Accession Number : AD0710283

Title :   IGNITION AND SUSTAINING OF COMBUSTION BY ENERGY ADDITION IN TURBULENT SUPERSONIC FLOW.

Descriptive Note : Final scientific rept.,

Corporate Author : NORTHERN RESEARCH AND ENGINEERING CORP CAMBRIDGE MASS

Personal Author(s) : Bray,Kenneth N. C. ; Fletcher,Ronald S.

Report Date : JUL 1970

Pagination or Media Count : 48

Abstract : The objective of the study is to obtain data on turbulent, supersonic combustion which will facilitate development of ignition systems for use in scramjet engines under conditions when combustion cannot occur spontaneously. To this end a simple analytical model of a reacting, turbulent flow is presented, based upon the a priori assumption that combustion and turbulent mixing can be uncoupled. Predictions from this model are compared with some new experimental data on the ignition of ethylene in air. Both premixed and unpremixed situations are included. Tests of the validity of the mixing model are made for the nonreacting case by comparing predicted and measured velocity profiles in a duct; a satisfactory agreement is obtained. The predicted ignition requirements also match the measured values in most cases, with mixing- and reaction-rate data taken from the literature. Until uncertainties in these mixing- and reaction-rate expressions can be substantially reduced, the use of more subtle coupling models in the determination of ignition requirements does not appear to be justified. A much simpler model is also presented and used to derive a useful criterion for the prediction of the ignition boundaries in premixed fuel-air flows. (Author)

Descriptors :   (*SUPERSONIC COMBUSTION, IGNITION SYSTEMS), (*SUPERSONIC COMBUSTION RAMJET ENGINES, IGNITION), TURBULENCE, SUPERSONIC FLOW, ENERGY, FLAMES

Subject Categories : Combustion and Ignition
      Jet and Gas Turbine Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE