THE INFLUENCE OF FEATURES OF VORTEX FLOW ON AERODYNAMIC CHARACTERISTICS OF THE SUPERSONIC MANEUVERABLE AIRCRAFT MODEL

The paper presents the influence of the vortex flow features, in particular, the phenomenon of vortex burst on the longitudinal and lateral aerodynamic characteristics of the maneuverable aircraft model with a sharp-edged fore-body. Numerical simulation of vortex flow has been conducted at low subsonic speeds (M = 0.15) in a wide range of angles of attack α = 0 ÷ 35° at zero sideslip β = 0°, as well as at fixed values of angles of attack a = 10,25,30,35° in a wide range of slip angles β = 0 ÷ 20° using k - ω SST turbulence model with curvature correction due to the insensitivity of the standard model to such effects. A satisfactory agreement of the numerical results with the experimental data on both longitudinal and lateral aerodynamic characteristics in a wide range of angles of attack and sideslip is obtained. According to the results of the numerical simulations, all the main nonlinearities in the integral characteristics associated with the vortex breakdown phenomenon and the interference of vortex structures were explained. The physical features of the vortex flow around the maneuverable aircraft model with a sharp-edged nose and their influence on the longitudinal and lateral aerodynamic characteristics are revealed. The phenomenon of vortex breakdown significantly affects the aerodynamic characteristics of the model. And with the increase of the angle of attack the point of vortex breakdown moves up the stream. At non zero sideslip vortices are destroyed asymmetrically, which leads to a loss of transverse stability of the model. The interaction of the nose and wing vortices, as well as the relative position of the points of vortex breakdown in the range of angles of attack 18° < α < 28° at zero slip angle lead to nonlinearities in the dependence of the lift coefficients and the longitudinal moment of the angle of attack. At large angles of attack, the main vortices forming from the sharp-edged nose make a major contribution to the change in the aerodynamic coefficients, in contrast to the round nose, where the yawing stability is often determined by secondary vortices. The phenomenon of vortex breakdown significantly affects the contribution of the sharp-edged nose to the yawing stability. Moreover, its effect can be radically different at different angles of attack (a = 25-30° and 35°). The local change in the contours of the fore-body in the plan view also significantly affects the directional stability due to the delaying of the vortex burst.

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