Turbulent Jets and Plumes


Book Description

Jets and plumes are shear flows produced by momentum and buoyancy forces. Examples include smokestack emissions, fires and volcano eruptions, deep sea vents, thermals, sewage discharges, thermal effluents from power stations, and ocean dumping of sludge. Knowledge of turbulent mixing by jets and plumes is important for environmental control, impact and risk assessment. Turbulent Jets and Plumes introduces the fundamental concepts and develops a Lagrangian approach to model these shear flows. This theme persists throughout the text, starting from simple cases and building towards the practically important case of a turbulent buoyant jet in a density-stratified crossflow. Basic ideas are illustrated by ample use of flow visualization using the laser-induced fluorescence technique. The text includes many illustrative worked examples, comparisons of model predictions with laboratory and field data, and classroom tested problems. An interactive PC-based virtual-reality modelling software (VISJET) is also provided. Engineering and science students, researchers and practitioners may use the book both as an introduction to the subject and as a reference in hydraulics and environmental fluid mechanics.




Physics of Turbulent Jet Ignition


Book Description

This book focuses on developing strategies for ultra-lean combustion of natural gas and hydrogen, and contributes to the research on extending the lean flammability limit of hydrogen and air using a hot supersonic jet. The author addresses experimental methods, data analysis techniques, and results throughout each chapter and: Explains the fundamental mechanisms behind turbulent hot jet ignition using non-dimensional analysis Explores ignition characteristics by impinging hot jet and multiple jets in relation to better controllability and lean combustion Explores how different instability modes interact with the acoustic modes of the combustion chamber. This book provides a potential answer to some of the issues that arise from lean engine operation, such as poor ignition, engine misfire, cycle-to-cycle variability, combustion instability, reduction in efficiency, and an increase in unburned hydrocarbon emissions. This thesis was submitted to and approved by Purdue University.




Computational Fluid Dynamics and Energy Modelling in Buildings


Book Description

COMPUTATIONAL FLUID DYNAMICS AND ENERGY MODELLING IN BUILDINGS A Comprehensive Overview of the Fundamentals of Heat and Mass Transport Simulation and Energy Performance in Buildings In the first part of Computational Fluid Dynamics and Energy Modelling in Buildings: Fundamentals and Applications, the author explains the fundamentals of fluid mechanics, thermodynamics, and heat transfer, with a specific focus on their application in buildings. This background knowledge sets the scene to further model heat and mass transport in buildings, with explanations of commonly applied simplifications and assumptions. In the second part, the author elaborates how the fundamentals explained in part 1 can be used to model energy flow in buildings, which is the basis of all commercial and educational building energy simulation tools. An innovative illustrative nodal network concept is introduced to help readers comprehend the basics of conservation laws in buildings. The application of numerical techniques to form dynamic simulation tools are then introduced. In general, understanding these techniques will help readers to identify and justify their choices when working with building energy simulation tools, rather than using default settings. Detailed airflow information in buildings cannot be obtained in building energy simulation techniques. Therefore, part three is focused on introducing computational fluid dynamics (CFD) as a detailed modelling technique for airflow in buildings. This part starts with an introduction to the fundamentals of the finite volume method used to solve the governing fluid equations and the related challenges and considerations are discussed. The last chapter of this part covers the solutions to some practical problems of airflow within and around buildings. The key aspect of Computational Fluid Dynamics and Energy Modelling in Buildings: Fundamentals and Applications is that it is tailored for audiences without extensive past experience of numerical methods. Undergraduate or graduate students in architecture, urban planning, geography, architectural engineering, and other engineering fields, along with building performance and simulation professionals, can use this book to gain additional clarity on the topics of building energy simulation and computational fluid dynamics.







Recent Research Advances in the Fluid Mechanics of Turbulent Jets and Plumes


Book Description

Challenging problems involvrllg jet and plume phenomena are common to many areas of fundamental and applied scientific research, and an understanding of plume and jet behaviour is essential in many geophysical and industrial contexts. For example, in the field of meteorology, where pollutant dispersal takes place by means of atmospheric jets and plumes formed either naturally under conditions of convectively-driven flow in the atmospheric boundary layer, or anthropogenically by the release of pollutants from tall chimneys. In other fields of geophysics, buoyant plumes and jets are known to play important roles in oceanic mixing processes, both at the relatively large scale (as in deep water formation by convective sinking) and at the relatively small scale (as with plume formation beneath ice leads, for example). In the industrial context, the performances of many engineering systems are determined primarily by the behaviour of buoyant plumes and jets. For example, (i) in sea outfalls, where either sewage or thermal effluents are discharged into marine and/or freshwater environments, (ii) in solar ponds, where buoyant jets are released under density interfaces, (iii) in buildings, where thermally-generated plumes affect the air quality and ventilation properties of architectural environments, (iv) in rotating machinery where fluid jet~ are used for cooling purposes, and (v) in long road and rail tunnels, where safety and ventilation prcedures rely upon an understanding of the behaviour of buoyant jets. In many other engineering and oceanographic contexts, the properties of jets and plumes are of great importance.




The Theory of Turbulent Jets


Book Description

The author's first monograph on turbulent jets, in 1936, dealt solely with a free submerged jet. Since that time, the theory of the turbulent jet has been developed in many published works both in the USSR and abroad: it has been enriched with a large amount of experimental material and has been applied in many new fields of engineering. In the last 10 years very substantial progress has been made, and it has now become possible to go beyond the free submerged jet and to solve the problem of a jet in a stream of fluid, to take into account the interaction between the jet and solid walls, to ascertain the relationship between the contour of the jet and the ratio of its density to the density of the surrounding medium, and to establish the characteristic features of a supersonic jet. This monograph contains the results of further research by the author and his colleagues, as well as a critical reappraisal of the more important theoretical and experimental data published by other investigators. The first section deals with the theory of a turbulent jet of incompressible fluid. It gives a systematic analysis of numerous experimental data on velocity profiles, temperature, and the impurity concentration, as well as the outlines of the turbulent mixing lone. The second section sets forth the theory of turbulent gas jets, including strongly preheated and supersonic jets. The theory of free turbulence in a gas, suitable in principle for any degree of compressibility, is revised, and the equations are derived for motion and heat exchange in the boundary layer of a jet at very high temperature. The third section solves several problems of the spreading of jets in finite and semifinite space, and the fourth section describes various applications of the theory of jets, many of which are reported for the first time or have been significantly revised.







Air Bubble Entrainment in Free-Surface Turbulent Shear Flows


Book Description

This book develops an analysis of the air entrainment processes in free-surface flows. These flows are investigated as homogeneous mixtures with variable density. Several types of air-water free-surface flows are studied: plunging jet flows, open channel flows, and turbulent water jets discharging into air. Experimental observations reported by the author confirm the concept that the air-water mixture behaves as a homogeneous compressible fluid in each case. This book will be of great interest to professionals working in many fields of engineering: chemical, civil, environmental, mechanical, mining, metallurgy, and nuclear. Covers new information on the air-water flow field: air bubble distributions, air-water velocity profiles, air bubble sizes and bubble-turbulence interactions Features new analysis is developed for each flow configuration and compared successfully with model and prototype data Includes over 372 references and more than 170 figures with over 60 photographs Presents useful information for design engineers and research-and-development scientists who require a better understanding of the fluid mechanics of air-water flows




Environmental Hydraulics for Open Channel Flows


Book Description

Environmental Hydraulics is a new text for students and professionals studying advanced topics in river and estuarine systems. The book contains the full range of subjects on open channel flows, including mixing and dispersion, Saint-Venant equations method of characteristics and interactions between flowing water and its surrondings (air entrainment, sediment transport).Following the approach of Hubert Chanson's highly successful undergraduate textbook Hydraulics of Open Channel Flow, the reader is guided step-by-step from the basic principles to more advanced practical applications. Each section of the book contains many revision exercises, problems and assignments to help the reader test their learning in practical situations.·Complete text on river and estuarine systems in a single volume·Step-by-step guide to practical applications·Many worked examples and exercises




Turbulent Jets


Book Description

Turbulent Jets