Simultaneous measurement of temperature and velocity using two-colour LIF combined with PIV with a colour CCD camera and its application to the turbulent buoyant plume

Abstract

In this present paper, a method for simultaneously measuring the temperature and the velocity in a planar cross-section of fluid flow with a colour CCD camera is described. This technique combines the laser-induced fluorescence (LIF) and particle image velocimetry (PIV). The temperature is evaluated by the two-colour LIF technique using red and green images of the colour CCD camera, while the velocity is obtained from two sequential blue images by PIV. It is found that the temperature sensitivity of the present technique is almost the same as that of the standard two-colour LIF technique by two monochrome CCD cameras with optimum filter setting, but it provides a simple and convenient system for simultaneous measurement of temperature and velocity in thermal flows. The uncertainty in the temperature measurement is found to be a function of concentration ratios of the fluorescent dyes in the two-colour LIF technique and it increases with an increase in the number of tracer particles for velocity measurement. This technique is successfully applied to the simultaneous measurement of temperature and velocity in the turbulent buoyant plume. The statistical properties of the plume, such as mean and turbulence characteristics of the plume as well as turbulent heat fluxes are evaluated in the initial region of the buoyant plume.