高雷诺数超音速射流的等离子体制动器主动控制
Active flow control of jets with Localized Arc Filament Plasma Actuators (LAFPAs) is conducted over awide range of the fully expanded jet Mach numbers (MJ or simply jet Mach number). The jet Machnumbers covered in the present research are 0.9 (with a converging nozzle), 1.2 (overexpanded), 1.3(perfectly expanded), and 1.4 (underexpanded) with a design Mach number 1.3. Additionally, limitedexperiments are carried out for an MJ = 1.65 perfectly-expanded jet. The exit diameter is 2.54 cm (1 inch)for all cases and eight LAFPAs are equally distributed on the perimeter of a boron nitride nozzleextension. The jet spreading is strongly dependent on duty cycle, forcing frequency, and azimuthal modes.The performance of LAFPAs for jet spreading is investigated using two-dimensional particle imagevelocimetry (PIV). There is an optimum duty cycle, producing maximum jet spreading, for each forcingfrequency. A relationship between the optimum duty cycle and forcing frequency is determined from theextensive results in the MJ 0.9, and this relation is used for all experiments. The effect of forcingfrequency is investigated for a wide range of forcing Strouhal numbers (StDF = fFD/Ue, where fF, D, andUe, are forcing frequency, nozzle exit diameter, and jet exit velocity respectively), ranging from 0.09 to3.0. The azimuthal modes (m) investigated are m = 0 – 3, ±1, ±2, and ±4 - this comprises all modesavailable with eight actuators. The performance of LAFPAs does also strongly depend on the stagnationtemperature of the jet and MJ. The effects of stagnation temperature are investigated for 1.0, 1.4, and 2.0times the ambient temperature in MJ 0.9 jet for very limited azimuthal modes and StDF. In an MJ 1.65perfectly-expanded jet, the control authority of LAFPAs is investigated for only m = ±1 and StDF ∼ 0.3.