Experimental Investigations on the Strut Controlled Thrust Vectoring of a Supersonic Nozzle

The attitude control of a rocket engine using the control surfaces becomes cumbersome particularly in larger rockets with high payload. In such cases, a more effective means of producing forces for controlling the flight is the deflection of exhaust gases, referred to as the gas-dynamic steering or the thrust vector control. In this study, the effect of a strut on the exhaust gas deflection, deployed at the locations; ۰.۶۲ L, ۰.۷۲ L and ۰.۸ L in the divergent-portion of a Mach ۱.۸۴ nozzle at over-expanded, correctly-expanded and under-expanded states of the jet, has been experimentally investigated. The level of expansion at the nozzle exit is varied by changing the settling chamber pressures from ۴ bar to ۸ bar, in steps of ۲ bar. Further, to study the effect of aspect ratio, the height of strut is varied as ۱.۵ mm, ۲.۵ mm and ۳.۵ mm. The strut of height ۳.۵ mm, deployed at x/L = ۰.۷۲, is found to be the most effective thrust vector control at overexpanded conditions; with a maximum jet deflection of about ۳.۶o, obtained at a settling chamber pressure of ۴ bar. The Schlieren flow visualization images confirm the findings of wall static pressure data.

Keywords:

Thrust vectoring , Wall static pressure , Schlieren technique , Strut , Mach number