Atomization of a Sheet Jet of Superheated Water Using a Passive Swirler

Abstract

In this paper, an experimental study of boiling-up of a superheated water jet at an outflow through a short slit nozzle into the atmosphere in the presence of a passive swirler (twisted tape, wire winding) has been carried out in order to affect and control the jet behavior. The evolution of jet disintegration with increasing liquid superheat during the outflow both from the saturation line and at a fixed initial pressure has been traced. The characteristic structures and shapes of the flow have been identified. The relationship between the jet shape and various mechanisms of vaporization has been noted. For small superheats when outflowing from the saturation line, both unswirling jet shapes and swirling jet ones have looked the same. When a liquid outflows at a fixed initial pressure, a more structured parabolic jet profile with a decreasing opening angle is observed when the pressure increases. The differences have been revealed at moderate superheats, when the parabolic jet profile has been replaced by a trapezoidal jet one with increasing temperature along the isobars. It has been established that in the case of attainable superheats, the intensive process of boiling-up plays the main role in the flow formation. In this case the jet shape remained unchanged at outflows both from the saturation line and from the isobars. In the experiments conducted, manifestations of the two-phase jet instability, which have been in experiments with a passive swirler for a short cylindrical nozzle have not been observed.