Untitled - Aerobib - Universidad Politécnica de Madrid

332 CHAPTER 13. COMBUSTION OF LIQUID FUELS
1.0
F
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
(0.5,1.5)
(1.5,1.0)
(1.0,1.0)
(1.5,1.5)
(1.0,1.5)
(1.0,0.5)
(0.5,0.5)
(0.5,1.0)
(1.5,0.5)
0.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
d / d max
Figure 13.9: Droplet size distribution without combustion according to Mugele and Evans
(fraction F of droplets with a diameter smaller than d/d max), for several values
of the parameters (ε , θ).
Magnitude (13.109) is interesting since the combustion intensity of the burner
should be considered inversely proportional to it.
Table 13.2 gives the values for g/G t v for three typical cases corresponding to
θ = 1.
ε 0.5 1 1.5
g
0.129 0.110 0.105
G t v
( )
ds
0.269 0.438 0.895
d max
spray
(
ds
d max
)flame
0.517 0.454 0.401
Table 13.2: Values of g/Gt v for θ = 1 and ε = 0.5, 1, 1.5.
It is seen that when ε increases, that is when the uniformity of the spray increases,
the mass fraction of fuel in the burner decreases. Consequently, it is advantageous
to work with spray as uniform as possible in order to decrease the volume of
the primary zone of the burner.