Effects of Impeller Gap on Rotor Vibration in a High Speed Centrifugal Compressor: A Numerical and Experimental Analysis (TECHNICAL NOTE)

Authors

1 Department of Mechanical Engineering, Islamic Azad University, Bushehr, Iran

2 Department of Mechanical Engineering, Razi University, Kermanshah, Iran

3 Department of Mechanical Engineering, Shahid Beheshti University, Tehran, Iran

Abstract

Centrifugal compressors produce high pressure ratio and rotate at speeds. So, a tiny unbalance can produce severe vibration. In this paper, effects of impeller gap on rotor vibration in a high speed centrifugal compressor is investigated. For this purpose, a numerical and experimental analysis are carried out. The moving reference frame method in FLUENT software is used for modeling of geometries. Then, the motion of rotation components is introduced using UDF (User-Difined-Function) writing in C++ software and Define CG Motion macro. By using cloud points, three-dimensional geometry model of blades of this compressor is prepared. Finally, two-dimensional geometry of diffuser is added to blades and the final geometry is presented. Fluid flow inside the centrifugal compressor with and without considering blades vibration is studied. The numerical and experimental analysis of power spectrum density to determine the dominant vibration frequency cause of horizontal and vertical forces exerted on the compressor is studied. Results show that the dominant frequency of vibrations of forces exerted on the compressor is in the range of 9800 Hz, that is in good agreements with those reported by earlier researchers. Also, the main reason of centrifugal compressors shaft vibration is static and dynamic unbalance in shaft and other components of the compressor. In other words, the forces exerted on compressors blades do not affect the centrifugal compressor vibration. In the numerical studies, distribution of pressure, temperature, velocity and velocity vectors at different times are studied. Horizontal and vertical forces exerted on the compressor is represented. The mass flow rate of the compressor output for different cases of A/G ratio is presented and does not depend on amplitude of vibrations.

Keywords

References

1.     Perdichizzi, A. and Savini, M., "Aerodynamic and geometric optimization for the design of centrifugal compressors", International Journal of Heat and Fluid Flow,  Vol. 6, No. 1, (1985), 49-56.
2.    Teipel, I. and Wiedermann, A., "A three-dimensional euler code for calculating flow fields in centrifugal compressor diffusers", Computers & Fluids,  Vol. 19, No. 1, (1991), 21-31.
3.     Leboeuf, F., Trébinjac, I., Ottavy, X. and Gourdain, N., "Aerodynamic studies in high-speed compressors dedicated to aeronautical applications", in 27th International Congress of The Aeronautical Sciences., 19-24.
4.     Prasad, V.V., Kumar, M.L. and Reddy, B., "Centrifugal compressor fluid flow analysis using CFD", Science Insight: An International Journal,  Vol. 1, No. 1, (2011), 6-10.
5.     Ding, L., Wang, T., Yang, B., Xu, W. and Gu, C., "Experimental investigation of the casing treatment effects on steady and transient characteristics in an industrial centrifugal compressor", Experimental Thermal and Fluid Science,  Vol. 45, (2013), 136-145.
6.     Engeda, A., "Experimental and numerical investigation of the performance of a 240 kw centrifugal compressor with different diffusers", Experimental Thermal and Fluid Science,  Vol. 28, No. 1, (2003), 55-72.
7.     Galindo, J., Climent, H., Guardiola, C. and Tiseira, A., "On the effect of pulsating flow on surge margin of small centrifugal compressors for automotive engines", Experimental Thermal and Fluid Science,  Vol. 33, No. 8, (2009), 1163-1171.
8.     Pinarbasi, A., "Experimental hot-wire measurements in a centrifugal compressor with vaned diffuser", International journal of heat and fluid flow,  Vol. 29, No. 5, (2008), 1512-1526.
9.     Pinarbasi, A., "Turbulence measurements in the inlet plane of a centrifugal compressor vaneless diffuser", International journal of Heat and Fluid Flow,  Vol. 30, No. 2, (2009), 266-275.
10.   Nakagawa, K., Tanaka, S. and Kaneko, J., "An aerodynamic investigation of a centrifugal compressor for HCFC123", International Journal of Refrigeration,  Vol. 15, No. 4, (1992), 199-205.
11.   Galindo, J., Serrano, J., Climent, H. and Tiseira, A., "Experiments and modelling of surge in small centrifugal compressor for automotive engines", Experimental Thermal and Fluid Science,  Vol. 32, No. 3, (2008), 818-826.
12.   Jiang, W., Khan, J. and Dougal, R.A., "Dynamic centrifugal compressor model for system simulation", Journal of Power Sources,  Vol. 158, No. 2, (2006), 1333-1343.
13.   Chen, S.-L. and Wang, W.-T., "Computer aided manufacturing technologies for centrifugal compressor impellers", Journal of Materials Processing Technology,  Vol. 115, No. 3, (2001), 284-293.
14.   Sun, H., Shin, H. and Lee, S., "Analysis and optimization of aerodynamic noise in a centrifugal compressor", Journal of Sound and Vibration,  Vol. 289, No. 4, (2006), 999-1018.
15.   Raitor, T. and Neise, W., "Sound generation in centrifugal compressors", Journal of sound and Vibration,  Vol. 314, No. 3, (2008), 738-756.
16.   Jansson, I., Åkerstedt, H.O., Aidanpää, J.-O. and Lundström, T.S., "The effect of inertia and angular momentum of a fluid annulus on lateral transversal rotor vibrations", Journal of Fluids and Structures,  Vol. 28, (2012), 328-342.
17.   Liu, A. and Zheng, X., "Methods of surge point judgment for compressor experiments", Experimental Thermal and Fluid Science,  Vol. 51, (2013), 204-213.
18.   Subramanian, S., Sekhar, A. and Prasad, B., "Rotordynamic characteristics of rotating labyrinth gas turbine seal with centrifugal growth", Tribology International,  Vol. 97, (2016), 349-359.
International Journal of Engineering
Volume 30, Issue 5
TRANSACTIONS B: Applications
May 2017
Pages 814-820

Files

Share

How to cite

Statistics