1 edition of Liquid crystal mapping of jet crossflow interactions found in the catalog.
Liquid crystal mapping of jet crossflow interactions
Michael David Johnson
The jet in crossflow, or transverse jet, is a flowfield that has relevance to a wide range of energy and propulsion systems. Over the years, our group's studies on this canonical flowfield have focused on the dynamics of the vorticity associated with equidensity and variable density jets in crossflow, including the stability characteristics of the jet's upstream shear layer, as a means of. This interaction can have significant impact on mixing, ignition and boundary layer dynamics. Global characteristics of JICF's, such as penetration, for example, have been found to primarily depend on a single parameter (see for example Margason, , for low speed JICF), the so-called jet-to-crossflow momentum flux ratio J defined as.
Considerable number of empirical correlations had been proposed by many investigators. It has generally known that the jet/spray trajectory of a liquid jet in a cross-flow is a function of the liquid to air momentum flux ratio and the normalized distance in the airstream direction from the injector. Patterns in thin liquid crystal films changes in the tilt angle increase the surface energy. If the function u(0) is monotonous, then the maixmum all = u(0 = n/2) will be reached at 0 = n/2. The anchoring coefficient W can be defined as the difference all -
T1 - The interaction of jets with crossflow. AU - Mahesh, Krishnan. PY - /1/1. Y1 - /1/1. N2 - It is common for jets of fluid to interact with crossflow. This article reviews our understanding of the physical behavior of this important class of flow in the incompressible and compressible regimes. Detailed large-eddy simulation of turbulent liquid atomization in a crossflow. The liquid is issued from a round-edged injector. Performed with NGA by Mark Owkes and Olivier Desjardins.
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Liquid Crystal Mapping of Jet Crossflow Interactions by Michael David Johnson Lieutenant, United States Navy B.S., United States Naval Academy, Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN MECHANICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL December Author 4 Approved by: __ Thesis Advisor.
Liquid crystal mapping of jet crossflow interactions. By Michael David Johnson. An experimental apparatus was designed and built to provide a heated surface coated with liquid crystals. For a range of jet-to-crossflow velocity ratios, the temperature field on the flat plate was visually represented.
The technique allowed continual visual Author: Michael David Johnson. Liquid crystal mapping of jet crossflow interactions book in crossflow interaction are depicted in figure 1. Four major coherent structures are found: a counter-rotating vortex pair (in the core of the jet), windward, leeward and spiral (at the nozzle sides) vortices.
Figure 1 Vortical structures resulting from jet-crossflow interaction. It has generally known that the jet/spray trajectory of a liquid jet in a cross-flow is a function of the liquid to air momentum flux ratio and the normalized distance in the airstream direction.
BREAKUP CHARACTERISTICS OF LIQUID JET IN SUBSONIC CROSSFLOW Approved by: Dr. Ben T. Zinn, Advisor School of Aerospace Engineering Georgia Institute of Technology Dr.
Jerry Seitzman Mapping of the breakup regimes as a function of We and q (adopted from. In this book, the essential elements of liquid crystal science are introduced and explained from the perspectives of both the chemist and the physicist.; The text begins with an historical account of the discovery of liquid crystals and continues with a description of how different phases are generated and how different molecular architectures Reviews: 2.
This book reviews comprehensively the technological, scientific, artistic and medical applications of liquid crystals. It starts with the basics of liquid crystals and covers electro-optical, thermo-optical, colour, polymeric, lyotropic, and scientific applications of liquid crystalline materials.
It discusses the fabrication and operational principles of a full range of liquid crystal. Liquid crystals can be modelled with various degrees of precision. At a very de-tailed level one can describe and simulate the interactions between the atoms in each liquid crystal molecule, and between these atoms and those of other molecules, but of course.
Liquid crystal phases possess orientational order (tendency of the molecules to point along a common direction called the director n) and in some cases positional order in one or two dimensions as shown in Fig I.1b and I.1c.
On the other hand, in the isotropic liquid state, the molecules move randomly and rotate freely about all. Liquid Crystal Phases The liquid crystal state is a distinct phase of matter observed between the crystalline (solid) and isotropic (liquid) states.
There are many types of liquid crystal states, depending upon the amount of order in the material. This section will explain the phase behavior of liquid crystal materials.
Nematic Phases. The spacing between the jet and target surface is 4 times the jet diameter. Particle Image Velocimetry (PIV) and Liquid Crystal Thermography (LCT) are used to measure the flow field and heat transfer, respectively. The interaction of the cross-flow and jet produces various vortices, and the jet is shown to be deflected downstream by the cross-flow.
Jet impingement heat transfer by using a rib with cross flow approach using liquid crystal thermography was investigated experimentally by Wang et al. The breakup processes and droplet characteristics of a liquid jet injected into a low-speed air crossflow in the finite space were experimentally investigated.
The liquid jet breakup processes were recorded by high-speed photography, and phase-Doppler anemometry (PDA) was employed to measure the droplet sizes and droplet velocities.
Through the instantaneous image observation, the liquid jet. It is common for jets of fluid to interact with crossflow. This article reviews our understanding of the physical behavior of this important class of flow in the incompressible and compressible regimes.
Experiments have significantly increased in sophistication over the past few decades, and recent experiments provide data on turbulence quantities and scalar mixing. Quantitative data at high. The terms “jet-to-crossflow momenturm flux ratio”, International journal of spray and combustion dynamics Volume.7 Number Crossflow Column breakup Ligament Droplets Liquid jet Jet dispersion Surface breakup Penetration height Liquid column Figure 1: Typical parameters of liquid jet in cross flow (modified from No ).
q = ρlvl 2 ρgvg 2 (1) Where ρ and v are the density and the velocity while the subscripts l and g refers to the liquid jet and the air- flow, respectively. As matter of fact a very bended jet could be observed when q is low. On the other hand when q is very high the liquid jet penetrates more causing an impact against the wall in extreme conditions.
Liquid Crystal State. Director and Order Parameter. Director Order Parameter. Anisotropy in Liquid Crystals. Optical Anisotropy of Liquid Crystals Dielectric Anisotropy of Liquid Crystals. Main Types of Liquid Crystals.
Nematic Liquid Crystals Cholesteric Liquid Crystals Smectic Liquid Crystals. Surface Anchoring. Orientation of. "Lipid bilayers are an example of a lyotropic liquid crystal. Liquid crystals are defined as lyotropic if the molecular order in the parent solid state is reduced by a solvent.
In biological membranes, water is the solvent which reduces this order. And in most cases, the parent lipid is. Abstract. The jet in crossflow or transverse jet has been studied extensively because of its relevance to a wide variety of flows in technological systems, including fuel or dilution air injection in gas turbine engines, thrust vector control for high speed airbreathing.
Turbulent jet flames in a crossflow: effects of some jet, crossflow, and pilot-flame parameters on emissions Combustion and Flame, Vol.No. Detailed measurements of the structure of a jet diffusion flame in a cross flow. The existence of liquid crystals has been known for nearly a centu ry; yet it is only in the last ten years that their unique optical, electri cal, electro-optic, and thermal properties have been exploited to any significant extent in such technological applications as digital d~ plays and thermography.
Digital watches equipped with liquid-crys tal displays (LCD's) have recently made their. It was found in the velocity vector maps at the streamwise locations, (a) x/d=0 and (c) x/d=10, in Fig. 9 that the impingement angle of the downstream-side jet is closer to 90° than the one of the upstream-side jet.
This could be a reason why the downstream peak is larger than the upstream one in the staggered arrangement. The PIV measurements are taken at planes normal to the target wall along the centerline for each individual jet, providing quantitative flow visualization of jet and crossflow interactions.
The heat transfer distributions on the target plate of the channels are evaluated with transient techniques and a multilayer of liquid crystals (LCs).