Fluid-thermal-structure coupled analysis of grid fins for hypersonic flight vehicle
Document typeConference report
Rights accessOpen Access
The aim of this work is to provide a numerical method of fluid-thermal-structure coupled simulation of grid fins in hypersonic flows. Hypersonic flight vehicle with grid fins offers many advantages under high speed condition. The main advantages are small hinge moments, efficient packaging and capability to produce effective aerodynamic force at high angles of attack over wide Mach number ranges. The structure, however, sustains complicated loads caused by aerodynamic forces and heating during hypersonic flight. The large aggregations of experimental studies are limited to parts of physical characteristic due to the difficulty in the data transmission. This study takes the full influence of fluid flow into account as well as heat transfer on structure strength and stiffness. The following work is done. Firstly, Reynolds-Averaged approach and Spalart-Allmaras turbulence model are employed to solve the problem of flowing fluid. The simulation is achieved by using second order upwind scheme and hexahedral mesh grids. Validation has done by comparing the computed normal force coefficient with wind tunnel data for a Mach number from 1.8 to 3.5 and different angles of attack. Secondly, computations are performed at free stream Mach number 6 at five angles of attack from 0 to 15 degrees. The data of aerodynamic forces and heat flux is obtained after fluid-thermal coupled calculation. The strength and stiffness calculations are carried out by taking the aerodynamic forces and heat flux as boundary condition of solid domain. Finally, two types of structure form are discussed for long time thermal protection. One is niobium alloy, the other is C/SiC composites. The article shows that different thermal and mechanical predictions are affected by various conditions such as angle of attack, material characteristics. The structure response takes on a whole different status under different angles of attack. This allows engineers to choose appropriate size and type for hypersonic thermal protection materials.