墙报-俘获湍动边界层流动的时间分辨层析PIV研究

A flat plate boundary layer flow was generated at the open test section of the circuit type 1m- wind tunnel of
the DLR, Gottingen, at a free stream velocity of U亣 = 7 m/s with zero pressure gradients. A transparent and
smooth surface glass plate is utilized to provide optical access from its bottom and a good flow quality. The
plate has an elliptic leading edge to prevent flow separation. Four tripping wires, one with 1.5 mm diameter
and three with 1 mm diameter were positioned with 1 mm x-distance close to the surface at (Rex). . 290
along the whole span-wise elongation of the plate. This bypass transition of the flow results in the
development of a turbulent boundary layer flow. In a box of about 34 x 18 x 35 mm3 in x-y and z-directions
around (Rex). . 450 tracer particles has been illuminated by laser light pulses at 4 kHz with 21 mJ each in
order to achieve PIV recordings without using the frame stradd领 method. The light source was a Nd:YAG
laser from Lee Laser inc. Two highly reflective dielectric mirrors aligned in the x-y-direction are installed
nearly parallel and close to the surface of the flat plate on opposite sides of the measurement region. The
collimated laser beam undergoes multiple reflections between the two mirrors passing through the
measurement volume approximately 15 times before exiting (see sketch left). This arrangement resulted in
a light amplification with a factor ~5 with respect to a single pass system. The specific illumination
arrangement has the advantage that all viewing directions collect scattered light both in forward and
backward directions, which provided the level of light needed for imaging particles in the whole volume. 自适应粒子成像测速场仪（PIV） 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) 体视层析粒子成像测速系统(Tomo-PIV)