Ren
Ansys Employee

If you just wanted to have a mixture that will be combustible, then you can try to increase the air mass flow rate (not velocity) to get an air-to-fuel ratio of, say, 19. The easiest way of doing this is to change the inlet boundaries to mass-flow-inlet type so that you can enter mass flow rate (MFR) values directly. Currently, you have 

fuel MFR = 1.832E-5 kg/s, so you can try

air MFR = 1.832E-5 * 19 = 3.4808E-4 kg/s

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