一种高超声速稀薄流激波干扰气动热测量技术

针对高超声速稀薄来流条件下的激波干扰气动热测量问题,设计了一种适用长时间、中低热流量值(5~500 kW/m2)的带封装结构的量热计,采用空气隔热设计方式降低其侧向传热,实现了有效一维传热,延长了测试时间;并通过热流传感器标定试验,实现了热流高精度测量。为验证量热计的测量性能,开展了地面标定实验和基于双锥模型的高超声速低密度风洞激波/边界层干扰实验(M10和M12),量热计与同轴热电偶的测量结果进行对比分析。研究结果表明,本文所设计的量热计适用于稀薄来流条件下激波干扰引起的复杂气动热问题的热流测量。相比于同轴热电偶,量热计响应时间较慢,但对于较大热流,由于极大减轻了侧向传热的影响,测量精度较高。同轴热电偶对低量值热流(5~20 kW/m2)的测量性能较好,信噪比(SNR)较高。研究成果为开展高超声速低密度风洞稀薄流激波干扰气动热试验研究提供支撑。

Effect of WC grain size on mechanical properties and microstructures of cemented carbide with medium entropy alloy Co-Ni-Fe binder

For developing new binder phase with high performance, Co-Ni-Fe alloy was used as binder in cemented carbides. The mechanical properties of WC-CoNiFe and WC-Co cemented carbides with different grain sizes were studied. The results show that the reprecipitation of WC-CoNiFe is inhibited compared with that of WC-Co during sintering process, and the grains in WC-CoNiFe cemented carbides are more of smooth shape, resulting in a slightly lower hardness and higher transverse rupture strength. With the increase of the grain size, the hardness of the two cemented carbides decreases, and the transverse rupture strength increases. However, the slope values of K in Hall-Petch relationship are higher in WC-CoNiFe than those in WC-Co, indicating the high toughness of medium entropy alloy Co-Ni-Fe.