Overall cooling performance of a densely packed multirow-hole-array plate for afterburner heat shields under coupled conduction–convection–radiation heat transfer

With increasing thermal loading, thermal radiation in components subject to coupled conduction–convection–radiation heat transfer has evolved from a negligible secondary factor to a key physical mechanism that must be explicitly considered. As a typical component involving coupled heat transfer in advanced aero-engines, the flat afterburner heat shield is commonly protected by film cooling based on densely packed multirow hole arrays. To quantify how blowing ratio, mainstream-to-coolant temperature ratio, and mainstream Reynolds number modulate overall cooling effectiveness after the introduction of radiation, a controlled-radiation experimental platform was developed in which radiative heat flux was imposed by a quartz-lamp array. The results show that the established understanding that increasing blowing ratio improves cooling performance remains valid under radiative conditions; moreover, radiation markedly amplifies the relative net gain associated with the same blowing-ratio increment, with a maximum increase of 56.4%. In the absence of radiation, both mainstream-to-coolant temperature ratio and mainstream Reynolds number exert negligible influence on overall cooling effectiveness. Once radiation is introduced, however, both become important modulation parameters. Increasing the mainstream-to-coolant temperature ratio reduces the radiative temperature difference and the net radiative heat flux absorbed by the hot component, producing a maximum increase in overall cooling effectiveness of 35.6% under strong radiative loading. Increasing mainstream Reynolds number likewise improves overall cooling effectiveness, and its effect becomes more pronounced as radiative intensity increases, reaching 59.3%. These results show that thermal radiation not only changes the absolute level of overall cooling effectiveness, but also reshapes the relative importance of key flow and thermal parameters.