Aerothermal analysis and thermal protection of grid fins for reentry rockets
- Paper ID
60027
- author
- company
Beijing Interstellar Glory Space Technology Co., Ltd
- country
China
- year
2020
- abstract
Grid fins are effective control surfaces for re-entry rockets. The grid fin which is a combination of thin metal sheets sustains severe aerodynamic loads and heating during the re-entry flight. The critical aerothermal environment at the leading edge causes a high temperature and high thermal stress. Aerodynamic thermal analysis has been conducted for the thermal protection design of the grid fins on a suborbital solid rocket, SQX-1Z, which is developed for verifying the reentry control technology of the reusable launch vehicles. The aerodynamic loads and heat flux distribution of the grid fin are obtained by fluid-thermal couple numerical calculation based on SST turbulence model and structural mesh grids. And the thermal analysis using the finite element method indicates that the maximum temperature of the grid fins exceeds the operating temperature of the structural material, titanium alloy, during the re-entry flight. So a heat-resistant coating is adopted as an ablative protection solution. In the suborbital flight test in September 2018, the practical temperature response of a grid fin was measured by sensors and acquired through the telemetry system. The deviation between the calculated result and the flight measurement result is less than 16\%. Base on the same analysis method, a small solid launch vehicle, SQX-1, adopts aluminum alloy as the material of its grid fins, which significantly reduces the structural weight and machining cost. And the design is validated by the maiden flight of SQX-1 in July 2019. This analysis technique is also applied in the development of a liquid propellant reusable launch vehicle, SQX-2, which adopts 4 titanium alloy grid fins without thermal insulation coating.