Effects of Turbulent Mixing on Chemical Reaction in an Aerosol-producing Co-flow Jet

Effects of Turbulent Mixing on Chemical Reaction in an Aerosol-producing Co-flow Jet
Author: Thomas Paris Jenkins
Publisher:
Total Pages: 580
Release: 1997
Genre: Aerosols
ISBN:

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Investigates the effects of mixing on chemical reaction in a turbulent co-flow jet. After a jet is produced by a mixture of HCl (hydrogen chloride), air, and N2 (nitrogen) issuing from a pipe into a co-flowing stream of NH3 (gaseous ammonia) and air, a chemical reaction in which NH4Cl (ammonium chloride) aerosol with negligible heat release is produced. The product concentration field as marked by the aerosol is then characterized through the collection of data from which probability density functions can be constructed.

A Chemical Reaction in a Turbulent Jet

A Chemical Reaction in a Turbulent Jet
Author: John R Shea (III.)
Publisher:
Total Pages: 139
Release: 1976
Genre:
ISBN:

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The turbulent mixing and subsequent chemical reaction of gases is an essential part of many technological processes ranging from gas furnaces to chemical lasers. Generally the chemical kinetics are well understood, but the process of turbulent mixing is not. Knowledge of where turbulent fluid is mixed on a molecular scale is critical for predicting chemical reaction rates in the flow. In this experiment the rate of a chemical reaction in an axisymmetric turbulent jet is studied, and the results are used to determine the rate of molecular mixing in the jet. A turbulent jet containing dilute ozone in an inert mixture of nitrogen and oxygen flows into a stagnant tank of nitric oxide and nitrogen. When the gases mix on a molecular scale, the ozone and nitric oxide rapidly react to produce oxygen and nitrogen dioxide. The rate at which the mixing and chemical reaction proceeds is determined by using an ultraviolet light absorption techniques to measure the time averaged ozone concentration at points throughout the jets mixing zone. The experiment establishes a criterion for determining when a reaction of known chemical kinetics is sufficiently rapid that chemical non-equilibrium has a negligible effect on the mean reactant profile.

Chemical Reactions in Turbulent Mixing Flows

Chemical Reactions in Turbulent Mixing Flows
Author:
Publisher:
Total Pages: 45
Release: 1990
Genre:
ISBN:

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This research conducted fundamental investigations of turbulent mixing, chemical reaction and combustion processes in turbulent, subsonic and supersonic flows. This program is comprised of an experimental effort, an analytical effort, a computational effort, a modeling effort, and a diagnostics development and data-acquisition effort; the latter as dictated by specific needs of the experimental part of the overall program. Our approach has been to carry out a series of detailed theoretical and experimental studies primarily in two, well-defined, fundamentally important flow fields: free shear layers and axisymmetric jets. To elucidate molecular transport effects, experiments and theory concern themselves with both liquids and gases, primarily in moderate to high Reynolds number flows. Modeling has been focused on both shear layers and turbulent jets, with an effort to include the physics of the molecular transport processes, as well as formulations of models that permit the full chemical kinetics of the combustion process to be incorporated. Our recent analytical efforts have concentrated on a hydrodynamic analysis of the stability of compressible shear layers. The computational studies are, at present, focussed at fundamental issues pertaining to the computational simulation of both compressible and incompressible flows.

Turbulent Reactive Flows

Turbulent Reactive Flows
Author: R. Borghi
Publisher: Springer Science & Business Media
Total Pages: 958
Release: 2013-03-08
Genre: Science
ISBN: 146139631X

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Turbulent reactive flows are of common occurrance in combustion engineering, chemical reactor technology and various types of engines producing power and thrust utilizing chemical and nuclear fuels. Pollutant formation and dispersion in the atmospheric environment and in rivers, lakes and ocean also involve interactions between turbulence, chemical reactivity and heat and mass transfer processes. Considerable advances have occurred over the past twenty years in the understanding, analysis, measurement, prediction and control of turbulent reactive flows. Two main contributors to such advances are improvements in instrumentation and spectacular growth in computation: hardware, sciences and skills and data processing software, each leading to developments in others. Turbulence presents several features that are situation-specific. Both for that reason and a number of others, it is yet difficult to visualize a so-called solution of the turbulence problem or even a generalized approach to the problem. It appears that recognition of patterns and structures in turbulent flow and their study based on considerations of stability, interactions, chaos and fractal character may be opening up an avenue of research that may be leading to a generalized approach to classification and analysis and, possibly, prediction of specific processes in the flowfield. Predictions for engineering use, on the other hand, can be foreseen for sometime to come to depend upon modeling of selected features of turbulence at various levels of sophistication dictated by perceived need and available capability.

Scientific and Technical Aerospace Reports

Scientific and Technical Aerospace Reports
Author:
Publisher:
Total Pages: 602
Release: 1995
Genre: Aeronautics
ISBN:

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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.

An Experimental Investigation of Ducted, Reactive, Turbulent Jet Mixing with Recirculation

An Experimental Investigation of Ducted, Reactive, Turbulent Jet Mixing with Recirculation
Author: D. E. Chriss
Publisher:
Total Pages: 52
Release: 1977
Genre: Gas flow
ISBN:

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An experimental investigation of ducted, two stream, subsonic, reactive, turbulent jet mixing with recirculation was conducted. A primary jet of air at a mass flow rate of 0.075 lb/sec and velocity of 700 ft/sec was surrounded by an outer, low velocity, hydrogen stream. Data were obtained with hydrogen-air ratios of 0.143 and 0.107. The duct-to-inner nozzle diameter ratio was ten. Radial distributions of hydrogen mass fraction, mean axial velocity, turbulence intensity, and total pressure as well as axial distributions of wall hydrogen mass fraction and wall static pressure are presented for axial stations from one-half to five duct diameters from the nozzle exit plane. Comparison of the experimental data with calculations assuming frozen or equilibrium chemistry indicate that he measured velocity, pressure, and composition data are, in general, self-consistent. The maximum turbulent intensities which occurred in the center of the mixing layer and within the recirculation eddy were very high having values of 20 percent of the jet exit velocity. The velocity and composition field indicate that, while and mixing in the reactive flow field is slower than for the nonreactive case, the reaction had little effect on the size and location of the recirculation zone within the mixing duct.