发动机舱内部传热和蒙皮的降温规律

建立了简化的发动机舱物理模型,对通风冷却和辐射遮挡的蒙皮降温效果进行了数值模拟和实验研究,并对发动机舱内部传热规律进行了分析.结果表明:数值计算得到的发动机舱蒙皮表面沿程分布与实验结果吻合良好.在加热壁面分段的热边界条件下,无辐射遮挡且无通风时蒙皮内侧表面接受的热流占热壁面加热热流的比值约为78%,当发动机舱通风速度达到1m/s时该比值降至20%;当通风速度从0m/s增大至3.5m/s时,发动机舱蒙皮峰值温度的降幅约为10%;无通风条件下有辐射遮挡的蒙皮峰值温度相对于无辐射遮挡的情形降幅约为6%;在通风冷却和辐射遮挡的综合作用下,蒙皮峰值温度相对于无通风且无辐射遮挡的基准状况可降低约50K,相对降幅约为14%. 

Internal heat transfer and skin temperature reduction law of engine nacelle

A simplified physical model of engine nacelle was established. The effects of ventilation cooling and radiation shelter on reducing skin temperature were investigated by numerical simulation and experimental research. The internal heat transfer of the engine nacelle was also analyzed. Results show that the computational temperature distribution on the skin surface is in good accordance with the experimental result. Under the present zonal thermal boundary conditions of the heated wall, the ratio of total heat flux imposing on the inner surface of skin to the heat flux of heated wall is about 78% in case of no ventilation and radiation shelter. This ratio reduces to 20% when the ventilating velocity of the engine nacelle is 1m/s. When the ventilating velocity is increased from 0m/s to 3.5m/s, the maximum temperature on the skin is reduced about 10% relatively. The maximum temperature on the skin with radiation shelter is reduced about 6% in relative to the case without radiation shelter under no ventilation condition. Combination of ventilation and radiation shelter can achieve 50K reduction of maximum skin temperature in relative to the case of no ventilation and radiation shelter, with about 14% relative reduction.