Convective heat transfer of a rotating multi-stage cavity with axial throughflow

The heat transfer characteristics in an engine-like rotating multi-stage cavity with axial throughflow are experimentally investigated. The cavity is a model of high pressure compressor in gas turbine, which has a gap ratio of 0.24 and a radius ratio of 0.23. Herein, the effects of inertial force, centrifugal buoyancy force, Coriolis force on the heat transfer coefficient (HTC) and the surface temperature distribution are analyzed and discussed. The heat transfer coefficient is measured with an innovative HTC sensor whereas the surface temperature is measured by embedded thermocouples when the shroud is heated by an induction heater. The measurements are conducted in a wide range of non-dimensional parameters: the maximum axial Reynolds numbers, rotational Reynolds numbers and buoyancy parameter can reach 9.87 × 10⁴, 1.81 × 10⁶ and 0.3, respectively. According to the experimental results, two regions with significantly different heat transfer characteristics could be identified on both side of the interested disc, namely, the forced convection zone caused by impingement cooling in the low radius area, and the Rayleigh-Bénard-like convection zone in the medium and high radius areas. On both windward and leeward sides of the disc, the heat transfer coefficients are zigzagging along the radial direction with two observed peak values.