The formation of pulsed supersonic underexpanded jets influenced by a background gas

We have studied the gasdynamics of a pulsed jet expansion of He, Ar, and N2 with moderate n (∼103–106) and Reynolds numbers in the interval ReL ∼ 1–102. The laws of motion of the leading front in pulsed jets of various gases are determined. It is found that the front velocities of such jets are significantly lower than the limiting values for a stationary expansion of the corresponding gases. The pulsed jet structure has been studied for various similarity parameters of the system. It is shown that the size of a quasi-stationary region in the gas moving away from the source decreases depending on n.