岩体工程无损探测技术研究综述

随着科学技术的日益发展,许多工程都在不断研究新的技术手段。为了使工程高效、安全地进行,对岩体工程探测方面提出了更高的要求,以往的接触式探测技术已不再适应现在高效安全的施工作业,更先进、更高效的技术应运而生。主要研究了声发射技术、红外探测技术、粒子成像技术、地质雷达声波技术等无损探测技术在岩体工程中的应用,分析总结了各类技术的原理与特点,以更好地应用在岩体工程探测。     

空调室外机流场特性研究

分析了空调器室外机组内的空气流场特性,采用体积法对三维不可压缩Navier-Stokes方程在旋转坐标系中进行非定常求解。在随叶片旋转的区域与固定区域的交接面处,采用滑移网格技术求解动静非定常作用。计算中采用两类入口边界条件,即流量入口和压力入口,并将流场数值结果与微粒图像测速实验数据进行比较。比较结果表明,在流量入口边界条件下数值模拟计算的结果接近实验结果,流场计算可以为气动声学分析奠定基础。     

一种在HCCI模式下的柴油机缸内微涡流场方法

寻找柴油机燃烧前油气混合的最佳配合方法是研究缸内流场的主要目的。应用PIV技术，在2135柴油机(倒拖)试验中发现：在不改变与燃烧室相关的部件位置和尺寸下，由螺旋进气道形成的强大惯性流很难被燃烧室形状左右，其在水平截面上的刚性涡流场中气体运动的速度差很大，如此不可能得到与燃油的均匀混合。试验中，在缸套上沿开孔形成的折壁，其产生射流与挡板的反作用使该截面上的刚性涡流场变成了速度分布均匀的微涡流场。结果说明微涡密度与折壁个数成正比。由此可得到HCCI模式下油气均匀混合的微涡流场。     

水封控制点对节水坐便器虹吸性能的影响

该文从企业现有的坐便器管道形状入手，首先应用水动力学知识计算水封控制点位置的变化对管道虹吸性能的影响，然后基于计算结果提出更优位置的假设，并依据试验确定其合理的变化范围，最后通过CFD方法模拟改进前后管道中的虹吸速度和虹吸压力，结果表明管道虹吸性能得到了优化。     

Experimental Studies of Hydrodynamics and Regime Transition in Bubble Columns

The detailed flow structures in bubble columns with and without internal draught tube have been investigated using the PIV technique. The onsets of transition due to vortex formation and different flow patterns with and without draught tube have been studied using the drift‐flux model and the experimentally measured Reynolds stresses. The role of solid particles and liquid viscosity, as well as bubbling orifice configuration on the flow patterns and regime transition has also been studied and discussed.     

Heat and mass transfer of a convective-stratified flow in a trough type tundish

Fluid flow, heat and mass transfer of liquid steel in a trough type tundish were physically and mathematically simulated using a water model. Flow structures were determined through particle image velocimetry (PIV) techniques. Under isothermal conditions fluid flow approaches that of a plug pattern. Non-isothermal conditions provoked long recirculating flows along the vessel and makes the flow to departure form the plug pattern. Buoyancy forces increased fluid velocities close to the bath surface and enhanced convection mass transfer of a tracer injected in the flow and the flotation of solid particles. Measured fluid velocity fields maintained an acceptable good agreement with mathematical simulations under isothermal and non-isothermal conditions.     

A PIV study of hydrodynamics in gas-liquid high throughput experimentation (HTE) reactors with eccentric impeller configurations

High-throughput experimentation (HTE) is used for the screening of novel catalyst formulations via miniature agitated gas-liquid reactors with vessel volumes of an order of magnitude below the laboratory scale. An investigation of the macroscopic hydrodynamic performance of a miniaturised unbaffled stirred vessel of diameter 45 mm for an air-water system has been carried out at gassing rates of 0.25 and 0.5 vvm (dispersed flow regime) using particle image velocimetry (PIV). Measurements of bubble size and gas hold-up were also made. Eccentric agitation was employed as a means of breaking solid body rotation within the vessel, using a 6-blade, up-pumping pitched blade turbine. The gas phase was introduced via sintered glass panel spargers mounted in the vessel base. Two different configurations were used: firstly where the sparger located directly below the impeller, and secondly where the sparger was located opposite the impeller on the other side of the vessel. Measured distributions of turbulent kinetic energy (TKE) for both gassed configurations were similar and showed significant differences to the ungassed case. Estimates of the gas-liquid interfacial area were at least 2-3 times higher than those found in conventional, lab-scale baffled vessels; this was attributed to the creation of very small bubbles at the sparger ().     

重力式油水分离设备内流场的PIV技术测试

粒子图像测速（PIV）系统是由图像采集部分（包括工业摄像机、录像机、监视器等）与图像处理部分（包括计算机、监视器、打印机等）所组成。并采用PIV技术对重力式油水分离试验模型的主要构件（入口件、整流件、聚结件和集液件）中的几种典型结构进行了模拟试验筛选，并成功地获得了模型流场的两维速度图像，进而提出了一些流动特性良好的分离设备优化结构模型，由此建立了一些新型分离设备的结构优化模型，为今后深入研究重力式分离设备打下了良好的基础。     

Flow in the nose region and annular film around a Taylor bubble rising through vertical columns of stagnant and flowing Newtonian liquids

The flow in the nose region and in the annular film around individual Taylor bubbles rising through stagnant and co-current vertical columns of liquid were studied, employing particle image velocimetry (PIV) and pulsed shadowgraphy techniques (PST) at the same time. The combined techniques enabled simultaneous determination of the bubble shape and the velocity profiles in the liquid film. Experiments were performed with water and aqueous glycerol solutions in a wide range of viscosities , in an acrylic column of 32 mm ID.Values for the distance ahead of the nose in which the flow is disturbed by the presence of the bubble are presented for the conditions studied. The bubble shapes in the nose region are compared with Dumitrescu's shape for potential flow. The velocity profiles show that after the nose region the liquid begins to accelerate downwards, and at a certain distance from the bubble nose the velocity profile and the liquid film thickness stabilise. The liquid film acquires characteristics of a free-falling film. Values of the developing length and film thickness are reported for the experimental conditions studied. Average velocity profiles in the fully developed film are also presented. A critical Reynolds number of around 80 (based on the mean absolute velocity in the liquid film and on the film thickness) is reported for the transition from laminar to turbulent regime. Shear stress profiles (in the fully developed film) are also provided.The data reported are relevant for the validation of numerical codes in slug flow.