Effects of Asymmetric Radial Clearance on Performance of a Centrifugal Compressor

2017 ◽  
Vol 140 (5) ◽  
Author(s):  
Cheng Xu ◽  
Ryoichi S. Amano
Keyword(s):  
Pressure Ratio ◽  
Industrial Applications ◽  
Radial Clearance ◽  
Centrifugal Compressors ◽  
Numerical Studies ◽  
Compressor Design ◽  
Compressor Performance ◽  
Manufacturing Tolerances ◽  
And Performance ◽  
Design Pressure

The centrifugal compressors are widely used in industrial applications. The design, manufacturing, and installation are all critical for the compressor performance. Many studies have been carried out in the past to optimize the compressor performance during compressor design. The manufacturing tolerances and installation errors can cause the performance drop. There are many compressor performance distortions that are not fully understood due to manufacturing and facilities. In this paper, an asymmetrical radial clearance of the impeller due to manufacturing and installation is studied in detail for the performance impacts. The numerical studies and experiments indicated that the asymmetric radial clearance impacts the compressor flow field structure and performance. Experimental results suggested that the manufacturing and installation cause asymmetric radial clearance which decreased the compressor performance in whole operating range. The numerical analysis demonstrated that the impeller asymmetric clearance impacts performance near the design pressure ratio more than other pressure ratios. The numerical studies showed that the maximum clearance location of asymmetric clearance might impact the compressor performance. The proper asymmetricity of diffuser verse the volute may benefit the compressor performance. The excellent compressor performances for centrifugal compressors especially for small centrifugal compressors not only need to have a good aerodynamic design but also need to control manufacturing and installation carefully.

Experimental Investigation of the Diffuser Vane Clearance Effect in a Centrifugal Compressor Stage With Adjustable Diffuser Geometry—Part I: Compressor Performance Analysis

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Stefan Ubben ◽  
Reinhard Niehuis
Keyword(s):  
Centrifugal Compressor ◽  
Negative Impact ◽  
Pressure Ratio ◽  
Industrial Applications ◽  
Experimental Investigations ◽  
Flow Measurements ◽  
Flow Phenomena ◽  
Compressor Performance ◽  
Compressor Map ◽  
The Impact

Adjustable diffuser vanes offer an attractive design option for centrifugal compressors applied in industrial applications. However, the knowledge about the impact on compressor performance of a diffuser vane clearance between vane and diffuser wall is still not satisfying. This two-part paper summarizes results of experimental investigations performed with an industrial-like centrifugal compressor. Particular attention was directed toward the influence of the diffuser clearance on the operating behavior of the entire stage, the pressure recovery in the diffuser, and on the diffuser flow by a systematic variation of the parameters diffuser clearance height, diffuser vane angle, radial gap between impeller exit and diffuser inlet, and rotor speed. Compressor map measurements provide a summary of the operating behavior related to diffuser geometry and impeller speed, whereas detailed flow measurements with temperature and pressure probes allow a breakdown of the losses between impeller and diffuser and contribute to a better understanding of relevant flow phenomena. The results presented in Part I show that an one-sided diffuser clearance does not necessarily has a negative impact on the operation and loss behavior of the centrifugal compressor, but instead may contribute to an increased pressure ratio and improved efficiency as long as the diffuser passage is broad enough with respect to the clearance height. The flow phenomena responsible for this detected performance behavior are exposed in Part II, where the results of detailed measurements with pressure probes at diffuser exit and particle image velocimetry (PIV) measurements conducted inside the diffuser channel are discussed. The experimental results are published as an open computational fluid dynamics (CFD) testcase “Radiver 2.”

Centrifugal Compressor Modifications and Their Effect on High-Frequency Pipe Wall Vibration

1998 ◽  
Vol 120 (3) ◽  
pp. 276-282 ◽  
Author(s):  
R. W. Motriuk ◽  
D. P. Harvey
Keyword(s):  
High Frequency ◽  
Pipe Wall ◽  
Centrifugal Compressors ◽  
Partial Removal ◽  
Vibration Attenuation ◽  
Internal Component ◽  
Compressor Performance ◽  
And Performance ◽  
Component Failures ◽  
Fatigue Failures

High-frequency pulsation generated by centrifugal compressors, with pressure wavelengths much smaller than the attached pipe diameter, can cause fatigue failures of the compressor internals, impair compressor performance, and damage the attached compressor piping. There are numerous sources producing pulsation in centrifugal compressors. Some of them are discussed in literature at large (Japikse, 1995; Niese, 1976). NGTL has experienced extreme high-frequency discharge pulsation and pipe wall vibration on many of its radial inlet high-flow centrifugal gas compressor facilities. These pulsations led to several piping attachment failures and compressor internal component failures while the compressor operated within the design envelope. This paper considers severe pulsation conditions at an NGTL compression facility which resulted in unacceptable piping vibration. Significant vibration attenuation was achieved by modifying the compressor (pulsation source) through removal of the diffuser vanes and partial removal of the inlet guide vanes (IGV). Direct comparison of the changes in vibration, pulsation, and performance are made for each of the modifications. The vibration problem, probable causes, options available to address the problem, and the results of implementation are reviewed. The effects of diffuser vane removal on discharge pipe wall vibration as well as changes in compressor performance are described.

Effect of Impeller-Extended Shrouds on Centrifugal Compressor Performance as a Function of Specific Speed

1983 ◽  
Vol 105 (3) ◽  
pp. 457-465 ◽  
Author(s):  
L. Sapiro
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Centrifugal Compressors ◽  
Gas Compression ◽  
Blade Tip ◽  
Compressor Performance ◽  
The Subject ◽  
Specific Speed ◽  
Vaneless Diffusers ◽  
Outside Diameter

Centrifugal compressors for gas compression applications usually employ low-pressure ratio, backward-swept impellers with vaneless diffusers. To increase the compressor flow range and speed, impeller blades are occasionally trimmed, resulting in an extended shroud configuration. The effect of extended front and back impeller shrouds on the performance of centrifugal compressors with vaneless diffusers, and the variation of this effect as a function of specific speed, is thus of concern and is the subject of this paper. An investigation was carried out on two backward-swept shrouded impellers of common blade tip and inducer hub diameters, but different inducer tip diameters (corresponding to low and high specific speeds), with the front and back shrouds extending 20 percent above the blade’s outside diameter.

Design and Performance of a High-Pressure Ratio Turbocharger Compressor Part 1: Design Considerations

1993 ◽  
Vol 207 (2) ◽  
pp. 115-124 ◽  
Author(s):  
A Whitfield ◽  
M D C Doyle ◽  
M R Firth
Keyword(s):  
High Pressure ◽  
Peak Pressure ◽  
Pressure Ratio ◽  
Design Procedure ◽  
Design Requirement ◽  
High Pressure Ratio ◽  
Design Considerations ◽  
Compressor Design ◽  
Turbo Charger ◽  
And Performance

The compressor design requirement was for a pressure ratio of 3.6, with a peak pressure ratio of 4.3 at the maximum non-dimensional speed of the impeller of 1.66. Due to the stress-limited speed, an aluminium alloy impeller was specified, the impeller discharge blade backsweep had to be restricted and the application of prewhirl was considered from the outset as a means of extending the operating range. A non-dimensional conceptual design procedure, including the effect of inlet prewhirl, was applied to the design of three turbo- charger impellers. An impeller, designated A, was designed with the inclusion of 25° of prewhirl. A second impeller, designated B, was designed with zero prewhirl for comparison purposes, but was not manufactured. A third impeller, C, was manufactured through the modification of an existing design and the design study was applied to the assessment of this third design.

Design and Performance of a High-Pressure Ratio Turbocharger Compressor Part 2: Experimental Performance

1993 ◽  
Vol 207 (2) ◽  
pp. 125-131 ◽  
Author(s):  
A Whitfield ◽  
M D C Doyle ◽  
M R Firth
Keyword(s):  
Experimental Study ◽  
High Pressure ◽  
Peak Pressure ◽  
Pressure Ratio ◽  
Design Requirement ◽  
Experimental Performance ◽  
Operating Range ◽  
High Pressure Ratio ◽  
Compressor Design ◽  
And Performance

The performance of two turbocharger impeller designs was evaluated experimentally. The compressor design requirement was for a pressure ratio of 3.6, with a peak pressure ratio of 4.3 at a maximum non-dimensional impeller speed of 1.66. Due to the stress-limited speed the impeller discharge blade backsweep had to be restricted and the application of prewhirl was considered from the outset as a means of extending the operating range. An impeller, designated A, was designed with 25° of prewhirl applied. A second impeller, designated B, was designed with zero prewhirl for comparison purposes, but was not manufactured. A third impeller, C, was manufactured, in place of impleller B, through the modification of an existing design. This experimental study includes the assessment of this third impeller together with impeller A.

Experimental Investigation of the Diffuser Vane Clearance Effect in a Centrifugal Compressor Stage With Adjustable Diffuser Geometry: Part I — Compressor Performance Analysis

2014 ◽  
Author(s):  
Stefan Ubben ◽  
Reinhard Niehuis
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Negative Impact ◽  
Pressure Ratio ◽  
Industrial Applications ◽  
Flow Measurements ◽  
Flow Phenomena ◽  
Compressor Performance ◽  
Compressor Map ◽  
The Impact

The combination of variable speed control and adjustable diffuser vanes offers an attractive design option for centrifugal compressors applied in industrial applications where a wide operating range at high efficiency level and a favorable surge line is required. However, the knowledge about the impact on compressor performance of a diffuser vane clearance between vane and diffuser wall which is mandatory since the diffuser geometry adjustment has to take place during operation, is still not satisfying. This two-part paper summarizes results of investigations performed at the Institute of Jet Propulsion and Turbomachinery at RWTH Aachen with an industrial-like centrifugal compressor, featuring a design pressure ratio of 4 and a design speed of 35200 rpm. Particular attention was directed to the influence of the diffuser clearance on the operating behavior of the entire stage, the pressure recovery in the diffuser and on the diffuser flow by a systematic variation of the parameters diffuser clearance height, diffuser vane angle, radial gap between impeller exit and diffuser inlet, and rotor speed. Compressor map measurements provide a summary of the operating behavior related to diffuser geometry and impeller speed, whereas detailed flow measurements with temperature and pressure probes allow a breakdown of the losses between impeller and diffuser and contribute to a better understanding of relevant flow phenomena. The results presented in Part I show that an one-sided diffuser clearance does not necessarily has a negative impact on the operation and loss behavior of the centrifugal compressor, but instead may contribute to an increased pressure ratio and improved efficiency. The flow phenomena responsible for this detected performance behavior are exposed in Part II [28], where the results of detailed measurements with pressure probes at diffuser exit and Particle Image Velocimetry (PIV) measurements conducted inside the diffuser channel, revealing the complex and unsteady flow leaving the impeller and passing the diffuser channel, are discussed. The experimental results are published as an open CFD testcase “Radiver 2” [26], extending the experimental data base of the testcase “Radiver” published in 2003 by Ziegler [31].

Centrifugal Compressor Design Impacts: Lean and Meridional Shape

2013 ◽  
Author(s):  
Cheng Xu ◽  
R. S. Amano
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Centrifugal Compressors ◽  
High Pressure Ratio ◽  
Combination Optimization ◽  
Structure Reliability ◽  
Compressor Performance ◽  
Meridional Shape ◽  
Meridional Profile

Optimization procedures are widely used in centrifugal compressor developments to enable high efficiency and wide operating ranges of compressors. It is very important to understand how to set the parameters and which parameter needs to be optimized. This paper demonstrates a case study on the importance of mechanical and structure combination optimization and also discusses the meridional impacts of compressor performance. Recently, the high pressure ratio and the efficiency of centrifugal compressors require impeller designs to pay attention to multi-disciplinary optimization. High efficiency and a wide operation range are always the design goal. The geometry of the blades and the meridional profile are very important contributors to compressor performance and structure reliability. Therefore, it is critical to consider all aspects of compressor optimization. The goal of currently used centrifugal compressors is to design a compressor with the same back-disc diameter with the best efficiency and the highest-pressure ratio.

Gas Dynamic Designs of Centrifugal Compressors for Gas Industry

2015 ◽  
Author(s):  
Y. Galerkin ◽  
A. Rekstin ◽  
K. Soldatova ◽  
A. Drozdov
Keyword(s):  
High Efficiency ◽  
Pressure Ratio ◽  
Design Procedure ◽  
Flow Coefficient ◽  
Design Parameters ◽  
Centrifugal Compressors ◽  
Gas Industry ◽  
Design Point ◽  
Optimal Values ◽  
And Performance

Centrifugal compressors for gas industry consume huge amount of energy. As a rule, they are single-shaft, with two or more stages and with comparatively low pressure ratio. Compressors operate at low Mach numbers and high Reynolds numbers. Two design parameters influence mostly stage performances. Stage flow coefficient optimal values lie in range 0.060–0.11. Chosen number of stages establishes value of this coefficient if speed of a rotor rotation is fixed. Design loading factor optimal values are 0.42–0.52. It corresponds to high efficiency, shifts a surge limit far from a design point and makes power maximal in a design point. Some considerations about impeller and diffuser types are presented. Design procedure consists on application of the Universal modeling programs for main dimensions optimization and performance calculations. Q3D non-viscid velocity diagrams are analyzed for optimization of blade configuration. Samples of design are presented, 32 MW single-stage pipeline compressor stage with record efficiency included.

Effect of Impeller Extended Shrouds on Centrifugal Compressor Performance as a Function of Specific Speed

1982 ◽  
Author(s):  
L. Sapiro
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Centrifugal Compressors ◽  
Gas Compression ◽  
Blade Tip ◽  
Compressor Performance ◽  
The Subject ◽  
Specific Speed ◽  
Vaneless Diffusers ◽  
Outside Diameter

Centrifugal compressors for gas compression applications usually employ low-pressure ratio, backward-swept impellers with vaneless diffusers. To increase the compressor flow range and speed, impeller blades are occasionally trimmed, resulting in an extended shroud configuration. The effect of extended front and back impeller shrouds on the performance of centrifugal compressors with vaneless diffusers, and the variation of this effect as a function of specific speed, is thus of concern and is the subject of this paper. An investigation was carried out on two backward-swept shrouded impellers of common blade tip and inducer hub diameters, but different inducer tip diameters (corresponding to low and high specific speeds), with the front and back shrouds extending 20 percent above the blade’s outside diameter.

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