Numerical investigation of transcritical turbulent channel flow

The prediction of heat transfer in regenerative tooling channels of liquid rocket engines is crucial for safety reasons and in order to improve the engine's performance. The fluid inside the cooling channels exceeds its critical pressure and is characterized by strong property variations in the vicinity of the pseudo-boiling position. These variations have a significant influence on the turbulent flow and on the heat transfer, which is still not fully understood. For this reason, we performed a well-resolved large-eddy simulation (LES) of a transcritical turbulent channel flow using methane as working fluid. The fully compressible Navier-Stokes equations in conservative form are solved in conjunction with a look-up table method for the thermodynamic and transport properties. The subgrid-scale model is implicitly included in the convective flux calculation based on the Adaptive Local Deconvolution Method (ALDM) for implicit LES. The lower wall temperature is set below and the top wall temperature above the pseudo-boiling temperature of methane at a bulk pressure of 4.9 MPa. Hence, a reduced pressure of 1.06 and a temperature ratio of 2.22 is obtained. Strong property variations are found near the cold wall, due to pseudo-boiling. The resulting density ratio is of the order of 10. The mean velocity and temperature feature an asymmetrical distribution, due to the unilateral heating. Furthermore, an attenuation of temperature is present in the vicinity of the pseudo-boiling due to the heat capacity peak.