Flow facility design and experimental studies of wall-bounded turbulent shear-flows
Flow facility design and experimental studies of wall-bounded turbulent shear-flows
复制标题
壁面湍流剪切流流动设施设计与实验研究
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
B. Lindgren
中科院分区：
文献类型：
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作者：
B. Lindgren
本论文涵盖了湍流领域内的一系列主题，从流动设施的设计到尺度规律的评估和通过使用实验数据的湍流建模方面。国防部已经设计、建造和评估了一个新的风洞。力学，香港理工学院特别注意的是转向叶片的设计，它不仅可以转动气流，还可以在角落里进行大的膨胀而不分离。流动质量的研究证实了扩角的概念是可行的，可以成功地应用于低湍流度风洞。KTH力学系的MTL风洞的流动质量也进行了调查，证实它仍然是非常好的。总的来说，这些结果与隧道新建时的测量结果相当，但由于冷却系统的改进，温度变化减少了1 / 4。研究了高雷诺数零压力梯度湍流层的实验数据。这些研究主要集中在尺度定律上，例如，在位于对数重叠区域外的一个区域，大约是边界层厚度的一半大小的指数速度缺陷定律的确认。当用局部均方根值进行缩放时，发现重叠区域的流向速度概率密度函数是自相似的。研究了近壁区和缓冲区的流动结构。随着雷诺数的增加，近壁条纹对流动的相对影响减小，但证实近壁条纹间距约为100个粘性长度单位。采用PIV和LDV对非对称平面扩散器内的分离流动进行了测定。所有三个速度分量都沿着扩散器的中心线在一个平面上测量。给出了平均速度、湍流强度和湍流动能的计算结果，以及描述分离区域的流线和回流系数的计算结果。瞬时速度场也显示了高波动的流动。上述速度量的结果，以及湍流动能和二次各向同性不变量的产生，也与基于k -w公式和EARSM模型的模拟数据进行了比较。模拟数据严重低估了分离泡的大小。关键词：流体力学，风洞，非对称扩散器，湍流边界层，流动结构，pdf，建模，对称方法
The presen present thesis spans a range of topics within thearea of turbulent flows, ranging from design of flow facilitiesto evaluation aluation of scaling laws and turbulence modelingdeling aspects through use of experimental data. A newwind-tunnel has been designed, constructed and evaluated at theDept. of Mechanics, KTH. Special attention was directed to thedesign of turning vanes that not only turn the flow but alsoallow for a large expansion without separation in the corners.The investigation of the flow quality confirmed that theconcept of expanding corners is feasible and may besuccessfully incorporated into low turbulence wind-tunnels. Theflow quality in the MTL wind-tunnel at the Dept. of Mechanics,KTH, was as also in investigated confirming that it still isvery good. The results are in general comparable to thosemeasured when the tunnel was as new, with the exception of thetemperature variation ariation that has decreased by a factorof 4 due to an improved cooling system.Experimental data from high Reynolds number zeropressure-gradient turbulent layers have been investigated.These studies have primarily focused on scaling laws withe.g.confirmation of an exponential velocity defect lawin a region, about half the size of the boundary layerthickness, located outside the logarithmic overlap region. Thestreamwise velocity probability density functions in theoverlap region was found to be self-similar when scaled withthe local rms value. Flow structures in the near-wall andbuffer regions were studied ande.g. the near-wall streak spacing was confirmed to beabout 100 viscous length units although the relative influenceof the near-wall streaks on the flow was as found to decreasewith increasing Reynolds number.The separated flow in an asymmetric plane diffuser wasdetermined using PIV and LDV. All three velocity componentswere measured in a plane along the centerline of the diffuser.Results for mean velocities, turbulence intensities andturbulence kinetic energy are presented, as well as forstreamlines and backflow coefficientcien describing theseparated region. Instantaneous velocity fields are alsopresented demonstrating the highly fluctuating flow. Resultsfor the above mentioned velocity quantities, together with theproduction of turbulence kinetic energy and the secondanisotropy inariant are also compared to data from simulationsbased on the k -wformulation with an EARSM model. The simulation datawere found to severely underestimate the size of the separationbubble.Keywords:Fluid mechanics, wind-tunnels, asymmetricdiffuser, turbulent boundary layer, flow structures, PDFs,modeling, symmetry methods.
影响因子：
3.7
作者：
Matsubara, M;Alfredsson, PH
通讯作者：
Alfredsson, PH