On the Mach Number Effects on Droplet Breakup in Laminar Flow


Book Description

A Volume of Fluid (VOF) multiphase numerical study was conducted using the commercial simulation software ANSYS Fluent to understand the effects of compressibility on droplet breakup in the laminar flow regime. A 2D axisymmetric domain which consists of four subdomains was used for the simulations. Validation of the setup and mesh was conducted by comparing to analytical shock tube equation, Engel’s, and Boger et al.’s work. Two regimes of flows, subsonic and supersonic, were used and were obtained by selection of the operating pressure, velocity, density, dynamic viscosity, and temperature to keep the Reynolds, Weber, and Mach numbers at fixed values between cases. The Reynolds number was held constant at 100. Significant differences within the stripping breakup mode between the supersonic and subsonic cases for similar values of the Weber and Reynolds numbers were observed. The difference was observed in terms of droplet deformation, droplet deformed shape, and droplet lifetime. A Weber number effect is also observed to influence the droplet lifetime. Differences in the pressure distribution were found to drive the different degrees of vertical elongation while the viscous stress mainly acts to bend the droplet downstream. The pressure was found to be the major factor while viscous stress acts as the smaller factor in the physics during most of the deformation process, but viscous stress shows to be the major role at the beginning of the process. Comparison to the solid sphere case provided confirmation of the pressure distribution difference observed between supersonic and subsonic case was expected. Comparison to solid sphere also shows how droplet deformation itself plays a role in effecting the flow field




Scientific and Technical Aerospace Reports


Book Description

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.




Combustion Engineering, Second Edition


Book Description

Combustion Engineering, Second Edition maintains the same goal as the original: to present the fundamentals of combustion science with application to today’s energy challenges. Using combustion applications to reinforce the fundamentals of combustion science, this text provides a uniquely accessible introduction to combustion for undergraduate students, first-year graduate students, and professionals in the workplace. Combustion is a critical issue impacting energy utilization, sustainability, and climate change. The challenge is to design safe and efficient combustion systems for many types of fuels in a way that protects the environment and enables sustainable lifestyles. Emphasizing the use of combustion fundamentals in the engineering and design of combustion systems, this text provides detailed coverage of gaseous, liquid and solid fuel combustion, including focused coverage of biomass combustion, which will be invaluable to new entrants to the field. Eight chapters address the fundamentals of combustion, including fuels, thermodynamics, chemical kinetics, flames, detonations, sprays, and solid fuel combustion mechanisms. Eight additional chapters apply these fundamentals to furnaces, spark ignition and diesel engines, gas turbines, and suspension burning, fixed bed combustion, and fluidized bed combustion of solid fuels. Presenting a renewed emphasis on fundamentals and updated applications to illustrate the latest trends relevant to combustion engineering, the authors provide a number of pedagogic features, including: Numerous tables with practical data and formulae that link combustion fundamentals to engineering practice Concise presentation of mathematical methods with qualitative descriptions of their use Coverage of alternative and renewable fuel topics throughout the text Extensive example problems, chapter-end problems, and references These features and the overall fundamentals-to-practice nature of this book make it an ideal resource for undergraduate, first level graduate, or professional training classes. Students and practitioners will find that it is an excellent introduction to meeting the crucial challenge of engineering sustainable combustion systems in a cost-effective manner. A solutions manual and additional teaching resources are available with qualifying course adoption.




Science and Engineering of Droplets:


Book Description

This is the first book to encompass the fundamental phenomenon, principles, and processes of discrete droplets of both normal liquids and melts. It provides the reader with the science and engineering of discrete droplets, and provides researchers, scientists and engineers with the latest developments in the field. The book begins with a systematic review of various processes and techniques, along with their applications and associations with materials systems. This is followed by a description of the phenomena and principles in droplet processes. Correlations, calculations, and numerical modeling of the droplet processes provide insight into the effects of process parameters on droplet properties for optimization of atomizer design. Droplets are found in the areas of metallurgy, materials, automotive, aerospace, medicine, food processing, agriculture, and power generation, and encountered in a huge range of engineering applications.