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In the present paper the theory is developed further by establishing an integral model for a jet in more general conditions with variable inclined angles, under effects of gravity and surrounding air velocity in any direction compared to the jet axis. | Vietnam Journal of Mechanics, NCST of Vietnam Vol. 23, 2001, No 2 (87 - 94) CALCULATION OF TURBULENT DIFFUSION JETS UNDER EFFECTS OF GRAVITY AND MOVING SURROUNDING AIR BUI VAN GA Technology School, Danang University NHAN HONG QUANG Centre for Labour Protection in Danang City JEAN MARC VIGNON Ecole Centrale de Lyon ABSTRACT. The basis theory for the turbulent diffusion of jet and flame has been presented previously [l, 2] . But that one applies only in quiet surrounding air with the effects of buoyancy neglected. In the present paper the theory is developed further by establishing an integral model for a jet in more general conditions with variable inclined angles, under effects of gravity and surrounding air velocity in any direction compared to the jet axis. The system of equations is closed by turbulence k-E model and is solved by 4th order RungeKutta method. In the first stage, the model is applied to predict the velocity field, the concentration field and width development of a 0.3 m diameter jet. 1. Introduction As compared to a premixed combustion process, the diffusion flame combustion of a nonpremixed mixture is process mainly controlled by the mass transfer of fuel and air comming from two separate sources. Considerations so far have provided little or no insight into the mechanism of the mass transfer but the most important point is how to determine the fuel distribution in diffusion jet. Then, basing on the distribution we can calculate both the combustion velocity and the formation of pollutants. Moreover, although turbulent diffusion flame are in common use, due to the lack of mathematical solution, many scientists have relied upon practical methods for determining the mechanism of mass transfer in order to improve· the diffusion process and limit pollution emission. Experimental measurement in the turbulent diffusion combustion process is considered to be very difficult and even impossible in some cases. So, mathematical modeling of the .
