What is the largest SMD value that is required to sustain combustion.

sgvaibhav

Using kerosene as a fuel in a gas turbine engine.
What can be the largest SMD that the atomizers HAVE to provide for engine start-up and to sustain combustion?

SMD : Sauter Mean Diameter or also known as D32 in drop size distributions model.

bigfooted

This is a difficult question to answer. Some guidelines: if your droplets are larger, you need a higher ignition energy. Also, you might need to adjust the ignition time, which should be probably longer.
The effective ignition energy depends on the droplet injection velocity, so the atomizer pressure. When there's premixing, a fuel lean mixture will need more ignition energy.

So, if you have an existing setup with an atomizer producing too large droplets, then increase the ignition energy. For an existing and working setup, if you increase the SMD by 10% you'll easily need 3-4 times higher ignition energy.