The Deduction of the Integral and the Estimation of the Local Core Rotation Ratio by Telemetric Pressure Measurements in a Two Cavity Test Rig

The heat transfer in rotating cavities, as found in the internal air system of gas turbines, is mainly governed by the flow passing through these specific machine structures. The core rotation ratio represents the circumferential velocity, and is thought to be an influential flow parameter for heat transfer in rotating cavities with radial flow-through. Therefore, this paper focuses on deducing the core rotation ratio and the estimation of its local distribution using telemetric pressure measurements. The local core rotation ratio depends on the radial pressure distribution in a rotating cavity system. Thus, an integral core rotation ratio can be determined from pressure measurements in the rotating cavity system. A flow structure-based approximation of the measurements allows an estimation of the radial distribution of the core rotation ratio in the rotating cavity. The results of the measurements with varied flow rates and revolving speeds are presented, as well as a discussion of the fit parameters and their dependency on the operation mode of the test rig.