An experimental study was performed to measure the heat transfer coefficient distributions on a flat blade model under rotating oper-ating conditions.A steady-state thermochromic liquid crystal technique was employed to measure the surface temperature,and all the signals from the rotating reference frame were collected by the telemetering instrument via a wireless connection.Both air and CO2 were used as coolant. Results show that the rotational effect has a significant influence on the heat transfer coefficient distributions.The pro-files of hg/ho,which is the ratio of heat transfer coefficient with film cooling to that without film cooling,deflect towards the high-radius locations on both the pressure surface and suction surface as the rotation number(Rt)increases,and the deflective tendency is more evident on the suction surface.The variations in mainstream Reynolds number(ReD)and blowing ratio(M)present different distribu-tions of hg/ho on the pressure and suction surfaces,respectively.Furthermore,the coolant used for CO2 injection is prone to result in lower heat transfer coefficients.