Application of Steady State and Transient IR-Thermography Measurements to Film Cooling Experiments for a Row of Shaped Holes

Abstract

This paper presents experimental investigations for the measurement of the adiabatic film cooling effectiveness as well as the heat transfer coefficient distribution in film cooling experiments with a row of fanshaped holes on a flat plate. The temperature distribution on the flat plate is measured using infraredthermography (IR). Adiabatic wall effectiveness data are obtained using a high-temperature plastic material. Although a low thermal conductivity material is used, the measured temperature distribution is not identical with the adiabatic temperature distribution. The measured temperature field shows influences of 3D heat conduction inside the test plate. The effects of the heat conduction inside the test plate are modeled using the FE-method to re-evaluate the adiabatic wall temperature and to calculate the coolant gas exit temperature, which is used for the adiabatic film cooling effectiveness. For the measurement of the heat transfer coefficient ratio with and without film cooling (h f /h 0 ) a transient method is used. Temperature transients on the test surface are initiated by switching the coolant flow and are recorded using IR-thermography. The measured wall temperature histories are converted into heat flux values assuming a semi-infinite wall model during the experiment. NOMENCLATURE α [°]stream-wise injection angle c p [J/(kgK)] heat capacity at constant pressure d [m] non-cylindrical length of the cooling hole 1

Film cooling of a contoured endwall nozzle vane through fan-shaped holes

“…In particular, coolant temperature decreases from plenum to hole exit due to heat transfer with the plenum and the hole sidewall (Brauckmann and von Wolfersdorf, 2005). So, basically, temperature of the coolant is supposed to vary with hole position, even if the plenum temperature is uniform.…”