Collective drop effects on vaporizing liquid sprays
A theoretical study of the dynamics and evaporation of drops in the thick spray regime is presented. In the thick spray regime a number of new physical effects can be important that have largely been ignored in previous theoretical studies of sprays. These include drop collisions and modifications of drop drag and vaporization rates due to close drop spacings. The purpose of this work is to begin to includee these effects in the equations for vaporizing sprays, to develop a numerical method for solving the resulting equations, and to assess the importance of the thick spray effects in comparisons with experiments. The thick spray problem is described in physical terms. A typical spray parcel is traced from a time when it is a group of isolated and non-interacting drops backward in time to when it is part of an intact column of liquid in the nozzle. The spray equation, as well as the gas phase equations, are derived. The derivation and equations are compared with others in the literature. Forms are postulated for the thick spray exchange functions and the functions defining collisional effects, i.e., the collision cross-sections and the transition probability function for collisions. A number of questions relating to the choice of a numerical solution procedure for the unsteady, two-dimensional equations of motion and the computer program, LDEF (Lagrangian Drop-Eulerian Fluid), written are discussed. Three solution procedures are described, and their advantages and disadvantages are discussed. The accuracy of the numerical method is assessed in comparison with other analytical solutions and with the results of a series of laboratory experiments. Recommendations are made for further laboratory and numerical experiments.
- Research Organization:
- Los Alamos National Lab., NM (USA)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 5201366
- Report Number(s):
- LA-9069-T; ON: DE82010958
- Country of Publication:
- United States
- Language:
- English
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FUELS
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