Spray Formation: Three-Dimensional Liquid Break-Up due to Surface Tension
Abstract
The growth instabilities on the interface between a liquid jet and its gaseous environment is an important mechanism in spray atomization, and it is the subject of the work reported herein. Numerical simulations based on the Navier-Stokes equations were used to model liquid/gas interface flows. An algorithm was developed for solving the unsteady Navier-Stokes equations for incompressible fluid with a discontinuity in density and with surface tensions and its accuracy was demonstrated. In flows representative of round pressure- atomized jets and pressure-swirl atomizers, nonuniform mean velocity distributions resulting from viscous boundary layers were found to have a significant effect on instability growth. In a round jet, the inclusion of a boundary layer-like velocity profile significantly reduced the growth rate of small wavelength instabilities. The velocity profile had a much greater effect than surface tension on the initial atomization process for the flow parameters considered. A good estimate of initial fuel droplet size was obtained by considering boundary layer effects but disregarding surface tension. In a flow representative of the fuel issuing from a pressure-swirl nozzle, nonuniformity of the velocity profile was found to increase the growth rate of a disturbance mode which is directly responsible for spray breakup. Keywords: Fuel sprays, Computational fluid dynamics.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 09, 1988
- Accession Number
- ADA200247
Entities
People
- Robert E. Childs
Organizations
- Nielsen Engineering & Research (United States)