Help combustion chamber
 

I am doing non-premixed combustion model analysis along with Heat exchanger. First there is venturimeter and then cylindrical chamber.The air velocity is 10 m/s and injection is given at 50m/sec and mass flow rate is 0.00694kg/sec. when i give energy then combustion stats in venturimeter. Can anyone give me the suggestion how to start combustion after venturimeter.