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.

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.

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.

Instantaneous Measurements in the Jet-Wake Discharge Flow of a Centrifugal Compressor Impeller

1975 ◽  
Vol 97 (3) ◽  
pp. 337-345 ◽  
Author(s):  
D. Eckardt
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Theoretical Models ◽  
Vaneless Diffuser ◽  
Impeller Blade ◽  
Measuring Systems ◽  
Compressor Design ◽  
Wake Patterns ◽  
Compressor Impeller ◽  
Critical Problems

One of the critical problems in centrifugal compressor design is the diffuser-impeller interaction. Up to now, theoretical models, which describe one of the salient features of this problem, the impeller discharge mixing process, appear to be proved experimentally only at low tip speeds. In the present study investigations on this subject were accomplished in the vaneless diffuser of a low-pressure ratio centrifugal compressor, running at tip speeds of 300 m/s. Detailed, instantaneous measurements in the impeller discharge mixing zone were performed by high-frequency measuring systems. Relative velocity distributions at the exit of impeller blade channels show pronounced jet/wake-patterns. The radial extension of flow distortions in the vaneless diffuser entry region, caused by rotating wakes, reached up to higher radius ratios than predicted by theoretical models.

Numerical Investigation on the Flow Characteristics of a Supercritical CO2 Centrifugal Compressor

2014 ◽  
Author(s):  
Hang Zhao ◽  
Qinghua Deng ◽  
Kuankuan Zheng ◽  
Hanzhen Zhang ◽  
Zhenping Feng
Keyword(s):  
Numerical Investigation ◽  
Centrifugal Compressor ◽  
Supercritical Co2 ◽  
Flow Characteristics ◽  
Low Pressure ◽  
Operating Conditions ◽  
Vaneless Diffuser ◽  
Vaned Diffuser ◽  
Compact Size ◽  
Wide Range

Supercritical CO2 closed-loop Brayton cycles offer the potential of better economical and practical efficiency due to its compact size and smaller compression work as compared with some traditional working fluids cycles, in which compressor is the key component. In this paper, the aerodynamic design and impeller aerodynamic optimization were conducted for a single stage centrifugal compressor with a combined vaneless and vaned diffuser, operating with CO2 slightly above the vapor-liquid critical point. The NIST REFPROP database was used for the computation of supercritical CO2 properties in design analysis and numerical investigation. The flow characteristics of the supercritical CO2 compressor were investigated by NUMECA FINE/Turbo. In order to weaken the low pressure regions, a vaneless diffuser was applied in this design, which would control and reduce the distribution differences of fluid thermodynamic states and increase fluid static pressure. The results indicate that there are no obvious low pressure regions occurring close to the leading edge of vaned diffuser. So it is observed in the design process that the vaneless diffuser could improve the aerodynamic performance of supercritical CO2 compressor. Compared with the operating conditions of the compressor only under centrifugal force, the pressure load from the aerodynamic analysis and the centrifugal load due to high speed of rotation were considered in the study of the stress and deformation of the structure of impeller by ANSYS/Mechanical. It can be concluded that supercritical CO2 provides unique properties for the compressor working process, which have a significant influence on finite element modeling in structural analysis. For the present design the maximum von Mises stress and total deformation are shown much smaller than the maximum allowable values, and thus the compressor could work in a wide range of operating conditions.

scholarly journals Effect of Vaneless Diffuser Shape on Performance of Centrifugal Compressor

2020 ◽  
Vol 10 (6) ◽  
pp. 1936
Author(s):  
Qian Zhang ◽  
Qiuhong Huo ◽  
Lei Zhang ◽  
Lei Song ◽  
Jianmeng Yang
Keyword(s):  
Numerical Simulation ◽  
Energy Loss ◽  
Pressure Distribution ◽  
Centrifugal Compressor ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Vaneless Diffuser ◽  
Centrifugal Compressors ◽  
Parallel Wall

The influence of four different vaneless diffuser shapes on the performance of centrifugal compressors is numerically studied in this paper. One of the studied shapes was a parallel wall diffuser. Two others had the width reduced only from hub and shroud and the rest had the width reduced from hub and shroud divided evenly. Then the numerical simulation was employed and the overall compressor aerodynamic performance was studied. The detailed velocity and pressure distribution and energy loss within the centrifugal compressor with different diffuser geometries and different operating conditions were analyzed. The results revealed that shroud pinch significantly improved the overall compressor aerodynamic performance more than any other pinch types, and the best performance can be achieved by pinched diffusers under the design condition compared with pinched diffusers under the near surge condition or choking condition. The range of energy loss, namely the static entropy area in the compressor, become reduced with the above three pinches diffusers.

scholarly journals Investigation of the Stage Performance and Flow Fields in a Centrifugal Compressor with a Vaneless Diffuser

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Ahti Jaatinen-Värri ◽  
Aki Grönman ◽  
Teemu Turunen-Saaresti ◽  
Jari Backman
Keyword(s):  
Centrifugal Compressor ◽  
Flow Fields ◽  
Tip Clearance ◽  
Vaneless Diffuser ◽  
Flow Area ◽  
Tip Clearance Flow ◽  
Diffuser Flow ◽  
Clearance Flow ◽  
Stage Performance ◽  
Large Width

The effect of the width of the vaneless diffuser on the stage performance and flow fields of a centrifugal compressor is studied numerically and experimentally. The diffuser width is varied by reducing the diffuser flow area from the shroud side (i.e., pinching the diffuser). Seven different diffuser widths are studied with numerical simulation. In the modeling, the diffuser widthb/b2is varied within the range 1.00 to 0.50. The numerical results are compared with results obtained in previous studies. In addition, two of the diffusers are further investigated with experimental measurement. The main finding of the work is that the pinch reduces losses in the impeller associated with the tip-clearance flow. Furthermore, it is shown that a too large width reduction causes the flow to accelerate excessively, resulting in a highly nonuniform flow field and flow separation near the shroud.

scholarly journals Numerical Modeling of the Flow in a Vaneless Diffuser of Centrifugal Compressor Stage

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Mykola Kalinkevych ◽  
Oleg Shcherbakov
Keyword(s):  
Experimental Data ◽  
Numerical Modeling ◽  
Centrifugal Compressor ◽  
Compressor Stage ◽  
Vaneless Diffuser ◽  
Flow Core ◽  
Flow Area ◽  
Centrifugal Compressor Stage ◽  
Ansys Cfx ◽  
Sst Turbulence Model

This paper presents the results of numerical investigation of the flow in a vaneless diffuser of centrifugal compressor stage. Simulations were performed using both a commercial CFD package ANSYS CFX and the own-designed computer program. Steady conditions involving SST turbulence model were used for the calculations using CFX. To consider the interaction between impeller and diffuser, not just a diffuser but the whole stage was calculated. The own-designed methodology is based on solving of conservation equations with assumptions that flow in a diffuser is steady state and axisymmetric. The flow area is divided into the flow core and boundary layers. Results of calculation were compared with experimental data.

Centrifugal Compressor Design for Near-Critical Point Applications

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Alireza Ameli ◽  
Ali Afzalifar ◽  
Teemu Turunen-Saaresti ◽  
Jari Backman
Keyword(s):  
Critical Point ◽  
Centrifugal Compressor ◽  
Compressibility Factor ◽  
Design Procedure ◽  
Operating Conditions ◽  
Brayton Cycle ◽  
Compressor Design ◽  
Lower Temperature ◽  
The Individual ◽  
Line Design

The supercritical CO2 (sCO2) Brayton cycle has been attracting much attention to produce the electricity power, chiefly due to its higher thermal efficiency with the relatively lower temperature at the turbine inlet compared to other common energy conversion cycles. Centrifugal compressor operating conditions in the supercritical Brayton cycle are commonly set in vicinity of the critical point, owing to smaller compressibility factor and eventually lower compressor work. This paper investigates and compares different centrifugal compressor design methodologies in close proximity to the critical point and suggests the most accurate design procedure based on the findings. An in-house mean-line design code, which is based on the individual enthalpy loss models, is compared to stage efficiency correlation design methods. Moreover, modifications are introduced to the skin friction loss calculation to establish an accurate one-dimensional design methodology. Moreover, compressor performance is compared to the experimental measurements.

Centrifugal Compressor Design for Near-Critical Point Applications

2018 ◽  
Author(s):  
Alireza Ameli ◽  
Ali Afzalifar ◽  
Teemu Turunen-Saaresti ◽  
Jari Backman
Keyword(s):  
Critical Point ◽  
Centrifugal Compressor ◽  
Compressibility Factor ◽  
Design Procedure ◽  
Operating Conditions ◽  
Brayton Cycle ◽  
Compressor Design ◽  
Lower Temperature ◽  
The Individual ◽  
Line Design

The supercritical CO2 (sCO2) Brayton cycle has been attracting much attention to produce the electricity power, chiefly due to its higher thermal efficiency with the relatively lower temperature at the turbine inlet compared to other common energy conversion cycles. Centrifugal compressor operating conditions in the supercritical Brayton cycle are commonly set in vicinity of the critical point, owing to smaller compressibility factor and eventually lower compressor work. This paper investigates and compares different centrifugal compressor design methodologies in close proximity to the critical point and suggests the most accurate design procedure based on the findings. An in-house mean-line design code, which is based on the individual enthalpy loss models, is compared to stage efficiency correlation design methods. Moreover, modifications are introduced to the skin friction loss calculation to establish an accurate 1-D design methodology. Moreover, compressor performances are compared to the experimental measurements.

Effect of Impeller Blade Trimming on the Performance of a 5.5:1 Pressure Ratio Centrifugal Compressor

2012 ◽  
Author(s):  
Daniel Swain ◽  
Abraham Engeda
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Compressor Blade ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Flow Coefficient ◽  
Impeller Blade ◽  
Compressor Design

Centrifugal compressor blade trimming can be used for the purpose of changing the performance characteristics of an impeller or allowing a single impeller design to be used for a range of operating conditions. There are a number of methods of impeller blade trimming that may be employed to change the impeller flowrate, the pressure ratio, or both; however, the limitations of blade trimming and the effect on the flow field are not well understood. In this study, CFD is used to model the effects of three different methods of blade trimming on a single centrifugal compressor design. Impeller performance characteristics and analysis of the flow field are presented for a series of trims for each of the three trimming methods. Each method of trimming was found to be limited at some point by choke. Shifting the original shroud profile both axially and radially in proportion to the desired flow coefficient allowed the pressure ratio and efficiency of the original impeller to be maintained while changing the flow coefficient. Trimming the blades along the meridional length in proportion to the desired new flow coefficient without regard to the original shroud profile produced similar results, but allowed the impeller to be trimmed further than was practical using the radial-axial shroud offset method. Trimming the blades axially so that the original shroud profile is maintained produced a change in pressure ratio while maintaining the original impeller flow coefficient.

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