Controlled atomization using a twin-fluid swirl atomizer

This paper presents the results of an experimental study of a twin-fluid internally mixed swirl atomizer. In this type of injectors, atomization is attained by injecting a small amount of air (i.e. of the order of less than 16% of the mass flow rate of liquid) into a liquid stream within the injector and the two-phase air liquid mixture is passed through a swirling passage to impart a swirling motion to the flow. Since most of the energy for atomization is supplied to the liquid by the atomizing air, a significantly small pressure drop can produce very fine spray with a small amount of atomizing air. At low values of air–liquid mass ratio (ALR), the appreciable tangential component of velocity with respect to the axial velocity provides a hollow cone spray structure, which turns into a solid cone spray with the increase in axial momentum, through either an increase in ALR or the liquid supply pressure. The results presented in this paper suggest that the investigated injector could be used to control the flow rate and spray characteristics (e.g. spray cone angle, spray solidity, breaking distance, and the droplet diameter) independent of each other by simultaneously varying the supply pressure of the liquid and the atomizing air flow rate. The controlled atomization studied in this paper for a twin-fluid internally mixed swirl atomizer makes it attractive to be used for various commercial applications as the atomizer is capable of providing various spray characteristics depending upon the application requirement.