To investigate the heat transfer mechanism, a sensor with high spatial and temporal resolution and high durability is necessary. Our research group has been developed a thin film thermal sensor by using the MEMS technologies. The sensor has three resistance temperature detectors with the size of 315 μm on an Al alloy substrate. In this work, heat flux measurement with the MEMS sensor was conducted in the laboratory engine under three equivalence conditions. The heat fluxes were measured for 200 cycles, and were discussed in terms of that on 200-cycle average and in each cycle. As a result, the wall heat flux decreases with the equivalence ratio because the gas temperature becomes low at the lean condition. In addition, the cyclic variation of the heat flux is significant in terms of the magnitude, rise and attenuation, and it was clarified that the instantaneous heat transfer in each cycle is stronger phenomena than that estimated from the averaged data. Furthermore, the instantaneous heat fluxes have different phase in spite of the close range of the measurement points. This result indicates that the combustion flame has turbulence on sub-millimeter scale, namely the distance between the measurement points of 780 μm.
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