ENGINE SYSTEM HAVING MIXING MECHANISM FOR EXHAUST AND INJECTED FLUID AND ENGINE EXHAUST TREATMENT STRATEGY

1 . An engine system comprising:

an internal combustion engine including an engine housing defining a plurality of engine cylinders; and

an exhaust system coupled with the engine housing and including an exhaust conduit having an exhaust inlet, an exhaust outlet, a fluid injector structured to inject a fluid into the exhaust conduit, and an aftertreatment mechanism coupled with the exhaust conduit;

the exhaust system further including a mixing mechanism positioned fluidly between the fluid injector and the aftertreatment mechanism, and having a turbulator positioned within a flow path of exhaust and injected fluid through the exhaust conduit at an upstream location, and a swirler positioned within the flow path at a downstream location.

2 . The system of claim 1 further comprising a supply of urea coupled with the fluid injector, and wherein the aftertreatment mechanism includes a selective catalytic reduction (SCR) module.

3 . The system of claim 2 wherein the exhaust conduit forms a bend upstream the aftertreatment mechanism, and the mixing mechanism being positioned upstream from the bend.

4 . The system of claim 3 wherein the engine includes a two-stroke engine.

5 . The system of claim 1 wherein the turbulator includes a plurality of turbulence-inducing elements positioned within the flow path.

6 . The system of claim 5 wherein the turbulence-inducing elements include leading surfaces facing an upstream direction and each having a rounded shape.

7 . The system of claim 6 wherein the leading surfaces each have a hemispheric shape.

8 . The system of claim 5 wherein the swirler includes a plurality of swirl-inducing blades positioned within the flow path.

9 . The system of claim 8 wherein the turbulator and the swirler are centered upon a center axis of the exhaust conduit, and at least some of the plurality of swirl-inducing blades are positioned so as to align with the turbulence-inducing elements in an axial projection plane.

10 . A mixing mechanism for an exhaust aftertreatment system comprising:

an exhaust conduit including an upstream end structured to receive a flow of exhaust gas and an injected fluid, and a downstream end structured to convey the flow of exhaust gas and injected fluid to an aftertreatment mechanism;

a turbulator mounted within the exhaust conduit at an upstream location and including flow impingement surfaces structured to induce turbulence in the flow of exhaust gas and injected fluid; and

a swirler positioned within the exhaust conduit at a downstream location and including flow impingement surfaces structured to induce swirl in the flow of exhaust gas and injected fluid.

11 . The mechanism of claim 10 wherein the turbulator flow impingement surfaces are located upon turbulence-inducing elements supported within the exhaust conduit at locations spaced radially inward from an inner wall of the exhaust conduit and radially outward from a center axis of the exhaust conduit.

12 . The mechanism of claim 11 wherein the swirler flow impingement surfaces are located upon swirl-inducing elements supported within the exhaust conduit in a stellate configuration.

13 . The mechanism of claim 11 wherein the swirl-inducing elements are positioned so as to overlap the turbulence-inducing elements in an axial projection plane.

14 . The mechanism of claim 11 wherein the swirler flow impingement surfaces include upstream surfaces of swirl-inducing blades each having sculpted contour.

15 . The mechanism of claim 11 wherein the turbulator flow impingement surfaces include leading surfaces each having a rounded shape.

16 . The mechanism of claim 15 wherein the turbulator flow impingement surfaces each has a hemispheric shape.

17 . A method of treating exhaust from an internal combustion engine comprising:

injecting a fluid into exhaust passing through an exhaust conduit;

feeding a flow of the exhaust and injected fluid toward an outlet of the exhaust conduit structured to fluidly connect with an aftertreatment mechanism; and

increasing mixing of the exhaust gas and injected fluid at least in part by impinging the flow upon turbulence-inducing surfaces of a turbulator within the exhaust conduit, and impinging the turbulated flow upon swirl-inducing surfaces of a swirler within the exhaust conduit, prior to discharging the flow from the outlet.

18 . The method of claim 17 wherein increasing mixing further includes impinging the flow upon hemispheric turbulence-inducing elements of the turbulator.

19 . The method of claim 17 further comprising changing a direction of the flow after the increasing of the mixing.

20 . The method of claim 19 wherein the injecting includes injecting a fluid containing urea, and further comprising feeding the mixed exhaust gas and injected fluid from the outlet into a selective catalytic reduction (SCR) module.