Study on water-vapor two-phase flow behavior in Venturi tube

Abstract

The filtered venting system has the functions of preventing the overpressure breakage of a primary containment vessel of a reactor and reducing the release amount of the radioactive materials to the environment. One of the filtered venting systems is a Venturi scrubber to remove small particles of the radioactive materials. However, the physics of the two-phase flow in the Venturi scrubber has not been clarified. In this study, the experimental results of the water-vapor two-phase flow in a Venturi tube are reported. As the gas flow rate increased, the supply amount of scrubbing water decreased and eventually stopped because the pressure at the throat increased with increasing the gas density. This phenomenon was caused by the gas compressibility. By visualizing the two-phase flow in the Venturi tube, we cannot measure the spraying from the water supply port, which is considered to affect decontamination of the Venturi scrubber. However, it was confirmed that the water film on the wall at the diverging part of the Venturi tube, and the dispersed water droplets were formed intermittently from the water film. In addition, generation of the liquid at the divergent area was observed even though scrubbing water-supply stopped.