Flow in a rotating cavity with axial throughflow at engine representative conditions

The prediction of compressor drum cavity heat transfer is an important factor in the overall design of an aero engine. The rotationally dominated flow field within the cavity governs the heat transfer conditions by suppressing the motion of the fluid. Without heating, the fluid in the outer region of the cavity can approach solid body rotation. The outer cavity fluid is disturbed by the bore flow at the inner radius. The resultant bore flow vortex has been shown to exhibit many different modes of behaviour, dependent on the Rossby number. At higher Rossby number the bore flow vortex has been shown to break down into a precessing radial arm. It has also been shown that the hot drive arm (shroud) between the compressor stages destabilises the flow field through natural convection. This paper presents data from the Sussex Multiple Cavity Rig, which matches the fluid dynamic conditions of a compressor bore in terms of axial throughflow, rotational Reynolds number and Grashof number. It features titanium alloy discs, which are instrumented with surface thermocouples. This paper presents data which helps to separate the effects of throughflow Reynolds number, rotational Reynolds number and Grashof number on the dimensionless disc temperature profiles. In order to illustrate the flow structures this paper presents a hybrid RANS/LES model for the two highest Reynolds number cases. For these cases, the numerical simulations show a change from stable to unstable stratification with an increase in the bore to shroud temperature ratio in good qualitative agreement with the measured data.