Characterization of plasma synthetic jet actuator with Laval-shaped exit and application to drag reduction in supersonic flow

Abstract

A plasma synthetic jet (PSJ) actuator (PSJA) with a Laval-shaped exit is investigated using a numerical method alongside a PSJA with a straight-shaped exit for comparison. The accuracy of the numerical method is first verified by comparing simulation results with experimental schlieren images and pressure measurement values. The performance of the PSJA with the Laval-shaped exit is then investigated in quiescent air. The results show that when the dimensionless energy ε > 5.06, the maximum exit velocity of the PSJA with the Laval-shaped exit becomes supersonic and is higher than that of the actuator with straight-shaped exit. The opposite is true when ε ≤ 5.06. The jet front velocity of the PSJ is much lower than the exit velocity, and no obvious improvement is seen when changing from the straight-shaped exit to a Laval-shaped exit due to the shock waves near the exit. Finally, the drag reduction effect of an opposing PSJ on a hemisphere in Ma3 flow is investigated. For a geometrically fixed PSJA, the flow field of a singled-pulsed opposing PSJ in Ma3 flow can be classified into three patterns according to the values of the maximum pressure ratio and ε: pattern 1 consists of only vortices and a slight change in the bow shock, pattern 2 consists of a typical long penetration mode (LPM) of the opposing PSJ, and pattern 3 consists of both a short penetration mode and a LPM. For PSJAs with both kinds of exits within a certain range, the average drag reduction increases with ε. However, when ε is higher than 48.02 for a Laval-shaped exit and 16.01 for a straight-shaped exit, the drag reduction effect decreases due to the rise in drag associated with the formation of the PSJ. The drag reduction effect associated with a PSJA with a Laval-shaped exit is significantly better than that of one with a straight-shaped exit when ε > 8. The optimal average drag reduction values, 25.82% and 20.55%, are obtained at ε = 48.02 and ε = 16.01, respectively, for a Laval-shaped exit and a straight-shaped exit.

Numerical Investigation on the Thermal Protection Characteristics of a New Active Jet Design Parameter for Hypersonic Flight Vehicle

“…International Journal of Aerospace Engineering (2) The PRsAJ-TPS is capable of removing the severe aerodynamic heating on the nose model effectively and extensively, as an average peak heat flux reduction of 72% and a rearward shift of the _ Q max by at least 82% of the model length are achieved for the "J" cases (3) A constant total pressure ratio PRs will result in a specific jet flow Mach disk location even under vastly different flight conditions (4) When the PRsAJ-TPS is in operation, the maximum surface heat flux _ Q max increases slightly with an increasing PRs, while the thermal protection range indicators x _ QN max /l and x _ QN=0:1 /l increase almost linearly (5) The tilted and with the nominal flight angle of attack aligned arrangement of the PRsAJ-TPS nozzle could provide robust thermal protection against the variation of angle of attack, especially when the angle of attack decreases, since the peak heat flux reduction could drop over 90% and the peak heat flux locates at the model bottom…”

“…The energy deposition method uses electromagnetic energy to interrupt and displace the bow shock ahead of the nose cone or leading edge to achieve the thermal protection of the stagnation point and drag reduction. Laser and plasma actuators are among the most popular options (see [3][4][5]). Transpiration cooling mimics the natural cooling mechanism "sweating" of living beings.…”

Experimental and numerical investigation of a self-supplementing dual-cavity plasma synthetic jet actuator

“…In this section, Fluent software was used to perform a 2D dynamic simulation of the SD-PSJA working process (mainly including energy deposition and jet expulsion) [20][21][22]. Firstly, the 2D model is selected, and the turbulence model is set as the classical k-ω model.…”