A Study On Dynamic Characteristic Of Grid Fin In Subsonic And Transonic Flow

In recent years, tactics missile develops very rapidly, and a main trait of shape designof tactics missile is that seeking stronger machine power. It is very attractive that grid fin isas a steady face or manipulative face of the aerocraft and tactics missile. Grid fin is anew-style missile fin, and it is provided with favorable dynamic characteristics, but itscomplicated structures enhance drag coefficient. It is the key to the reseach of dynamiccharacteristics how to cut down drag and enhance lift to drag ratio of grid fin.The dissertation mostly investigates, in subsonic and transonic flow, dynamiccharacteristics of grid fin is effected by the shapes and width to chord ratios of grid, andthe dynamic characteristics of a single grid fin when missile body and fins do or do notdisturb, and the dynamic characteristics of combined object of missle and grid fins. Theshapes of grid include upright square, 45-degree tilted square, upright hexagon, uprighttriangle, rhombus, rectangle and so on. The width to chord ratios are in the range of 0.7 to3.0.The results indicate: dynamic characteristics of grid fin is effected largely by theshapes, the optimal width to chord ratio is 2.0.Before or after disturbing, incrementpercentum of drag coefficient of grid fin is not too much, but one of its lift coefficient iscontrary, this makes out that molestations cause local attack angle becoming bigger. Alongwith roach number increasing, increment percentum of lift coefficient of grid fin cuts down.When molestations exist, along with roach number increment, the lift coefficient ofcross-model-position grid fin facing to wind reduces, but one of grid fin backing to wind isjust contrary, one of two side grid fin is uniform at same roach number. The lift coefficientcurve appears a characteristics of "two up two down".