Euler Equations And Efficient Numerical Methods And Delta Wing At High Angles Of Attack Off The Vortex Characteristics

This paper deals with the numerical solution of the Euler equation for airfoils using approximate boundary conditions and the effects dorsal fin on vortex over delta wing at high angles of attack.1. This paper develops approximate boundary conditions theories and use rectilinear grid. Boundary conditions on the surface of an airfoil are implemented by using their first-order expansions on the mean chord line. The method is not restricted to flows with small disturbances since there are no restrictions on the mean angles of attack of the airfoil. This study use of a stationary rectilinear grid offers substantial advantage in saving computer time and program design since it does not require the generation and implementation of time-dependent body-fitted grids.2. Application multi-grid method proceeds the increasing calculation speed. We success applied multi-grid method in solve Euler equation by used approximate boundary conditions. The result express that this method is acceleration computer speed.3. Presents a numerical simulation method researcher the vortex flow over a delta wing with dorsal fin at high angles of attack. A sharp-edged flat-plate delta wing of 82.5 sweep angle at an angle of attack of 30 and zero sideslip, the ration of the local fin height to the local wing semi-span are 0, 0.75 and 1.5. The analysis of the results from the numerical simulation shows the vortices over a flat-plate delta wing at high angles of attack with zero slip were conical, symmetric and stable but adding a low dorsal fin to the wing would destabilize the vortices and therefore render the originally symmetric vortices non-conical and asymmetric. The flow would recover symmetry and conicity only when the fin height is increased to a critical level. The results are in good agreement with experiments.