在跨音速气体动力学装置上使用粒子成像测量技术，采用CO2作示踪粒子进行边界层测量

Particle image velocimetry (PIV) is utilized with solid carbon dioxide (CO2)
seeding material to conduct boundary layer measurements in the test section of the Air
Force Research Laboratorys Trisonic Gas-dynamics Facility (TGF), which has a 24 inch
by 24 inch cross-section. Freestream velocity was set at Mach 0.3, Mach 0.5, or Mach
0.8 while stagnation pressure ranged from 500 to 2400 pounds per square foot (psf). High
pressure liquid CO2 was directed through expansion nozzles into shroud tubes which led
to solidified particles in the wind tunnel stagnation chamber. Two different sets of
shroud tubes were used to modify the size of dry ice particles produced and the particle
number density. Shroud tubes with an inside diameter (ID) of 0.824 inches provided
good particle count and coverage for stagnation pressures between 500 and 1500 psf,
while 0.364 inch ID shroud tubes demonstrated good particle count and coverage for
stagnation pressures over 1000 psf. Overall, the PIV results produced freestream velocity
measurements and boundary layer profiles which compared well with expected values.
After initial processing, turbulence data closely followed trends expected within
boundary layer, but levels were somewhat higher than anticipated. When the PIV data
was processed using elliptical interrogation regions, elongated in the streamwise
direction, resulting turbulence levels were much closer to expectations. 德国LaVision PIV/PLIF粒子成像测速场仪 三维立体PIV Imager sCMOS PIV相机