Selective catalytic reduction with integrated decomposition chamber with exhaust flow swirl generating design

A selective catalytic reduction including a decomposition section including an intake chamber, with a swirl generating plate disposed in an internal volume of the intake chamber. The swirl generating plate includes a curved sidewall, a first end defining an opening, and a second end. The curved sidewall is oriented substantially normal to the direction of an intake flow of exhaust gas and a convex surface of the curved sidewall is oriented to face the direction of the intake flow. The swirl generating plate is configured to divide the intake flow into a first flow portion flowing through the opening, a second and a third flow portion which are directed substantially normal to the direction of intake flow and the flow direction of the first flow portion, and in opposite directions to each other towards a backwall of the intake chamber so as to create opposing swirls.