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首页> 外文期刊>Aerospace science and technology >Unsteady pressure distributions at the wind tunnel model of a pitching Lambda wing with development of vortical flow
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Unsteady pressure distributions at the wind tunnel model of a pitching Lambda wing with development of vortical flow

机译：随着涡流的发展，Lambda变桨机翼风洞模型的非定常压力分布

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Unsteady pressure distributions at a pitching Lambda wing with 530 sweep angle are described in this paper. The tests with a half wing model with a purely round leading edge were conducted in the Transonic Wind Tunnel Gottingen. The free stream Mach number was varied between 0.3 and 0.7. Oscillation frequencies up to 22 Hz and amplitudes smaller than 1 were used. The pressure distributions suggest flow conditions that can be divided into three Regimes, depending on the mean angle of attack: I) Above 10, at the rear outboard part of the wing, the suction increases which is caused by a vortical flow occurring close to the surface. A strong suction peak emerges at the leading edge. II) At higher angles of attack, the strong suction peak at the leading edge breaks down, and a typical hump like pressure distribution below a vortex core is generated further downstream. This is the sign for a vortex flow further separating from the surface. Features of a vortex breakdown can be found. However, it lacks the typical signs for a transformation from a jet-like to a wake-like flow. III) Finally, the low pressure region below the vortex moves inboard and a deadwater type of flow exists at the outboard part of the wing. The unsteady pressure distributions strongly depend on the mean angle of attack. The highest unsteady pressures occur in Regimes II and III. Especially the out of phase parts drastically increase in Regime II. Furthermore, the quasi-steady effects strongly lag the motion. This means, the sign of the imaginary part of the unsteady pressure distribution is opposite to that of the real part. The lag increases with frequency. For angles of attack above that of the maximum lift, the negative lift slope turns positive with increasing frequency due to the strong lag of the vortex. (C) 2015 Elsevier Masson SAS. All rights reserved.
机译：本文描述了在具有530度后掠角的Lambda俯仰翼上的非定常压力分布。在Transonic风洞Gottingen中使用前缘为半圆形的半翼模型进行了测试。自由流马赫数在0.3至0.7之间变化。使用高达22 Hz的振荡频率和小于1的振幅。压力分布表明，根据平均攻角，流动状况可分为三种情况：I）大于10，在机翼的后外侧部分，吸力增加，这是由于靠近机翼的涡流产生的。表面。前沿出现一个很强的吸力峰。 II）在较大的迎角下，前缘处的强吸力峰破裂，并且在下游进一步产生典型的驼峰，如涡流核心下方的压力分布。这是涡流进一步从表面分离的迹象。可以发现涡旋破坏的特征。但是，它缺乏从喷射流向尾流转化的典型迹象。 III）最后，涡旋下方的低压区域向内移动，并且机翼的外侧部分存在死水流。不稳定压力分布在很大程度上取决于平均攻角。在制度II和III中出现了最大的不稳定压力。特别是第二阶段，异相部分急剧增加。此外，准稳态效应严重滞后于运动。这意味着，非稳态压力分布的虚部的符号与实部的符号相反。滞后随频率增加。对于大于最大升力的迎角，由于强烈的旋涡滞后，负升力斜率随着频率增加而变为正值。 （C）2015 Elsevier Masson SAS。版权所有。

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