Development of force measurement technique for preheated model in hypersonic combined test facility

This paper presents a new force measurement technique to investigate the effect of aerothermodynamic phenomena, particularly aerodynamic heating, on aerodynamic forces. This technique is successfully applied within a hypersonic combined test facility that integrates arc-jet and shock tunnel. A preheated model transport system is developed to axially immobilize the model during preheating, safe transport to the shock tunnel, and ensure quasi-free-body axial motion during force measurement tests. A comparative evaluation revealed a significant 11.2 % increase in drag coefficient for test models preheated in the arc-jet tunnel, followed by an 8.56 % decrease when cooled to room temperature. By closely comparing drag coefficients under three conditions (cold, hot, and cooled), this study analyzes the distinct effects of ablation-induced shape change and surface temperature on drag coefficients, respectively. This technique allows for a more realistic simulation of hypersonic flight conditions within ground test facilities.