Effect of Boattail Angle on Pressure Distribution and Drag of Axisymmetric Afterbodies under Low-Speed Conditions

Abstract

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 © 10 4 under the experimental conditions. Two types of flows, a fully-attached flow (¢ = 10°) and a flow with a separation bubble (¢ = 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.

The Effect of Boattail Angles on the Near-Wake Structure of Axisymmetric Afterbody Models at Low-Speed Condition

“…However, this effect is reduced for the boattail model. Tran et al [15], who conducted a free-levitated test and measurement with support system for axisymmetric boattail model at low-speed conditions, showed that the drag in the free-levitated test and drag using support system shows a similar trend for different boattail angles. Additionally, the effect of strut support on pressure distribution at lower and upper surfaces in the symmetric plane is the same.…”

Phân Tích Dòng Chảy Trên Bề Mặt Bằng Xử Lý Ảnh Và Ứng Dụng Trong Xác Định Trường Ma Sát Trên Bề Mặt Cánh Tam Giác

“…Mặc dù các giá trị chỉ là định tính, mô phỏng số đóng góp lớn trong quá trình nghiên cứu và xây dựng mô hình ban đầu. Trần Thế Hùng và cộng sự [3]- [7], nghiên cứu dòng chảy trên mô hình đuôi vát chỉ ra rằng, khi mô hình mô phỏng số phù hợp được lựa chọn, các kết quả tính toán tương đối đồng nhất với thực nghiệm. Lê Đình Anh và cộng sự cũng cho thấy mô hình mô phỏng số rất hiệu quả trong nghiên cứu dòng hai pha [8]- [10] cũng như ứng dụng hiệu quả trong xây dựng và tối ưu hóa mô hình tua bin gió trục đứng [11], [12].…”

Effect of ribs in a suddenly expanded flow at sonic Mach number

“…At transonic Mach number contribution from the base, drag is 60 % of the total vehicle drag. This contribution is due to the low-pressure region formed at the base [ 1 ], and increasing the base pressure reduces the base drag [ 2 ]. The base pressure can be controlled by using active and passive control approaches.…”