Effect of cold jet plume on aerodynamics coefficients

Experiments are carried out on a blunt-cone-cylinder-flare geometry to study the effect of Mach 2.65 jet plume interaction with Mach 5 freestream on overall aerodynamic coefficients. Supersonic jet plume pressure ratios P_j/MP_inf of 0 to 158 are simulated, and the angle of attack α is varied from+4 to -4 deg. Flow features are captured through Schlieren and oil flow visualization. The isolation of load measuring and load nonmeasuring parts and elimination of jet reaction force are confirmed through tests. Under jet-off conditions, with an increase in the angle of attack, the flow separation on the leeward side moves toward the nose, whereas, on the windward side, the separation moves toward the base. Similar behavior is seen under jet-on conditions. However, due to jet-plume/Cfreestream interaction, separation is more pronounced on the leeward side. In general, as P_j/MP_inf increases, the aerodynamic coefficients decrease irrespective of angles of attack. At the maximumP_j/MP_inf of 158,C_N,C_m, and C_A are decreased by 15, 22, and 30%, respectively. Also X_CP moves toward the nose by 1.15D, 0.6D, and 0.25D for α = 1, 2, and 4 deg, respectively.