Surface ignition of a fuel spray/air mixture in a heated cylindrical duct
Abstract
A numerical analysis for entrance-type flows involving fuel sprays in a heated cylindrical duct was performed by means of a modified CONCHAS-SPRAY code. Changes were made in the original code to handle duct flows and to properly treat the evaporation physics. The analysis assumed an axisymmetric flow. A two-fluid model was chosen for the droplet-gas formulation. The gas phase is a continuum formulation while the liquid phase employed a discrete droplet model. The couplings of the interface mass, momentum and energy transfer between the two phases are represented by the source terms in the gas phase governing equations. For transient droplet heating, infinite liquid thermal conductivity was assumed. The evaporation model used remains the same as used in CONCHAS-SPRAY which is basically the Ranz-Marshall type with a correction factor for the convective heating. The interfacial drags include Stokes and the aerodynamic drag contributions. Validation of gas phase computations was done through the calculation of an entrance duct flow problem with a uniform entry velocity profile. Numerical computations for the experimental system with both spray/air and vapor/air mixtures were performed. Results are compared with experimental data taken at conditions leading to spray ignition. Comparisons of computational results with experimental data show reasonable agreement in bulk spray transport. Prediction may be further improved by providing more detailed spray characterization information to remove the uncertainties in those parameters.
Degree
Ph.D.
Advisors
Skifstad, Purdue University.
Subject Area
Mechanical engineering
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