Study on the Burning of a Fuel Drop in Heated and Pressurized Air Stream : 1st Report, Experiment

Numerical simulation of fuel droplet extinction due to forced convection

“…All of these studies neglect gravity effects. Wu et al [26] used the axisymmetric boundary layer equations with large activation energy asymptotics and predicted that the extinction velocity varies linearly with the droplet diameter, which is in agreement with the experiments of Spalding [6] and Sami and Ogasawara [9] and actually even with Agoston et al [8], who curiously claimed a d 0.5 dependence although their data vary linearly with the diameter (see discussion on Fig. 3 below).…”

“…Experimental studies on convective extinction of fuel droplets (mostly simulated with porous spheres) under normal gravity are also available in the literature [6][7][8][9][10][11][12][13]. The Richardson number (the inverse of the Froude number) provides a ratio of the strength of buoyancy-induced to forced convection flows in the experiments.…”

“…However, the effect of natural convection on extinction velocity depends on the orientation of the gravitational vector relative to the forced flow. In general, three different orientations have been used in experimental studies: the buoyancy-induced flow either (1) aids [7,[9][10][11][12], (2) opposes [8], or (3) is normal to [6] the forced convection. The characteristic lengths in the Richardson number would differ greatly between these orientations.…”

Entropy generation during the quasi-steady burning of spherical fuel particles

“…(6) Thermal radiation effects are neglected, which amounts to assuming a non-luminous flame, as the fuel employed is methanol. (7) The partial pressure of vapor adjacent to the particle surface is assumed to be equal to the vapor pressure of the fuel at the interface temperature. Thus, the fuel mole fraction adjacent to the particle can be written using the ClausiusClayperon equation.…”

“…These quasi-steady models are applicable for the low pressure burning of fuel particles, after the initial ignition and internal heating transients are over. Verification of the quasi-steady models has been carried out using the porous sphere experiment technique [7,8]. The effect of a convective flow field on the rate of burning of liquid droplets has been investigated by several authors in the past [9][10][11][12].…”