- Author
-
Mostafa, A. A.
|
Elghobashi, S. E.
- Title
- Effect of Liquid Droplets on Turbulence in a Round Gaseous Jet. Contractor Report.
- Coporate
- California Univ., Irvine
- Sponsor
- National Aeronautics and Space Admin., Washington, DC
- Report
-
NASA CR-175063,
February 1986,
208 p.
- Contract
- NAG-3-176
- Keywords
-
droplets
|
turbulence
|
sprays
|
equations
|
combustion chambers
|
shear stress
- Identifiers
- spray modeling; turbulence interactions
- Abstract
- The main objective of this investigation is to develop a two-equation turbulence model for dilute vaporizing sprays or in general for dispersed two-phase flows including the effects of phase changes. The model that accounts for the interaction between the two phases is based on rigorously derived equations for the turbulence kinetic energy and its dissipation rate of the carrier phase using the momentum equation of that phase. Closure is achieved by modeling the turbulent correlations, up to third order, in the equations of the mean motion, concentration of the vapor in the carrier phase, and the kinetic energy of turbulence and its dissipation rate for the carrier phase. The governing equations are presented in both the exact and the modeled forms. The governing equations are solved numerically using a finite-difference procedure to test the presented model for the flow of a turbulent axisymmetric gaseous jet laden with either evaporating liquid droplets or solid particles. The predictions include the distribution of the mean velocity, volume fractions of the different phases, concentrtion of the evaporated material in the carrier phase, turbulence intensity and shear stress of the carrier phase, droplet diameter distribution, and the jet spreading rate. Predictions obtained with the proposed model are compared with the data of Shearer et al. (1979) and with the recent experimental data of Solomon et al. (1984) for Freon-11 vaporizing sprays. Also, the predictions are compared with the data of Modarress et al. (1984) for an air jet laden with solid particles. The predictions are in good agreement with the experimental data.