Surface temperature effects on the compressible flow past a rotating cylinder

Spinning cylinders have been the subject of numerous studies because of not only their interesting flow patterns but also their widespread applications. In this study, the effects of the surface temperature of a spinning cylinder on the compressible flow characteristics have been studied numerically. Simulations are performed in the laminar flow regime at Re = 200, M∞ = 0.1-0.4, and Pr = 0.7. The dimensionless cylinder surface velocity is considered from 0 to 7 for a wide range of cylinder surface temperatures. Results show that increasing the cylinder surface temperature leads to a considerable reduction in the lift coefficient. However, surface temperature effects on the drag coefficient do not follow a regular trend due to various vortex shedding patterns. The results also reveal that the vortex shedding pattern and the position of the stagnation points not only depend on the speed ratio but also depend on the surface temperature. Furthermore, at a narrow band of speed and temperature ratios, an oscillatory flow without vortex shedding occurs which has not been reported in previous studies. The heat transfer analysis shows that the cylinder mean surface Nusselt number decreases as the surface temperature increases at both Mach numbers and all speed ratios. Moreover, increasing the speed ratios increases the mean Nusselt number at M∞ = 0.3; however, there is no such trend at M∞ = 0.2. Investigating the compressibility effects also shows that the lift coefficient decreases with increasing Mach number, while the drag coefficient and Nusselt number increase.