Numerical analysis of the effect of sweep-back angle on the stability derivatives of the grid fin

Abstract

Because of high hinge moment of planar fin in supersonic flow, designers have become more attentive to the grid fin configuration in recent years. One of the disadvantages of the grid fin is its high drag force. Fortunately, this problem could be handled by implementing sweep-back angle. Few studies have been carried out to investigate the effects of the sweep-back angle on dynamic coefficients. In this paper, computational fluid dynamics is used to investigate the effect of grid fin’s sweep-back angle on the rolling and pitching dynamic coefficients in supersonic flow regime. The first step is dedicated to simulating two experimental geometries and detecting optimal mesh number and appropriate turbulence model. Unsteady dynamic coefficients along with moving mesh have been extracted by simulations. These coefficients are reported for different Mach numbers. In order to scrutinize the results, the static stability derivatives have been discussed, too. According to the simulations, each sweep-back angle has a unique trend of changing dynamic and static coefficients in terms of the Mach number. This trend is justified by studying Mach number contours for few states. Afterward, dynamic coefficients of the planar fin are presented and compared with the grid fin.