Abstract:In order to study the impact of the vehicle on the flow field and drag permeance of the cross parachute, the PISO algorithm was used to conduct numerical calculations of the unsteady flow around the cross parachute- vehicle system based on the Realizable k-ε model, and a detailed flow field was obtained. The flow field distribution rules of the cross parachute-vehicle system and the changes in aerodynamic characteristics of the parachute and the vehicle under different trailing distance were studied. The results show that when the trailing distance λ≤2, the vehicle and the parachute form a closed flow. The drag loss of the parachute is serious, and when the trailing distance λ>2, the pressure in the wake area of the underwater vehicle recovers, a stable positive pressure area is formed at the bottom of the parachute, the flow form gradually changes from closed to open. The pressure difference Δp when the trailing distance λ is the largest increases by 12% compared to the pressure difference when the trailing distance is the smallest. The resistance of the parachute is restored and the resistance fluctuation is reduced. When the drag ratio λ=4, the resistance of the parachute and the vehicle increases by 1.8% and 25% respectively. The velocity and pressure contour show that the flow field and pressure distribution of the cross parachute-vehicle system are more symmetrical and the aerodynamic characteristics are in the best state.
