Need help simulating burner cooling down


I’m trying find out how long it takes to cool down the the burner and the steel part inside of it by blowing chill air. I set an initial condition of high temp at the burner and steel part domain and boundary conditions of small mass flow rate inlet and ambient pressure outlet. The result seems not right as the whole thing cool down under 1000s. I’m not sure if there is anything wrong with my setup. Could you help me with this?

Thank you

Hi! Make sure to post a link to your project so it’s easier to help.