| Summary: | 碩士 === 國防大學理工學院 === 機械工程碩士班 === 102 === In this research, computational fluid dynamics was applied and low-speed wind tunnel experiments were performed to study the aerodynamic characteristics of lift and drag exhibited by a three-dimensional Javelin antiarmor missile. The missile had various numbers of wings (0,4,8, or 12 and a tail of 4) with Mach numbers ranging from 0.2 to 0.6 and angles of attack ranging from -5° to 5°. The types of missiles were denoted as BT, BW4T, BW8T, and BW12T, where B is the missile body, W is the wing, T is the tail, and the arabic numeral is the number of wings.
The results indicated that when the fin did not swing, the drag coefficient of the number of fins increased. When the angle of attack increased, the drag coefficient also increased. When the angles of attack had the same positive and negative values, the drag coefficient values were symmetrical. A simulation indicated that the lift of the wing is the main lift source for the missile body; its lift coefficient increased linearly with the relationship between the angle of attack. When the number of fins was from 4 to 8, the rate increased. A higher number of fins (from 8 to 12) filmsincreased it significantly reduce lift. This study explored the reasons for the excessive number of pieces produced for the wing that generate interference. A comparison of BW8T and BW12T indicated that the lift and drag coefficient ratios of these missiles are nearly identical and greater than those of BW4T and BT. Therefore, the Javelin antiarmor missile in top attack mode works the most efficiently with 8 wings. The configuration in the present study indicated that four model types can reach more than 40° in the stall angle of attack.
Because of hardware limitations, a low-speed wind tunnel that velocity was used in an incompressible flow test on four types of models. Considerations of fluid compressibility when the missiles flew at subsonic speeds, references to the PG and VT transformation formulas, and simulation results were derived to calculate the three-dimensional missile lift and drag coefficient transformation formula. The experimental transformation data and the simulation data were compared. The drag coefficient and lift coefficient errors were less than 1.5% and 10%, respectively. These results can be used to reduce the cost of future subsonic wind tunnel experiments. The methods used in this study were ideal and acceptable, and the contributions of this paper include a gradual improvement in research and development capabilities for antiarmor missiles.
Keywords：Javelin antiarmor missile, computational fluid dynamics (CFD), low-speed wind tunnel, aerodynamic characteristics, compressibility
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