Numerical Simulation Of Decrease In Drag For Grid Fins

Grid fin contains out frame and many inner grid walls, which is lifting surface. It can befound, by studying for aerodynamic characteristics, that grid fins has more importantaerodynamic characteristics than planar fins. But the problem of having more drag force thanplanar fins limits it to application. At present, there are four measures to decrease dragforce,which contain decreasing thickness of grid walls, chamfering leading edge and trailingedge, reducing grid number and choosing appreciate cross-section of grid walls, which usedifferent theory for decreasing drag force positively or negatively. But this paper has a newmethod to reducev∞and raise critical Mach number,which can reduce drag force. To makeswept-back grid walls is the method. The method is significant for people to go a step to studythe aerodynamic characteristics of grid fins.The swept-back wings of airplane used to reduce drag force can be transplanted to gridfins. The drag force can be reduced by a wide margin if every grid walls have swept-backangle, because grid fin is the system with multitudinous lifting-surface,which has moreefficiency.For this,the3D model swept-back grid fin is established directly, numericalsimulation is carried out on the aerodynamic characteristics of subsonic and transonic regionof grid fins, and analysis of relevant parameters, and opened up a new direction in order tostudy the technology of drag reduction of grid fin.In this paper, the analysis of the shape and structure of grid fin is given, than the newdrag reduction principle is introduced, which is demonstrated the feasibility beforeestablishing the model of grid fins. The data of the two different groups are compared andstudied through the simulation to analyze the before and after improvement of grid fins.Thenumerical simulation of The single grid fin’s simulation includes horizontal layout andvertical layout, due to the Aerodynamic layout of grid fin is "+" font along the circumferentialdirection of missile. And then, the simulation of the data of the bodies and the grid fin wereanalyzed, which, respectively, contain the lift coefficient and drag coefficient and lift-dragratio. The swept-back grid fin has the positive function to decrease drag and increase lift-drag ratio.