عنوان مقاله [English]
A fin in an aircraft accounts for stability and control which can be in planar or latticed shape. A latticed fin consists of several crossing planes placed in a frame and in contrast to planar fin, is perpendicular to flow direction. In comparison to planar fins, latticed fins have low hinge moment, high stall angel, high axial force and low roll dynamic coefficient. Recently, designers have more focused on latticed fins, because of high hinge moment of them in supersonic flow regime. Due to smaller chord length, latticed fin has lower roll coefficient in comparison to planar fin, which is important in roll stability of aircraft. Therefore, design of a latticed fin with low axial force and high roll dynamic coefficient is very important. In this paper, impact of latticed fin sweep back angle on roll dynamic and static coefficients in supersonic regime is investigated using computational fluid dynamics (CFD). Firstly, simulation of two geometries with known experimental results was done and then, optimum grid and proper turbulence model is chosen. Simulation for obtaining static coefficients was done in steady state and for dynamic coefficients; it was done in unsteady condition. Figures of axial force coefficient, normal force coefficient gradient and roll dynamic coefficient is given for flight Mach of 1.1, 1.5 and 2. Results show that the effect of fin sweep back angle relates to flight Mach. In low flight Mach, sweep back angle improves fin performance, but in high flight Mach, it causes poor aerodynamic performance of fin.
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