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为了深入理解再生冷却过程中碳氢燃料的超临界湍流传热特性,以正癸烷为研究对象,对其在非对称受热(上壁面外侧加热)方形通道内的流动传热进行了数值研究。在数值方法可靠性得到充分验证的基础上,详细探讨了进口温度和压力等运行参数对通道上壁面和侧壁面内侧平均壁温和平均努塞尔数分布的影响。计算结果表明:在运行压力接近临界压力且主流温度处于拟临界温度附近的综合条件下,流体热物性剧烈变化导致的类膜态沸腾效应,引起了上壁面内侧显著的传热恶化现象。同时,不平衡压差诱发的通道截面速度场异常分布,进一步影响了上壁面内侧近壁区域流体的换热性能。另外,类膜态沸腾效应致使上壁面热流更多地传递到侧壁面,导致侧壁面平均努塞尔数大幅增大,相比于正常换热的最大增幅约为50%。
In order to further understand the supercritical turbulent heat transfer characteristics of hydrocarbon fuels during regenerative cooling, n-decane was used as a numerical example to investigate the heat transfer in a square channel heated asymmetrically (heated on the upper wall). On the basis of fully verifying the reliability of the numerical method, the effects of inlet temperature and pressure on the average wall temperature and the average Nusselt number distribution in the upper and lower sides of the channel are discussed in detail. The calculation results show that under the condition of the operating pressure approaching the critical pressure and the mainstream temperature being near the quasi-critical temperature, the membrane-like boiling phenomenon caused by the drastic thermal physical property of the fluid causes a significant heat transfer deterioration on the inside of the upper wall surface. At the same time, the anomalous distribution of the cross-section velocity field induced by the unbalanced pressure difference further affects the heat transfer performance of the fluid near the inner wall of the upper wall. In addition, the film-like boiling effect causes more heat transfer from the upper wall surface to the side wall surface, resulting in a substantial increase in the Nusselt number of the side wall surface, which is about 50% of the maximum increase compared to normal heat exchange.