Date of Award

2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical and Aerospace Engineering

Committee Chair

C. P. Chen

Committee Member

Shankar Mahalingam

Committee Member

Sarma Rani

Committee Member

Kader Frendi

Committee Member

Ramon L. Cerro

Subject(s)

Fluid dynamics., Liquid fuels--Combustion., Transport theory., Materials--Thermal properties., Thermal conductivity., Thermal diffusivity.

Abstract

The overarching goal of this study is to develop a mathematical methodology for finding a fuel surrogate mixture composition and implementing computationally effective models that can predict the evaporation of multi-component fuel droplets/spray using a multidimensional Computational Fluid Dynamics (CFD) code. A new concept for modeling fuel surrogate is initially developed. Following this, a multi-component fuel droplets/spray coalescence model that builds on previously developed models is derived. Finally, a multi component fuel evaporation model is developed. All the sub-models are implemented for the first time in a multidimensional CFD code, and results are shown to be in good overall agreement with experimental data available in the published literature. Several new surrogates were developed by using the new proposed mathematical methodology. The distillation characteristics of the new surrogates show superior agreement in respect to previously developed surrogates with experimental measurements. A new coalescence model for droplets with different mixture composition has been developed and is implemented for spray calculations. The coalescence of droplets with different radii, densities, and temperatures is modeled in a constant volume chamber at high pressure and temperature. Each droplet contains several components, which represent the diesel fuel surrogate. The new approach for modeling heat and mass transfer inside a droplet accounts for finite thermal conductivity, finite mass diffusivity, and turbulence effects within the atomizing liquid droplet/spray for multi-component fuel droplet evaporation. By implementing the new approach into spray modeling, the evaporation of fuel surrogate was predicted and compared with available experimental measurements. The model shows good predictive capability and was demonstrated to improve the accuracy of multi-phase flow simulations.

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