Numerical investigation of aerodynamic effects of opposite wrap-around fins at supersonic speeds

Abstract

In this research work, using numerical simulations, the three-dimensional flow around a standard projectile is investigated with two fin arrangement models, namely opposite and conventional wrap-around fins. Eliminating the rolling moment and investigation of aerodynamic performance of the new geometries are the purpose of this paper. Finite volume method is used to undertake the numerical simulations where flow is considered to be compressible, steady, nonviscous, and three-dimensional. For this purpose, the research begins with simulating the flow around a projectile with conventional fin arrangement and then the obtained values of drag coefficients and rolling moment are compared against experimental data, indicating the validity of the simulation results. After then, the effect of wrap-around fins in an opposite arrangement is investigated, with the results compared against those of the conventional configuration. The opposite fins are investigated at different opening angles and joint position, while the area of fins shading is assumed constant in all cases. Simulations were conducted at three Mach numbers of 1.5, 2.5, and 3.5, different angles of attack ranging within 0–14°, and lateral wind angles up to 8°. According to the results, the rolling moment in conventional wrap-around fins is a result of the pressure difference between sides of the fins, so that it can be avoided by configuring the fins in an opposite arrangement, which contributes to slightly higher drag coefficients too. Fin dimensions and their opening angle influence the regime of the flow passing through the fins, making their aerodynamic performance variable at different Mach numbers.

The simulation of single wraparound fin on a semi-cylindrical missile body

“…The validation of these simulations, for the results from Mach ∼2.7-3.0 M, were extended to the drag and rolling moment coefficients obtained by other wind tunnel and computational research studies as well (Dahlke and Craft, 1973; Fournier, 1977; Vitale et al , 1992; Edge, 1994; McIntyre et al , 1998; Paek et al , 1999; Mao et al , 2007; Liu et al , 2013; Li et al , 2015; Bagheri et al , 2018). The drag coefficient vs Mach number graph (Figure 16) show a general trend of decreasing with an increase in Mach number.…”

“…The aerodynamics of flow around the fin and the fin passage (area between the adjoining fins) have been examined again and again for improvement. It has been illustrated that at 0° angle of attack the pressure on both sides of the fins is different (Bagheri et al , 2018). The flow is influenced by the fin leading and trailing edge, and thus, many research studies have been carried out on them previously.…”

Comparison of Flow field in the proximity of A Single Planar & Wrap-around Fin

“…The fin drag comparison, between the planar and the wrap-around, showed that the WAFs had 10% higher value as that of the planar fins. In the past, numerous numerical studies (Bagheri, Pasandidehfard, & Tavakoli Sabour 2018;Li, Abbas, & Rui, 2015;Krishna, Surit, Kushari, & Ghosh, 2009;Eidell, Nance, McGowan, Carpenter, & Moore, 2012;Murman, 2007) have been performed on planar and wrap-around finned missiles which have used inviscid, viscid and turbulent flow conditions. However, most of these studies were performed on a complete missile body with four fins, these studies form the basis of implying turbulence modelling to the current model.…”