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Articles 1 - 4 of 4
Full-Text Articles in Engineering
The Impact Of Crystal Morphology On The Thermal Responses Of Ultrasonically-Excited Energetic Materials, J. K. Miller, J. O. Mares, I. E. Gunduz, Steven F. Son, Jeff Rhoads
The Impact Of Crystal Morphology On The Thermal Responses Of Ultrasonically-Excited Energetic Materials, J. K. Miller, J. O. Mares, I. E. Gunduz, Steven F. Son, Jeff Rhoads
Purdue Energetics Research Center Articles
The ability to detect explosive materials may be significantly enhanced with local increases in vapor pressure caused by an elevation of the materials'temperature. Recently, ultrasonic excitation has been shown to generate heat within plastic-bonded energetic materials. To investigate the impact of crystal morphology on this heating, samples of elastic binder are implanted with single ammonium perchlorate crystals of two distinct shape groups. Contact piezoelectric transducers are then used to excite the samples at ultrasonicfrequencies. The thermal responses of the crystals are recorded using infrared thermography, and the rate of heating is estimated. Surface temperature increases up to 15 °C …
Entropy Minimization Design Approach Of Supersonic Internal Passages, Jorge Sousa, Guillermo Paniagua
Entropy Minimization Design Approach Of Supersonic Internal Passages, Jorge Sousa, Guillermo Paniagua
School of Aeronautics and Astronautics Faculty Publications
Fluid machinery operating in the supersonic regime unveil avenues towards more compact technology. However, internal supersonic flows are associated with high aerodynamic and thermal penalties, which usually prevent their practical implementation. Indeed, both shock losses and the limited operational range represent particular challenges to aerodynamic designers that should be taken into account at the initial phase of the design process. This paper presents a design methodology for supersonic passages based on direct evaluations of the velocity field using the method of characteristics and computation of entropy generation across shock waves. This meshless function evaluation tool is then coupled to an …
Simulations Of Nanoscale Ni/Al Multilayer Foils With Intermediate Ni2al3 Growth, I. E. Gunduz, S. Onel, C. C. Doumanidis, C. Rebholz, Steven F. Son
Simulations Of Nanoscale Ni/Al Multilayer Foils With Intermediate Ni2al3 Growth, I. E. Gunduz, S. Onel, C. C. Doumanidis, C. Rebholz, Steven F. Son
Purdue Energetics Research Center Articles
Nanoscale multilayers of binary metallic systems, such as nickel/aluminum, exhibit self-propagating exothermic reactions due to the high formation enthalpy of the intermetallic compounds. Most of the previous modelingapproaches on the reactions of this system rely on the use of mass diffusionwith a phenomenological derived diffusion coefficient representing single-phase (NiAl) growth, coupled with heat transport. We show that the reaction kinetics, temperatures, and thermal front width can be reproduced more satisfactorily with the sequential growth of Ni2Al3 followed by NiAl, utilizing independently obtained interdiffusivities. The computational domain was meshed with a dynamically generated bi-modal grid consisting of fine and coarse zones …
Waste And Duplication In Nasa Programs: The Need To Enhance U.S. Space Program Efficiency, Bert Chapman
Waste And Duplication In Nasa Programs: The Need To Enhance U.S. Space Program Efficiency, Bert Chapman
Libraries Faculty and Staff Scholarship and Research
The U.S. Government faces acute budgetary deficits and national debt problems in the Obama Administration. These problems have been brought about by decades of unsustainable government spending affecting all agencies including the National Aeronautics and Space Administration. (NASA). An outgrowth of this fiscal profligacy is the presence of wasteful and duplicative programs within NASA that prevent this agency from achieving its space science and human spaceflight objectives. These problems occur due to mismanagement of these programs from NASA and the creation of these programs by the U.S. Congress and congressional committees. This occurs because congressional appropriators tend to be more …