tailieunhanh - Bài giảng Khí động lực học: Bài 3 - Nguyễn Mạnh Hưng

Bài giảng Khí động lực học bài 3 cung cấp cho người học những kiến thức về phân bố lực nâng, các loại cánh trong phân bố lực nâng và ví dụ thực tế về một thiết bị ứng dụng phân bố lực nâng. Đây là tài liệu tham khảo phục vụ cho các bạn chuyên ngành Kỹ thuật hàng không và những ngành có liên quan. | Khí động lực học (bài 3) Phân bố lực nâng-lift distribution Các loại cánh khác nhau cho phân bố lực nâng khác nhau. Phân bố lực nâng elip cho lực cản là nhỏ nhất thiết kế cánh để có phân bố lực nâng theo yêu cầu Cánh elip-elliptical wing Cánh hình chiếu dạng elip The term downwash has two meanings within the field of aerodynamics. One meaning, used most often by non-engineers, refers to the forcing of air downward during the creation of lift. This usage is most common with regard to helicopters where the effect is most dramatic. The other meaning, used most often by engineers and pilots, refers to the flow of air behind a wing. The downwash immediately behind a wing is a consequence of the wing vortex system (also see horseshoe vortex). This downwash is experienced by a horizontal tail placed in the flow behind a wing. The primary influence of downwash on the horizontal tail is an increase in angle of attack on the tail. (The horizontal tail generates lift in the downward direction, unlike the wing. A disturbance that causes an increase in angle of attack on the wing will cause a decrease in angle of attack on the horizontal tail, and vice versa.) These meanings are closely related. They differ primarily in terms of scale. The "pilot's meaning" is a much larger-scale effect than the "engineer's meaning". Downwash is also related to the difference in pressure between the top and bottom of a wing. At the tip of a wing, this difference in pressure will "leak" around the tips from the bottom to the top, resulting in wingtip vortices. Downwash is a component of the vortex system generated by a wing (see horseshoe vortex). The energy stored in trailing vortices is the product of induced drag multiplied by true airspeed. [edit] Upwash If an airfoil's vortex produces downwash, somewhere else the airframe must also produce a similar amount of upwash. In stable flight this occurs approximately within the airframe surface envelope; it can also occur outside of the | Khí động lực học (bài 3) Phân bố lực nâng-lift distribution Các loại cánh khác nhau cho phân bố lực nâng khác nhau. Phân bố lực nâng elip cho lực cản là nhỏ nhất thiết kế cánh để có phân bố lực nâng theo yêu cầu Cánh elip-elliptical wing Cánh hình chiếu dạng elip The term downwash has two meanings within the field of aerodynamics. One meaning, used most often by non-engineers, refers to the forcing of air downward during the creation of lift. This usage is most common with regard to helicopters where the effect is most dramatic. The other meaning, used most often by engineers and pilots, refers to the flow of air behind a wing. The downwash immediately behind a wing is a consequence of the wing vortex system (also see horseshoe vortex). This downwash is experienced by a horizontal tail placed in the flow behind a wing. The primary influence of downwash on the horizontal tail is an increase in angle of attack on the tail. (The horizontal tail generates lift in the downward .