Fourier Mode Decomposition of Unsteady Flows in a Single Injection Port Fluidic Thrust Vectoring Nozzle

The flow field structure of a single injection port fluidic thrust vectoring nozzle was studied by introducing secondary flow injection in the expansion section of the two-dimensional convergent-divergent nozzle. To determine the motion characteristics of unsteady flow in a shock-induced fluidic vectoring nozzle, detached eddy simulation was conducted to simulate the three-dimensional flow field, and the flow mechanism in the nozzle was analyzed. Fourier mode decomposition was used to analyze the pressure coefficient on the symmetrical surface of the nozzle. Results show three natural frequencies in the flow field of the shock-induced fluidic vectoring nozzle. The first-order mode corresponding to frequency f1 = 512.8 Hz mainly illustrates the oscillation of shock waves. The second-order mode corresponding to frequency f2 = 2825 Hz illustrates the shedding of vortices. The third-order mode corresponding to frequency f3 = 4650 Hz is similar to the second-order mode; however, the spatial scales of vortices decrease.