Experimental and Numerical Investigation of the Behavior of a Vapor–Liquid Mixture in a Venturi Tube

A flashing flow occurs after a high-temperature liquid flows through a Venturi tube, forming a flashing region downstream of the throat and generating an adaptive back pressure which will affect a vapor flow in front of the throat. To reveal the phenomenon, the effect of the condensate flow rate on the steam flow rate in a Venturi tube is explored experimentally with consideration for the installation angle impact. The two-phase mixture approach is used to numerically explain the flashing flow behavior. The radial steam volume fraction is not equal in the flashing region, and the highest steam fraction appears near the wall. The maximum water discharge for various constructions is predicted numerically. The steam flow rate at the output can be maintained low if the condensate flow rate is near the expected value. Furthermore, flashing is significantly more visible at smaller throat diameters, which results in a continuous increase in the radial steam volume fraction.