scholarly journals Characterization of the Performance of a Turbocharger Centrifugal Compressor by Component Loss Contributions

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2711 ◽  
Author(s):  
Nima Khoshkalam ◽  
Mohammad Mojaddam ◽  
Keith R. Pullen
Keyword(s):  
Numerical Model ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Blade Angle ◽  
Loss Mechanism ◽  
Impeller Blade ◽  
Operating Range ◽  
Surge Margin ◽  
Wide Range ◽  
Loss Mechanisms

The performance of an automotive turbocharger centrifugal compressor has been studied by developing a comprehensive one-dimensional (1D) code as verified through experimental results and a three-dimensional (3D) model. For 1D analysis, the fluid stream in compressor is modeled using governing gas dynamics equations and the loss mechanisms have been investigated and added to the numerical model. The objective is to develop and offer a 1D model, which considers all loss mechanisms, slip, blockage and also predicts the surge margin and choke conditions. The model captures all features from inlet duct through to volute discharge. Performance characteristics are obtained using preliminary geometry and the blade characteristics. A 3D numerical model was also created and a viscous solver used for investigating the compressor characteristics. The numerical model results show good agreement with experimental data through compressor pressure ratio and efficiency. The effect of the main compressor dimensions on compressor performance has been investigated for wide operating range and the portions of each loss mechanism in the impeller. Higher pressure ratio is achievable by increasing impeller blade height at outlet, impeller blade angle on inlet, diffuser outlet diameter and by decreasing impeller shroud diameter at inlet and blade angle at outlet. These changes may cause unfavorable consequences such as a lower surge margin or shorter operating range, which should be compromised with favorable changes. At lower rotational speeds, impeller skin friction mainly impacts the performance and at higher rotational speeds, impeller diffusion, blade loading and recirculation losses are more important. The results allow the share of each loss mechanism to be quantified for different mass flow rates and rotational speed, shedding new light on which losses are most important for which conditions. For a turbocharger, which must operate over a wide range of conditions, these results bring new insight to engineers seeking to optimize the compressor design as part of an internal combustion engine system.

The performance of a centrifugal compressor with a tandem impeller in off-design conditions

2019 ◽  
Vol 234 (2) ◽  
pp. 156-172 ◽  
Author(s):  
Ziliang Li ◽  
Xingen Lu ◽  
Ge Han ◽  
Yanfeng Zhang ◽  
Shengfeng Zhao ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Performance Enhancement ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Complex Flow ◽  
Maximum Enhancement ◽  
Operating Range ◽  
Wide Range ◽  
Compressor Performance ◽  
Low Efficiency

Centrifugal compressors often suffer relatively low efficiency and a terrible operating range particularly due to the complex flow structure and intense impeller/diffuser interaction. Numerous studies have focused on improving the centrifugal compressor performance using many innovative ideas, such as the tandem impeller, which has become increasingly attractive due to its ability to achieve the flow control with no additional air supply configurations and control costs in compressor. However, few studies that attempted to the investigation of tandem impeller have been published until now and the results are always contradictory. To explore the potential of the tandem impeller to enhance the compressor performance and the underlying mechanism of the flow phenomena in the tandem impellers, this paper numerically investigated a high-pressure-ratio centrifugal compressor with several tandem impellers at off-design operating speeds. The results encouragingly demonstrate that the tandem impeller can achieve a performance enhancement over a wide range of operating conditions. Approximately 1.8% maximum enhancement in isentropic efficiency and 5.0% maximum enhancement in operating range are achieved with the inducer/exducer circumferential displacement of [Formula: see text] = 25% and 50%, respectively. The observed stage performance gain of the tandem impellers decreases when the operating speed increases due to the increased inducer shock, increased wake losses, and deteriorated tandem impeller discharge flow uniformity. In addition, the tandem impeller can extend the impeller operating range particularly at low rotation speeds, which is found to be a result from the suppression of the low-momentum fluid radial movement. The results also indicate that the maximum flux capacity of the tandem impeller decreases due to the restriction of the inducer airfoil Kutta–Joukowsky condition.

scholarly journals The Effect of Variable Geometry on the Operating Range and Surge Margin of a Centrifugal Compressor

1976 ◽  
Author(s):  
A. Whitfield ◽  
F. J. Wallace ◽  
R. C. Atkey
Keyword(s):  
Centrifugal Compressor ◽  
Peak Pressure ◽  
Pressure Ratio ◽  
Variable Geometry ◽  
Vaneless Diffuser ◽  
Flow Rates ◽  
Lower Flow ◽  
Operating Range ◽  
Surge Margin ◽  
Isentropic Efficiency

Two variable geometry techniques have been applied to a small turbocharger compressor, with the objective of trying to move the peak pressure ratio operating point to lower flow rates, thereby yielding a broad flow range map. Variable prewhirl guide vanes and variable vaneless diffuser passage height have been studied separately. The results obtained with both techniques are compared and the relative merits and demerits with respect to improved flow range and isentropic efficiency penalties are considered.

Design and Experimental Study on the Surge Performance Improvement by the Effects of Bleed Slot Casing of a Centrifugal Compressor

2014 ◽  
Author(s):  
Hong Won Kim ◽  
Jae Hoon Chung ◽  
Hyo Seong Lee ◽  
Min Ouk Choi
Keyword(s):  
Centrifugal Compressor ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Design Parameters ◽  
Navier Stokes Equations ◽  
Operating Range ◽  
Surge Margin ◽  
Commercial Code

The primary design goal of a compressor is focused on improving efficiency. Secondary objective is to widen the compressor’s operating range. This paper presents a numerical and experimental investigation of the influence of the bleed slot to enlarge operating range for the 1.2MW class centrifugal compressor installed in a turbocharger. The main design parameters of the bleed slot casing are upstream slot position, inlet pipe slope, downstream slot position and width. The DOE (design of experiment) method was carried out to optimize the casing design. Numerical analyses were done by the commercial code ANSYS-CFX based on the three dimensional Reynolds-averaged Navier-Stokes equations. From the analysis, as the downstream slot position and width are smaller and upstream position is located away from impeller inlet, efficiency and pressure ratio are increased. Experimental works were done with and without the bleed slot casing. The simulation results were in good agreement with the test data. In case without the bleed slot casing, the surge margin value came out to be only 11.8% but with the optimized bleed slot design, the surge margin reached 23%. Therefore, the surge margin increase of 11.2% was achieved.

scholarly journals The Performance of a Centrifugal Compressor With High Inlet Prewhirl

1997 ◽  
Author(s):  
A. Whitfield ◽  
A. H. Abdullah
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Low Flow ◽  
Variable Geometry ◽  
Pressure Pulsations ◽  
Operating Range ◽  
Swirl Generator ◽  
Geometry Design ◽  
Wide Range ◽  
Inlet Swirl

The performance requirements of centrifugal compressors usually include a broad operating range between surge and choke. This becomes increasingly difficult to achieve as increased pressure ratio is demanded. In order to suppress the tendency to surge and extend the operating range at low flow rates inlet swirl is often considered through the application of inlet guide vanes. To generate high inlet swirl angles efficiently an inlet volute has been applied as the swirl generator, and a variable geometry design developed in order to provide zero swirl. The variable geometry approach can be applied to progressively increase the swirl or to switch rapidly from zero swirl to maximum swirl. The variable geometry volute and the swirl conditions generated are described. The performance of a small centrifugal compressor is presented for a wide range of inlet swirl angles. In addition to the basic performance characteristics of the compressor the onset of flow reversals at impeller inlet are presented, together with the development of pressure pulsations, in the inlet and discharge ducts, through to full surge. The flow rate at which surge occurred was shown, by the shift of the peak pressure condition and by the measurement of the pressure pulsations, to be reduced by over 40%.

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.

The Performance of a Centrifugal Compressor With High Inlet Prewhirl

1998 ◽  
Vol 120 (3) ◽  
pp. 487-493 ◽  
Author(s):  
A. Whitfield ◽  
A. H. Abdullah
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Low Flow ◽  
Variable Geometry ◽  
Pressure Pulsations ◽  
Operating Range ◽  
Swirl Generator ◽  
Geometry Design ◽  
Wide Range ◽  
Inlet Swirl

The performance requirements of centrifugal compressors usually include a broad operating range between surge and choke. This becomes increasingly difficult to achieve as increased pressure ratio is demanded. In order to suppress the tendency to surge and extend the operating range at low flow rates, inlet swirl is often considered through the application of inlet guide vanes. To generate high inlet swirl angles efficiently, an inlet volute has been applied as the swirl generator, and a variable geometry design developed in order to provide zero swirl. The variable geometry approach can be applied to increase the swirl progressively or to switch rapidly from zero swirl to maximum swirl. The variable geometry volute and the swirl conditions generated are described. The performance of a small centrifugal compressor is presented for a wide range of inlet swirl angles. In addition to the basic performance characteristics of the compressor, the onsets of flow reversals at impeller inlet are presented, together with the development of pressure pulsations, in the inlet and discharge ducts, through to full surge. The flow rate at which surge occurred was shown, by the shift of the peak pressure condition and by the measurement of the pressure pulsations, to be reduced by over 40 percent.

Numerical Study on the Range Enhancement of a Centrifugal Compressor With a Ring Groove System

2011 ◽  
Author(s):  
ChiYong Park ◽  
YoungSeok Choi ◽  
KyoungYong Lee ◽  
JoonYong Yoon
Keyword(s):  
Centrifugal Compressor ◽  
High Performance ◽  
High Efficiency ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Low Flow ◽  
Ring Groove ◽  
Guide Vanes ◽  
Operating Range ◽  
Surge Margin

This paper presents a numerical study of casing treatments on a centrifugal compressor in order to improve stability and the surge margin. High efficiency, a high pressure ratio, and a wide operating range are required for a high-performance centrifugal compressor. A ring groove casing treatment is effective for flow range enhancement in centrifugal compressors. In the present study, compressor performance was analyzed according to the ring groove location and the results were compared with the case without a ring groove. The effect of guide vanes in the ring groove was also investigated. Four more variants of grooves were modeled and simulated using computational fluid dynamics (CFD) in order to optimize the groove location. The numerical analysis was carried out using a commercial code ANSYS-CFX program. The simulation results showed that the ring groove increased the operating range of the compressor. The ring groove with guide vanes improved both the compressor’s performance at low flow rates and improved the compressor’s surge margin.

Experimental Study of a Novel Centrifugal Compressor with Two Successive and Independent Rotors

2021 ◽  
Author(s):  
Van-Thang Nguyen ◽  
Cheikh Brahim Abed ◽  
Amélie Danlos ◽  
Florent Ravelet ◽  
Richard Paridaens ◽  
...  
Keyword(s):  
Experimental Study ◽  
Centrifugal Compressor ◽  
Design Method ◽  
Pressure Ratio ◽  
Second Step ◽  
Operating Parameters ◽  
Rotor Speed ◽  
Flow Rates ◽  
Surge Margin ◽  
Wide Range

Abstract The present study deals with a low pressure-ratio centrifugal compressor consisting of two counter-rotating rotors called a Counter-Rotating Centrifugal Compressor (CRCC). The design method based on the loss model was presented to determine the geometric parameters of the two counter-rotating rotors. According to this method, the rotor of a selected Single Rotor Centrifugal Compressor (SRCC) has been redesigned into two counter-rotating rotors (upstream and downstream rotors) by choosing the value of meridional Length Ratio (LR). The meridional view, the volute shape, and the operating parameters of SRCC are preserved during the design process. In the first step, the counter-rotating mode at a constant rotor speed of 11k rpm has been carried out. The overall characteristics of CRCC are compared to those of SRCC. In the second step, the map-characteristic of CRCC is established for seven speed ratios. The results show that CRCC increases up to 4,6% for the pressure ratio and 3.5% for the efficiency compared to SRCC at the same tip-speed. In addition, CRCC can operate at a lower tip-speed by about 2k rpm to produce the same characteristics as SRCC, with better efficiency over a wide range of flow rates. However, the surge margin of the CRCC is shifted to higher flow rates. This disadvantage of the CRCC was solved by choosing the adequate pair of the rotational speeds of the two rotors that will be presented in other publication.

Numerical Efforts of Aerodynamic Re-Design in a Transonic Centrifugal Compressor: Part 1 — Basic Approach

2017 ◽  
Author(s):  
Justin (Jongsik) Oh
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Design Flow ◽  
Angle Distribution ◽  
Aerodynamic Design ◽  
Blade Angle ◽  
Original Design ◽  
Trailing Edge ◽  
Impeller Blade ◽  
Transonic Centrifugal Compressor

Growing demands for higher specific output power in turbomachinery applications have drawn attention to aerodynamic design philosophy for a single-stage transonic centrifugal compressor with higher pressure ratios. As Part 1 of numerical efforts, some fundamental approaches in aerodynamic design were carried out in a classical 6:1 pressure-ratio compressor design of 1970’s which was selected as a baseline. The effects of the impeller blade angle distribution, the addition of the splitter blade, the changes of the tangential divergence angle of the channel-wedge diffuser and some tweaks in diffuser vane shapes near the trailing-edge were investigated in steady-state RANS CFD solutions with the conventional mixing plane interface. New blade angle distributions together with the introduction of splitter blades in the impeller brought significant improvements in the compressor pressure ratio, efficiency and operability, thanks to reduced shock strengths and enhanced blade loadings in the spanwise direction. Helicity contours on the cross sectional planes in the impeller support the benefits observing a power balance among the shroud passage vortex, the blade vortices and the tip leakage vortex. With a reduced tangential divergence in the channel-wedge diffuser passage from the original design, an impressively extended surge margin was obtained. It was confirmed from the helicity contours that a streamwise vortex structure at the entrance region of the diffuser vane plays a key role in the range of operation. A diffuser vane shape with the curved pressure surface near the trailing-edge provided a slightly higher pressure ratio and efficiency around design flow than that with the original cut-off trailing-edge. An elliptical trailing-edge diffuser vane showed rather performance drops because of the counter-clockwise hub vortex breakdown near the suction surface, resulting in less flow diffusion. Through investigations of a set of design cases, two final compressor designs, differing in the diffuser vane shape near the trailing-edge, were obtained within the work scope of the present study. However, selecting one of the two will depend on design duties for the following component because of the level of exit swirls and their rate of changes over the flow rates.

scholarly journals Genetic Algorithm Optimization of the Volute Shape of a Centrifugal Compressor

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Martin Heinrich ◽  
Rüdiger Schwarze
Keyword(s):  
Numerical Model ◽  
Centrifugal Compressor ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Maximum Efficiency ◽  
Algorithm Optimization ◽  
Cross Sectional ◽  
Design Variables ◽  
Design Speed

A numerical model for the genetic optimization of the volute of a centrifugal compressor for light commercial vehicles is presented. The volute cross-sectional shape is represented by cubic B-splines and its control points are used as design variables. The goal of the global optimization is to maximize the average compressor isentropic efficiency and total pressure ratio at design speed and four operating points. The numerical model consists of a density-based solver in combination with the SSTk-ωturbulence model with rotation/curvature correction and the multiple reference frame approach. The initial validation shows a good agreement between the numerical model and test bench measurements. As a result of the optimization, the average total pressure rise and efficiency are increased by over1.0%compared to the initial designs of the optimization, while the maximum efficiency rise is nearly 2.5% atm˙corr=0.19 kg/s.

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