Development of Three-dimensional Grid-free Solver and its Applications to Multi-body Aerospace Vehicles

Grid-free solver has the ability to solve complex multi-body industrial problems with minimal effort. Grid-free Euler solver has been applied to number of multi-body aerospace vehicles using Chimera clouds of points including flight vehicle with fin deflection, nose fairing separation of hypersonic launch vehicle. A preprocessor has been developed to generate connectivity for multi-bodies using overlapped grids. Surface transpiration boundary condition has been implemented to model aerodynamic damping and to impose the relative velocity of moving components. Dynamic derivatives are estimated with reasonable accuracy and less effort using the grid-free Euler solver with the transpiration boundary condition. Further, the grid-free Euler solver has been integrated with six-degrees of freedom (6-DOF) equations of motion to form store separation dynamics suite which has been applied to obtain the trajectory of a rail launch air-to-air-missile from a complex fighter aircraft.Defence Science Journal, 2010, 60(6), pp.653-662, DOI:http://dx.doi.org/10.14429/dsj.60.58

Influence of Aircraft Flow Field on the Longitudinal Stability of a Missile

An air-to-air missile launched from a fighter aircraft needs to be stable at launch to enable safe separation from the aircraft, and less stable in the terminal phase of its flight to become highly maneuverable to intercept the targets. A study has been carried out to estimate the effect of the aircraft flow field on the longitudinal stability of the missile using an in-house developed 3-D grid-free Euler solver. Initially, the missiles are placed in the captive location in the launcher of the aircraft. One of the missiles is then moved to various pre-determined locations ahead of the wing of the aircraft, keeping the other missile at the captive location. The centre of pressure and stability margin of the missile is determined at these locations. It is observed that the presence of aircraft has a substantial effect on the longitudinal stability of the missile. The centre of pressure of the missile is seen to move aft as it leaves the launcher. As the missile moves, the centre of pressure reaches a maximum aft position and then moves forward till it reaches a position where the missile is free from the influence of the aircraft. It is observed that as the missile moves away from the region of strong influence of the aircraft, its aerodynamic characteristics approach asymptotically to that of the isolated missile.Defence Science Journal, 2013, 63(3), pp.242-248, DOI:http://dx.doi.org/10.14429/dsj.63.209

Separation Dynamics of Air-to-Air Missile and Validation with Flight Data

Prediction of flight characteristics of a store in the vicinity of an aircraft is vitally important for ensuring the safety of the aircraft and effectiveness of the store to meet the mission objective. Separation dynamics of an agile air-to-air-Missile from a fighter aircraft is numerically simulated using an integrated store separation dynamics suite. Chimera cloud of points along with a grid-free Euler solver is used to obtain aerodynamic force on the missile and the force is integrated using a rigid body dynamics code to obtain the missile position. In the present work, the suite is applied to a flight test case and sensitivity of trajectory variables on launch parameters is studied. Further, the results of the suite are compared with the flight data. The predicted body rates and Euler angles of missile compare well with the flight data. 

Theory and application of 3-D LSKUM based on entropy variables

This paper describes the theory and application of a grid-free kinetic upwind scheme known as LSKUM.The basic principle in LSKUM is the determination of derivatives occurring in the conservation laws using the least squares method. The grid-free nature of the scheme is obtained because the least squares method can be used on an arbitrary distribution of nodes, i.e. the nodes need not form a structured/unstructured grid