The Development Of High-temperature Thin Film Thermopile Sensor For Heat Flux Measurement Of Aeroengine Hot Section

The heat flux is the most key parameter which affects the performance and lifetime of engine hot section,which are exposed to high temperature enviroments.The real-time monitoring and acquiring the surface heat flux distribution and changing on hot section of engine are very important for engine performance verification and health monitoring.The thin film thermopile?TFTP?heat flux senor has the advantages of small size,small measuring terminal,low thermal mass,little effect and doing no harm to components.It becomes one of the most promising heat flux measurement technologies and the developing trend of surface heat flux measurement for engine hot section.For TFTP on the turbine blades,as part work of the project on developing TFTPs on turbine blade,this study focuses on high-temperature TFTPs fabricated on Al₂O₃ ceramic substrate using micromachining technology,especially two types of TFTPs with different thermal insulator.Spin-coated polyimide?PI?or the ion beam deposited silicon dioxide was used as the thermal insulator for low or high temperature application respectively.While for high temperature operation,silicon oxide was chosen as the thermal insulator.According to heat flux measurement theory,the circular and rectangluar structure of the TFTPs are designed.The property of TFTPs with different structure was modeled and analyzed by FEA COMSOL in order to optimize the performance with a smaller device dimensions.Two types of TFTPs were proposed and manufactured based on the optimum design from the COMSOL simulation.And it verifies the feasibility of the design.In order to enlarge TFTPs output voltage,the rectangular TFTPs with 80 series of thermocouple are designed,respectively.Two types of rectangular TFTPs with different thermal insulator are fabricated by surface micromachining technology.In order to realize in situ measurement of temperature and heat flux on the turbine blades,TFTP is fabricated on zirconia coated nickel-chromi?m alloy,the fabrication process was tried on.The testing systems are built to characterize the performance of the TFTPs.The high-temperature TFTPs can withstand 1000^oC high temperature.It can be found that the output voltage responses were consistent with simulation results when a step heat flux was loaded.The test results also show that the output voltage of TFTPs responded linearly with the reference heat flux.