Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-27T21:55:21.103Z Has data issue: false hasContentIssue false
  • English
  • Français

An Explicit, Non-Iterative, Single Equation Formulation for an Accurate One Dimensional Estimation of Vaneless Radial Diffusers in Turbomachines

Published online by Cambridge University Press:  21 October 2014

R. Amirante ,
F. De Bellis ,
E. Distaso  and
P. Tamburrano
R. Amirante*
Affiliation:
Department of Mechanic Mathematic and Management, Polytechnic University of Bari, Bari, Italy
F. De Bellis
Affiliation:
Department of Mechanic Mathematic and Management, Polytechnic University of Bari, Bari, Italy
E. Distaso
Affiliation:
Department of Mechanic Mathematic and Management, Polytechnic University of Bari, Bari, Italy
P. Tamburrano
Affiliation:
Department of Mechanic Mathematic and Management, Polytechnic University of Bari, Bari, Italy
*
* Corresponding author (amirante@poliba.it
Get access

Abstract

The present paper proposes a very simple one dimensional (1-D) model that accounts for the energy loss caused by the fluid dynamic losses occurring in the vaneless diffusers of centrifugal compressors and pumps. Usually, the present techniques to design turbomachines (pumps, compressors and turbines) emphasize numerical methods and their use is relatively complex because several parameters need to be chosen and a lot of time is required to perform the calculation. For this reason, it is relevant to perform an accurate preliminary design to simplify the numerical computation phase and to choose a very good initial geometry to be used for accelerating and improving the search for the definitive geometry. However, today 1-D modeling is based on the classical theory that assumes that the angular momentum is conserved inside a vaneless diffuser, although the flow evolution is considered as non-isentropic. This means that fluid-dynamic losses are taken into account only for what concerns pressure recovery, whereas the evaluation of the outlet tangential velocity incoherently follows an ideal behavior. Starting from such considerations, a new conservation law for the angular momentum is analytically derived, which incorporates the same fluid-dynamic losses modeled by the thermodynamic transformation law that is employed for correlating pressure recovery with enthalpy increase. Similar arguments hold for incompressible flows. Detailed and very accurate three-dimensional flow simulations are employed to analyze if the new model is capable of predicting the outlet tangential velocity more accurately than the classical theory. Results provided for both compressible (centrifugal compressors) and incompressible (centrifugal pumps) flows and for different inlet velocity profiles show a significant accuracy improvement of the new conservation law in the prediction of the outlet flow conditions when compared with the classical theory, thus demonstrating that the proposed model can be employed in the preliminary design of vaneless diffusers (i.e., in the estimation of the outlet diameter) more effectively than the classical ideal theory. Furthermore, the model is validated against industrial experimental campaigns. Even further experimental data, reported in a previous paper by the same authors, confirm the reliability of the employed approach.

Keywords

Energy lossTurbomachinery efficiencyCentrifugal compressor and pumpVaneless diffuser
Type
Research Article
Information
Journal of Mechanics , Volume 31 , Issue 2 , April 2015 , pp. 113 - 122
Copyright
Copyright © The Society of Theoretical and Applied Mechanics, R.O.C. 2014 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1.Johnston, J. P. and Dean, R. C. Jr, “Losses in Vaneless Diffusers of Centrifugal Compressors and Pumps: Analysis, Experiment, and Design,” Journal of Engineering for Power, 88, pp. 49–60 (1966).CrossRefGoogle Scholar
2.Bryans, A. C., “Diffuser for a Centrifugal Compressor,” U.S. Patent No. 4,576, 550. Washington, DC: U.S. Patent and Trademark Office (1986)Google Scholar
3.Nakagawa, K., Takagi, T., Abe, Y. and Sakai, H., “Diffuser for centrifugal Compressor,” U.S. Patent No. 4,877, 370. Washington, DC: U.S. Patent and Trademark Office (1989).Google Scholar
4.Arndt, N., Acosta, A. J., Brennen, C. E. and Caughey, T. K., “Experimental Investigation of Rotor-Stator Interaction in a Centrifugal Pump with Several Vaned Diffusers,” Journal of Turbomachinery, 112, pp. 98–108 (1990).Google Scholar
5.Dawes, W. N., “Simulation of the Unsteady Interaction of a Centrifugal Impeller with its Vaned Diffuser: Flow Analysis,” Transactions Journal of Turbomachinery, 117, pp. 213–222 (1995).Google Scholar
6.Oh, H. W., Yoon, E. S. and Chung, M. K., “An Optimum Set of Loss Models for Performance Prediction of Centrifugal Compressors,” Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 211, pp. 331–338 (1997).Google Scholar
7.Hazby, H. R., Xu, L. and Schleer, M., “Study of the Flow in a Vaneless Diffuser at Part Speed Operating Conditions,” Proceedings of ASME Turbo Expo 2010: Powerfor Land, Sea and Air, GT2010-22605, Glasgow, UK (2010).Google Scholar
8.Anish, S. and Sitaram, N., “Steady and Transient Computations of Intercation Effects in a Centrifugal Compressor with Different Type of Diffusers,” Proceedings of ASME Turbo Expo 2010: Power for Land, Sea and Air, GT2010-22913, Glasgow, UK (2010).Google Scholar
9.Amirante, R., Catalano, L. A., Dadone, A. and Daloiso, V. S. E., “Design Optimization of the Intake of a Small-Scale Turbojet Engine,” Computer Modeling in Engineering and Sciences, 18, pp. 17–30 (2007).Google Scholar
10.Amirante, R., Catalano, L. A., Poloni, C. and Tamburrano, P., “Fluid-Dynamic Design Optimization of Hydraulic Proportional Directional Valves,” Engineering Optimization, 46, pp. 1295–1314 (2014).Google Scholar
11.Ferguson, T. B., The Centrifugal Compressor Stage, Butterworths, London (1963).Google Scholar
12.Lakshminarayana, B., Fluid Dynamics and Heat Transfer of Turbomachinery, John Wiley & Sons, Hoboken, New Jersey (1996).Google Scholar
13.Turton, R. K., Principles of Turbomachinery, Chapman and Hall Ltd., London (1984).CrossRefGoogle Scholar
14.Gulich, H., Centrifugal Pumps, 2nd Edition, Springer, Berlin (2010).Google Scholar
15.Pfleiderer, C., Kreiselpumpen für Flüssigkeiten und Gase, Aufl, Springer, Berlin (1961).Google Scholar
16.Lüdtke, K. H., Process Centrifugal Compressors, Springer, Berlin (2004).Google Scholar
17.FLUENT 6.3 User s Guide, FLUENT INC. (2006).Google Scholar
18.Schlichting, H., Boundary-Layer Theory, McGraw Hill, New York (1968).Google Scholar
19.De Bellis, F., Grimaldi, A., Rubino, D. T., Amirante, R. and Distaso, E., “Accurate Vaneless Radial Diffuser 1-D Model with a Single Loss Parameter,” Proceedings of ASME Turbo Expo 2014: Turbine Technical Conference and Exposition, GT2014-25232, Düsseldorf, Germany (2014).Google Scholar