Turbulent mass flux measurements using a laser/hot-wire technique

A laser-Doppler anemometer and a hot-wire type concentration probe are used to measure the velocity and species concentration fields simultaneously in an axisymmetric sudden-expansion flow. The presence of the probe has a negligible effect on the Doppler signals. Furthermore, the presence of small liquid droplets in the flow does not affect the hot-wire measurements. Resulting measurements of axial velocity and species concentration are compared with corresponding data obtained by applying the LDA and hot-wire probe separately to measure the flow properties. Excellent agreement is obtained. Therefore, the measured mass flux is valid and reliable. The technique is used to examine the behavior of the turbulent mass flux in an axisymmetric sudden-expansion flow. (Author)