency and surge margin. Thus a design of a high efficiency and wide operation range for a low flow coefficient centrifugal compressor is a great challenge. This paper describes a new development of high efficiency and large surge margin low flow coefficient (0.145) centrifugal compressor. A viscous turbomachinery optimal design method developed by the authors for axial flow machine was further extended and used in this centrifugal compressor design. The new compressor has three main parts: impeller, a low solidity diffuser and volute. The tip clearance is under a special consideration in this design to allow impeller insensitiveness to the clearance. A three-dimensional low solidity diffuser design method is proposed and applied to this design. This design is successful to extend the low solidarity diffusers to high-pressure ratio compressor. It is demonstrated that the design is in a great success. The design performance range of the total to static efficiency of the compressor is about 85% and stability range is over 35%. The experimental results showed that the test results are in good agreement with the design.

Study of the Flow in Centrifugal Compressor

2009 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
High Efficiency ◽  
Design Method ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Tip Clearance ◽  
Low Flow ◽  
High Pressure Ratio ◽  
Surge Margin

An unshrouded centrifugal compressor would give up clearance very large in relation to the span of the blades, because centrifugal compressors produce a sufficiently large pressure rise in fewer stages. This problem is more acute for a low flow high-pressure ratio impeller. The large tip clearance would cause flow separations, and as a result it would drop both the efficiency and surge margin. Thus a design of a high efficiency and wide operation range for a centrifugal compressor is a great challenge. This paper describes a new development of high efficiency and a large surge margin flow coefficient of 0.145 centrifugal compressor. A viscous turbomachinery optimal design method developed by the authors for axial flow machine was further extended and used in this centrifugal compressor design. The new compressor has three main parts: impeller, a low solidity diffuser and volute. The tip clearance is under a special consideration in this design to allow impeller insensitiveness to the clearance. A three-dimensional low solidity diffuser design method is proposed and applied to this design. This design demonstrated to be successful to extend the low solidarity diffusers to high-pressure ratio compressor. The design performance range showed the total to static efficiency of the compressor being about 85% and stability range over 35%. The experimental results showed that the test results are in good agreement with the design.

Numerical Study on the Range Enhancement of a Centrifugal Compressor With a Ring Groove System

2011 ◽  
Author(s):  
ChiYong Park ◽  
YoungSeok Choi ◽  
KyoungYong Lee ◽  
JoonYong Yoon
Keyword(s):  
Centrifugal Compressor ◽  
High Performance ◽  
High Efficiency ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Low Flow ◽  
Ring Groove ◽  
Guide Vanes ◽  
Operating Range ◽  
Surge Margin

This paper presents a numerical study of casing treatments on a centrifugal compressor in order to improve stability and the surge margin. High efficiency, a high pressure ratio, and a wide operating range are required for a high-performance centrifugal compressor. A ring groove casing treatment is effective for flow range enhancement in centrifugal compressors. In the present study, compressor performance was analyzed according to the ring groove location and the results were compared with the case without a ring groove. The effect of guide vanes in the ring groove was also investigated. Four more variants of grooves were modeled and simulated using computational fluid dynamics (CFD) in order to optimize the groove location. The numerical analysis was carried out using a commercial code ANSYS-CFX program. The simulation results showed that the ring groove increased the operating range of the compressor. The ring groove with guide vanes improved both the compressor’s performance at low flow rates and improved the compressor’s surge margin.

scholarly journals Meridional Considerations of the Centrifugal Compressor Development

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Angle Distribution ◽  
High Pressure Ratio ◽  
Structure Reliability ◽  
Compressor Performance ◽  
Meridional Profile ◽  
Compressor Efficiency ◽  
Wide Operating

Centrifugal compressor developments are interested in using optimization procedures that enable compressor high efficiency and wide operating ranges. Recently, high pressure ratio and efficiency of the centrifugal compressors require impeller design to pay attention to both the blade angle distribution and the meridional profile. The geometry of the blades and the meridional profile are very important contributions of compressor performance and structure reliability. This paper presents some recent studies of meridional impacts of the compressor. Studies indicated that the meridional profiles of the impeller impact the overall compressor efficiency and pressure ratio at the same rotational speed. Proper meridional profiles can improve the compressor efficiency and increase the overall pressure ratio at the same blade back curvature.

Aerodynamics of a Transonic Centrifugal Compressor Impeller

2002 ◽  
Author(s):  
Seiichi Ibaraki ◽  
Tetsuya Matsuo ◽  
Hiroshi Kuma ◽  
Kunio Sumida ◽  
Toru Suita
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Centrifugal Compressor ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Flow Analysis ◽  
Flow Distortion ◽  
Flow Measurements ◽  
High Pressure Ratio ◽  
Compressor Impeller

High pressure ratio centrifugal compressors are applied to turbochargers and turboshaft engines because of their small dimensions, high efficiency and wide operating range. Such a high pressure ratio centrifugal compressor has a transonic inlet condition accompanied with a shock wave in the inducer portion. It is generally said that extra losses are generated by interaction of the shock wave and the boundary layers on the blade surface. To improve the performance of high pressure ratio centrifugal compressor it is necessary to understand the flow phenomena. Although some research works on transonic impeller flow have been published, some unknown flow physics are still remaining. The authors designed a transonic impeller, with an inlet Mach number is about 1.3, and conducted detailed flow measurements by using Laser Doppler Velocimetry (LDV). In the result the interaction between the shock wave and tip leakage vortex at the inducer and flow distortion at the downstream of inducer were observed. The interaction of the boundary layer and the shock wave was not observed. Also computational flow analysis were conducted and compared with experimental results.

scholarly journals Numerical characteristics of a centrifugal compressor with a low flow coefficient

2019 ◽  
Vol 140 ◽  
pp. 06010 ◽  
Author(s):  
Aleksey Yablokov ◽  
Ivan Yanin ◽  
Nikolay Sadovskyi ◽  
Yuri Kozhukhov ◽  
Minh Hai Nguyen
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Flow Coefficient ◽  
Ultrahigh Pressure ◽  
Low Flow ◽  
Classical Type ◽  
Numerical Characteristic ◽  
Wall Cell ◽  
Low Flow Coefficient ◽  
Near Wall

The study presents the simulation results of the viscid gas flow in low flow coefficient centrifugal compressor stages. The problem is solved in a stationary formulation using the Ansys CFX software package. The numerical simulation is carried out on three ultrahigh-pressure model stages; two stages have blades of the classical type impeller and one stage is of the bodily type. The value of the conditional flow coefficient is 0.0063 to 0.015. As part of the study, block-structured design meshes are used for all gas channel elements, with their total number being equaled as 13–15 million. During the calculations a numerical characteristic was validated with the results of tests carried out at the Department of Compressor, Vacuum and Refrigeration Engineering of Peter the Great St. Petersburg Polytechnic University. With an increase of inlet pressure as a result of a numerical study, it was found that for a given mathematical model the disk friction and leakage coefficient (1 + βfr + βlk) is overestimated. The analysis of flow in labyrinth seals has shown an increase of total temperature near the discs by 30–50 °С, nevertheless this fact did not influence gas parameters in the behind-the-rotor section. The calculation data obtained with finer design mesh (the first near-wall cell was 0.001 mm) is identical to those obtained with the first near-wall cell 0.01 mm mesh.

scholarly journals Design and Development of an Advanced Two-Stage Centrifugal Compressor

1994 ◽  
Author(s):  
D. L. Palmer ◽  
W. F. Waterman
Keyword(s):  
Centrifugal Compressor ◽  
High Performance ◽  
Low Cost ◽  
Pressure Ratio ◽  
Tip Clearance ◽  
Development Effort ◽  
Design And Development ◽  
Two Stage ◽  
Surge Margin ◽  
The Impact

This paper describes the aero-mechanical design and development of a 3.3 kg/sec (7.3 lb/sec), 14:1 pressure ratio two-stage centrifugal compressor which is used in the T800-LHT-800 helicopter engine. The design employs highly nonradial, splitter bladed impellers with swept leading edges and compact vaned diffusers to achieve high performance in a small and robust configuration. The development effort quantified the effects of impeller diffusion and passive inducer shroud bleed on surge margin as well as the effects of impeller loading on tip clearance sensitivity and the impact of sand erosion and shroud roughness on performance. The developed compressor exceeded its performance objectives with a minimum of 23-percent surge margin without variable geometry. The compressor provides a high performance, rugged, low-cost configuration ideally suited for helicopter applications.

scholarly journals Research on the Simplified Design of a Centrifugal Compressor Impeller Based on Meridional Plane Modification

2018 ◽  
Vol 8 (8) ◽  
pp. 1339 ◽  
Author(s):  
Hong Xie ◽  
Moru Song ◽  
XiaoLan Liu ◽  
Bo Yang ◽  
Chuangang Gu
Keyword(s):  
Centrifugal Compressor ◽  
Design Method ◽  
Pressure Ratio ◽  
Aerodynamic Characteristics ◽  
Low Flow ◽  
Measure Data ◽  
Meridional Plane ◽  
Stall Margin ◽  
Numerical Result ◽  
Compressor Impeller

This study mainly focuses on investigating the influence of meridional contour of a steam centrifugal compressor on aerodynamic performance. An optimal design method is put forwards, in which the hub-line on the meridional plane is modified and optimized. Based on the data from numerical simulation, aerodynamic characteristics are compared in detail among a prototype and three modified impellers. It is shown that stall margin of the optimized impeller can be enlarged by approximately 50%, though at design point efficiency and pressure ratio is decreased a little bit. Under the working conditions with low flow rate, the optimized impeller exhibits the best performance compared with the prototype and two other impellers. Furthermore, numerical result is validated by the experiment and is matched the measure data very well.

Study of Geometric Parameter Influence on Fishtail Pipe Diffuser Performance

2016 ◽  
Author(s):  
Ge Han ◽  
Xingen Lu ◽  
Yanfeng Zhang ◽  
Shengfeng Zhao ◽  
Chengwu Yang ◽  
...  
Keyword(s):  
High Pressure ◽  
Geometric Parameter ◽  
Centrifugal Compressor ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Critical Parameters ◽  
Complex Flow ◽  
High Pressure Ratio ◽  
Area Distribution ◽  
Parameter Influence

Centrifugal compressor stages with pipe diffusers are characterized by their high efficiency, especially under high pressure ratio conditions. Although it is believed that pipe diffuser scallop leading edge formed by the intersection of two pipes is a critical point in pipe diffuser design, there is another crucial and influential point, which is how to guide and decelerate the flow from pipe diffuser throat to the inlet of combustor chamber, with minimum loss and maximum outflow uniformity. Fishtail pipe diffuser passage is employed by Pratt&Whitney to connect impeller exit and combustor chamber inlet due to its improved performance characteristics. However, only a few comprehensive results have been published describing the complex flow patterns in the fishtail diffuser. Therefore, in the present work fishtail pipe diffusers with several different geometries were designed for a pressure ratio 8.3 centrifugal compressor stage used on a small turbo engine, aiming at providing detailed understanding of geometric parameter influence on fishtail pipe diffuser performance and flow mechanisms in complex fishtail passages. Cone length, streamwise area distribution and centerline shape are critical parameters of a fishtail pipe diffuser. Hence, parametric studies on fishtail pipe diffuser of this high pressure ratio centrifugal compressor by varying cone length, area distribution and centerline shape of the diffuser passage were performed using a state-of-the-art multi-block flow solver. These three parameters were changed respectively, while keeping other parameters unchanged. Detailed analysis was done to identify the influence on flow field in fishtail diffuser passage when these parameters were changed. It was found that increase of fishtail diffuser cone length could alleviate separation in diffuser passage, thus compressor performance is improved. And linear area distribution along passage centerline could build a more efficient fishtail pipe diffuser. A trumpet-shaped or bell-shaped passage is more likely to make flow separate. The centerline is of vital importance for a fishtail passage and it was built by two lines tangent to an ellipse in this work. It was modified by changing major and minor axes of the ellipse. Stage total pressure ratio and adiabatic efficiency maps for varying fishtail passage centerlines were obtained by numerical method, which indicate that there is an optimum range for both axes to make the fishtail pipe diffuser have a better performance. Through these works, the geometric parameter influence on fishtail diffuser performance was uncovered and physical insight into complex flows in fishtail pipe diffuser passage was obtained to give some guidelines on diffusing system design with fishtail pipe diffuser.

Impact of Main and Splitter Blade Leading Edge Contour on the Performance of High Pressure Ratio Centrifugal Compressors

2014 ◽  
Author(s):  
Rodrigo R. Erdmenger ◽  
Vittorio Michelassi
Keyword(s):  
High Pressure ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Centrifugal Compressors ◽  
Operating Range ◽  
High Pressure Ratio ◽  
The Impact ◽  
Blade Leading Edge

The impact of leading edge sweep in an attempt to reduce shock losses and extend the stall margin on axial compressors has been extensively studied, however only a few studies have looked at understanding the impact of leading edge contouring on the performance of centrifugal compressors. The present work studies the impact of forward and aft sweep on the main and splitter blade leading edge of a generic high flow coefficient and high pressure ratio centrifugal compressor design and the impact on its overall peak efficiency, pressure ratio and operating range. The usage of aft sweep on the main blade led to an increase of the pressure ratio and efficiency, however it also led to a reduction of the stable operating range of the impeller analyzed. The forward sweep cases analyzed where the tip leading edge was displaced axially forward showed a slight increase in pressure ratio, and a significant increase on operating range. The impact of leading edge sweep on the sensitivity of the impeller performance to tip clearance was also studied. The impeller efficiency was found to be less sensitive to an increase of tip clearance for both aft and forward sweep cases studied. The forward sweep cases studied also showed a reduced sensitivity from operating range to tip clearance. The studies conducted on the splitter leading edge profile indicate that aft sweep may help to increase the operating range of the impeller analyzed by up to 16% while maintaining similar pressure ratio and efficiency characteristics of the impeller. The improvement of operating range obtained with the leading edge forward sweep and splitter aft sweep was caused by a reduction of the interaction of the tip vortex of the main blade with the splitter tip, and a reduction of the blockage caused by this interaction.

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