摘要:

Recently obtained exact solutions for the transport-controlled lifetime of an isolated sphere of arbitrary density and “solubility” in a quiescent, constant-property fluid are exploited to predict the corresponding behavior of a fuel droplet evaporating (with or without vapor phase combustion) into a surrounding dense gas. Emphasis is placed on (i) systematic errors associated with the familiar quasi-steady (QS) approximation when applied to the vaporization of droplets which are not much denser than their surroundings, (ii) the chamber pressure-droplet temperature conditions under which the droplet will be driven to a subcritical (wet-bulb) temperature, or to its thermodynamic critical temperature, and (iii) the effects of gas/liquid solubility on the predicted lifetime of a fuel droplet. Illustrative calculations are included for the case of a kerosene-like (x-dodecane) droplet evaporating into compression-heated air, as encountered in diesel engine cylinders.

ISSN:0010-2202    

DOI:10.1080/00102207308952353

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Nitric oxide emissions from a premixed propane-air flame were controlled by extracting energy from a steady state reaction zone using a cooled flat flame porous metal disk burner. Energy flux variations and, hence, nitric oxide formation rate changes were obtained for specific mixtures by changing the fuel-air inlet velocity. It was possible to stabilize flames for inlet flow velocities of from 3 cm/sec. up to approximately twice the laminar burning velocity of the mixture. Data were obtained for pressures of 5, 25 and 40psig and equivalence ratios from 0.7 to 1.3. Nitric oxide concentrations were reduced by more than a factor of 10 compared to the adiabatic case. However, energy fluxes to the porous disk of over 25 per cent of the lower heating value of the fuel were observed. Hydrocarbon emissions were less than 10 ppm hexane and the carbon monoxide levels were equal to the chemical equilibrium concentrations.

ISSN:0010-2202    

DOI:10.1080/00102207308952354

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The problem of linearized one-dimensional motions in a non-uniform flow field is re-examined. Earlier work is clarified, and some assumptions previously used are relaxed. The formalism accommodates all processes occurring in combustion chambers, including sources of mass, momentum, and energy at the lateral boundary. The work is intended partly to provide some results required for subsequent analyses of linear and nonlinear three-dimensional unsteady motions.

ISSN:0010-2202    

DOI:10.1080/00102207308952355

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Differences in ammonium perchlorate (AP) combustion behavior as evidenced by the effects of pressure, sample temperature and acceleration environments on burning rate are shown for samples prepared in various manners. The sample preparation parameters investigated include pellet compaction time and pressure, the particle sizes of the AP powder from which samples were pressed, and the type of AP (ultra-pure, propellant grade, and propellant grade with conditioners) from which the pellets were made.

ISSN:0010-2202    

DOI:10.1080/00102207308952356

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Based on the mechanism of heat losses, the known effects of external disturbances (pressure waves or turbulences) on the flammability limits are explained. This includes the sensitivity of near-limit flames to perturbations and the flame quenching by disturbances. The significance of the unstable solution as the criterion for dynamic extinction is stressed.

ISSN:0010-2202    

DOI:10.1080/00102207308952357

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor