The Effect of Tangential Swirl Angle on NOX Formation in a Non-Premixed LPG/Air Flame

Abstract

In the present study the effect of tangential swirl angle on NO x formation in non premixed liquefied petro gas (LPG)air flame is examined. The liquefied petrol gas used (LPG) contains of 50% Propane and 50% Butane. A new injection swirl ratio has been introduced for the new Circumferential Arranged Air and Fuel Burner (CAFB) burner namely the injection swirl number (ISN), ISN = tan θ, where θ is the injection angle. The injection swirl number (ISN) used is 0, 0.27, 0.57, 1 and 1.73 which corresponding to the injection angles 0, 15, 30, 45 and 60 degree respectively. An empirical correlation has been derived for the new CAFB burner flame length as a function of the new derived (ISN). The experiments are conducted in an ax symmetric cylindrical combustion chamber for a range of equivalence ratio and swirl angle. The numerical simulations are carried out with the CFD code, Fluent Ansys 6.3. The turbulence k-ε model is employed. Both predictions and experiments show that as the swirl number increase, the temperature and the thermal NO x first slightly increase and then strongly decrease at the exit of the combustion chamber. An empirical correlation has been derived for the new CAFB burner. Numerical simulations by Fluent Ansys 6.3 were able to obtain reasonable agreement with the experimental results.