熱線流速計による垂直大口径管内の気液二相流の計測

Abstract

In this study, local measurements of flow parameters, such as void fraction, liquid velocity and turbulence intensity were performed in a vertical upward air-water two-phase flow in a 200 mm inner diameter and 24 m in height pipe by using a hot-film anemometer. The measured mean void fraction and mean liquid velocity agreed well with those by the differential pressure method and the liquid Venturi flow meter respectively. The experimental results are summarized as follows: (1) The radial profile of void fraction changes from a wall peak shape to a core peak shape and the radial profile of liquid velocity changes from a flat shape to a core peak shape as the flow develops. (2) When the average void fraction increases, the shape of void fraction radial profile changes from a wall peak to a core peak and the radial profile of liquid velocity shows a gradually increasing core peak shape. (3) The turbulence intensity increases with the increase in void fraction, flow direction and radial direction. The predicted liquid velocities by using existing algebraic turbulence models of Sato et al. and Kataoka and Serizawa were compared with the present experimental data. The comparison indicates that those models do not reasonably predict the liquid velocity distribution in a two-phase flow in a large diameter pipe mainly due to the defect in the predictive model of the liquid shear stress. It is necessary for us to establish a new model for the radial pressure distribution when we predict the liquid velocity distribution by using the measured void fraction distribution and algebraic turbulence models in a large diameter pipe. (author)