In this study, the effect of a cylindrical protuberance on the thrust vector of a supersonic jet was investigated as a new method in thrust vector control. For this purpose, a convergent-divergent nozzle was designed and constructed. This nozzle is such that the Mach number is its nominal output in full expansion conditions 2. The wall of the nozzle is equipped with pressurized holes to measure pressure variations. Also, there is a duct wall in the nozzle wall to apply a protuberance inside the nozzle. Pressure sensors for pressure measurement and also the schlieren system are used to check the outlet flow field. The total pressure of the compartment is constant at all tests and is 5.7bar. The results of this study show that the depth of penetration of the protuberance in the flow field has a significant effect on the amount of deviation and even the direction of the deviation of the jet stream exited from the convergent-divergent nozzle. The maximum jet outlet flow from the nozzle is 5.7degrees, which occurred at a rate of H/D*=0/4. In addition, these results indicate that with the increase in bulge penetration within the nozzle, the nozzle axial thrust has slightly decreased.

In this study, the effect of the use of dual protuberances as a thrust vector control method in a supersonic convergent-divergent nozzle with a Mach number of 2 is experimentally investigated. The nozzle total pressure in all experiments is considered constant. Air is the working fluid in these experiments. The used protuberances are two cylindrical elements that are placed in front of the flow in the divergent part of the nozzle. These protuberances are installed at 60% and 90% of the length of the nozzle divergent portion from the nozzle throat and are simultaneously applied in the main flow path. The protuberances are installed in opposite walls. Effect of changing the penetration ratio of the protuberances [H/D] on the thrust vector angle and the components of the thrust vector is obtained by measuring the forces acting on the nozzle. Also, the flow field was measured by a Schlieren system, as well as, the pressure variations on the nozzle walls were measured. The results show that the use of dual protuberances can have a significant effect on the angle of the thrust vector and increase the angle of the thrust vector up to 4.35 degrees in the implemented conditions of this study. Also, the results reveal that this method can reduce the axial component of thrust up to 5.5% in the worst case of implemented conditions.