The Physical Structure of Turbulent Flames,
SHEFFIELD UNIV (ENGLAND) DEPT OF CHEMICAL ENGINEERING AND FUEL TECHNOLOGY
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This paper reports on measurements made in the mixing region of an axisymmetric turbulent propaneair jet issuing from a round nozzle into a low-velocity, low-turbulence intensity, unconfined co-flowing airstream. The exit velocity of the jet fluid and its turbulence intensity are sufficiently low to allow the formation of ring vortices within the mixing layer, bounded, on the inside, by the potential core of the jet and, on the outside, by the secondary airstream. High speed cine films show evidence of formation of vortices and flamelets at the interfaces. The changes in shape, movement and coalescence downstream of the nozzle are examined. Measurements of fluctuating velocity are made by a single particle-counting forwardscatter laser anemometer. Fluctuating temperature is measured with micro-thermocouples with in situ measurement of time constant and direct compensation by digital signal recording and analysis. Variation in location and amplitude of peaks of velocity and temperature traces are directly associated with flame structures recorded by film. Signals from all probes are acquired and processed by PDP-8 and PDP-1103 Digital Equipment Corporation computers.
- Fluid Mechanics
- Combustion and Ignition