考虑间隙内流的陶瓷隔热瓦气动载荷分析

Ceramic tile is an important component in thermal protection system (TPS) of high-speed aircraft. Severe internal flow in tile gaps arises from the pressure gradient when aerodynamic shock acts on the tile during transonic flight. Internal flow in tile gaps and porous media flow in tiles and strain isolation pad(SIP) have significant influence on the aerodynamic loads of ceramic tiles. This paper establishes a model to calculate aerodynamic loads of ceramic tiles considering internal flow. Based on Navier-Stokes equations and Spalart-Allmaras turbulence model, we simulate internal flow in gaps and SIPs using FLUENT. The simulation results agree well with the NASA experiment data (less than 3.3%). The effects of SIP permeability and gap width on the aerodynamic loads of ceramic tiles are furtherly studied. Numerical results show that:①Because of the minor loss, theoretical result is more accuracy than linear creep flow theory. The pressure deviation between the present simulation and the linear creeping flow result reaches 10.6%. ②For a given shock intensity, the pressure gradient in the SIP increases with the increase of the Darcy coefficient of permeability when the Darcy coefficient is less than 1.7×10⁹/m²,but decreases with the increase of the Darcy coefficient of permeability when it is larger than 1.7×10⁹/m².③The aerodynamic load on the bottom of the ceramic tiles increases with the increase of the gap width in the entrance of internal flow(high pressure end). The variation of gap width between tiles can arise from the displacement of the tile under high pressure due to shock wave on the top of the tile.