时间分辨粒子成像测速系统(TR-PIV)

层析PIV

湍流本质上具有三维（3D）立体结构属性。普通的二维（2D）包 括采用激光照明的成像测量无法在所有三个空间维度上分辨湍流 的结构。而利用多视角成像信息，采用层析重构技术则可以在三 个空间维度上同时捕捉记录复杂流动的瞬态结构。应用针对体像 素的三维（3D）相关处理技术，可以由时间相关的体成像数据计 算出瞬态三维空间的流场。 LaVision功能强大的，基于层析粒子成像测速（Tomo-PIV）和层 析粒子跟踪测速（Tomo-PTV）技术的FlowMaster激光成像系统， 能够以极高的空间分辨率记录强湍流，火焰以及喷雾对象的瞬态 体视流场。

利用2维粒子成像测速技术研究鲨鱼自由游动的水动力学推动机制用于优化水中船舶的推进特性

Two-dimensional velocity fields around a freely swimming freshwater black shark fish in longitudinal (XZ) plane and transverse (YZ) plane are measured using digital particle image velocimetry (DPIV). By transferring momentum to the fluid, fishes generate thrust. Thrust is generated not only by its caudal fin, but also using pectoral and anal fins, the contribution of which depends on the fish’s morphology and swimming movements. These fins also act as roll and pitch stabilizers for the swimming fish. In this paper, studies are performed on the flow induced by fins of freely swimming undulatory carangiform swimming fish (freshwater black shark, L = 26 cm) by an experimental hydrodynamic approach based on quantitative flow visualization technique. We used 2D PIV to visualize water flow pattern in the wake of the caudal, pectoral and anal fins of swimming fish at a speed of 0.5–1.5 times of body length per second.

游动的未成熟海胆幼虫的个体发育变化和湍流中的取向

Many marine organisms have complex life histories, having sessile adults and relying on the planktonic larvae for dispersal. Larvae swim and disperse in a complex fluid environment and the effect of ambient flow on larval behavior could in turn impact their survival and transport. However, to date, most studies on larvae–flow interactions have focused on competent larvae near settlement. We examined the importance of flow on early larval stages by studying how local flow and ontogeny influence swimming behavior in pre-competent larval sea urchins, Arbacia punctulata. We exposed larval urchins to grid-stirred turbulence and recorded their behavior at two stages (4- and 6-armed plutei) in three turbulence regimes. Using particle image velocimetry to quantify and subtract local flow, we tested the hypothesis that larvae respond to turbulence by increasing swimming speed, and that the increase varies with ontogeny.

落到倾斜箔片上的液体薄膜流动的时间空间分辨热传导过程的实验研究

This paper describes the development of an experimental technique that combines simultaneous planar laser-induced fluorescence (PLIF) and infrared (IR) thermography imaging, and its application to the measurement of unsteady and conjugate heat-transfer in harmonically forced, thin liquid-film flows falling under the action of gravity over an inclined electrically heated-foil substrate. Quantitative, spatiotemporally resolved and simultaneously conducted measurements are reported of the film thickness, film free-surface temperature, solid–liquid substrate interface temperature, and local/instantaneous heat flux exchanged with the heated substrate. Based on this information, local and instantaneous heat-transfer coefficients (HTCs) are recovered. Results concerning the local and instantaneous HTC and how this is correlated with the local and instantaneous film thickness suggest considerable heat-transfer enhancement relative to steady-flow predictions in the thinner film regions.

湍流预混钝体火焰引燃几率的模拟和实验研究

The ignition characteristics of a premixed bluff-body burner under lean conditions were investigated experimentally and numerically with a physical model focusing on ignition probability. Visualisation of the flame with a 5 kHz OH* chemiluminescence camera confirmed that successful ignitions were those associated with the movement of the kernel upstream, consistent with previous work on non-premixed systems. Performing many separate ignition trials at the same spark position and flow conditions resulted in a quantification of the ignition probability Pign, which was found to decrease with increasing distance downstream of the bluff body and a decrease in equivalence ratio. Flows corresponding to flames close to the blow-off limit could not be ignited, although such flames were stable if reached from a richer already ignited condition.

DaVis-PIV系统图像数据采集和硬件控制的集成软件平台

DaVis是德国LaVsion公司推出的应用于反应和非反应流场测量，材料表面成像和追迹以及超快成像的智能（激光）成像技术的完整软件平台。 DaVis以灵活的图像采集模块，可用户定制的应用界面和特殊应用软件包三大特色功能成就了完美的成像系统所需软件。 DaVis软件可满足用户以纳秒量级的精度进行相机曝光，外部照明以及外部触发的同步控制并能自由选择采集图像序列。除此之外，DaVis软件拥有各种成像设置和控制的功能。 DaVis软件对用户开放，这种特色结合软件本身的宏命令语言，能够使得成像系统快速适应从高深的科学研究到可靠的工业应用等各种不同测量需求。 不仅如此，DaVis还拥有灵活的图像采集模式，先进的图像处理算法，多维图像数据的智能存储和显示，多种硬件的软件控制等功能。 集成了2DPIV和3DPIV功能模块的DaVis软件，参加了连续三年的PIVChallenge（http://www.pivchallenge.org）评测活动，均取得了优异成绩。客观证明了DaVis软件平台的出色性能。 PIVChallenge的组织者将两次PIVChallenge 活动的结果作了详尽的总结，并将结果发表在了公开的网站和杂志上。有关文章和下载网址如下： 1. Stanislas M, Okamoto K, Kaehler C (2003) Main results of the First International PIV Challenge. Meas Sci Technol 14:R63-R89 下载地址： http://stacks.iop.org/0957-0233/14/R63 或： http://www.oplanchina.com/download/Stanislas PIV challenge 2001.pdf 2. Stanislas M, Okamoto K, Kaehler C, Westerweel J (2005) Main results of the Second International PIV Challenge. Exp Fluids 39: 170-191 下载地址：http://www.oplanchina.com/download/PIV Challenge 2003 Results.pdf

粒子成像测速PIV测量中速度矢量不确定度的定量分析

The latest issue of the journal Measurement Science and Technology is focusing on uncertainty quantification in Particle Image Velocimetry The need to put an uncertainty band on a PIV vector has long been missing in the PIV community. In recent years, several methods that address this need have emerged in the literature. For this reason, Measurement Science and Technology is addressing uncertainty quantification in PIV with its recent issue. In addition to an editorial written by Prof. Kenneth T. Christensen and Prof. Fulvio Scarano, this issue contains four papers dealing with uncertainty quantification in Particle Image Velocimetry. Three of these papers are from LaVision and its research collaboration partners. These papers are (1) the introduction of the correlation statistics (CS) method, (2) the creation of an experimental database for evaluating existing PIV uncertainty methods, (3) a detailed comparison of existing PIV uncertainty methods (using this database). Please find more information about the latest issue here. Share this article: