Flame theory and combustion technology

The study of combustion processes is in a sufficiently early stage so that there is no strong connection between combustion theory and the technology of combustion chamber development. To clarify such a connection is the principal task of workers engaged in establishing combustion as an engineering science. The equations of aerothermochemistry are reviewed for the case in which temperature and composition gradients are small. Solutions have been obtained in very few cases and under very restrictive circumstances; most detailed considerations are restricted to the plane laminar flame front. The current situation in the theory of plane laminar flames is discussed. The few extensions that have been made to two-dimensional problems are then described. Several directions of work which would assist in establishing theoretical results approaching technological requirements appear possible

Search for SUSY at LHC: Precision Measurements

Methods to make precision measurements of SUSY masses and parameters at the CERN Large Hadron Collider are described.Comment: 7 pages, Latex using included prhep97.sty, 9 figures; To appear in the Proceedings of the International Europhysics Conference on High Energy Physics (Jerusalem, 1997

Burrow Construction From the Ground Surface in \u3ci\u3eLyroda Subita\u3c/i\u3e (Hymenoptera: Sphecidae)

Plasticity in the nesting behavior of Lyroda subita, a species that renovates and then uses pre-existing burrows and other subterranean cavities for nesting sites, is illustrated by one female which apparently excavated her burrow from the ground surface. Details of burrow construction are described. Information on nest structure and dimensions and cell contents is presented

Theoretical Analysis of Nitric Oxide Production in a Methane/Air Turbulent Diffusion Flame

The coherent flame model is applied to the methane-air turbulent diffusion flame with the objective of describing the production of nitric oxide. The example of a circular jet of methane discharging into a stationary air atmosphere is used to illustrate application of the model. In the model, the chemical reactions take place in laminar flame elements which are lengthened by the turbulent fluid motion and shortened when adjacent flame segments consume intervening reactant. The rates with which methane and air are consumed and nitric oxide generated in the strained laminar flame are computed numerically in an independent calculation. The model predicts nitric oxide levels of approximately 80 parts per million at the end of the flame generated by a 30.5 cm (1 foot) diameter jet of methane issuing at 3.05 x 10^3 cm/sec (100 ft/sec). The model also predicts that this level varies directly with the fuel jet diameter and inversely with the jet velocity. A possibly important nitric oxide production mechanism, neglected in the present analysis, can be treated in a proposed extension to the model

Nozzle contours for minimum particle-lag loss

The flow of a gas-particle mixture through a rocket nozzle is analyzed under the approximation that the particle slip velocity is small compared with the average mixture velocity, using one-dimensional gasdynamics, the Stokes drag law, and corresponding approximations for the heat transfer between solid and gas phase. The variational problem defining the pressure distribution giving the minimum impulse loss due to particle lag is formulated and solved for nozzles of prescribed mass flow, length, and of given exit pressure or area. The throat section of the optimum nozzle is considerably elongated and more gradual than that of the conventional nozzle. The velocity and temperature lags were much lower (about 1/3) in the throat region than those for the conventional nozzle. The impulse loss of the optimum nozzle was, however, reduced only about 30% below that of the conventional nozzle. It is concluded that contouring of the nozzle to improve gas-particle flow performance will result in only very modest gains. As a direct consequence, the impulse losses calculated herein for optimum nozzles can be used as a rough but convenient approximation for the impulse losses in conventional nozzles having the same area ratio or pressure ratio

Observations on the Nesting Behavior of \u3ci\u3eAuplopus Caerulescens Subcorticalis\u3c/i\u3e and Other Auplopodini (Hymenoptera: Pompilidae)

Nest searching and mud and prey transport behavior in a small aggregation of Auplopus caerulescens subcorticalis nesting in a concrete cellar foundation in upstate New York are delineated. The contents of nine cells of this subspecies are identified, the mud cells and wasps\u27 eggs are described and measured and the site of the egg attachment on the spider is defined. Selectivity in prey capture at the family level by certain females was indicated, with Thomisidae reported as a new prey family. The method of prey transport and a new prey family (Clubionidae) for Auplopus mellipes variitarsatus are given. Two prey records for Ageniella fulgifrons are included

Dynamics of a gas containing small solid particles

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Reply to comments by S. L. Soo

If one takes due regard for the condition under which my collision model is valid, explicitly stated by Eq. (15), Ref. 1, the difficulties experienced by Soo(2) will not arise