volume fraction in multiphasic flow in fluent

max

hey everybody,

I want to simulate the cooling of very hot air by injection of cold water. There is two inlets : one for hot air and one for water and 1 outlet. I see I could use dpm to simulate this but only for volume fraction less than 10-12% (fluent help and tutorials). My question is : how I calculate my volume fraction? inlet massflow water : 15 kg/s inlet hot air : 90 kg/s And if I couldn't use dpm, could I use Eulerian or mixture?

thanks

Max