Experimental analysis and numeric simulation of steady state flow forces on valves of mechatronic pressure regulators for natrual gas powered combustion engines

Abstract

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.This paper deals with the experimental analysis and numerical simulation regarding the flow forces of a mechatronical pressure regulator for natural gas powered internal combustion engines. For the experimental analysis a measurement device was constructed to determine these forces as well as other global flow parameters by variation of the pressure ratio and the strokes of the valve gate. The series of tests were simulated on the basis of the Computational Fluid Dynamics (CFD)-code FLUENT. Thereby the model was validated through the comparison of the results deriving from the experimental analysis and the results provided by the numerical simulation. It was shown that the flow forces have a strong dependence on the pressure ratio but are not influenced by the mass flow rate. Accordingly the flow forces are independent of the stroke. By the use of the numerical simulation a visualization of the inner flow characteristics was obtained. Thus the potential for an improvement in the geometry was derived. Besides a generation of eddies in the low and high pressure chamber, backflow occurred in the valve bung as a result of shocks. This took place at low pressure ratios and resulted in a decreasing flow coefficient due to contraction and deceleration of the fluid entering the control edge. At high pressure ratios, a relocation of the flow contraction towards the theoretical flow cross sectional area and a decreasing of the generation and impact of eddies in the valve bung were detected.