2019 Volume 62 Issue 4 Pages 219-226
This study is focused on the effect of boattail angle on the pressure distribution and drag force of axisymmetric afterbodies under low-speed conditions. Experiments were conducted on three conical boattails with angles of 10°, 14° and 20°. The diameter-based Reynolds number is approximately 4.3 × 104 under the experimental conditions. Two types of flows, a fully-attached flow (β = 10°) and a flow with a separation bubble (β = 14°, 20°), were observed. The aerodynamic drag measurements were conducted using both a strut-supported model and a support-free (levitated) model. The results show that boattail model with the angle of 20° has a relatively large effect on the pressure distribution. The pressure drag resulting from pressure distribution on the vertical plane indicates that the model with a boattail angle of 14° has the lowest drag. A good trend in agreement between afterbody drag (measured using pressure taps) and total aerodynamic drag (measured using the levitated system) was obtained. The effect of strut support on pressure distribution at different polar angles is also explained in this study.
