Proposal and Experimental Verification of Design Guidelines for Centrifugal Compressor Impellers With Curvilinear Element Blades to Improve Compressor Performance

2014 ◽  
Author(s):  
Kiyotaka Hiradate ◽  
Kazuyuki Sugimura ◽  
Hiromi Kobayashi ◽  
Toshio Ito ◽  
Hideo Nishida
Keyword(s):  
Velocity Distribution ◽  
Coordinate System ◽  
Numerical Simulations ◽  
Centrifugal Compressor ◽  
Design Guidelines ◽  
Compressor Stage ◽  
Stall Margin ◽  
Cylindrical Coordinate ◽  
Forward Part ◽  
Stage Efficiency

This study numerically and experimentally examines the effects of applying curvilinear element blades to fully-shrouded centrifugal impellers on the performance of the centrifugal compressor stages. The design suction coefficient of the target impellers was 0.073. Our previous study confirmed that the application of curvilinear element blades could improve the stage efficiency of similar types of centrifugal compressors. However, a detailed explanation of the relation between the stall margin and the application of the curvilinear element blades remains to be given. The purpose of this study is to investigate the effects of using these blades on the impeller flow field and the stall margin in further detail. The curvilinear element blades we developed for centrifugal turbomachinery were defined by the coordinate transformations between a revolutionary flow-coordinate system and a cylindrical coordinate system. All the blade sections in the transferred cylindrical coordinate system were moved and stacked spanwise in accordance with the given “lean profile,” which meant the spanwise distribution profile of movement of the blade sections, to form a new leaned blade surface. The effects of the curvilinear element blades on the impeller flowfield were investigated by conducting numerical simulations using this method. We next considered the optimum design guidelines for impellers with curvilinear element blades. Then we designed a new impeller using these design guidelines and evaluated the performance improvement of a new compressor stage by conducting numerical simulations. As mentioned in several papers, we numerically confirmed that curvilinear element blades with a negative tangential lean profile improved the velocity distribution and stage efficiency because they help to suppress the secondary flows in the impeller. The negative tangential lean mentioned in this paper represents the lean profile in which the blade hub end leans forward in the direction of the impeller rotation compared to the blade shroud end. At the same time, we also found that the stall margin of these impellers deteriorated due to the increase in relative velocity deceleration near the suction surface of the shroud in the forward part of the impeller. Therefore, we propose new design guidelines for impellers with the curvilinear element blades by applying a negative tangential lean to line element blades in which the blade loading of the shroud side in the forward part of the impeller is reduced. We confirmed from the numerical simulation results that the performance of the new compressor stage improved compared to that in the corresponding conventional one. The new design guidelines for the curvilinear element blades were experimentally verified by comparing the performance of the new compressor stage with the corresponding conventional one. The measured efficiency of the new compressor stage was 2.4 % higher than that of the conventional stage with the stall margin kept comparable. A comparison of the measured velocity distributions at the impeller exit showed that the velocity distribution of the new impeller was much more uniform than that of the conventional one.

Proposal and Experimental Verification of Design Guidelines for Centrifugal Compressor Impellers With Curvilinear Element Blades to Improve Compressor Performance

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Kiyotaka Hiradate ◽  
Hiromi Kobayashi ◽  
Kazuyuki Sugimura ◽  
Toshio Ito ◽  
Hideo Nishida
Keyword(s):  
Velocity Distribution ◽  
Coordinate System ◽  
Numerical Simulations ◽  
Centrifugal Compressor ◽  
Design Guidelines ◽  
Cylindrical Coordinate System ◽  
Compressor Stage ◽  
Stall Margin ◽  
Cylindrical Coordinate ◽  
Forward Part

This study numerically and experimentally examines the effects of applying curvilinear element blades to fully shrouded centrifugal impellers on the performance of the centrifugal compressor stages. The curvilinear element blades we developed for centrifugal turbomachinery were defined by the coordinate transformations between a revolutionary flow-coordinate system and a cylindrical coordinate system. All the blade sections in the transferred cylindrical coordinate system were moved and stacked spanwise in accordance with the given “lean profile,” which meant the spanwise distribution profile of movement of the blade sections, to form a new leaned blade surface. The effects of the curvilinear element blades on the impeller flowfield were investigated using numerical simulations, and the optimum design guidelines for impellers with curvilinear element blades were considered. Then, a new impeller using these design guidelines was designed and the performance improvement of a new compressor stage was evaluated by numerical simulations. As mentioned in several papers, we numerically confirmed that curvilinear element blades with a negative tangential lean (TGL) profile improved the velocity distribution and stage efficiency because they help to suppress the secondary flows in the impeller. The negative TGL mentioned in this paper represents the lean profile in which the blade hub end leans forward in the direction of the impeller rotation compared to the blade shroud end. At the same time, we also found that the stall margin of these impellers deteriorated due to the increase in relative velocity deceleration near the suction surface of the shroud in the forward part of the impeller. Therefore, we propose new design guidelines for impellers with the curvilinear element blades by applying a negative TGL to line element blades in which the blade loading of the shroud side in the forward part of the impeller is reduced. We confirmed from the numerical simulation results that the performance of the new compressor stage improved compared to that in the corresponding conventional one. The new design guidelines for the curvilinear element blades were experimentally verified by comparing the performance of the new compressor stage with the corresponding conventional one. The measured efficiency of the new compressor stage was 2.4% higher than that of the conventional stage with the stall margin kept comparable. A comparison of the measured velocity distributions at the impeller exit showed that the velocity distribution of the new impeller was much more uniform than that of the conventional one.

Investigation on Effect of Curvilinear Element Blades on Centrifugal Impeller Performance

2017 ◽  
Author(s):  
Kiyotaka Hiradate ◽  
Hiromi Kobayashi ◽  
Takahiro Nishioka
Keyword(s):  
Centrifugal Compressor ◽  
Performance Test ◽  
Design Guidelines ◽  
Secondary Flows ◽  
Flow Coefficient ◽  
Numerical Calculations ◽  
Centrifugal Impeller ◽  
Compressor Stage ◽  
Vaneless Diffuser ◽  
Compressor Impeller

This study experimentally and numerically investigates the effect of application of curvilinear element blades to fully-shrouded centrifugal compressor impeller on the performance of centrifugal compressor stage. Design suction flow coefficient of compressor stage investigated in this study is 0.125. The design guidelines for the curvilinear element blades which had been previously developed was applied to line element blades of a reference conventional impeller and a new centrifugal compressor impeller with curvilinear element blades was designed. Numerical calculations and performance tests of two centrifugal compressor stages with the conventional impeller and the new one were conducted to investigate the effectiveness of application of the curvilinear element blades and compare the inner flowfield in details. Despite 0.5% deterioration of the impeller efficiency, it was confirmed from the performance test results that the compressor stage with the new impeller achieved 1.7% higher stage efficiency at the design point than that with the conventional one. Moreover, it was confirmed that the compressor stage with the new impeller achieved almost the same off-design performance as that of the conventional stage. From results of the numerical calculations and the experiments, it is considered that this efficiency improvement of the new stage was achieved by suppression of the secondary flows in the impeller due to application of negative tangential lean. The suppression of the secondary flows in the impeller achieved uniformalized flow distribution at the impeller outlet and increased the static pressure recovery coefficient in the vaneless diffuser. As a result, it is thought that the total pressure loss was reduced downstream of the vaneless diffuser outlet in the new stage.

Trailing Edge Filings and a Modified Stodola’s Slip Factor for Centrifugal Impeller

2015 ◽  
Author(s):  
Guang Xi ◽  
Huijing Zhao ◽  
Zhiheng Wang
Keyword(s):  
Numerical Simulations ◽  
Good Accuracy ◽  
Centrifugal Impeller ◽  
Pressure Side ◽  
Compressor Stage ◽  
Trailing Edge ◽  
Obvious Effect ◽  
Quantitative Calculation ◽  
Slip Factor ◽  
Stage Efficiency

The paper investigates the effect of trailing edge filing in the impeller on the performances of impeller and compressor stage. The 3D viscous numerical simulations are carried out under different positions, thicknesses and lengths of filing. The results show that, the filing on the trailing edge has an obvious effect on the pressure ratios of impeller and compressor stage. The trailing edge filing has little effect on the impeller efficiency while the filing on the pressure side is favorable to improving the stage efficiency. Then, through correcting the blade angles at the suction and pressure sides, considering the viscosity and 3D characteristics of the flow, a modified slip factor formula is proposed for the centrifugal impeller with a trailing edge filing. The validation to the proposed formula shows that the proposed formula can be used to predict the slip factors of different filing cases with a good accuracy. It can provide a theoretical guidance for the quantitative calculation when using the filing technology to improve the performance of centrifugal impeller as well as the stage.

Effects of Flow Loss and Inlet Distortions Caused by Radial Inlet on the Performance of Centrifugal Compressor Stage

2015 ◽  
Author(s):  
Fenghui Han ◽  
Jiajian Tan ◽  
Yijun Mao ◽  
Datong Qi ◽  
Yiyun Zhang
Keyword(s):  
Numerical Simulations ◽  
Centrifugal Compressor ◽  
Computational Models ◽  
Compressor Stage ◽  
Centrifugal Compressors ◽  
Centrifugal Compressor Stage ◽  
Preliminary Work ◽  
Flow Loss ◽  
Main Factors

Radial inlet is a typical upstream component in centrifugal compressors. Compared to axial inlet, radial inlet generates additional flow loss and introduces inlet distortions to the impeller inlet, which negatively impacts the performance of the whole centrifugal compressor. In this paper, two centrifugal compressor stages with different radial inlets were investigated with numerical simulations. Three computational models, (i) with radial inlet (ii) without flow loss and inlet distortions (iii) with flow loss but no inlet distortions, were built for each compressor stage, and calculations were carried out to analyze the respective effects of flow loss and inlet distortions caused by radial inlet on the performances of the compressor stage and the downstream components. The present study validates that flow loss and inlet distortions caused by radial inlet are the main factors by means of which the radial inlet affects the performance of the centrifugal compressor. What’s more, the results indicate that flow loss in radial inlet only affects the performance of the whole radial inlet stage, but has little effect on the downstream components such as the impeller; while inlet distortions caused by radial inlet not only negatively influence the performance of the whole radial inlet stage, but also have significant effects on the downstream components. This research, as a preliminary work of the improvement study, provides references for the structure modifications of radial inlet in the next stage.

Aerodynamic Investigation on a 3D-Vaned Diffuser Applied on a High Flow 3D Impeller

2012 ◽  
Author(s):  
H. Strohmeyer ◽  
A. Hildebrandt
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
High Flow ◽  
Compressor Stage ◽  
Vaned Diffuser ◽  
High Incidence ◽  
High Pressure Stage ◽  
Stage Efficiency ◽  
Ratio Reduction ◽  
Aerodynamic Investigation

This paper discusses the effect of a diffuser ratio reduction from r4/r2 = 1.55 to r4/r2 = 1.35 of a centrifugal compressor stage and an approach to retain the efficiency by applying a vaned diffuser. Initially, the diffuser ratio of a high flow, high pressure stage is decreased. Following, the stage having the smallest diffuser ratio is used to investigate the performance of a vaned diffuser, whose trailing edge is shifted into the U-turn. The discussion shows a possible improvement by the diffuser vane enlargement. The total stage efficiency of the diffuser ratio of r4/r2 = 1.55 can be retained as long as the separation due to high incidence of the vaned diffuser is low.

Effect of Rotor Tip Casing Treatment on the Performance and Stability of a Transonic Axial Compressor

2021 ◽  
Author(s):  
Subbaramu Shivaramaiah ◽  
Mahesh K. Varpe ◽  
Mohammed Afzal
Keyword(s):  
Research Work ◽  
Stability Margin ◽  
Leakage Flow ◽  
Compressor Stage ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Casing Treatment ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Stage Efficiency

Abstract In a transonic compressor rotor, tip leakage flow interacts with passage shock, casing boundary layer and secondary flow. This leads to increase in total pressure loss and reduction of compressor stability margin. Casing treatment is one of the passive endwall geometry modification technique to control tip leakage flow interaction. In the present investigation effect of rotor tip casing treatment is investigated on performance and stability of a NASA 37 transonic compressor stage. Existing literature reveals, that endwall casing treatment slots i.e., porous casing treatment, axial slots axially skewed slots, circumferential grooves, recirculating casing treatment etc. are able to improve compressor stability margin with penalty on stage efficiency. Turbomachinery engineers and scientists are still focusing their research work to identify an endwall casing treatment configuration with improves both compressor stall margin as well as stage efficiency. Hence in the current work, as an innovative idea, effect of casing treatment slot along rotor tip mean camber line is investigated on NASA 37 compressor stage. Casing treatment slot with rectangular cross-section was created along the rotor tip mean camber line. Four different casing treatment configurations were created by changing number of slots on rotor casing surface. In all four configurations casing treatment slot width and height remains same. Flow simulation of NASA 37 compressor stage was performed with all these four casing treatment configurations. A maximum stall margin improvement of 3% was achieved with a particular slot configuration, but without any increase in compressor stage efficiency.

Investigation of variable geometry orifice design for improving centrifugal compressor low-end performance and stable operating range

2021 ◽  
pp. 095441002110476
Author(s):  
Ben Zhao ◽  
Qingjun Zhao ◽  
Xiaorong Xiang ◽  
Wei Zhao ◽  
Jianzhong Xu
Keyword(s):  
Numerical Simulations ◽  
Centrifugal Compressor ◽  
Control Device ◽  
Design Parameters ◽  
Variable Geometry ◽  
Flow Area ◽  
Stall Margin ◽  
Setting Angle ◽  
Compressor Inlet ◽  
Two Parameters

Active control of the inlet flow area in a centrifugal compressor is a method to improve compressor aerodynamic performance and stall margin. As a core part of the area control device, the variable geometry orifice is investigated and its two key design parameters are analyzed in detail, the setting angle of the orifice with respect to the shroud casing and the radial height of the orifice to the shroud casing from the orifice inner rim. This paper proposes a physics-based equation that describes the relationship of the two parameters with compressor mass flow rate and then validates the equation using numerical simulations. As far as the setting angle, the physics-based equation suggests not to be larger than 90°. The numerical results not only validate the physics-based equation but also show the most optimal angle of 78°. In terms of the orifice height, both the physics-based equation and the numerical simulations suggest an active height control of orifice in the compressor inlet duct.

Numerical investigation of a highly loaded centrifugal compressor stage with a tandem bladed impeller

2017 ◽  
Vol 232 (3) ◽  
pp. 240-253 ◽  
Author(s):  
Ziliang Li ◽  
Xingen Lu ◽  
Yanfeng Zhang ◽  
Ge Han ◽  
Chengwu Yang ◽  
...  
Keyword(s):  
Flow Structure ◽  
Centrifugal Compressor ◽  
Compressor Stage ◽  
Suction Surface ◽  
Flow Angle ◽  
Flow Solver ◽  
Stall Margin ◽  
Centrifugal Compressor Stage ◽  
Compressor Design ◽  
Highly Loaded

This study numerically investigated a highly loaded centrifugal compressor stage with various tandem-designed impellers and a wedge diffuser using a state-of-the-art multi-block flow solver to better understand the fundamental mechanism of tandem impellers. The flow topologies in the impeller are analyzed in detail to identify the underlying physical mechanism of the effect of the tandem-impeller design on the performance of the compressor stage. Particular emphasis is placed on the evolution of the flow structure in the tandem bladed impeller by varying the inducer–exducer clocking arrangements. The results demonstrate that a tandem compressor design is more efficient than a conventional compressor design for the majority of the tested clocking configurations, and the tandem clocking friction significantly affects the impeller performance. For the tested centrifugal compressor stage, an approximately 1.4% increase in isentropic efficiency and 1.3% increase in stall margin are achieved with an inducer–exducer clocking fraction of 25%. The improvement in the primary centrifugal compressor stage performance by the tandem-impeller design is a result of the manipulation of the flow structure and the reduction in the highly distorted jet/wake exit flow pattern. Compared to the conventional impeller designs, the tandem-impeller clocking arrangement variation significantly affects the high-momentum flow along the exducer suction surface and inducer wake diffusion, inlet axial velocity, and flow angle of the exducer blade. Therefore, this variation is advantageous for shortening the length of the boundary layers on both parts of the blade and enables an intense mixing at the exducer passage to improve the flow uniformity of the impeller exit. As a result, the impeller efficiency, diffuser recovery, and stalling margin can be improved compared with the conventional design.

Component Matching of Centrifugal Compressors for Turbocharger Application

2017 ◽  
Author(s):  
Hua Chen
Keyword(s):  
Centrifugal Compressor ◽  
Design Guidelines ◽  
Operating Conditions ◽  
Vaneless Diffuser ◽  
Flow Area ◽  
Matching Process ◽  
Compressor Design ◽  
Component Matching ◽  
Key Aspects ◽  
Stage Efficiency

Matching of various components (impeller exducer to impeller inducer, and vaneless diffuser and volute to the impeller) in a centrifugal compressor is critical for stage performance, but this is often neglected during compressor design and selection. This paper studies the importance of flow area matching for stage efficiency and how this matching process can be performed rapidly following a few simple principles. Methods for achieving optimum efficiency under different compressor operating conditions and size constraint are proposed and compared with experimental results. The purpose of this work is to draw attention to the key aspects of the matching, and provide easy-to-use design guidelines for engineers.

Numerical Investigation of Different Casing Treatments on Performance of a High Speed Centrifugal Compressor Stage

2011 ◽  
Author(s):  
Yan Ma ◽  
Guang Xi ◽  
Guangkuan Wu
Keyword(s):  
Numerical Investigation ◽  
Centrifugal Compressor ◽  
High Speed ◽  
The Other ◽  
Compressor Stage ◽  
Stall Margin ◽  
Casing Treatment ◽  
Centrifugal Compressor Stage ◽  
And Performance ◽  
Casing Treatments

In this paper, two different casing treatment devices—one adopting inlet recirculation at the shroud side of the impeller inlet and the other adopting circumferential casing grooves at the shroud side of the vaneless space, are designed for a high speed centrifugal compressor stage. The effects of different casing treatments to the flow range and performance of the centrifugal compressor stage are studied numerically. The results indicate that traditional inlet recirculation at impeller inlet does not extend the stall margin of the stage and the performance deteriorates due to the adding of the extra device. The study also shows that, when the location of the bleed slot moves downstream, the performance of the stage deteriorates due to the longer flow path. Moreover, the 2mm depth circumferential casing grooves extend the stall margin by about 12.05%. By contrast, the 6mm depth and 10mm depth grooves extend the stall margin by 3% and 2.4% respectively.

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