Porous Structures in Aspects of Transpirating Cooling of Oxycombustion Chamber Walls

A wet oxycombustion chamber, which must be effectively cooled due to high temperature evolved during the oxy-combustion process, by using the phenomena of Reynolds thermal transpiration and Navier slip velocity. Closures needed to execute mass flow rate in a microchannel, which should be treated as a single porous structure in the walls of the combustion chamber, have been obtained by applying a local 3D approach. The Navier-Stokes model of the surface layer, which has been proposed and implemented, and presented in numerous publications has been used. The most important part was the incorporation of the thermal mobility force into the commercial code. The Computational Fluid Dynamic simulation of the benchmark experiment has been performed for basic data corresponding to helium. An original and easy-to-implement method has been developed to numerically confirm that at the final equilibrium zero-flow state there is connection between the Poiseuille flow in the centre of channel and the counter thermal transpiration flow at the surface. Therefore, the numerical implementation of the Reynolds model of thermal transpiration and its usefulness for the description of the benchmark experiment has been established. Additionally, taking Reynolds', Navier's and Poiseuille's solution into consideration for round capillary pipe flow, the flow enhancement due to the temperature difference at the surface and the presence of a drop (slip), can be easily identified. Nevertheless, these issues demand further work and calibration through dedicated experiment.