Measurement of heat transfer coefficients at up to 25,500 g – A sensor test at a rotating free disk with complex telemetric instrumentation

Abstract

Heat transfer coefficients (HTC) are important for the design of efficient energy machines as for instance gas turbines for industrial, power generation and propulsion applications. Published HTC measurement data considering geometries and operating conditions which are relevant for these applications are very rare or not available.This study presents an experimental investigation using a telemetric setup for the direct HTC measurement at metallic boundaries with gaseous flow. The rotor rig has a complex instrumentation using one of the in house developed telemetry systems. The experimental investigation relies on a recent measurement/sensor concept tested for the first time in the rotating frame with high centrifugal acceleration. The measurement setup has miniaturized sensor dimensions and low energy consumption. Therefore, the sensor concept is suitable for integration in a telemetry system as necessary for turbomachinery research. The sensor setup features good local resolution, short response time and a high resolution versus temperature and HTC.Measurements of the radial distribution of the heat transfer coefficient of a rotating free disk are presented. Additionally a comparison with correlations found in literature as well as a calibration of the HTC sensors for the test case forced convection at the flat plate is included.