Development of MEMS Heat Flux Vector Sensor for Internal Combustion Engines

Abstract

Heat flux sensors for internal combustion engines were developed with MEMS technologies. Firstly, a plug shape MEMS heat flux sensor was produced as prototype, and its performance was tested in an open chamber and a rapid compression and expansion machine. The sensor measured heat fluxes with noise of 23.7 kW/m² at a sampling frequency of 25 kHz and endured a harsh environment with pressure of 9 MPa and heat flux load of 26 MW/m². Then, a new MEMS sensor for measuring heat flux vector was developed. This sensor has three thin film RTDs of a square 300 μm on a side in rotational symmetry, and these RTDs measure wall surface temperatures simultaneously in order to detect heat fluxes of not only a vertical direction component against the sensor surface but also a planer direction one. In the measurement test in the open chamber, the sensor could measure the heat flux vector reflecting a gas flow with noise of 8.3-9.0 kW/m² at a sampling frequency of 10 kHz.