Accession Number : ADA141418

Title :   Wall Effects on Combustion in an Engine.

Descriptive Note : Final rept. 15 Mar 83-14 May 84,


Personal Author(s) : Fendell,F E

Full Text :

Report Date : 14 May 1984

Pagination or Media Count : 9

Abstract : This project utilized theoretical modeling and laboratory experiment to elucidate the role of chamber shaping on the combustion event in a four-stroke-cycle, reciprocating-piston-type internal-combustion-engine cylinder. First, theoretical modeling was carried out to evaluate heat transfer as a determent of end-gas knock during nonisobaric flame propagation across a homogeneous charge in a variable-volume enclosure. Via a semi-empirical model, turbulent combustion in an automotive cylinder was considered; a three-zone generalization (to encompass end gas, unburned bulk gas and burned gas) of the standard two-zone Otto-cycle-combustion model was developed. Via a selfcontained model, laminar combustion in a specially designed rapid-compression machine was considered; an asymptotic analysis valid in the limit of large Arrhenius activation temperature was developed. For given operating conditions, the fraction of the charge (if any) that undergoes autoconversion to product prior to flame arrival can be ascertained, along with the heat transfer sufficient to preclude such homogeneous explosion. Second, two-wall, or crevice-type, quenching of flame propagation through a stoichiometric or fuel-lean hydrocarbon-air-type premixture is examined because this phenomenon is now believed to be the major source of unburned-hydrocarbon emissions from homogeneous-charge engines.

Descriptors :   *Internal combustion engines , *Heat transfer , *Combustion chambers , Flame propagation , Automotive components , Hydrocarbons , Raman spectroscopy , Laboratory tests , Mathematical models , Heat of combustion , Fuel additives , Fuel burn up , Knocking , Quenching , Walls , Temperature

Subject Categories : Combustion and Ignition
      Reciprocating and Rotating Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE