The Structure of Eddies in Turbulent Flames - I.
Abstract
High frequency response measurement techniques are used with data processing and conditional sampling to measure large eddy structure and coherence in the transitional flow region of turbulent diffusion flames. Comparisons are made between nonburning and burning flow conditions; these show physical similarity for cold and burning flows in the transitional region. Flow visualization shows quasi-laminar interface layers which are distorted, stretched and convoluted by vortex interactions. High-speed Schlieren color movies show axisymmetric wave and vortex ring formation. Velocity, temperature and ionization density measurements show that the transitional flow and the potential core of the jet are much longer in the flame than in the nonburning jet. A marked difference is found between the initial fundamental instability frequencies of the shear layers; the most amplified frequency predicted by stability theory for cold inviscid flow is found in the cold jet but not the flame. Increase in viscosity due to heat release causes delay and damping of the processes of vortex formation and coalescence; dilatation and buoyancy forces also contribute to differences between the flame and cold jet. Large eddies are shown to play an important role in the transitional region of turbulent jet flames.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1979
- Accession Number
- ADA078625
Entities
People
- Andrew J. Yule
- Norman A. Chigier
Organizations
- Purdue University