Accession Number : ADA201293


Title :   Flame Driving of Longitudinal Instabilities in Liquid Fueled Dump Combustors


Descriptive Note : Final rept. 1 Jul 1984-29 Feb 1988


Corporate Author : GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING


Personal Author(s) : Zinn, Ben T ; Hegde, Uday G ; Reuter, Dierk ; Daniel, B R


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a201293.pdf


Report Date : 01 Oct 1988


Pagination or Media Count : 124


Abstract : This reports describes the results of experimental and theoretical investigations of the mechanisms by which the core flow combustion process in coaxial, single inlet, dump type ramjet engines drives longitudinal combustion instabilities. To this end, the behavior of V-shaped flames, similar to those often occurring in ramjet combustors, stabilized in longitudinal acoustic fields has been studied. The presence of burning vortical structures is observed in the flame region. These structures appear at frequencies close to the first natural acoustic frequency of the combustor and are believed to be connected with a shear layer type of instability of the flame. Experiments conducted show that the unsteady combustion in these structures is capable of driving the acoustics at the fundamental acoustic mode frequency. With increase in fuel air ratio, a spontaneous instability involving the fundamental mode is observed and explained in terms of increased driving associated with the higher, unsteady heat release rates. Keywords: Coaxial dump type ramjet, Flame driving, Combustion, Acoustics longitudinal instability, Vortex shedding, Shear layer instability.


Descriptors :   *COMBUSTORS , *COMBUSTION , *RAMJET ENGINES , LAYERS , STRUCTURAL PROPERTIES , THEORY , VORTICES , VORTEX SHEDDING , REGIONS , RESONANT FREQUENCY , COAXIAL CONFIGURATIONS , ACOUSTICS , FUEL AIR RATIO , FLOW , FLAMES , INLETS , ACOUSTIC FIELDS , CORES , AUDIO FREQUENCY , SHEAR PROPERTIES , STABILITY


Subject Categories : Combustion and Ignition
      Jet and Gas Turbine Engines


Distribution Statement : APPROVED FOR PUBLIC RELEASE