平板湍流边界层流向—法向平面发卡涡的PIV实验研究

发布时间：2018-02-17 00:49

本文关键词： PIV 湍流边界层发卡涡涡包漩涡强度涡识别　出处：《船舶力学》2016年Z1期 　论文类型：期刊论文

【摘要】：湍流边界层流动精细涡结构的分析对于水下航行体表面减阻乃至降噪机理的深入研究都具有重要意义。文章应用粒子图像测速技术(PIV),对Re_θ=1 743和5 400时的平板湍流边界层的流向一法向平面流场进行了测试研究。一方面,直接对瞬时速度场精细涡结构进行提取分析,通过Galilean分解和λ_(ci)准则识别出流向—法向平面中的发卡涡及发卡涡包。研究表明,发卡涡和雷诺应力的分布特征具有高度相关性;发卡涡包产生了流向动量的法向不规则分层分布特征。另一方面,文中通过对500个瞬时速度场子样进行时间平均分析,获得了不同雷诺数下平均速度以及湍流度分量的法向分布规律。此外,文中还对发卡涡的几何尺寸和漩涡强度λ_(ci)进行了统计分析。研究表明,在y~+50范围内无量纲化的漩涡强度λ_(ci)δ/u_τ沿法向迅速衰减,且在不同雷诺数下变化曲线基本一致;在y~+50后λ_(ci)δ/u_τ衰减平缓,且低雷诺数下的值较大。
[Abstract]:The analysis of the fine vortex structure of turbulent boundary layer flow is of great significance for the deep study of drag reduction and even noise reduction on the surface of underwater vehicle. In this paper, the particle image velocimetry technique is applied to the plate turbulence at Re胃 1 743 and 5 400. The flow field of the boundary layer in a normal plane is studied. The fine vortex structure of instantaneous velocity field is extracted and analyzed directly, and the hairpin vortex and the hairpin vortex package in the flow direction normal plane are identified by the Galilean decomposition and 位 _ S _ (cic) criterion. The study shows that the distribution characteristics of the hairpin vortex and the Reynolds stress are highly correlated. On the other hand, 500 samples of instantaneous velocity field are analyzed in time average. The normal distribution of the mean velocity and turbulence component at different Reynolds numbers is obtained. In addition, the geometric size and swirl intensity of the hairpin vortex are analyzed statistically. In the range of y50, the dimensionless swirl strength 位 _ C _ I) 未 / u _ 蟿 attenuates rapidly along the normal direction, and the variation curve is basically the same at different Reynolds numbers, and the attenuation of 未 / u _ 蟿 is gentle after y50, and the value at low Reynolds number is larger.
【作者单位】：中国船舶科学研究中心船舶振动噪声重点实验室;
【基金】：国家自然科学基金项目(51379193) 江苏省自然科学基金项目(BK2012536)
【分类号】：O357.5

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