MEASUREMENT METHOD OF EMBEDDED TEMPERATURE SENSITIVE PAINT UNDER HYPERSONIC HIGH ENTHALPY CONDITIONS

The heat flux measurement results of point sensors cannot fully reveal the detailed heat flux distribution characteristics, especially for the areas with large heat flux gradient and complex heat flux distribution. Measurement methods of heat flux field are needed to meet the demand. The method of temperature sensitive paint has been widely used to measure heat flux field. However, the stagnation temperature of the test condition is much lower than the real flight condition. The radiation effect under hypersonic high enthalpy conditions seriously limits the application of temperature sensitive paint. To solve this problem, the embedded temperature sensitive paint method is proposed. The heat flux field is determined by the solution of the inverse heat conduction problem with inner wall temperature history measured by temperature sensitive paint. In this paper, the measurement principle, system composition, data processing method, design principle and advantages of the embedded temperature sensitive paint method are introduced in detail. The feasibility of this method is verified by numerical simulation with typical heat flux distribution. Also, the influence of temperature measurement accuracy and noise on the measurement results are analyzed. The embedded temperature sensitive paint method can be applied in the hypersonic real flight condition to reveal the detailed characteristics of the heat flux field. This method extends the application of temperature sensitive paint and solves the problem of heat flux field measurement under hypersonic high enthalpy conditions.