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Premixed, turbulent combustion of a sudden-expansion flow

1983; Elsevier BV; Volume: 50; Linguagem: Inglês

10.1016/0010-2180(83)90058-5

1556-2921

Y. El Banhawy, S. Sivasegaram, J. H. Whitelaw,

Computational Fluid Dynamics and Aerodynamics

Measurements of mean values of velocity, temperature and concentrations of carbon monoxide, carbon dioxide, unburned hydrocarbon, and oxygen have been obtained in the two-dimensional flows downstream of two backward facing steps which stabilized premixed methane-air flames of equivalence ratios 0.77, 0.90 and 0.95. The maximum mean temperature increased from 1710 to 2000K with equivalence ratio, and the maximum intensity of the temperature fluctuations, like those of velocity fluctuations, was close to coincident with inflections in the mean profiles. The intensity of the temperature fluctuations achieved values in excess of unity and, at the locations of maximum mean temperature, in excess of 0.5. The larger step gave rise to a wider reaction region and to a slightly different trajectory. An increase in the flow rate of cooling water and, therefore, a decrease of wall temperature resulted in increased concentrations of unburned hydrocarbon and carbon monoxide in the near-wall region. Discrete frequency fluctuations occurred at the natural frequency of the flow chamber: the magnitude of the energy of these fluctuations was small.