Experimental study of unsteady thermal convection in heated rotating inclined cylinders

An experimental study through temperature measurements was conducted to investigate the thermal characteristics induced by the interaction between the thermal buoyancy and rotation-induced Coriolis force and centrifugal force in an air-filled heated inclined cylinder rotating about its axis. Results were obtained for the following ranges of the governing groups: thermal Rayleigh number Ra=2.3×106 and 4.6 × 106, Taylor number 0≤Ta≤2.2×1010, rotational Rayleigh number 0≤RaΩ≤5.9×108 and inclined angle 0≤Ψ≤90°. The experimental data suggested that when the cylinder is stationary, the thermal buoyancy driven flow is random oscillation at small amplitude after initial transient for inclined angle Ψ<60°. Rotating the cylinder was found to destabilize the temperature field when the rotation speed Ω is less than 30 rpm and to stabilize it when the Ω exceeds 30 rpm. Additionally, the distributions of time-average temperature θav in the Z-direction for various inclined angles become widely separate only at low rotation rates, Ω<60 rpm.