Tracer Studies of Jets and Diffusion Flames in Cross-Flow

Abstract

SO₂ was used as a tracer gas in an experimental study of turbulent air jets and propane diffusion flames in cross-flow. Measurements of the SO₂ concentration field were used to obtain data on the shape and size of the bent-over plumes in the vortex zone, between 60 and 220 diameters downwind of the discharge. Data on the variation of plume cross sectional area with distance led to estimates of the variation of entrainment with distance. It appears that for turbulent diffusion flames in cross-flow, in which both initial jet momentum and flame buoyancy are significant influences, the trajectory can be expressed by a power law of the form [Ztilde]=M X¯ ⁿ in which the distances are nondimensionalized by the momentum length scale and n is a function of the Froude number. Even though the wind tunnel was too short to permit it, the SO₂ tracer technique seems to be useful also for studies of the buoyant plume several hundred discharge diameters downwind of the flame.