The numerical simulations of flow over a spinning finned projectile at angles of attack ranging from 4 • to 30.3 • in supersonic conditions were carried out to investigate the flow mechanism of the Magnus effect. The finite volume method, a dual-time stepping method, and a γ − Re θ transition model were combined to solve the Reynolds-averaged Navier-Stokes (RANS) equations. The validation of temporal resolution, grid independence, and turbulence models were conducted for the accuracy of the numerical method. The numerical results were in certain agreement with archival experimental data. A comparison of the transient lateral force and time-averaged Magnus force between the body of finned projectile and the nonfinned body, the projectile fin and single fin was given. The key lies in the analysis of the reasons for the production of the Magnus force. The simulation provided a profound insight into the flow structure and revealed the following. The fin leading edge shock contributes to the unsteady interference on body lateral force, while the time-averaged body Magnus force is similar to that of the nonfinned body. At α = 30.3 • , the shielding effect of body on crossflow weakens the time-averaged body Magnus force induced by asymmetrical flow separation, the magnitude of which is reduced to the value at α = 8 • . The leeward separation vortices and the resistance on wingroot flow are responsible for the nonlinear interference of the projectile body on fin Magnus force at different angles of attack. When the low pressure region of the vortex core is equivalent to the size and position of fin, leeward separation vortices contribute more the time-averaged Magnus force and induce high frequency variation to the transient fin lateral force.
ARTICLE HISTORY
Reynolds-averaged simulations of flow over spinning finned missiles with and without canards were carried out at Ma = 0.6, 0.9, 1.5, and 2.5; a= 4°, 8°, and 12.6°; and v = 0:025 to investigate different mechanisms of the Magnus effect. An implicit dual-time stepping method and the g À Re ut transition model were combined to solve the unsteady Reynolds-averaged Navier-Stokes equations. Grid independence study was conducted, and the computed results were compared with archival experimental data. The transient and time-averaged lateral force coefficients were obtained, and the flow field structures were compared at typical rolling angles. The results indicate that in subsonic conditions, the canards interference intensifies the asymmetrical distortion of the body surface boundary layer and flow separation at different angles of attack, doubling the absolute value of the time-averaged body lateral force; the wash flow effect strengthens on the leeward tail due to the canards interference, increasing its time-averaged lateral force; in supersonic conditions, the shock and expansion waves induced by canards, the vortex system, and the flow separation are responsible for the fluctuation of the body lateral force; the direction of the canard induced wash flow alters as angle of attack increases, increasing first and then decreasing the time-averaged tail lateral force.
Based on the three-dimensional Navier–Stokes (N–S) equations, using unsteady numerical technology, flow over a dual-spin projectile was simulated to investigate its aerodynamic characteristics during flight. Spin was achieved via the sliding mesh method. The influence laws of the aftbody spin rate, Mach number, and angle of attack on the aerodynamic characteristics of the projectile are presented, and the flow mechanisms for the laws are revealed. The results demonstrate that the influence of the aftbody spin rate on the normal force coefficient is very small, whereas, on the lateral force coefficient, it is larger. With the increase in the Mach number, the time-averaged normal force coefficient and lateral force coefficient increase, while the fluctuation quantities of the normal force coefficient and the lateral force coefficient decrease. The variation of angle of attack will influence the size, distribution, and interference effect of the shedding vortices.
When the canard-controlled missile is conducting roll control, the asymmetric downwash induced by the canard impacts on the fins and produces a reverse rolling moment, resulting in the aerodynamic coupling between the canards and the fins. The rolling coupling can cause the reduction and even failure of the missile roll control. However, the current rolling decoupling methods always have adverse effects on the lift-drag ratio or flight stability of the missile. Based on the numerical simulation, this paper proposes a new method to reduce the roll coupling by adding a jet system between the canards and the fins. The effect of jet control was obtained under different freestream conditions. The influence of jet control factors on the missile aerodynamic characteristics was investigated and analyzed. The outcomes demonstrate that the jet control can effectively decrease the roll coupling between the canards and the fins, and eliminate the reverse rolling problem in most cases. With the same mass flow rate, the control effect is better at lower Mach number. Jet location and jet mode have a higher influence on the control effect. An optimal mass flow rate exists for the best control efficiency. This decoupling method is simple in structure and can reduce the side force and yawing moment without destroying the lift-drag ratio.
Obvious aeroelastic deformation occurs in spinning projectiles with large slenderness ratio, which seriously affects flight stability and maneuverability. This paper investigates the aeroelastic response of spinning projectiles with large slenderness ratio under supersonic speed. Based on a dynamic mesh method, an unsteady numerical simulation method is developed to study the aeroelasticity of spinning projectiles by coupling aerodynamics and structural dynamics. The numerical simulation method is well validated by the experimental results of AGARD 445.6 wing flutter. Then, the aeroelastic response of spinning projectiles with large slenderness ratio is numerically explored under different flight conditions. The aeroelastic response is obtained, revealing the presence of beat vibrations and variations in response frequency. Furthermore, the influence mechanism of flight conditions on the aeroelastic response is analyzed. The results suggest that the coupling of the first two modes of the projectile caused by the spinning motion leads to the occurrence of beat vibrations in the aeroelastic response; the coupling degree of the first two modes decreases as the angle of attack increases and it increases with the increase in spinning speed; and the time−averaged deformation caused by the time−averaged aerodynamic force is beneficial to the convergence of the aeroelastic response of spinning projectiles, while the rotation−induced Magnus effect is counterproductive.
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