Abstract The blade tip clearance within an aero-engine high pressure (HP) compressor is an important factor influencing the efficiency of the engine. The transient clearance of the blades depends directly on the radial expansion of the rotating compressor disks. In the shroud area, these disks are heated by the hot main gas flow, where the flow of the secondary air system cools these disks in the cob area. At high rotational speeds, buoyancy forces dominate the flow within the cavities. Thus, it is necessary to have a deep knowledge of the heat transfer and flow structure in buoyancy-dominated rotating cavities with modern disk geometries. Therefore, a novel dualcavity test rig for experimental investigation in rotating cavities is described within this paper. The rig consists of three rotor disks, that form two symmetrical cavity sections. These cavities are limited by an inner shaft, which is designed to be either stationary or rotating. In order to investigate operating points with a thermal gradient, the shroud is heated by a heating module. To determine the mass flow exchange ratio of the first cavity, fluid temperatures are measured in the middle of the axial bore flow and on both sides of the cavity. To calculate the core swirl ratio of the rotating core, the static air pressure is measured at various radial positions in the first cavity as well as the radial distribution of the disk surface temperature. Inlet and outlet conditions of the fluid were measured by the internal telemetry system. Finally, this paper presents time-averaged measurement data of the core swirl ratio β and the mass flow exchange ratio M within the variation of various non-dimensional parameter in the range of 4.2 · 103 ≤ Rez ≤ 1.2·105, 4.6·105 ≤ Reϕ ≤ 1.0·107 and 9.0·10−2 ≤ βTΔT ≤ 3.5·10−1.
Kinne et al. (Tue,) studied this question.
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