Confined impinging air jet on a heated cylinder at low Mach number

Use of onboard electrical systems is vastly expanding in all aeronautical programs. This means that new cooling systems must increasingly be researched. More specifically, this paper focuses on the cooling of a small turbo engine, represented experimentally as a heating cylinder. This new cooling process designed at Pau University, France, provides quite an original experimental set-up. Given the confined nature of the motion fluid, only experimental measurements of medium physical values such as temperature and velocity can be made. In order to better understand and master such a cooling system, which seemingly could have many industrial applications, two different numerical simulations have been investigated. Because of the confined nature of the motion fluid (V = 6.13 m/s, Mach = 0.018) and the highly complex geometrics, no conclusion can be drawn about the fluid compressibility assumption. Therefore, the incompressible model study is carried out using ANSYS-FLUENT software whereas the compressible model study is conducted with elsA software. These two computer programs were chosen because of their capacity for double modelling in the hope that some of the major challenges facing the vast research community in the field of low Mach may be addressed. This study is carried out on two different scales. On the coarse scale there are significant similarities between the experimental results and some 2D simulations on the global convective wall heat flux (better than a 10% relative gap). On the smaller scale, code-to-code comparisons of both assumptions (via both codes) show different vortex structures inside the computational domain. Those vortices have a remarkable influence on the inner-wall heat flux's behaviour but their effect is moderate since their average values do not vary much. Though the velocity is relatively low inside the cavity, we will show that the fluid compressibility is of importance in such computations.