Numerical simulation of fluid flow in poppet valves

Simulations offlow through poppet valves were performed using a proprietary finite volume computational fluid dynamics program. A range of valve geometries was simulated, and the fzow was turbulent, incompressible and steady. Simulations were compared with experimental measurements and visualized flow patterns. Qualitative agreement between simulated and visualized flow patterns was good. However, errors in lhe prediction of jet separation and reattachment resulted in yuantitutive inaccuracies. These errors were due to the limitations of the upwind differencing scheme employed and the representation of turbulence by the k--E model, which is known to be inaccurate when applied to recirculating pow. NOTATION orifice area face area of valve = nd;/4 force coefficient of valve = thrust/(APA,) flow coefficient of valve = Q/[ad{(2AP)/p)] inlet diameter geometric weighting factor for cell face flux of 4 through cell face turbulent kinetic energy mass flux through cell face flowrate Reynolds number inlet axial velocity axial opening of valve non-dimensional opening = z/do blending factor for upwind differencing scheme pressure drop across valve turbulent dissipation rate effective turbulent viscosity predicted by the k--E model fluid density dependent variable (u, u, k or c