Performance Analyses of Fluidic Thrust Vector Control System Using Dual Throat Nozzle

Flows in the rocket engine nozzles have been numerically analyzed to assess the performance of thrust vector control system of fluidic type by the direct simulation Monte Carlo method. Secondary jet is injected through a small port at one side of two-dimensional dual throat nozzle wall. If the cross-sectional areas of both throats are identical (nozzle A), and the injection port is near the first throat, the main flow separation caused by the secondary jet is observed, and a steady-state thrust deflection of about 18 degrees is obtained when the flow rate of the secondary jet is 5% of the total fluid. However, the deflection also occurs randomly when the secondary jet is stopped. To avoid it, the second throat is widened to 1.50 times the cross-sectional area of the first throat (nozzle B), and it is observed that the thrust deflection is nearly zero for all cases without secondary jet injection. However, the thrust deflection is only about 5 degrees when the secondary jet is injected near the first throat of nozzle B. When the injection port is placed further downstream of the first throat in nozzle B, thrust deflections between 14 and 15 degrees are obtained.