Help:Combustion

SAM

I have constructed a rectangular combustion chamber. First i carried out the analysis using the Producer gas as the fuel. Here i have given the initialization temperature as 300K and species transport is used. then in that i carried out the non-premixed combustion using LDO as the fuel and iontialization temp as 2000K.Here diameter of the air and fuel is changed.In both the cases the temperature distribution is opposite. In producer gas the maximum temperature is inside and as we move outside temp decreases.while in LDO max temp is outside and as we go inside temp decreases.I am not getting the reason why this happens. Please tell me if you know. Thank you