Frequency characteristics of breakdown vortices over delta wings with small amplitude oscillation at the high angle of attack
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摘要: 在风洞和水洞中分别进行了小振幅振荡三角翼的动态测压和热膜测速实验,目的是研究振荡的无量纲频率 n 对于三角翼前缘涡的频率特性的影响.对风洞中测得的压力数据进行频谱分析,发现 n 值在0.018~0.036时,即与三角翼翼面上涡破裂点的振荡频率接近时,会发生耦合现象,使振动能量明显加强;对水洞中测得的速度数据进行频谱分析,则发现 n 在0.8~1.4的范围内,即与螺旋波的传播频率接近时,三角翼的振荡会使涡破裂点向后缘移动,延缓了涡的破裂,使螺旋波频率增大.Abstract: Experiments of dynamic unsteady pressure measurement and hot film velocity measurement with the small amplitude oscillation delta wings were carried out in a water channel and a wind tunnel respectively in order to investigate the influence of the nondimensional oscillation frequency n on the frequency characteristics of leading-edge vortices over delta wings. Power spectral analysis of pressure signal measured in the wind tunnel shows that at n =0.018~0.036, which is close to the oscillation frequency of vortex breakdown point, resonant phenomenon will happen and oscillatory energy will be largely enhanced. Power spectral analysis of velocity signal measured in the water channel shows that at n =0.8~1.38, which is close to the propagation frequency of spiral wave, the vortex breakdown point moves towards trailing edge, and therefore breakdown of vortices will be delayed and the dominant frequency will be increased.
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Key words:
- delta wing /
- small amplitude /
- oscillation /
- frequency
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