Effects of two blowing jets on aerodynamic characteristics of a 20 percent thick, non-cambered airfoil are described. Free stream wind tunnel velocity is 10m/s and the Reynolds number is 1.7×105. Section lift, drag and pitching moment coefficients are given at some effective angles of attack. The position of the second slot has a strong effect on the characteristics and the highest lift to drag ratio is given at the position of 55° measured from the first one. Two-jet system is found to be more effective in producing high lift than one-jet system at the same jet-power coefficient.
In high-temperature argon plasma flows, temperature of Teflon ablation layers have been measured spectroscopically with the C2 Swan (0, 0) and (1, 1) bands emitted from the layers. Experimental intensity distributions of these bands are measured and compared with synthetic ones based on the simplified line-by-line calculations to determine the rotational and vibrational temperatures. The results show that the present method is very effective. It is also found that the both temperatures are significantly in nonequilibrium state with each other near the nozzle exit, approaching equilibrium rapidly with the axial distance from the exit, and that they almost proportionally increase with an increase of the plasma heat flux.
Measurements were made on the mean and fluctuating velocities in a turbulent boundary layer without pressure gradient, but with streamwise vortices introduced artificially by a series of vanetype vortex generators. Effect of the streamwise vortices is observed explicitly from spanwise variation of the profiles of mean and fluctuating velocities. In particular, the shape factor of the mean velocity profile (the ratio between the displacement and momentum thicknesses) exhibits values lower than that of the undisturbed flow in the majority of the spanwise sections, suggesting the tendency toward delaying boundary layer separation. The mean streamwise vorticity is mostly concentrated in the vicinity of the vortex core, and this is accounted for as produced by the anisotropy of the normal Reynolds stresses. In the adjoining spanwise section there exists also a region of counter-rotating streamwise vorticity, which is weaker in strength but inhibits the diffusion of the primary streamwise vorticity. Both the anisotropy of normal Reynolds stresses and the generation of counter streamwise vorticity appear to contribute to the mechanism by which the streamwise vorticity could persist for a long distance.
The induced normal force and rolling moment due to wing-tail interference is studied experimentally. Wind tunnel tests of TT-500A rocket model and a roll-controllable rocket model was performed at NAL 2m×2m Transonic Wind Tunnel and 1m×1m Blowdown Supersonic Wind Tunnel. Characteristics of normal-force-induced normal force and rolling moment, and rolling-moment-induced rolling moment on the tail-fins are obtained varying flow Mach number, angle of attack and bank angle. The results are compared with theoretical results based on the strip-theory.
Freejet flow-fields are computed using the piecewise-linear method. The results show better descriptions of the freejet configurations in that the shock discontinuities such as the barrel shock and the Mach disk appear much sharper than those figures obtained by using the two-step LaxWendroff scheme. The calculated shapes of the barrel shock and the Mach disk agree very well with those obtained experimentally using the laser induced fluorescence method.