THE SIMULATION OF TURBULENT AIR FLOW THROUGH THE PISTON ENGINE VALVE PORTS

Abstract

The determination of the air flow parameters in the valve ports is an important part of the working process modeling of the piston engine, since the losses in the ports determine the working mixture amount that can be used by the engine during combustion. In this paper the air flow, as a turbulent flow of a viscous compressible fluid, is simulated in the engine valve ports in a spatial setting with the help of the ANSYS Fluent program, which implies the solution of the Navier-Stokes equations system averaged over Reynolds. This system is not closed, and to close it the SST (Shear Stress Transport) Menter turbulence model was used. The calculation of the air flow has been carried out at different valve strokes with a pitch of 0.76 mm. The knowledge of the average air mass flowing through the engine cylinder for the maximum torque mode and the law of the valve movement made it possible to find out an approximate air flow corresponding to each valve stroke. Thus, a series of calculations considering different valve strokes for each port was performed. To verify the mathematical model including a system of equations, adjustments to the solver, grids and others, a blowdown of the gasoline engine cylinder head at the SuperFlow test bench was made. The obtained flow model agreed well with the experimental data. The dependence of the inlet and outlet flow coefficient was obtained, which could be used later to build a mathematical model of the engine working process (for example, with the help of the AVL Boost program).