This study is focused on the effects of a high temperature gradient on a turbulent flow, basically, the flow circulating in the solar receiver of the PEGASE project (Production of Electricity using GAs turbine and Solar Energy). To predict the impact of the thermal gradients on a turbulent flow, we perform Thermal Large Eddy Simulation on a turbulent channel flow with imposed wall temperatures. We consider the low Mach number equations and use the Sutherland law to solve the viscosity and the conductivity. The numerical simulations are realized for two different wall Reynolds numbers and four different temperature ratios.

The first analysis of the temperature gradient effects, for the strongly non-isothermal cases, shows that a dissymmetry appears in all the profiles and points out a strong effect on the fluctuation parts. A case of relaminarisation on the hot side was picked up for a simulation with a weak turbulent intensity and for a high temperature ratio. In that case, the tendencies noted for the effect of a high temperature gradient on a turbulent flow are not the same. In the spectral domain, a visible effect of the temperature gradient is noted on the turbulent kinetic energy and turbulent temperature. The differences can be seen on the range and on the distribution of the energy between the large and the small eddies.