Vapor core turbulence in annular two-phase flow

This paper reports a new technique to measure vapor turbulence in two-phase flows using hot-film anemometry. Continuous vapor turbulence measurements along with local void fraction, droplet frequency, droplet velocity and dro plet diameter were measured in a thin, vertical duct. By first eliminating the portion of the output voltage signal resulting from the interaction of dispersed liquid droplets with the HFA sensor, the discrete voltage samples associated with the vapor phase were separately analyzed. The data reveale d that, over the range of liquid droplet sizes and concentrations encounter ed, the presence of the droplet field acts to enhance vapor turbulence. In addition, there is evidence that vapor turbulence is significantly influenc ed by the wall-bounded liquid film. The present results are qualitatively c onsistent with the limited data available in the open literature.