Experimental and numerical investigation of transpiration cooling with gradient porosity layout for the thermal protection of nose cone

Transpiration cooling with liquid phase change has been widely regarded as one of the most promising thermal protection technology for aerospace vehicles. However, when applied to the nose cone with small curvature radius, cooling failure may occur due to the extreme high heat flux and pressure at the stagnation point. In order to deal with this issue, a wedged-shaped nose cone structures with a gradient porosity layout is designed in this work to optimize the coolant distribution in the porous nose cone, and the corresponding transpiration cooling performance with liquid phase change is experimentally and numerically investigated. At last, to meet the thermal protection requirements under different flight conditions as best as possible, an orthogonal experiment and fuzzy gray analysis were carried out to optimize the particle diameter, porosity layout and division interval of the porous nose cone with gradient porosity layout, taking a specific flight condition as an example. The results obtained in this work showed that gradient porosity layout can significantly improve the cooling efficiency at the stagnation point and the temperature uniformity on the outer surface. The porosity has the highest impact on the cooling performance, while the division interval has little impact. By optimizing, the cooling efficiency at the stagnation point can reach 74.5%, and the maximum temperature difference is less than 500K.