Validation and analyses of RANS CFD models for turbulent heat transfer of hydrocarbon fuels at supercritical pressures

Turbulent heat transfer of hydrocarbon fuels at supercritical pressures exists in many power-generation and propulsion systems. Comprehensive validations and analyses of Reynolds averaged Navier Stokes (RANS) CFD models for supercritical-pressure heat transfer of hydrocarbon fuels, including n-decane and aviation kerosene, have been conducted under a broad range of operation conditions. Results indicate that a CFD model incorporating the standard k-ε turbulence model with an enhanced wall treatment works well for supercritical-pressure heat transfer of hydrocarbon fuels without buoyancy effect, both with and without fuel pyrolysis. The main weakness of the model is in the inlet region, in which it tends to under-predict the wall temperature at a low inlet Reynolds number. This model is also qualitatively applicable in calculating heat transfer of hydrocarbon fuels in downward flows with buoyancy effect and without fuel pyrolysis. The SST k-ω turbulence model generally produces results very similar to those from the standard k-ε turbulence model with an enhanced wall treatment, but in cases of supercritical-pressure heat transfer of aviation kerosene with fuel pyrolysis, it strongly over-predicts the wall temperature in the early inlet region as inlet flow is initially laminar. No turbulence model tested in the present study is applicable in supercritical-pressure heat transfer of hydrocarbon fuels in upward flows with buoyancy effect, in which strong heat transfer deterioration occurs.