I am a little confused as to when (during T/O, cruise, etc.) and how the combined pressure-swirl atomizer and airblast atomizer is used.
Lefebvre writes that "the merits of the pressure-swirl atomizer at low fuel flows, namely, easy lightup and wide stability limits, are combined with all the virtues of airblast atomization (notably a soot-free exhaust) at high-fuel flow rates."
From this I understood, that if a combined pressure-swirl and airblast atomizer is used, then the swirl atomizer would be more used during cruise (lower fuel flow rates) and the airblast more during takeoff (higher fuel flow rates).
However, it is also stated by the author just before that for an airblast atomizer "The major practical disadvantages are rather narrow stalobility limits and poor atomization quality at startup, owing to the low air velocity through the atomizer."
At takeoff isn't the air velocity lower? And if that is the case, then this for me puts into question the use of the airblast during takeoff.
So are the conditions for the airblast atomizer: high fuel flow rate and high velocity and for swirl atomizer: low fuel flow rate and low velocity?
If so, how do they interact during engine operations?
All citations are taken from Chapter 1 of Gas Turbine Combustion by Lefebvre.
I know I am wrong and I would love to know why. Thank you for your help!