To clarify the mechanisms of heat transfer on an engine wall is an important challenge because the heat loss on the wall is one of the dominant factors that limit the thermal efficiency. A thin-film resistance type heat flux sensor fabricated with Micro-Electro-Mechanical Systems (MEMS) technologies was applied to research on the heat transfer of an impinging diesel jet. The MEMS sensor had a high sensitivity and multiple measurement points with a scale comparable to the turbulence of in-cylinder flow for the investigation of local instantaneous heat transfer characteristics in engines. Measurements of wall temperature and heat flux were conducted in a constant volume chamber under the reference conditions of Engine Combustion Network (ENC) Spray A with variations in injection pressure. As a result, the maximum heat flux and heat transfer coefficient reached about 5 MW/m² and 3 MW/(m² K), respectively. The results were compared to those obtained with a commercially available thermocouple, and both sensors produced similar trends. In addition, fluid motion near the wall was estimated from the heat flux fluctuations using a cross-correlation analysis. The relationship between heat transfer and flow was investigated in a dimensionless number fashion, and it was compared to a semi-theoretical prediction that was based on a steady state laminar flow heat transfer model.

阐明发动机壁上的传热机制是一项重要的挑战，因为壁上的热损失是限制热效率的主要因素之一。利用微机电系统（MEMS）技术制造的薄膜电阻式热通量传感器被用于研究撞击柴油机射流的传热。MEMS传感器具有高灵敏度和多个测量点，其规模可与缸内流的湍流相比，可用于研究发动机中的局部瞬时传热特性。壁温和热通量的测量是在恒定体积的室内，在发动机燃烧网络（ENC）喷雾A的参考条件下进行的，喷射压力有所变化。结果是，²和3 MW /（m ²  K）。将结果与使用市售热电偶获得的结果进行了比较，并且两个传感器都产生了相似的趋势。另外，使用互相关分析根据热通量波动估算壁附近的流体运动。以无因次数方式研究了热传递与流动之间的关系，并将其与基于稳态层流热传递模型的半理论预测进行了比较。