نوع مقاله : مقاله پژوهشی
نویسندگان
1 مجتمع دانشگاهی مکانیک و هوافضا، دانشگاه صنعتی مالک اشتر، اصفهان
2 دانشکده مهندسی مکانیک و هوافضا، دانشگاه صنعتی مالک اشتر، اصفهان
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
In this research, the flow fields over two lambda shaped wings were investigated. The velocity distributions were obtained using a hot wire anemometer. A lambda wing is one type of delta wing with a crank in its trailing edge, and the application of this type of wing is increasing in flying wings. In the present work, two different leading edge shapes, namely, sharp and round, were applied for the lambda wing. The wing had two sweep angles of 55 and 30 degrees. The experiments were conducted in a closed circuit wind tunnel at V=20 m/s and angles of attack of 5 to 20, with the step of 5 degrees. The Reynolds number of the model was about $2\times 10^{5}$ according to the model length. The turbulence intensity across the tunnel working section was measured by the hot wire, and was obtained between 0.2 to 0.25\%. To move the holder of the hot wire, a traversing system with three degrees of freedom was used. The pressure measurement of the flow field over the wing was also performed using a pitot tube for validation of the hot wire results. The experimental results showed multiple vortical flows over the wing. A dual vortex structure was formed above the wing surface before the leading edge crank, and another vortex flow was seen after the change of the leading edge sweep. The standard deviation of the measured velocity increased at the core of the vortices, reflecting the instability of the flow at that region. By increasing the angle of attack, i) the pressure drop increased and the vortices became wider; ii) the vortices moved inboard along the wing, and away from the surface; and iii) the flow separation initiated from the outer portion of the wing and progressed to its inner part. The vortices of the wing of the sharp leading edge were stronger than those of the round one.
کلیدواژهها [English]
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