Numerical simulations of the propane/air nonpremixed combustion in a curved duct are carried out using the RNG k-εturbulent model. The combustion model and the radiation model are the conserved scalar probability density function (PDF) model and discrete ordinates (DO) model respectively. Coupling of pressure and velocity uses the SIMPLE algorithm. Based on velocity of the propane at the entrance of the same circumstance, we change velocity of air intake under five conditions. The simulation results show that, with increase of air velocity, fuel and oxidizer molecules are mixed more evenly, combustion rate, overall velocity in the velocity field of the flame space, turbulent intensity, and radial pressure gradient are all increased. Therefore, in order to control the velocity field of the flame space and the extent of combustion, we can control the speed of air intake. To improve combustion efficiency, we can minimize the intake air speed while ensuring full combustion to meet the industrial requirements.
