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本文对超临界压力下航空煤油在圆管内(竖直向上流)的对流传热特性进行实验研究,讨论了入口温度及热流密度对于换热的影响规律;并对实验过程中出现的传热及流动不稳定现象进行了分析。结果表明:入口段的传热恶化仅在入口温度较低时发生。3 MPa压力下在高热流密度工况会发生传热恶化现象。传热及流动不稳定现象发生于低压力、低入口温度及高热流密度工况下;不稳定现象发生时伴随着外壁温的剧烈振荡,并发出连续而尖锐的声响。最后,选取Gnielinski公式进行Nu数的计算,与实验结果进行对比分析。
In this paper, the convective heat transfer characteristics of aviation kerosene in a circular tube (vertical upward flow) under supercritical pressure were studied. The influence of inlet temperature and heat flux density on heat transfer was discussed. The heat transfer and Flow instability was analyzed. The results show that the deterioration of heat transfer in the inlet section occurs only when the inlet temperature is low. Under the condition of high heat flux density, the heat transfer will deteriorate under the pressure of 3 MPa. Heat transfer and flow instability occur at low pressure, low inlet temperature and high heat flux density conditions; instability occurs with the outer wall temperature of the violent oscillation, and issued a continuous and sharp sound. Finally, we choose the Gnielinski formula to calculate the Nu number, and compare with the experimental results.