Valery Rosenband
Technion – Israel Institute of Technology
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Featured researches published by Valery Rosenband.
Journal of Propulsion and Power | 1995
Valery Rosenband; Benveniste Natan; Alon Gany
A theoretical model for the ignition of titanium-coated boron particles in dry air has been developed. In general, the results indicate reduction in ignition time due to a high heating rate of the particle resulting from the reactions of titanium with both boron and oxygen and the deterioration of the protective properties of the coating layers due to mechanical stresses. However, ignition strongly depends on the titanium coating thickness and the ambient temperature.
Combustion Science and Technology | 2001
Valery Rosenband; Alon Gany
Aluminum powders added to solid propellants burn either as single particles or agglomerates. Combustion efficiency is very dependent on the final aluminum particle size injected into the chamber flowfield. This work has investigated experimentally the microscopic behavior of powdered aluminum particles during gradual heating in inert and oxidative atmospheres. Effects of surrounding gas composition, particle size, initial oxide layer thickness, and dilution by refractory compound on the particles behavior during heating have been studied. A novel model of a crucial stage in aluminum particles agglomeration based on estimation of mechanical stresses appearing in the oxide layer during particle heating has been suggested. Results of estimation confirm that disruption of oxide layer takes place during aluminum melting. This disruption results in the flow of a molten metal through cracks formed in the oxide layer and in the formation of large liquid drops. Results of theoretical calculations are in a good agreement with experimental data.
Oxidation of Metals | 1995
Valery Rosenband; Alon Gany; Y. M. Timnat
The existence and influence of mechanical stresses, appearing at a metal-oxide interface, on the rate and regularities of metal oxidation is analyzed. The source of these stresses involves, in particular, the difference in thermal-expansion coefficients and densities of metal and oxide. From this point of view, the oxidation parameters of Al, Ti, Zr, and Mg are calculated. It is shown that the suggested approach well describes qualitatively, and in some cases quantitatively, the numerous experimental data concerning oxide-layer structures, complex multistep parabolic oxidation, transition from protective to nonprotective oxidation, etc. Results of the calculations indicate that for cylindrical vessels internal pressure may result in significant intensification of the oxidation process.
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering | 2014
Yinon Yavor; Valery Rosenband; Alon Gany
The effects of using porous aluminum particles in solid propellants were studied, with emphasis on the agglomeration phenomena. Burning strands containing either regular (as-received) or porous aluminum were photographed by a high-speed camera, and particulate combustion products were analyzed in a laser particle analyzer. Results obtained from experiments conducted in a pressure-range of 1–34 atmospheres show that porous aluminum particles produce smaller agglomerates than regular aluminum. The median diameter of agglomerates resulting from porous aluminum reached, on average, 70% of the one originating from regular aluminum. This reduction in agglomerate diameter corresponds to a substantial volume (and hence, mass) decrease of approximately 65%. It is assumed that the high-specific area of the porous aluminum particles (10–18 m2/g, similar to that of nano-Al) results in high reactivity, leading to shorter ignition time and hence to the formation of smaller agglomerates.
Combustion Science and Technology | 1995
Valery Rosenband; Alon Gany; Y. M. Timnat
Abstract A new theoretical model for the low-temperature ignition process of magnesium particles is proposed. The model is based on physical-mechanical effects resulting from the buildup of oxide layers on the particle surface and their possible destruction as a result of mechanical stresses attributed to thermal and pressure expansion which are due to temperature elevation, melting and, in some instances, liberation of dissolved hydrogen and generation of magnesium vapors. The model attempts to describe and predict peculiar and unexplained phenomena, which have been observed experimentally during the low temperature ignition of magnesium particles, such as increase or pulsations in particle size, formation of hollow spheres, and fragmentation of particles
Wear | 1998
Valery Rosenband; Y. Schneebaum; Alon Gany
A thermodynamic analysis of the reactive erosion of steels by pure high-temperature gases and combustion products of solid propellants has been carried out. The temperature dependencies of the oxygen partial pressure and carbon activity of the gas mixtures as well as of main components of the steel alloy were calculated. Comparison of experimental results and thermodynamic calculations was presented. It was shown that thermodynamic approach can interpret various experimental results of steel erosion.
42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit | 2006
Valery Rosenband; Alon Gany
†Metals are incorporated in propellant and fuel compositions primarily because of their high energy and energy density. Nanosize metal powders with a particle size less than 0.1 µm may be good candidates as fuel components because of their high reactivity due to the large reaction surface. Such metal powders burn close to the propellant surface, significantly increase the propellant burning rate. The present paper reports a novel technology for the production of nanosized titanium and zirconium powders, whose size distribution and high purity were determined by different methods. Study of the ignition behavior of these powders revealed their very high reactivity and shorter ignition times in comparison to coarser (>1 µm) titanium and zirconium powders, which may imply not only better combustion characteristics, but also lower agglomeration.
International Journal of Hydrogen Energy | 2010
Valery Rosenband; Alon Gany
International Journal of Hydrogen Energy | 2014
Shani Elitzur; Valery Rosenband; Alon Gany
Proceedings of the Combustion Institute | 2005
Evgeny Shafirovich; P. Escot Bocanegra; Christian Chauveau; Iskender Gökalp; U. Goldshleger; Valery Rosenband; Alon Gany