CFD Analysis Prediction of Heat Transfer Coefficient in Rotating Cavities With Radial Outflow

Abstract

This paper documents two related investigations. The first investigation was to benchmark commercial CFD code Fluent in rotating cavities for velocity profiles and beat transfer coefficients. The second investigation was to evaluate the methods of extracting heat transfer coefficients from CFD solution with direct method and Reynolds analogy approach. The rotating cavities examined include rotor-stator, contra-rotating and co-rotating disks. The velocity profiles benchmark was conducted prior to heat transfer coefficient benchmark. Several turbulence models were compared for closed rotating cavity flows. The comparisons between test data and CFD results of tangential and radial velocity profiles showed that the SST k-ω turbulence model performed the best among turbulence models tested. Hence, the SST k-ω model was chosen for heat transfer coefficient benchmarking. The comparisons of heat transfer coefficients between test data and CFD results were presented in the form of local Nusselt number. The thermal wall boundary conditions applied to all the computations were curved-fitted wall temperature distributions from available test data. The wall temperature distributions include approximately constant, positive and negative profiles. It was found that the accurate information of the thermal wall temperature distribution was critical to the benchmark and that only the CFD results with well defined information of wall temperature distributions matched well with test data. The Nusselt number extracted from the CFD solution with the Reynolds analogy approach tends to over predict the heat transfer coefficient on the higher radii and only matched test data at low Reynolds number with positive wall temperature profile. The error increases with higher Reynolds number and decreases with larger flow rate.