Study of Hydrodynamic Lubication Mechanism based on the Theory of Turbulence

首先，对平面湍流Couette流进行了实验研究，以考虑空载滑动轴承中湍流润滑的结构。测量了从层流到湍流区基本完全发展的流动中的平均速度和湍流。将过渡区的平均速度分布与理论分布和直接数值模拟结果进行了比较。在充分发展的湍流区，速度在壁区服从Telbany和Reynolds得到的对数速度分布U^+=2.5lny^++5.1，在核心区服从速度分布和速度亏损定律(U_c-U)/u*=R_f(1-y/h)，其中U_c、u~*和h分别为中心线涡量、摩擦速度和半通道深度。文中还讨论了表面摩擦系数、湍流强度、雷诺剪应力和能量密度谱，并与前人的结果进行了比较。随后，…实验研究了偏心比m=0.3时，在正弦波形壁和平面波纹带之间的二维流道中，偏心比m=0.3时滑动轴承润滑中的湍流结构。流动在主流方向上加速和减速，压力梯度符号交替，使湍流处于不平衡状态，受流动惯性效应的影响较大。壁面区域的速度分布随y^+和x/1(x=主流方向上的坐标；1=正弦波壁的一个波长)而移动到湍流Ciuette流的对数速度分布之上。壁面区域的U^+值可由Van最干阻尼常数A^+和卡曼常数k的函数给出，这取决于压力梯度参数&lt；nu&gt；dp/dx/(&lt；Rho&gt；u*^3)和惯性效应参数。在梯度层和核心区分别发现了半幂定律和速度缺陷定律。二次流引起的法向速度分量的惯性效应对雷诺-谢拉应力的分布有很大影响。还测量和讨论了强度的湍流，Roo&lt；U‘^2&gt；和√&lt；V’^2&gt；。较少

First of all, turbulent plane Couette flow has been experimentally investigated to consider the structure of turbulent lubrication in an unloaded journal bearing. Mean velocity and turbulence have been measured in essentially fully developed flow from laminar to turbulent region. Mean velocity profiles are compared with theoretical profiles and the results of direct numerical simulation in the transition region. In the fully developed turbulent region, the velocity follows the logarithmic velocity profile U^+=2.5lny^++ 5.1 obtained by telbany and Reynolds in the wall region but outside the buffer layer layer, and the velocitybany and the velocity-defect law (U_c-U)/u*=R_f(1-y/h) in the core region, where U_c, u* and h are centerline vrlocity, friction velocity and half channel depth, respectively. Skin friction coefficient, turbulence intensity, Reynolds shear-stress and energy-density spectra are also discussed in comparison with the other results obtained previously.Subsequently, the … More structure of turbulent flow in the lubrication for the eccentricity ratio m=0.3 in a loaded journal bearing has been experimentally investigated in the two-dimensional channel between a sinusoidally waved wall and a plane noving belt. The flow is accelerated and decelerated in the main flow direction with the pressure gradient alternating in sign,so that the turbulence is in disequilibrium and greatly influenced by the inertia effect of the flow. The velocity profiles in the wall region are displaced above the logarithmic velocity profile of the turbulent Ciuette flow, depending on y^+ and x/1 (x=coordinate in the direction of main flow ; 1=one wavelength of sinusoidally waved wall). The value of U^+ in the wall region can be given by the function of both Van Driest damping constant A^+ and Karman constant k, which depend on a perssure gradient parameter <nu>dp/dx/(<rho>u*^3) and an inertia effect parameter. Half-power law and velocity defect law were also found in the gradient layer and the core region, respectively. Distribution of Reynolds shera-stress is much influenced by the inertia effect of normal velocity component caused by the secondary flow. Turbulence in tensities,ROO<<U'^2>> and √<V'^2>, were also measured and discussed. Less