湍动管道流中非线性行波的实验观察

With stereoscopic particle image velocimetry (SPIV) we can measure all 3 components (3C)
of the velocity in the plane of a laser light sheet. SPIV makes use of 2 cameras that view the
laser light sheet from two different directions. In each measurement point in the plane of the
light sheet, each camera measures the projection of the particle displacement perpendicular to
its viewing direction, and the complete velocity vector can be reconstructed from these projections.
First the 2C-vector fields from each camea must be mapped (dewarped) from the image
planes onto the measurement plane of the light sheet and interpolated on a common grid. Then
the displacement vectors from both cameras are combined to calculate (reconstruct) the 3 components
of the particle displacement. The dewarping and reconstruction can in principle be
based on the exact knowledge of the geometry of the setup, but most often they are based on a
calibration procedure. The geometry of the setup is then derived from a set of calibration images
from a grid placed in the measurement plane. A more extensive discussion of the dewarping,
the reconstruction and the 3D-calibration procedure is given in (S1-S6). 德国LaVision PIV/PLIF粒子成像测速场仪 时间分辨粒子成像测速系统(TR-PIV) 三维立体PIV