NUMERICAL PREDICTIONS OF FLOW AND THERMAL FIELDS IN A RECIPROCATING PISTON-CYLINDER ASSEMBLY

Abstract

An efficient solution method for predicting unsteady, compressible flow and thermal fields in a reciprocating piston-cylinder assembly is developed in this study. The solution method, based on a two-stage pressure correction scheme, is applied for simultaneously determining the absolute pressure, density, temperature, and velocity components of the fluid inside the cylinder at any instant during the start-up and the periodically stable periods. Discretization equations are derived from the integral mass, momentum, and energy equations on a moving grid, which is deforming to accommodate the movement of the piston. A test problem is solved by means of the proposed method to illustrate the validity of the numerical procedure. Results show that the two-stage pressure correction scheme can be readily incorporated into existing numerical techniques to yield reasonably accurate results. Effects of the influential factors, including gravity (g) and rotation speed of the crank shaft (f), thus can be evaluated.