Effects of Changes in Split-Line Location on the Moveable Nozzle Performance in Thrust Vector Control System

In this paper، numerical simulation of the gas flow is carried out to investigate the effects of changes in split line location on the amplification factor، side force and thrust vector magnitude of the moveable nozzle with supersonic split line. The comparisons between the numerical results and experimental data for two different deviation angles show that RNG k-ε turbulence model with enhanced wall treatment gives better results than other turbulence models. By using the mentioned turbulence model، it is observed that for greater distances between the split line location and the rotation center of the movable part، the amplification factor، side force and thrust vector magnitude of the nozzle will decrease. For greater distances، the oblique shock will occure at the section in which the flow has higher Mach number. Therefore the change in normal velocity of the flow across the oblique shock will be more which results in more reduction in exhaust flow momentum and the amplication factor. The results show that by increasing the distance between split line location and the rotation center of moveable part، the deviation angle of the thrust vector magnitude will be lower than nozzle rotation angle. Effects of surface roughness is also investigated.