Imager LX PIV相机

采用德国LaVision公司2D2C平面粒子成像测速(PIV)系统。对边生物工程涂料边界层流场，采用高空间分辨率的PIV+PTV分析方法计算流体速度矢量场，分析了生物工程涂料用于被动流动控制的可行性。

The objective of this work was to examine the effect of samplingprobe geometry on Dissolution Testing. Particle Image Velocimetry(PIV) was used to examine the flow effects of two different probe types. Dissolution testing will be briefly described followed by an overview of the experimental setup. A description of PIV will be introduced along with a short description of the flow mathematics. The experimental results will be presented in several formats including: •PIV Images •PIV Vector maps •Vector concentration maps

采用2台Litron激光器。三台LX Imager 16M相机。构成2DPIV测量系统。采用拼接方式测量大视场。利用2DPIV快照结果求得压力场。

采用12台Lavision公司的Imager LX 2MP型PIV相机，在图像采集和控制软件平台DaVis构成了一套高空间分辨率体视层析3D3C速度场测量系统，并利用开系统实现了四脉冲层析粒子成像测速（Tomo-PIV）确定跨音速基流中的瞬时压力的研究。

We discuss a new phenomenon of turbulent thermal diffusion associated with turbulent transport of aerosols in the atmosphere and in laboratory experiments. The essence of this phenomenon is the appearance of a nondiffusive mean flux of particles in the direction of the mean heat flux, which results in the formation of large-scale inhomogeneities in the spatial distribution of aerosols that accumulate in regions of minimum mean temperature of the surrounding fluid. This effect of turbulent thermal diffusion was detected experimentally. In experiments turbulence was generated by two oscillating grids in two directions of the imposed vertical mean temperature gradient. We used Particle Image Velocimetry（PIV） to determine the turbulent velocity field, and an Image Processing Technique based on an analysis of the intensity of Mie scattering to determine the spatial distribution of aerosols. Analysis of the intensity of laser light Mie scattering by aerosols showed that aerosols accumulate in the vicinity of the minimum mean temperature due to the effect of turbulent thermal diffusion.

This paper presents preliminary results of research being conducted at MIT on the dynamics of an azimuthing podded propulsor, with emphasis on the application to nonlinear vehicle maneuvering dynamics. The paper focuses on the experimental investigation of propulsor-induced maneuvering forces and moments, as well as characterization and documentation of the vortex wake. A test program of quasi-steady and unsteady/dynamic tests on an azimuthing podded propulsor unit has been carried out in the MIT ship model towing tank. Forces and motor current were measured for subsequent implementation of a multi-parameter dynamic model of an azimuthing propulsor within nonlinear vehicle maneuvering simulations. Additional testing was conducted with the azimuthing propulsor installed in a surface vehicle attached to a Planar Motion Mechanism (PMM), where quasi-steady forces and moments were measured. Parameterized results, as well as notable maneuvering force effects and visualizations of the wake are presented. Parametric results clearly illustrate unique characteristics of vectored-propulsion, including significant increase in vectored thrust and strong “destabilizing” thrust and normal force with propulsor azimuth, plus other important related effects. Limited results of wake flow visualization, using Particle Image Velocimetry (PIV), are also presented.

Abstract—In-cylinder flow field structure in an internal combustion (I.C) engine has a major influence on the combustion, emission and performance characteristics. Fluid enters the combustion chamber of an I.C engine through the intake manifold with high velocity. Then the kinetic energy of the fluid resulting in turbulence causes rapid mixing of fuel and air, if the fuel is injected directly into the cylinder. With optimal turbulence, better mixing of fuel and air is possible which leads to effective combustion. A good knowledge of the flow field inside the cylinder of an I.C engine is very much essential for optimization of the design of the combustion chamber for better performance especially in modern I.C engines like gasoline direct injection (GDI), homogeneous charge compression ignition (HCCI) engines.The main objective of this work is to study the incylinder fluid flow field characteristics of a single-cylinder engine to see the effect of intake manifold inclination at equivalent rated engine speed using Particle Image Velocimetry (PIV) under various static intake valve lift conditions. To facilitate the PIV experiments, the metal cylinder of the engine was replaced by a transparent one. For every operating test condition, 50 image pairs were captured and processed using DAVIS software. From the results, it is seen that the in-cylinder flow structure is greatly influenced by the intake manifold inclinations irrespective of intake valve lift. Maximum Turbulent Kinetic Energy (TKE) was highest at full intake valve lift irrespective of the inclination. Also, the maximum TKE was the highest for 600 intake manifold inclination compared to other inclinations irrespective of the intake valve lift at equivalent rated engine speed. Finally, it is concluding that the analysis carried in this work is useful in predicting the flow and inturn optimizing combustion chamber of modern I.C engines.

采用四台LaVision的16百万像素ImagerLX型相机构成体视层析PIV测量系统。从测量的单次层析PIV成像结果求得PIV的压力谱。

由5台LaVision ImagerLX 2MP型相机构成3D3C体视层析PIV测量系统。利用DaVis8.1软件平台进行数据采集控制和分析处理。并利用PIV结果求得可压缩流体的平均压力。

飞行器空气动力学领域关于3维失速团和翼型压力关系的研究报告。发表在实验流体上《Exp Fluids》2016年第57卷。

Plasma actuators have been identified as having great promise for flow control applications. A single dielectric barrier discharge (SDBD) plasma actuator consists of two staggered electrodes separated by a dielectric layer (Fig. 1). When an AC voltage of sufficient amplitude (a few kV) is supplied to the exposed electrode, it causes the air over the covered electrode to weakly ionize, resulting in a cold plasma. An electro-mechanical coupling with the ambient air is provided by the interaction between the ionized air and the electric field between the two electrodes, generating a body force.

Memorial University purchased a Particle Image Velocimetry (PIV) system in January 2004. So far it has been used to study flow around a small propeller and a tug hull. Studies have also been made to determine the best seeding particles and the best method of introducing the seeding particles into the flow. This report describes the major components of the PIV system, and the analysis software. Some studies on the selection of seeding particles were made and they are described in this report. The PIV system was used to measure the flow field around a small model propeller and a model of a tug. The results of these experiments are also described. Finally, some recommendations are made for improving the experiment procedures and analysis techniques for future experiments.

In the present work the process of a transient fuel injection in a constant high-pressure atmosphere is investigated experimentally. As fuel, dimethyl ether (DME) is used. The goal is to receive new information about the charac-teristics referring to the droplet size, the droplet velocity and the droplet shape in the jet. The high-pressure chamber has a constant pressure of 2 MPa and the fuel spray is injected with a pressure of 6 MPa, 7 MPa and 8 MPa. The spray is analysed by a Shadow-Sizing-technique and digital image analysis with temporal and spatial resolution, which even allows investigating non-spherical droplets. The correlations of d velocity and droplet shape are presented as Joint Probability Density Functions (JPDF). The conclusion of the investigation shows that little increase of the injection pressure has a remarkable effect on the droplet size. Furthermore, the centricity is widely influenced by the injection pressure. With lower injection pressure the droplet velocity decreases. Moreover, the droplets mean diameter shows a significant decrease with increasing time after the injection

采用LaVision的StrainMaser应变形变测量系统。测量人类活动造成的岩土沉积层，在含水情况下发生崩塌，崩溃的规律。目的是为了预警防范如泥石流等地质灾害的发生。

The focus of this study is an experimental apparatus that serves as a model for studying blood flow in a total artificial lung (TAL), a prototype device intended to serve as a bridge to lung transplantation or that supports pulmonary function during the treatment of severe respiratory failure. The TAL consists of hollow cylindrical fibers that oxygen-rich air flows through and oxygen-poor blood flows around. Because gas diffusivity in the TAL is very small, a convection mechanism dominates the gas transport, which is why we focus on the velocity around the fibers (modeled as a 0.05-cm-in-diameter and 5-cm-long cylinder). We designed a low-speed water tunnel to study the flow mechanism around the cylinder, across which the flow is generated by a linear actuator that allows different flow patterns to mimic the flow in a TAL. We tested the flow in the test section by numerical simulation and by the particle image velocimetry method to study the flow profile. The results show a uniform flow near the centerline of the water tunnel where the cylinder is placed. This decreases the effects of free-stream turbulence in the shear layers and reduces the uncertainty in determining the flow patterns around the cylinder. Knowledge gained from the flow around one cylinder (fiber) is beneficial for understanding vortex formation around multiple cylinders. We present a summary of vortex formation behind a cylinder for Reynolds numbers (Re) of 1, 3, and 5 and Stokes numbers (Ns) of 0.18 to 0.37; results show that higher Re and Ns favor vortex formation. These findings regarding the parameter range for vortex formation may provide principles for designing artificial lungs to enhance convective mixing. We anticipate that the pulsatile flow circuit presented here can be used to mimic the flow not only in TALs but in other physiological systems.

In this paper, a comparative study between numerical and experimental results from PIV measurements is presented in the case of two-dimensional electrohydrodynamic plumes that arise when a sharp metallic blade, submerged in non conducting liquids, supports high electric potential. Experiments and numerical simulations have been conducted in order to confront the both approaches. A very good agreement has been found through velocity profiles and velocity fields which testifies the relevance of our numerical model. For high potentials the jet flow issued forth from the blade becomes unsteady and starts to flap on the vertical wall. Some captions of the temporal evolution of the isocontours of charge density which is not accessible from experiment are presented thanks to the numerical simulation.