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The conclusions are that: the breakup of full-cone Diesel jets is due primarily to aerodynamic interaction between the liquid surface and the chamber gas; the initial average size and velocity of the drops formed by the breakup of the outer surface of the jet can now be estimated and so can the length of the intact core but with greater uncertainty; after breakup a steady full-cone spray undergoes a development similar to that of incompressible jets; in Diesel engines it is the development region that is of importance; the major parameter in the difference between full-cone sprays and incompressible jets is the liquid-to-gas density ratio; in the absence of vaporization the most advanced of the available spray model reproduce full-cone sprays with adequate realism for applications; it is not yet known how vaporization changes the structure of these sprays and if available models adequately reproduce the changes.

Results of research on a two dimensional, transient catalytic combustion model and on a high temperature perovskite catalyst are presented. A recently developed two dimensional, transient model has been used to study the ignition of carbon monoxide/air mixtures in a platinum coated catalytic honeycomb. Comparisons between calculated and measured steady state substrate temperature profiles and exhaust gas compositions show good agreement. A platinum doped perovskite catalyst has been proposed which will exhibit low temperature light off and high temperature stability. Preliminary tests using a perovskite powder with one percent by weight platinium are encouraging, showing very little change in surface activity when used with propane fuel. Variations in catalytic activity from sample to sample have also been found and after extensive testing the cause of these variations have not been identified. However, preliminary tests using Fourier transform infrared photoacoustic spectroscopy do indicate differences in the various catalyst samples that may be related to the difference in catalytic activity. The use of bench top oven and differential scanning calorimetry techniques for screening catalysts in terms of relative activity and aging characteristics has also been demonstrated. Originator-supplied keywords include: Catalytic combustion, and Perovskite catalysts.

Lean combustion of propane in platinum/alumina/cordierite catalysts has been studied at atmospheric pressure, gas velocities of 10-40 m/s, C3H8 equivalence ratios of .19 to .32 and H2O concentration of 1.2 to 1.7 mol %. Measurements of substrate temperature and gas composition, pressure, and temperature inside and downstream of the catalyst have been made. The dependences of substrate temperature, gas temperature, and gas composition of inlet temperature, reference velocity, and equivalence ratio have been investigated. A two-dimensional model of the gas-phase including the effect of finite-rate chemical kinetics at the substrate surface has been developed and tested. When the experimental wall temperature is used as boundary condition for the gas-phase equations, the emission predictions are in reasonably good agreement with the measured ones. The indications obtained from the model are that propane is oxidized via a multi-step kinetic mechanism, that in the range of temperatures and equivalence ratios explored, most of the fuel is burnt at the catalytic wall rather than in the gas phase, and that wall kinetics is slower than gas diffusion transport.

Ignition of a quiescent propane/air mixture by a stationary, hot, inert particle has been modeled. The tentative conclusion from the model is that an abraded aluminum particle must have a diameter greater than 800 microns to ignite a stoichiometric propane/air mixture. Experimental data show that a burning aluminum particle must be initially larger than 20-40 microns in diameter to ignite a stoichiometric methane/air mixture. Lean combustion of propane in platinum/alumina/cordierite catalysts has been studied at atmospheric pressure and gas velocities of 5-30 m/s. Measurements of substrate temperature and gas composition, pressure and temperature inside and downstream of the catalyst have been made. The dependences of substrate temperature, gas temperature, and gas composition on inlet temperature, reference velocity, and equivalence ratio have been investigated. Homogeneous reactions in the exhaust are observed only at the higher equivalence rations. Broader interpretation of the variation in exhaust composition with inlet conditions awaits completion of the development of the numerical model. (Author)

Measurements of catalytic combustion of lean mixtures of propane/air at atmospheric pressure over platinum/alumina/cordierite catalysts were carried out over a broad range of equivalence ratios and flow velocities. Substrate (honeycomb) temperatures, chemical species at the catalyst were measured. A substantial data base for catalytic oxidation C3H8 over platinum catalysts was obtained. A two-dimensional model of the gas-phase oxidation of propane was developed. When the experimental wall temperature is used as the boundary condition for the gas-phase reactions; emissions predicted from the model agree well with measured values. From comparison with the experimental data, indications are that propane oxidation takes place via a three-step kinetic mechanism. Also from study of the relative importance of gas-phase vs. surface oxidation, conclusions are that most of the propane is burnt in the gas-phase rather than at the catalytic wall and that the wall kinetics is slower than the gas diffusion transplant. (Author)

The main objective of these grants has been to study the fundamental processes which lead to the atomization of high pressure jets injected into compressed gases through single hole nozzles. Specific topics include: Dependence of Spray Angle and Other Spray Parameters on Nozzle Design and Operating Conditions; Ultra High Speed Filming of Atomizing Jets; Mechanism of Breakup of Highly Super Heated Liquid Jets; Measurements of the Spray Angle of Atomizing Jets; Mechanism of Atomization of a Liquid Jet; Scaling of Transient Laminar, Turbulent, and Spray Jets; Computations of Drop Sizes in Pulsating Sprays and of Liquid Core Length in Vaporizing Sprays; and Scaling of Impulsively Started Sprays., Sponsored in part by Grant DAAG29-78-G-0132.