Prediction of Ballistic Separation Effect by Direct Calculation of Incremental Coefficients

Abstract

The ballistic separation effect in an aircraft flowfield was predicted via the direct calculation of incremental coefficients. A highly robust flow solver, including a Chimera grid module, was used to create the trajectory of a released store and to calculate incremental coefficients. The incremental coefficients were computed according to the difference between the aerodynamic coefficients in the aircraft flowfield and in the freestream condition. Two different calculations can be executed simultaneously in a parallel computing environment. The aircraft flowfield effect was measured using the incremental coefficients. This method of direct calculation of the incremental coefficients was tested in the case of released stores in two-dimensional subsonic and supersonic flow regions. The accuracy of the unsteady trajectory calculation was verified through comparisons with the captive trajectory system data in the Eglin wing/pylon/store separation problem. The method was then applied to a generic bomb released from a full-body aircraft. The computational results show that the current method is capable of simulating the store trajectory and investigating aircraft flowfield effects. NomenclatureC l , C m , C n = store rolling, pitching, and yawing moment coefficients= contravariant velocities along the generalized coordinates U g = grid velocity u, v, w = Cartesian velocity components C x = incremental force coefficient in the x direction , p, e = density, pressure, and total energy , , = roll, yaw, and pitch angles

Study on Influencing Factors of Two-Body Parallel Separation

“…At present, there are many studies on the separation of two bodies. Ai [2] et al presented the progress and main problems of the separation of embedded weapons; Kim [3] et al provided a ballistic separation trajectory prediction method, and used nested grid and 6-DOF equations to numerically simulate the separation problem of airborne missiles and verified the rationality of the method; Liu [4] et al studied the inter-stage separation process of TSTO model based on the nested grid technique and concluded that there is an aerodynamic interference phenomenon in the two-stage separation process that seriously affects the aerodynamic characteristics of the separated bodies; Bordelon [5] et al changed the relative positions of the two bodies to observed the aerodynamic characteristics at different discrete positions and showed the relationship between aerodynamic characteristics and relative positions. Song [6] et al summarized the multi-body vehicle separation problem and proposed the existence of complex aerodynamic environmental phenomena such as excitation reflection, diffraction and mutual interference in the clearance of the multi-body separation process; Gong [7] et al studied the parallel inter-stage separation process of the TSTO model and illustrated that sufficient safety distance should be left in the two-body separation process.…”

Assessment of turbulence models and mesh types for the simulation of multi-body separation by coupling the CFD and rigid body dynamics

“…Xu et al find that the effect of aerodynamic interference caused by release is only significant at its beginning, and almost negligible with the increase of the distance between the aircraft and the external stores. Kim and Kwon [13] used overlapping grid technique to solve the Euler equation and 6-DOF equation. Kim and Kwon examined the separation of store from KT-1 aircraft and estimated the target point.…”