Kiel head calibration (temperature measurement)
Kiel heads are used to measure total pressure and total temperature in flows with widely varying angles of attack. Their geometric design allows high incidence angles and ensures good measurement results in complex conditions.
Knowledge of the Recovery Factor is crucial when measuring the total temperature of a flow with a kiel head probe. The Recovery Factor is the relation of the measurement result to the real temperature in the flow. It is highly dependent on the kiel head geometry and flow conditions. For our project partner Siemens, knowledge of the recovery factor dependency on incidence angle and flow Mach number is crucial.
Measurements for Siemens were carried out on the calibration channel at the Technical University of Darmstadt laboratory. The necessary air mass flow is provided for an external compressor, which makes it possible to obtain a constant Mach number (up to Ma = 1) at constant temperature conditions. Within the project, a customized nozzle geometry was developed as well as a self-traversing unit. This made it possible to vary both the yaw and the pitch angle at a constant probe head position to advance the desired measurement grid.