Air Assisted Atomization in Spiral Type Nozzles

Processes utilizing various spraying cooling are widely used in many gas treatment applications. Effective spray cooling system design optimization often depends on the approach used to investigate such gas cooling problems. The mass transfer efficiency of spray cooling problems depends on the ability of the liquid to atomize and disperse into the gas by interacting in a controlled manner. Experimental methods coupled with Computation Fluid Dynamics (CFD) can be used effectively in application design of a certain classes of spray evaporation processes. In this study, a spiral type nozzle was studied. Both water and air flow at different respective mass fractions (mass flow rate of water over mass flow rate of air) were included while keeping the water flow the same. Phase Doppler Interferometry (PDI) and Laser Sheet Imaging (LSI) were used to measure the drop size and distribution throughout the range of operation conditions. The results indicated a slight reduction in drop size as air mass flow rate was increased. Additionally the increase in air flow caused a shift of the spray plume from predefined center axis. At the same flow conditions, an internal and external two-phase flow of the nozzle was simulated with a Volume of Fluid (VOF) model which is a Computation Fluid Dynamics (CFD) method for multiphase problems. The fluids' velocity environment at the nozzle's orifice was investigated. As expected, the exit (from nozzle's orifice) velocities of the liquid increased as the mass fraction decreased due to increased total volume flow rate of both fluids. * Corresponding author: [email protected]