Optimization transpiration cooling of nose cone with non-uniform permeability

With the development of active thermal protection techniques (TPTs), optimization transpiration cooling (OTC) design, to enhance the cooling effect in stagnation regions and decrease coolant load, has become a critical issue in the research and development of hypersonic vehicles. One of the possible OTC approaches is using a non-uniform porous material to vary the coolant allocation within pores. This paper presents an experimental and numerical investigation on the transpiration cooling performances of two wedge shaped nose cones. One is for OTC, made of a special porous matrix with non-uniform permeability to ensure the largest porosity near the stagnation point, and the other is for traditional transpiration cooling (TTC), consisting of a general uniform porous matrix. Surface temperature and cooling effectiveness of the two nose cones are investigated in the experiments. The data show that in comparison with TTC, OTC can effectively enhance the cooling effectiveness in stagnation regions through a locally high permeability, and improve the uniformity of the temperature distribution within the entire nose cone. To exhibit the coolant flow characteristics within the pores, two-dimensional numerical simulations are carried out by commercial software FLUENT, and the numerical method is validated by the experimental data. The numerical results indicate that OTC with non-uniform permeability can provide an optimized coolant allocation and decrease the driving force required by the coolant transport to the stagnation region.