Simulation of Store Separation using Low-cost CFD with Dynamic Meshing

Abstract

The simulation of the store separation using the automatic coupling of dynamic equations with flow aerodynamics is addressed. The precision and cost (calculation time) were considered as comparators. The method used in the present research decreased the calculation cost while limiting the solution error within a specific and tolerable interval. The methods applied to model the aerodynamic forces are time-dependent dynamic meshes and quasi-static methods. In the time-dependent method, a dynamic unstructured tetrahedral mesh approach using combination of spring-based smoothing and local remeshing is employed in respect of bodies motion with an implicit, second-order upwind accurate 3d Euler solver. In this method, a 6dof dynamic code is coupled with the flow solver to update the store trajectory information. In the quasi-static method, a 3-D implicit, steady state Euler solver is automatically integrated with a grid generation software and a 6dof dynamic code. Although the time-dependent method is more precise and reliable, it is not proper and appropriate for the initial design of the separation system due to its high cost. The quasi-static solution is very fast, but unable to simulate realistically because of not satisfying the problem conditions due to solution divergence as the store speed increases. The method used in the present research decreased the calculation cost while limiting the solution error within a specific and tolerable interval. In this way, the time step can be enlarged, the solution can be carried out with a few calculation points, and the solution can have considerably more speed with a limited error magnitude. Simulation of the store separation using the automatic coupling of dynamic equations with flow aerodynamics with the new Low-Cost method is the innovative aspect of this paper. To validate the solution method, the transonic store separation was simulated that agreed well with the wind tunnel test outcomes.