Effect of Tapered Interference Fit between Impeller and Shaft in Turbo Machines

Open access

Abstract

In Turbo machines, there are many components which are provided with interference to transmit torque and to maintain contact between them. There are transient scenarios where impeller and shaft lose interference and limits the speed of the impeller. In this paper, a case study on centrifugal compressor has been presented to see the effect of taper pairing of shaft with impeller. When the centrifugal compressor starts then a transient condition is dominant wherein the impeller of the centrifugal compressor gains higher temperature quickly compared to shaft. Since the thermal expansion of the impeller will be much more than the shaft, interference between impeller and shaft is likely to reduce. With reduced interference, the impeller should retain minimum required contact pressure with the shaft and the torque transmitting capability. For conventional fitted impeller, stress built up is a major concern especially at higher speeds. This paper gives a proposal about the importance of tapered interference fit method compared to cylindrical fitted impeller assembly. An effective analysis between the conventional straight fitted impeller and impeller having tapered bore is presented for the same torque transfer capability. The analysis reveals that for the impeller with tapered bore, the stress for impeller reduces and a healthy contact pressure exists.

[1] David B. Herrick. Impeller and Shaft Assembly, International patent application no. US3884595, 1975.

[2] J. Bender, C. Hentrich, J. Koll, T. Mayer, R. Reinhardt, H. Zechmann, R. Paasch. Friction-welded shaft-disc assembly and method for the manufacture thereof. International patent application no. US6660407, 2003.

[3] P. Šlesar, R. Jančo. Press-fit evaluation and study of displacement in temperature changes. Journal of Mechanical Engineering - Strojnícky časopis, 2018 (68), 103 - 108.

[4] Ronald L. Haugen, Robert King, Jeff Schmidt. Tapered Polygon Coupling. International patent application no. US 0164252, 2002.

[5] V. Ramamurti, R. Karthikeyan. Stress analysis of taper locks. Computers & structures 1997 (62), 721 - 736.

[6] A. Ozel, S. Temiz, M. D. Aydin, Sadri Sen. Stress analysis of shrink-fitted joints for various fit forms via finite element method. Materials & design 2005 (26), 281 - 289.

[7] I. T. Cook, H. Fessler, T. H. Hyde, N. A. Warrior. Assembly stresses in taper - locking shaft couplings Part 1: Photoelastic work. Journal of Strain Analysis for Engineering Design 2001 (1), 25 - 34.

[8] D. Bozkay, S. Muftu. Mechanics of the tapered interference fit in dental implants. Journal of Biomechanics 2003 (11), 1649 - 1658.

[9] X. Q. Zhao, P. Shang. Exact Solution of Stresses of Tapered Interference Fit. Applied Mechanics and Materials 2014 (556 - 562), 4284 - 4287.

[10] Y. Zhang, B. McClain, X. D. Fang. Design of interference fits via finite element method. International Journal of Mechanical Sciences 2000 (42), 1835 - 1850.

[11] B. Parsons, E. A. Wilson. A method for determining the surface contact stresses resulting from interference fits. Journal of Engineering for Industry 1970 (92), 208 - 218.

[12] R. Owsiński, A. Niesłony. Identification of fatigue cracks on the basis of measurable changes in system dynamics, Journal of Mechanical Engineering - Strojnícky časopis 2017 (67), 77 - 84.

[13] S. Sen, B. Aksakal. Stress analysis of interference fitted shaft - hub system under transient heat transfer conditions, Journal of Materials & Design 2003 (25), 407 - 417.

[14] V. Nilesh, V. M. Phalle. Analyze Different Taper Sized Assembly. International Research Journal of Engineering and Technology 2017 (4), 2990 - 2993.

[15] Edge, LLC. Engineers. Shrink Thermal Fit Review, Engineers Edge - Engineering and Manufacturing Solutions 2012.

[16] T. Juuma. Torsional fretting fatigue strength of a shrink-fitted shaft. Journal of Wear 1999 (231), 310 - 318.

Journal Information

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 146 146 14
PDF Downloads 127 127 34