Accurate animation of the thermo‐fluidic performance of the pressure‐wave machine and its balanced material operation

Abstract

Modelling, computation and performance animation of turbomachinery systems has recently enjoyed remarkable attention in CAD research. This is also reflected its application to exhaust machine components such as turbo loaders and the exceptionally novel pressure wave machine (Comprex) in the automobile industry and gas turbines. The necessity for the thermo‐fluidic performance animation of such pressure wave machines results from the fact that the machine geometry must be adapted to the technical and thermo‐fluidic properties of the exhaust flow of the gas turbine or automobile engine. Experimental adaptation or adjustment is costly and should be validated for every application case. Thus the potential to apply accurate animation for such shock‐tube like behaviour of compressible flow is now economically promising with a view to optimizing the design of the pressure wave machine. This paper presents briefly the problem oriented algorithms used and illustrates the performance animation of the pressure wave machine operating under constant speed drive. After introducing the pressure wave machine operation, the principles and summary of the algorithms used to compute the thermodynamic behaviour within the cell, the boundary models and the accuracy of computation. A Comprex cycle operating on an engine exhaust gas with T = 920°K, p = 2bar is illustrated through 3‐dimensional representations for pressure, speed of flow and temperature. The particle path (gas and air) together with time representation of the state variables at different points of the Compex will be shown. The mass balance problem is discussed and the conditions for mass balanced flow for the gas as well as for the air side are given. The results achieved for such materially balanced pressure wave machines indicate a reduction in the costs for subsequent experimental validation and to deliver the sound base for further development towards considering the pre‐balanced transient operation cases as well.

Citation

Oberhem, H. and Nour Eldin, H.A. (1995), "Accurate animation of the thermo‐fluidic performance of the pressure‐wave machine and its balanced material operation", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 5 No. 1, pp. 63-74. https://doi.org/10.1108/EUM0000000004057