NOx Formation Characteristic of Lean-Rich Combustion in Unsteady-State. Numerical Unsteady-State Analysis of Laminor Lean-Rich Combustion Flames.

Abstract

Recently a lean-rich combustion is drawing attention as a way to decrease the level of NOx. But the flame structure and NOx formation process of the lean-rich flame in the unsteady-state was not made clear sufficiently. So we performed the numerical analysis in the unsteady-state in which we took the NO formation mechanism into the consideration by using the Skeletal Chemistry combined with a part of GRI-mech. And we found that thermal NO is generated not only in the high temperature region formed in the downstream of the rich flame, but also in the swell formed in the downstream of the lean flame. In the swell formed in the downstream of the lean flame, the chemical reaction is occurred actively due to the fluctuation of lateral flow that carries CH4. The faster the lateral flow is, the larger NO mole production rate becomes.