Effect of gas properties on accelerated laminar boundary layer over a heated wall

Abstract

The paper reports on numerical investigation of an accelerated laminar boundary layer over a heated wall at Prandtl numbers from 0.23 to 2.39. Properties of three gases were simulated: air, helium-xenon mixture and superheated water vapor. The finite difference method was applied to solve a system of laminar boundary layer equations with variable gas properties. It has been shown that the influence of Prandtl number, viscosity, heat conductivity and heat capacity on the flow at studied conditions is secondary relative to gas density, which is the determinant factor for the overshoot magnitude and other flow parameters. Nevertheless, at insignificant differences in density distributions the overall decrease of Prandtl number and decrease of viscosity and heat capacity and increase of heat conductivity separately lead to an increase of maximal velocity within the boundary layer.