流体中速度场,浓度场检测方案(粒子图像测速)

The present study discusses a test case for the application of digital Particle Image Velocimetry (PIV) and planar Laser Induced Fluorescence (LIF) as a combined technique. In this measurement, a water filled Rayleigh-Bénard cell with a fluorescent dye (Rhodamine B) for LIF and tracer particles for PIV was used. Rhodamine B fluorescence is sensitive to the temperature of the fluid. Lensing effects, due to local variations in the refractive index of the fluid, were solved by means of a spectral filter applied to the LIF images. Two cameras, with appropriate optical filters to separate PIV and LIF signals, were used to simultaneously grab images of the scattering particles and of the dye fluorescence. After separate processing for the velocity and for the temperature calculation, these fields are recombined to evaluate the turbulent heat flux.