The angular and energy distribution of the ionic products from the reaction of B + in its first excited state. Jp". with molecular deuterium was studied over a projectile energy range of I to 40 eV in the laboratory system. The product states as determined from the limiting values of the translational exoergicity were BD+ el:+) and BD+ en). The experimental velocity contour maps indicated that BD+el:+) was arising through complex formation whereas BD+ en) was proceeding by a direct mechanism.
Combustion using aluminum particles as fuel is an attractive energy source where high energy densities are desired. Very little experimental literature or computational results are available for metal combustion in high-pressure chambers, as most experimental and computational work has been done on chamber operating at near atmospheric pressures. This paper attempts to improve our understanding of metal-fueled combustion chambers at pressures above atmospheric. A numerical model of solid Aluminum fuel particle combustion is developed to investigate the effects of radiation and fuel particle size on the combustion process. Of specific interest are particle specific burn rate, residence time, combustion efficiency, coupled radiation effects, and flame characteristics. This computational model is applied to a linear-type dump combustor. The effects of a range of particle sizes are investigated using mono-dispersed and poly-dispersed particle distributions. Combustion efficiency and characterization of the combustion process are addressed by studying particle ignition delay, surface combustion time, and particle flame radiation intensity as a function of particle diameter and mass fraction. The computational results of this detailed theoretical combustor reveal fundamental physics relating particle sizes and distributions to the variables commonly used to define the effectiveness and performance of the combustion process. The computational models include nonisotropic turbulence models, empirically derived ignition criteria and reaction rates, as well as convective and radiant heat transfer. The numerical results were compared with test data with reasonable agreement.
A novel type of Kelvin–Helmholtz instability model is developed from hydrodynamic theory. The classical Kelvin–Helmholtz instability involves a horizontal interface between two fluids with different parallel, uniform, horizontal velocities. If the upper fluid is a gas with a much smaller density than the lower fluid which is a liquid, then the phase velocity of the critical disturbance equals the liquid’s velocity, so that the liquid sees a standing interfacial wave. The inertial force driving the interfacial instability involves only the gas, no matter how small its density is. In a much more realistic flow model, the liquid velocity at the free surface is not uniform, but varies across the free surface. The disturbance phase velocity can only equal the liquid velocity at one point, while liquid on either side of this point moves faster or slower than the wave. The inertial forces in the liquid then dominate and the gas plays a negligible role. The concept is developed from a Couette flow hydrodynamic model where the fluid flows between two parallel vertical walls with a free surface. The importance of a nonuniform liquid velocity is demonstrated. This modified theory will be applied in future work to study the ejection instability at the interface of the liquid metal and inert cover gas in sliding electrical contacts.
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