A Computational Investigation of Vane Clocking Effects on Embedded Compressor Stage Efficiency

2010 ◽  
Author(s):  
Jonathan Salontay ◽  
Nicole Key ◽  
Roy Fulayter
Keyword(s):  
Compressor Stage ◽  
Computational Investigation ◽  
Vane Clocking ◽  
Stage Efficiency

An Experimental Study of Vane Clocking Effects on Embedded Compressor Stage Performance

2008 ◽  
Author(s):  
Nicole L. Key ◽  
Patrick B. Lawless ◽  
Sanford Fleeter
Keyword(s):  
Effective Means ◽  
Leading Edge ◽  
Maximum Efficiency ◽  
Frequency Noise ◽  
Compressor Stage ◽  
Performance Measurements ◽  
Refining Performance ◽  
Stage Performance ◽  
Vane Clocking ◽  
Stage Efficiency

Previous research has shown that vane clocking, the circumferential indexing of adjacent vane rows with similar vane counts, can be an effective means to increase stage performance, reduce discrete frequency noise, and/or reduce the unsteady blade forces that can lead to high cycle fatigue. The objective of this research was to experimentally investigate the effects of vane clocking in an embedded compressor stage, focusing on stage performance. Experiments were performed in the intermediate-speed Purdue 3-Stage Compressor, which consists of an IGV followed by three stages. The IGV, Stator 1, and Stator 2 vane rows have identical vane counts, and the effects of vane clocking were studied on Stage 2. Much effort went into refining performance measurements to enable the detection of small changes in stage efficiency associated with vane clocking. At design loading, the change in stage efficiency between the maximum and minimum efficiency clocking configurations was 0.27 points. The maximum efficiency clocking configuration positioned the Stator 1 wake at the Stator 2 leading edge. This condition produced a shallower and thinner Stator 2 wake compared to the clocking configuration that located the wake in the middle of the Stator 2 passage. At high loading, the change in Stage 2 efficiency associated with vane clocking effects increased to 1.07 points; however, the maximum efficiency clocking configuration was the case where the Stator 1 wake passed through the middle of the downstream vane passage. Thus, impingement of the upstream vane wake on the downstream vane leading edge resulted in the best performance at design point but provided the lowest efficiency at an off-design condition.

An Experimental Study of Vane Clocking Effects on Embedded Compressor Stage Performance

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Nicole L. Key ◽  
Patrick B. Lawless ◽  
Sanford Fleeter
Keyword(s):  
Effective Means ◽  
Leading Edge ◽  
Maximum Efficiency ◽  
Frequency Noise ◽  
Compressor Stage ◽  
Performance Measurements ◽  
Refining Performance ◽  
Stage Performance ◽  
Vane Clocking ◽  
Stage Efficiency

Previous research has shown that vane clocking, the circumferential indexing of adjacent vane rows with similar vane counts, can be an effective means to increase stage performance, reduce discrete frequency noise, and/or reduce the unsteady blade forces that can lead to high cycle fatigue. The objective of this research was to experimentally investigate the effects of vane clocking in an embedded compressor stage, focusing on stage performance. Experiments were performed in the intermediate-speed Purdue three-stage compressor, which consists of an IGV followed by three stages. The IGV, Stator 1, and Stator 2 vane rows have identical vane counts, and the effects of vane clocking were studied on Stage 2. Much effort went into refining performance measurements to enable the detection of small changes in stage efficiency associated with vane clocking. At design loading, the change in stage efficiency between the maximum and minimum efficiency clocking configurations was 0.27 points. The maximum efficiency clocking configuration positioned the Stator 1 wake at the Stator 2 leading edge. This condition produced a shallower and thinner Stator 2 wake compared with the clocking configuration that located the wake in the middle of the Stator 2 passage. At high loading, the change in Stage 2 efficiency associated with vane clocking effects increased to 1.07 points; however, the maximum efficiency clocking configuration was the case where the Stator 1 wake passed through the middle of the downstream vane passage. Thus, impingement of the upstream vane wake on the downstream vane leading edge resulted in the best performance at design point but provided the lowest efficiency at an off-design condition.

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.

scholarly journals Assessment of the Severity of Unsteady Mach Number Effects in a 3-Stage Transonic Compressor

2017 ◽  
Author(s):  
Anthony Dent ◽  
Liping Xu ◽  
Roger Wells
Keyword(s):  
Leading Edge ◽  
Compressor Stage ◽  
Pressure Potential ◽  
Cfd Simulations ◽  
Transonic Compressor ◽  
Inlet Guide Vanes ◽  
Great Consideration ◽  
Stator Blade ◽  
Front Stage ◽  
Stage Efficiency

In this paper results from steady and unsteady CFD simulations of an industrial transonic compressor are compared, in order to gain a better understanding of the cause of the differences in the predicted efficiencies between the steady and unsteady simulations. Initially the first stage is simulated as an isolated compressor stage with inlet guide vanes in order to analyse the effect of individual blade rows on the stage performance. It is found that the rotor efficiency is lower for steady simulations than for unsteady simulations due to stronger shock waves. The stator efficiency is greater in the steady simulations due to not being able to model the interaction of the rotor wakes with the stator blade leading edge and boundary layers. Greater variation between steady and unsteady predictions is found at higher operating speeds. In the 3-stage unsteady simulations, the front stage efficiency characteristic is the same as the efficiency calculated from the isolated unsteady simulations. This shows that the unsteady pressure potential propagating from the downstream stages has no significant effect on the front stage efficiency meaning that the designer does not need to give great consideration to the downstream blade rows when predicting the characteristics of the front stage.

Effects of Endwall Profiling on Axial Flow Compressor Stage

2009 ◽  
Author(s):  
Jialing Lu ◽  
Wuli Chu ◽  
Yanhui Wu
Keyword(s):  
Flow Field ◽  
Engineering Design ◽  
Axial Flow ◽  
Design Tool ◽  
Operating Conditions ◽  
Compressor Stage ◽  
Corner Separation ◽  
Axial Flow Compressor ◽  
Flow Compressor ◽  
Stage Efficiency

In recent years endwall profiling has been well validated as a major new engineering design tool for the reduction of secondary loss in turbines. However, its application on compressors have been rarely performed and reported. This paper documents the findings of the analysis for diminishing compressor stator corner separation using endwall profiling; In the study, novel profiled endwalls were designed and numerically studied on a subsonic axial-flow compressor stage. The compressor stator endwalls were profiled on both axial and azimuthal directions. The results showed, the stator corner separation was significantly suppressed under all the operating conditions by implementing this profiled endwall. Significant improvements on stage pressure ratios and stage efficiency were observed. Detailed flow field changes, as well as endwall profiling methods are provided in the paper, so that the results of this research can be referenced to other compressor designs.

Performance Improvement of a Centrifugal Compressor Stage by Increasing Degree of Reaction and Optimizing Blade Loading of a 3D Impeller

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Takanori Shibata ◽  
Manabu Yagi ◽  
Hideo Nishida ◽  
Hiromi Kobayashi ◽  
Masanori Tanaka
Keyword(s):  
Performance Improvement ◽  
Relative Velocity ◽  
High Efficiency ◽  
Pressure Coefficient ◽  
Flow Coefficient ◽  
Compressor Stage ◽  
Blade Loading ◽  
Surge Margin ◽  
Velocity Diffusion ◽  
Stage Efficiency

Performance improvement of 3D impellers in a high specific speed range was investigated using computational fluid dynamics analyses and experimental tests. In order to reduce the loss production within the stator passages, the backsweep angle of the impellers was increased. At the same time, the inlet-to-exit relative velocity diffusion ratio was also increased by increasing the impeller exit width to prevent the reduction in the pressure ratio. Moreover, the blade loading distribution at the impeller shroud side was optimized to suppress the surge margin reduction caused by the increased relative velocity diffusion ratio. Five types of unshrouded impellers were designed, manufactured, and tested to evaluate the effects of blade loading, backsweep angle, and relative velocity diffusion ratio on the compressor performance. The design suction flow coefficient was 0.125 and the machine Mach number was 0.87. Test results showed that the compressor stage efficiency was increased by 5% compared with the base design without reducing the pressure coefficient and surge margin. It was concluded that an increased relative velocity diffusion ratio coupled with large backsweep angle was a very effective way to improve the compressor stage efficiency. An appropriate blade loading distribution was also important in order to achieve a wide operating range as well as high efficiency.

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.

Effect of Impeller Blade Loading on Compressor Stage Performance in a High Specific Speed Range

2011 ◽  
Vol 134 (4) ◽  
Author(s):  
Takanori Shibata ◽  
Manabu Yagi ◽  
Hideo Nishida ◽  
Hiromi Kobayashi ◽  
Masanori Tanaka
Keyword(s):  
Relative Velocity ◽  
Compressor Stage ◽  
Test Results ◽  
Blade Loading ◽  
Degree Of Reaction ◽  
Surge Margin ◽  
Speed Range ◽  
Specific Speed ◽  
Velocity Diffusion ◽  
Stage Efficiency

The authors previously found that compressor stage efficiency in a high specific speed range was significantly improved by employing an increased relative velocity diffusion ratio coupled with a high backsweep angle (Shibata et al., “Performance Improvement of a Centrifugal Compressor Stage by Increasing Degree of Reaction Optimizing Blade Loading of a 3D-Impeller,” ASME Paper No. GT2009-59588). In spite of such a high relative velocity diffusion ratio, the same surge margin as with a conventional design was able to be achieved by using a special front loading distribution with a lightly loaded inducer. In the present study, the blade loading distribution was further optimized in order to achieve a larger surge margin than previously. Four types of fully shrouded impellers were designed, manufactured, and tested to evaluate the effects of blade loading, backsweep angle, and relative velocity diffusion ratio on compressor performance. The design suction flow coefficient was 0.125 and the machine Mach number was 0.87. Test results showed that the developed impeller achieved 3.8% higher stage efficiency and 11% larger surge margin than the conventional design without reducing the pressure coefficient and choke margin. It was concluded that aft loading coupled with a high degree of reaction was a very effective way to improve surge margin as well as stage efficiency. Stator matching was also investigated by changing the design incidence angle, which was shown to have a little influence on surge margin in the present test results.

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.

scholarly journals Hub and shroud fillets influence on the radial compressor stage efficiency

2015 ◽  
Vol 92 ◽  
pp. 02090 ◽  
Author(s):  
Tomáš Syka ◽  
Richard Matas ◽  
Jindřich Kňourek
Keyword(s):  
Compressor Stage ◽  
Radial Compressor ◽  
Stage Efficiency
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