旋转绕丝圆柱的数值研究

A. Begum, Komal Gada, H. Rahai
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引用次数: 0

摘要

以前的调查[1-3]对旋转圆柱体的影响,无论是光滑的表面或圆柱体与不同的表面几何形状,放置在前缘或对称翼型的后缘对其气动参数表明,在前缘旋转不提供显著升力,而放置旋转圆柱体在训练边缘结果超过20%的升力增加在所有攻角(AOA)调查。增加旋转速率(α),即圆柱表面切向速度(Uτ)与自由流平均速度(U∞)之比,可以增加升力,且槽形圆柱比光滑圆柱产生更大的升力。有一个增加阻力时,旋转圆柱被放置在翼型的后缘。本文对一个旋转的绕丝圆柱进行了非定常数值研究,该圆柱体置于定常流动中,α在0和2之间变化。自由流平均速度恒定在10米/秒。光滑圆柱直径为5 cm,对应的雷诺数约为3.2 × 104。缠绕的丝径为5mm,节距与圆筒直径之比为1。电线紧紧地缠绕在整个汽缸上。圆筒的长径比为20。旋转速率(α)为0.5 ~ 2.0。结果表明,绕丝旋转气缸的升力高于旋转光滑气缸,在α = 2时,绕丝旋转气缸的升力接近光滑气缸的150%。然而,在较高的转速下,绕丝气缸具有较大的阻力。α = 2时,光滑旋转气缸的升阻比为3.89,绕丝旋转气缸的升阻比为3.54。流动的细节表明,绕丝降低了相干性,增加了旋涡的相位角,从而增加了升力。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Numerical Investigations of a Rotating Wire-Wrapped Cylinder
Previous investigations [1–3] on the effects of rotating cylinder with either a smooth surface or cylinders with different surface geometries, placed at either the leading or the trailing edge of a symmetric airfoil on its aerodynamic parameters have shown that rotation at the leading edge does not provide significant lift, while placing the rotating cylinder at the training edge results in more than 20% increase in lift at all angles of attack (AOA) investigated. Increasing the rotation rate (α), the ratio of tangential velocity at the surface of the cylinders (Uτ) to the free stream mean velocity (U∞), increases the lift and grooved cylinders produced more lift than the smooth cylinder. There is an increase in drag when the rotating cylinder is placed at the trailing edge of the airfoil. Here we performed unsteady numerical investigations of a rotating wire-wrapped cylinder, placed in steady flow with α varied between 0 and 2. The free stream mean velocity was constant at 10 m/sec. and the smooth cylinder diameter was 5 cm, which corresponds to an approximate Reynolds number of 3.2 × 104. The wire wrapped had a wire diameter of 5 mm and the ratio of pitch spacing to the cylinder diameter was 1. The wire was wrapped tightly around the entire cylinder. The cylinder has a length to diameter ratio of 20. The rotation rate (α) ranged from 0.5 to 2.0. Results indicate wire-wrapped rotating cylinder produce higher lift than the rotating smooth cylinder and at α equal to 2, the lift for the wire-wrapped cylinder is nearly 150% of the lift of the smooth cylinder. However, wire-wrapped cylinder has higher drag force at higher rotation rate. At α = 2, the lift to drag ratio for the smooth rotating cylinder is 3.89, while the corresponding value for the rotating wire-wrapped cylinder is 3.54. Details of the flow indicates wire-wrapping reduces coherency and increases phase angle of vortices, resulting in increased lift.
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