Study on heat flux analysis method and accuracy on combustion chamber wall in internal combustion engine using coaxial type thin film temperature sensor

In order to improve thermal efficiency of automobile engine, it is necessary to reduce the cooling loss. A method for analyzing local cooling loss (heat flux) using coaxial type thin film temperature sensor has been developed. Recently, results of heat flux analysis using the sensor composed of thermocouple materials standardized based on ANSI and JIS have been reported, but structure and measurement accuracy of its sensor are not clear enough. In this study, the measurement accuracy of sensor A composed of K type materials and sensor B whose body is combustion chamber material (aluminum alloy) was compared using numerical analysis (two-dimensional coordinate heat conduction equation when the sensor is embedded in combustion chamber). As a result, it was important to use same material as combustion chamber for sensor body to measure wall surface instantaneous temperature with high accuracy. Additionally, results of one-dimensional (axial direction) heat flux analysis when the material of the combustion chamber and the material of the sensor body are different had error, it was considered to effect of heat flow (temperature difference) in radial direction due to different thermal conductivity. Therefore, it was confirmed that newly proposed two-dimensional heat flux analysis method using temperature distribution in axial and radial direction can analyze more accurately than one-dimension. These numerical analysis results showed same tendency as measured verifications results.