Department of Thermal Engineering, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 10084, People's Republic of China.
Bioinspir Biomim. 2017 Sep 1;12(5):056002. doi: 10.1088/1748-3190/aa753b.
Transpiration cooling is an effective way to protect high heat flux walls. However, the pumps for the transpiration cooling system make the system more complex and increase the load, which is a huge challenge for practical applications. A biomimetic self-pumping transpiration cooling system was developed inspired by the process of trees transpiration that has no pumps. An experimental investigation showed that the water coolant automatically flowed from the water tank to the hot surface with a height difference of 80 mm without any pumps. A self-adaptive transpiration cooling system was then developed based on this mechanism. The system effectively cooled the hot surface with the surface temperature kept to about 373 K when the heating flame temperature was 1639 K and the heat flux was about 0.42 MW m. The cooling efficiency reached 94.5%. The coolant mass flow rate adaptively increased with increasing flame heat flux from 0.24 MW m to 0.42 MW m while the cooled surface temperature stayed around 373 K. Schlieren pictures showed a protective steam layer on the hot surface which blocked the flame heat flux to the hot surface. The protective steam layer thickness also increased with increasing heat flux.
蒸腾冷却对于保护高热通量壁面是一种有效的方法。然而，蒸腾冷却系统的泵使系统更加复杂，并增加了负载，这对实际应用是一个巨大的挑战。受树木蒸腾过程的启发，一种无需泵的仿生自吸蒸腾冷却系统被开发出来。实验研究表明，水冷却剂在 80mm 高度差的情况下自动从水箱流向热表面，无需任何泵。然后基于这一机制开发了一种自适应蒸腾冷却系统。当加热火焰温度为 1639K 且热通量约为 0.42MW/m 时，该系统有效地冷却了热表面，使表面温度保持在约 373K 左右。冷却效率达到 94.5%。当火焰热通量从 0.24MW/m 增加到 0.42MW/m 时，冷却剂质量流量自适应地增加，而冷却表面温度保持在 373K 左右。纹影照片显示热表面上有一层保护性蒸汽层，阻止了火焰热通量到达热表面。保护性蒸汽层的厚度也随着热通量的增加而增加。
