Performance Variation of Transonic Centrifugal Compressor at Different Tip Clearances Using Numerical Simulations

Abstract Inlet distortion has influence on the aerodynamic performance of turbomachinery such as compressors, turbines and fans. On turbochargers, bent pipes are installed around the compressor due to the spatial limitations in the engine room of the vehicle. As the result, the compressor is operated with the distorted inflow. In the low flow rate operation, the distorted inflow also affects the flow instability like stall and surge. Especially, the operation range on the low flow rate side is defined based on the flow rate where surge occurs, so it is important to investigate the effect of the distorted inflow on surge. In this study, the effect of the inlet distortion to surge phenomena has been investigated by the experiments with a transonic centrifugal compressor. A bent pipe has been installed at the upstream of the compressor to generate a distorted flow. Experiments have been also conducted under the condition that a straight pipe was installed upstream of the compressor, and unsteady measurements with high response pressure sensors and an I-type hot wire probe have been carried out to each experiments. In addition, Fast Fourier transform (FFT) and Wavelet transform have been applied to the unsteady measurement results obtained from each experiment.

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Mechanisms of Sweep on the Performance of Transonic Centrifugal Compressor Impellers

Applied Sciences ◽

10.3390/app7101081 ◽

2017 ◽

Vol 7 (10) ◽

pp. 1081 ◽

Cited By ~ 2

Author(s):

◽

Keyword(s):

Centrifugal Compressor ◽

Transonic Centrifugal Compressor

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Influences of Tip Leakage Flows Discharged From Main and Splitter Blades on Flow Field in Transonic Centrifugal Compressor Stage

Volume 2B: Turbomachinery ◽

10.1115/gt2018-75345 ◽

2018 ◽

Cited By ~ 1

Author(s):

Masanao Kaneko ◽

Hoshio Tsujita

Keyword(s):

Flow Field ◽

Centrifugal Compressor ◽

Leading Edge ◽

Tip Clearance ◽

Blade Loading ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Leakage Flows ◽

Transonic Centrifugal Compressor ◽

Tip Leakage Flows

A transonic centrifugal compressor impeller is generally composed of the main and the splitter blades which are different in chord length. As a result, the tip leakage flows from the main and the splitter blades interact with each other and then complicate the flow field in the compressor. In this study, in order to clarify the individual influences of these leakage flows on the flow field in the transonic centrifugal compressor stage at near-choke to near-stall condition, the flows in the compressor at four conditions prescribed by the presence and the absence of the tip clearances were analyzed numerically. The computed results clarified the following noticeable phenomena. The tip clearance of the main blade induces the tip leakage vortex from the leading edge of the main blade. This vortex decreases the blade loading of the main blade to the negative value by the increase of the flow acceleration along the suction surface of the splitter blade, and consequently induces the tip leakage vortex caused by the negative blade loading of the main blade at any operating points. These phenomena decline the impeller efficiency. On the other hand, the tip clearance of the splitter blade decreases the afore mentioned acceleration by the formation of the tip leakage vortex from the leading edge of the splitter blade and the decrease of the incidence angle for the splitter blade caused by the suction of the flow into the tip clearance. These phenomena reduce the loss generated by the negative blade loading of the main blade and consequently reduce the decline of the impeller efficiency. Moreover, the tip clearances enlarge the flow separation around the diffuser inlet and then decline the diffuser performance independently of the operating points.

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Flow With Shock Waves in a Transonic Centrifugal Compressor With a Low-Solidity Cascade Diffuser Using PIV

Volume 5: Turbo Expo 2004, Parts A and B ◽

10.1115/gt2004-53268 ◽

2004 ◽

Cited By ~ 5

Author(s):

Hiroshi Hayami ◽

Masahiro Hojo ◽

Norifumi Hirata ◽

Shinichiro Aramaki

Keyword(s):

Shock Wave ◽

Shock Waves ◽

Centrifugal Compressor ◽

Gas Flow ◽

Pressure Ratio ◽

Transonic Centrifugal Compressor ◽

Image Velocimetry ◽

Rotor Stator Interaction ◽

Rotating Impeller ◽

Low Solidity Cascade Diffuser

A single-stage transonic centrifugal compressor with a pressure ratio greater than six was tested in a closed loop with HFC134a gas. Flow at the inducer of a rotating impeller as well as flow in a stationary low-solidity cascade diffuser was measured using a double-pulse and double-frame particle image velocimetry (PIV). Shock waves in both flows were clearly observed. The effect of flow rate on a 3D configuration of shock wave at the inducer and a so-called rotor-stator interaction between a rotating impeller and a stationary cascade were discussed based on a phase-averaged measurement technique. Furthermore, the unsteadiness of inducer shock wave and the flow in a cascade diffuser during surge were discussed based on instantaneous velocity vector maps.

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Influence of blade geometry on secondary flow development in a transonic centrifugal compressor

Journal of the Global Power and Propulsion Society ◽

10.22261/jgpps.i1rsj3 ◽

2018 ◽

Vol 2 ◽

pp. I1RSJ3 ◽

Cited By ~ 4

Author(s):

Moritz Mosdzien ◽

Martin Enneking ◽

Alexander Hehn ◽

Daniel Grates ◽

Peter Jeschke

Keyword(s):

Secondary Flow ◽

Centrifugal Compressor ◽

Large Scale ◽

Optimization Methods ◽

Experimental Investigations ◽

Compressor Stage ◽

Impeller Blade ◽

Flow Development ◽

Transonic Centrifugal Compressor ◽

Increasing Demand

Due to the increasing demand for higher efficiencies of centrifugal compressors, numerical optimization methods are becoming more and more relevant in the design process. To identify the beneficial features of a numerical optimized compressor design, this paper analyses the influence of arbitrary blade surfaces on the loss generation in a transonic centrifugal compressor. The paper therefore focuses on an analysis of the secondary flow development within the impeller blade passages. To do this, steady simulations were performed on both a baseline and an optimized blade design. Two distinct design features of the optimized compressor stage were identified, which lead to a more homogenous impeller exit flow and thus to an increase in total-to-static efficiency of 1.76% points: the positive lean in the near-tip region and the positive blade curvature in the rear part of the optimized impeller. Furthermore, through extensive experimental investigations conducted on a large scale test rig it has been possible to prove the particular impeller outflow characteristics of the baseline compressor stage.

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Low-solidity cascade diffuser for transonic centrifugal compressor.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.55.758 ◽

1989 ◽

Vol 55 (511) ◽

pp. 758-763 ◽

Cited By ~ 2

Author(s):

Hiroshi HAYAMI ◽

Yasutoshi SENOO ◽

Koji UTSUNOMlYA ◽

Hiroshi HASEGAWA ◽

Nobumasa KAWAGUCHI

Keyword(s):

Centrifugal Compressor ◽

Transonic Centrifugal Compressor ◽

Low Solidity Cascade Diffuser

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1D and 3D-Design Strategies for Pressure Slope Optimization of High-Flow Transonic Centrifugal Compressor Impellers

Volume 2B: Turbomachinery ◽

10.1115/gt2018-76154 ◽

2018 ◽

Author(s):

A. Hildebrandt ◽

T. Ceyrowsky

Keyword(s):

Centrifugal Compressor ◽

High Flow ◽

Flow Coefficient ◽

Design Parameters ◽

Angle Distribution ◽

Compressor Stage ◽

Impeller Blade ◽

Design Point ◽

Centrifugal Compressor Stage ◽

Transonic Centrifugal Compressor

The present paper deals with the numerical and theoretical investigations of the effect of geometrical dimensions and 1D-design parameters on the impeller pressure slope of a transonic centrifugal compressor stage for industrial process application. A database being generated during the multi-objective and multi-point design process of a high flow coefficient impeller, comprising 545 CFD (Computational Fluid Dynamics) designs is investigated in off-design and design conditions by means of RANS (Reynolds Averaged Navier Stokes) simulation of an impeller with vaneless diffuser. For high flow coefficients of 0.16 < phi < 0.18, the CFD-setup has been validated against measurement data regarding stage and impeller performance taken from MAN test rig experimental data for a centrifugal compressor stage of similar flow coefficient. The paper aims at answering the question how classical design parameter, such as the impeller blade angle distribution, impeller suction diameter and camber line length affect the local and total relative diffusion and pressure slope towards impeller stall operation. A second order analysis of the CFD database is performed by cross-correlating the CFD data with results from impeller two-zone 1D modelling and a rapid loading calculation process by Stanitz and Prian. The statistical covariance of first order 1D-analysis parameters such as the mixing loss of the impeller secondary flow, the slip factor, impeller flow incidence is analyzed, thereby showing strong correlation with the design and off-design point efficiency and pressure slope. Finally, guide lines are derived in order to achieve either optimized design point efficiency or maximum negative pressure slope characteristics towards impeller stall operation.

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