围绕窄圆柱的低雷诺数流体的三维影响

如何保护好你的CCD相机——PIV必读 CCD相机是PIV系统最重要的硬件之一。CCD相机内含有一个高感光度的芯片，因此如果暴露在任何强光下，都有可能造成损害。而该感光芯片是CCD的核心，其价值可能占到整个相机的80%，并且由于这种损坏属于人为损坏，不在保修范围之内，因此，如果使用不当，将造成重大损失及不必要的

Stereo-μPIV measurements have been performed to investigate the wake behind a vibrissa (facial hair) from a seal. Previous experiments have proven the capability of seals to detect the wake swimming fish by using only their vibrissae as a sensory system. Also it can be observed that the vibrissae of seals exhibit a unique 3D shaped structure. The aim of the present investigation is, to learn the fluid mechanic aspects of the wake detection and to understand the influence of the 3D surface structure on the detection capabilities. The measurements have made extensive use of a Stereo-μPIV device,which allows the capturing of the full un-steady 3D vector field on a set of 2D planes with microscopic length scales.

In the present investigation, Laser Induced Plasma Spectroscopy (LIPS) is performed with an original two dimensional approach. The spectrometer usually used to record light emission from plasma and compare well-chosen peak intensity is here replaced by two intensified cameras equipped with band pass filters. The ratio of emission intensities recorded with the two cameras at two different wavelengths provides the concentration of identified species in given mixtures. This technique gives information on mixture composition on the whole plasma volume increasing both the spatial resolution and the probe volume of the measurement. Tests are performed on coaxial jets of air and nitrogen showing the ability of the method to catch the mixing layer developed at the nozzle exit.

Turbulent kinetic energy budgets are presented for a highly curved flow generated by the collision of plane wall turbulent jet with a low-velocity boundary layer. The different terms are obtained in the vertical plane of symmetry by quadratic interpolation of the LDV measurements, for a wall jet-to-boundary layer velocity ratio of 2. The results, which have relevance to flows encountered by powered-lift aircraft operating in ground effect, quantify the structure of the complex ground vortex flow resulting from the collision of a wall jet with a boundary layer. The analysis of turbulent energy equation terms using the measured data revealed that production by normal and shear stresses are both very important to the turbulent structure of the impact zone of the ground vortex. The analysis of turbulent kinetic energy indicates the modeling of turbulence of deflected flow resultant from the collision between the wall jet and the boundary layer this may require an adequate treatment.