A Study of Convective Heat Transfer in a Model Rotor–Stator Disk Cavity

In this study, the fluid (air) temperature field and the convective heat flux distribution on the rotor disk surface were measured and computed in a model rotor–stator disk cavity. Both mainstream flow and secondary air flow were provided. The radial distribution of convective heat transfer coefficient on the rotor disk surface, which was calculated as the ratio of the local heat flux and the local temperature difference across the thermal boundary layer on the disk, is also reported. In the experiments, the disk rotational Reynolds number, Reϕ, ranged from 4.65×105 to 8.6×105, and the nondimensional secondary air flow rate, cw, ranged from 1504 to 7520. The secondary air was supplied at the cavity hub. All experiments were carried out at the same mainstream air flow rate, Rem=5.0×105. The cavity fluid temperature distribution was measured by traversing miniature thermocouples, and the rotor disk surface temperature and heat flux were measured by a quasi-steady thermochromic liquid crystal technique in conjunction with resistance temperature detectors embedded in the disk. The measurements are compared with predictions from the commercial CFD code Fluent. The Fluent simulations were performed in the rotationally symmetric mode using a two-zone description of the flow field and the RNG k-ε model of turbulence. The convective heat transfer coefficient distribution on the rotor disk surface exhibited the influence of the source region and the core region of air flow in the cavity. In the source region, which is radially inboard, the convective heat transfer was dominated by the secondary air flow rate. In the core region, which is radially outboard, the heat transfer was dominated by the rotational motion of the fluid relative to the rotor disk. An empirical correlation for the local Nusselt number on the rotor disk surface is suggested for the core region.