Simulation of Droplet Evaporation in Supercritical Environments Using Parallel Molecular Dynamics
Simulation of Droplet Evaporation in Supercritical Environments Using Parallel Molecular Dynamics

Author:

Publisher:

Published: 1996

Total Pages: 169

ISBN-13:

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The complete evaporation of three-dimensional submicron droplets under both subcritical and supercritical conditions has been modeled using molecular dynamics (MD). This work represents a first step toward an accurate analytical modeling of combustion in supercritical environments. In this initial study the two-phase simulations consist entirely of argon atoms distributed between a single droplet and its surrounding vapor. The inter-atomic forces are based on a Lennard-Jones 12-6 potential, and the resultant atomic displacements are determined using a modified velocity Verlet algorithm. Linked cell lists in combination with Verlet neighbor lists allow efficient modeling of the large and diverse simulations. A non-cubic periodic boundary, specifically a truncated octahedron, is used to minimize periodicity effects. A unique method, using the linked cell structure, streamlines the associated boundary computations. The linked cells are also used as domains for density, temperature and surface tension computations. This allows a contouring of these properties. The surface tension measure is a unique development. p7.

Analysis of Droplet Combustion - A Theoretical Approach
Analysis of Droplet Combustion - A Theoretical Approach

Author: Shah Shahood Alam

Publisher: LAP Lambert Academic Publishing

Published: 2015-03-23

Total Pages: 192

ISBN-13: 9783659335266

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The findings of this work provides an insight into the fundamental aspects of liquid droplet combustion modelling by developing different droplet sub models. An unsteady, spherically symmetric, sub critical, single component gas phase model is developed first and tested for various ambient conditions of temperature, pressure, composition and fuels.It is further extended to include the effects of convection, droplet heating and emissions.A high pressure droplet vaporization model is evolved in view of the supercritical vaporization occuring in diesel engines and liquid rockets.Also, simple and detailed multi component droplet vaporization/combustion models are developed, since commercial fuels used in engines are multi component fuels.The discrete droplet sub models are simple and realistic requiring less computation time and therefore feasible for their implementation in spray combustion codes where CPU economy is vital.

Application of Parallel Processing to the Investigation of Supercritical Droplet Evaporation and Combustion Using Molecular Dynamics
Application of Parallel Processing to the Investigation of Supercritical Droplet Evaporation and Combustion Using Molecular Dynamics

Author: Michael Micci

Publisher:

Published: 1997

Total Pages: 12

ISBN-13:

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Molecular dynamics (MD) implemented on parallel processors was used to model supercritical droplet phenomena occurring in combustion devices. The use of molecular dynamics allows the modeling of supercritical phenomena without an a priori knowledge of the equation of state or transport properties of the individual components or the mixture. Three-dimensional supercritical oxygen vaporization into gaseous oxygen and helium using two-site Lennard-Jones potentials for the oxygen has been modeled and both the disappearance of surface tension above the critical point and the modification of the critical point for a binary mixture have been observed. A distinct change in droplet morphology was observed when passing through its critical point. The droplet remains spherical as it vaporizes under subcritical conditions but becomes broken and cloud-like when supercritical. Equations of state and transport coefficients for mass, momentum and energy have been calculated for supercritical argon, nitrogen and oxygen which agree with NIST values.

Improved Modeling of Drop Vaporization and Combustion in Sprays
Improved Modeling of Drop Vaporization and Combustion in Sprays

Author:

Publisher:

Published: 2001

Total Pages: 28

ISBN-13:

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In this work, multicomponent and single component droplet vaporization characteristics are investigated by employing computational models. It is shown that simplified droplet vaporization models that do not solve temperature gradients or flow within the droplet and do not solve gradients in temperature or species in the immediate surrounding of the droplet are able to reproduce droplet vaporization rates and droplet lifetime with about 15% accuracy compared to detailed models for typical Diesel operating conditions. Under high temperature (> 1200 K) conditions the differences begin to increase. However, it is also shown that under such conditions as well as at even lower temperatures (> 900 K) the vaporization process is mixing limited i.e., the droplet lifetime is not controlling but rather the characteristic time for mixing of ambient air with the vapor phase the liquid, vapor and air are in phase equilibrium. It is shown that droplets are not likely to react the critical state under typical engine conditions. With application to multidimensional spray models as focus, a new model for predicting the outcome of drop collisions has been developed. Such models are important because they predict the drop sizes in the spray following atomization.

Chemical Kinetics in Combustion and Reactive Flows: Modeling Tools and Applications
Chemical Kinetics in Combustion and Reactive Flows: Modeling Tools and Applications

Author: V. I. Naoumov

Publisher: Cambridge University Press

Published: 2019-08-22

Total Pages: 449

ISBN-13: 1108427049

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Introduces advanced mathematical tools for the modeling, simulation, and analysis of chemical non-equilibrium phenomena in combustion and flows, following a detailed explanation of the basics of thermodynamics and chemical kinetics of reactive mixtures. Researchers, practitioners, lecturers, and graduate students will find this work valuable.