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.

Influence of Tandem Inducers on the Performance of High Pressure Ratio Centrifugal Compressors

2015 ◽  
Author(s):  
Rodrigo R. Erdmenger ◽  
Vittorio Michelassi
Keyword(s):  
High Pressure ◽  
Pressure Ratio ◽  
Suction Side ◽  
Flow Coefficient ◽  
Centrifugal Compressors ◽  
Vaned Diffuser ◽  
High Pressure Ratio ◽  
Significant Performance ◽  
Inlet Conditions ◽  
The Impact

The uses of tandem inducers has been proposed in the past in an attempt to reduce the inducer shock losses and to improve the performance and operating range of centrifugal compressors. However throughout the literature the benefits/penalties of this type of compressor design are still unclear, with contradictory conclusions and very few studies attempting to understand the causes of the observed benefits/penalties. Additionally none of the cases reported for centrifugal compressors has looked into the impact of overlap between the inducer and the main blade. The current study looks into the different aspects of the design of centrifugal compressors with tandem inducers and their effect on the performance of a high flow coefficient, high pressure ratio centrifugal compressor. Aspects such as clocking, axial gap between the inducer and the compressor main blade, axial overlap, and the performance in combination with a vaned diffuser are discussed. Overall the results indicate that it is possible to design centrifugal compressors with tandem inducers that provide similar or even a slight performance benefit at design point, and that tandem inducers can provide significant performance benefits at off design conditions by improving the flow conditions along the main blade suction side, and by improving the inlet conditions to a vaned diffuser. The results also indicate that the impact of the axial gap between the inducer and the main blade has little impact on the compressor performance, that clocking will have a significant impact on the performance of the compressor and that the best performance will be obtained when the tandem inducer is almost aligned with the main blade of the compressor, since this avoids the blockage and losses incurred by other clocking arrangements.

Experimental Aerodynamic Analysis Relative to Three High Pressure Ratio Centrifugal Compressors

1987 ◽  
Author(s):  
Y. Ribaud
Keyword(s):  
High Pressure ◽  
Pressure Ratio ◽  
Flow Coefficient ◽  
Careful Study ◽  
Test Results ◽  
Centrifugal Compressors ◽  
Inlet Flow ◽  
High Pressure Ratio ◽  
Experimental Parameters ◽  
Surge Line

The test results of three high pressure ratio centrifugal compressors are analyzed. Two of them show one or two discontinuities in the surge line. A careful study of the different experimental parameters indicates the existence of three different operating zones for the rotor. For the low inlet flow coefficients, two recirculations take place in the rotor: one at the inlet and the other at the outlet. For moderate flow coefficients, the outlet recirculation disappears. In these regions, the occurrence of these recirculations is explained and a simple model is given. The inlet recirculation can stabilize the flow if a 2D blade stall occurs but it is not possible in the third zone where the inlet flow coefficient is higher than the critical value.

Influence of Splitter Blades on the Performance of a Single-Stage Centrifugal Compressor With Pressure Ratio 12.0

2020 ◽  
Author(s):  
Wenchao Zhang ◽  
Zhenzhong Sun ◽  
Baotong Wang ◽  
Xinqian Zheng
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Flow Separation ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
High Pressure Ratio ◽  
Clearance Flow ◽  
Aerodynamic Configuration

Abstract High performance centrifugal compressors with high pressure ratio are highly applied in turboshaft engines in order to obtain higher power-to-weight ratio and lower fuel consumption. The optimization of the aerodynamic configuration design of splitter blades is one of the effective ways to achieve higher efficiency. An in-house designed single-stage centrifugal compressor with a pressure ratio up to 12.0 is studied in this paper. By using a three-dimensional CFD (computational fluid dynamic) method, this paper investigates influences of the number of splitter blades and their leading edge position on the flow field characteristics and aerodynamic performance of the centrifugal compressor with ultra-high pressure ratio. Results show that three critical flow characteristics lead to severe losses in centrifugal compressor impeller when only full blades are applied. Those flow characteristics include the strong shock wave, the severe tip clearance flow at the inlet region and the severe flow separation at the rear region. Therefore, the inlet blade number should be reduced to decrease the loss caused by strong shock waves and tip clearance flow, while the outlet blade number should be sufficient enough to suppress flow separation. By optimizing the number and the leading edge position of splitters, the performance can be improved under the reduction of combined losses caused by shock waves, tip clearance flow and flow separation. When an aerodynamic configuration with single-splitters is used, numerical results indicate that the leading edge position of splitter blades should be located at 60% of the main blade chord length, and the centrifugal impeller isentropic efficiency with ultra-high pressure ratio can be increased from 82.4% (the aerodynamic configuration with only full blades) to 89.5%; when an aerodynamic configuration with double-splitters is used, the leading edge positions of middle and short splitter blades should be respectively located at 40% and 60% of the main blade chord length, and the impeller isentropic efficiency can be further improved to 90.9%.

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.

Investigations of the Flow Through a High Pressure Ratio Centrifugal Impeller

2002 ◽  
Author(s):  
Gernot Eisenlohr ◽  
Hartmut Krain ◽  
Franz-Arno Richter ◽  
Valentin Tiede
Keyword(s):  
High Pressure ◽  
Flow Separation ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Centrifugal Impeller ◽  
Angle Distribution ◽  
Blade Angle ◽  
Minor Variation ◽  
Design Point ◽  
High Pressure Ratio

In an industrial research project of German and Swiss Turbo Compressor manufacturers a high pressure ratio centrifugal impeller was designed and investigated. Performance measurements and extensive laser measurements (L2F) of the flow field upstream, along the blade passage and downstream of the impeller have been carried out. In addition to that, 3D calculations have been performed, mainly for the design point. Results have been presented by Krain et al., 1995 and 1998, Eisenlohr et al., 1998 and Hah et al.,1999. During the design period of this impeller a radial blade at the inlet region was mandatory to avoid a rub at the shroud due to stress reasons. The measurements and the 3D calculations performed later, however, showed a flow separation at the hub near the leading edge due to too high incidence. Additionally a rather large exit width and a high shroud curvature near the exit caused a flow separation near the exit, which is enlarged by the radially transported wake of the already addressed hub separation. Changes to the hub blade angle distribution to reduce the hub incidence and an adaptation of the shroud blade angle distribution for the same impeller mass-flow at the design point were investigated by means of 3D calculations first with the same contours at hub and shroud; this was followed by calculations with a major change of the shroud contour including an exit width change with a minor variation of the hub contour. These calculations showed encouraging results; some of them will be presented in conjunction with the geometry data of the original impeller design.

A Performance Autopsy of Three Centrifugal Compressors for a Small Gas Turbine

2010 ◽  
Author(s):  
Colin Rodgers ◽  
Dan Brown
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Radial Flow ◽  
Pressure Ratio ◽  
Test Results ◽  
Design Features ◽  
Centrifugal Compressors ◽  
High Pressure Ratio ◽  
Flow Type ◽  
The One

Three 140mm tip diameter centrifugal compressors were designed and tested to determine the one exhibiting the best performance most suitable for eventual application to a small 60KW radial flow type gas turbine. The design features, and stage test results of these three moderately high pressure ratio impellers are presented, together with a comparison of their respective test and CFD computed performance maps.

Deterioration of Compressor Performance Due to Tip Clearance of Centrifugal Impellers

1987 ◽  
Vol 109 (1) ◽  
pp. 55-61 ◽  
Author(s):  
Y. Senoo ◽  
M. Ishida
Keyword(s):  
High Pressure ◽  
Pressure Ratio ◽  
Tip Clearance ◽  
Slip Coefficient ◽  
Clearance Ratio ◽  
Flow Rates ◽  
High Pressure Ratio ◽  
Compressor Performance ◽  
Loss Efficiency ◽  
Good Agreement

The authors’ theory on the tip-clearance loss of centrifugal impellers is modified to include the variation of slip coefficient of the impeller due to the tip clearance, by deriving a rational relationship between two empirical parameters in the theory. In order to compare experimental data in the literature with prediction, examination was made regarding accuracy of available data and the way to select corresponding flow rates of a compressor with different values of tip clearance. Good agreement between data and prediction was observed. These examples demonstrate the following tendency regarding effects of various parameters on the tip clearance loss. Efficiency drop due to the tip clearance of high-pressure-ratio compressors is less than that of low-pressure-ratio compressors if the tip clearance ratio at the impeller exit is equal. The magnitude of clearance loss becomes smaller as the flow rate is reduced and also at a reduced shaft speed in cases of high-pressure-ratio compressors. The equations in the theory clearly show these tendencies.

scholarly journals Investigation on the Optimal Design and Flow Mechanism of High Pressure Ratio Impeller with Machine Learning Method

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Weilin Yi ◽  
Hongliang Cheng
Keyword(s):  
Machine Learning ◽  
High Pressure ◽  
Flow Field ◽  
Performance Improvement ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Design Parameters ◽  
Support Vector ◽  
Peak Efficiency ◽  
High Pressure Ratio

The optimization of high-pressure ratio impeller with splitter blades is difficult because of large-scale design parameters, high time cost, and complex flow field. So few relative works are published. In this paper, an engineering-applied centrifugal impeller with ultrahigh pressure ratio 9 was selected as datum geometry. One kind of advanced optimization strategy including the parameterization of impeller with 41 parameters, high-quality CFD simulation, deep machine learning model based on SVR (Support Vector Machine), random forest, and multipoint genetic algorithm (MPGA) were set up based on the combination of commercial software and in-house python code. The optimization objective is to maximize the peak efficiency with the constraints of pressure-ratio at near stall point and choked mass flow. Results show that the peak efficiency increases by 1.24% and the overall performance is improved simultaneously. By comparing the details of the flow field, it is found that the weakening of the strength of shock wave, reduction of tip leakage flow rate near the leading edge, separation region near the root of leading edge, and more homogenous outlet flow distributions are the main reasons for performance improvement. It verified the reliability of the SVR-MPGA model for multiparameter optimization of high aerodynamic loading impeller and revealed the probable performance improvement pattern.

scholarly journals Casing Treatments on a Supersonic Diffuser for High Pressure Ratio Centrifugal Compressors

1982 ◽  
Author(s):  
Y. Ribaud ◽  
P. Avram
Keyword(s):  
High Pressure ◽  
Mass Flow ◽  
Pressure Ratio ◽  
Centrifugal Compressors ◽  
Flow Variation ◽  
High Pressure Ratio ◽  
Supersonic Inlet ◽  
Diffuser Flow ◽  
Supersonic Diffuser ◽  
Casing Treatments

Centrifugal compressors with high pressure ratios from 7 to 10 often have a very slow mass flow margin. Suitable casing treatments, including large openings at the diffuser throat connected to annular plenums, greatly increase the reduced mass flow range of the diffuser during supersonic inlet operation. In the region of reduced mass flow variation, the reduction of the diffuser flow is associated with a drop of the effectiveness. The use of a backswept centrifugal rotor allows the experiment to overcome this penalty.

Inlet Duct Treatment for Stability Improvement on a High Pressure Ratio Centrifugal Compressor

2013 ◽  
Author(s):  
Mingyang Yang ◽  
Ricardo Martinez-Botas ◽  
Yangjun Zhang
Keyword(s):  
High Pressure ◽  
Flow Control ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Control Method ◽  
Pressure Ratio ◽  
Operating Range ◽  
High Pressure Ratio ◽  
Wide Range ◽  
Inlet Duct

The operating range of a centrifugal compressor, determined by surge and choke flow rate, is a key issue for turbocharging since a vehicle internal combustion engine (ICE) is usually operated across a wide range. In this paper a new flow control method is developed and validated numerically, in which an array of circumferentially distributed holes is designed in the inner wall of the inlet duct of a high pressure ratio centrifugal compressor of a turbocharger. Firstly the numerical method is validated by experimental results of the original turbocharging centrifugal compressor with a pressure ratio of 4. Next the validated method is used to investigate the new flow control method and its effect on the compressor’s performance. Results show that the method can enhance the compressor stability and widen the operating range effectively at all investigated speeds. At meantime, the choke flow reduces slightly. The flow details in the compressor are further analysed according to the CFD results. It is found that the flow near the blade tip at inlet is pre-swirled by the method as the conventional IGV does while the flow in the middle span or near the hub remains in an axial direction. As a result, the stability of the compressor is enhanced by the pre-swirl effect at the tip while minimally sacrificing the choke flow rate, thus the map is extended effectively by the flow control method.

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