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An exhaust aftertreatment system is provided. The exhaust aftertreatment system includes a mixing arrangement for mixing flows of exhaust along a flow path. The mixing arrangement radially and angularly rearranges segments of two different portions of flow to mix the different portions of flow. The

An exhaust aftertreatment system is provided. The exhaust aftertreatment system includes a mixing arrangement for mixing flows of exhaust along a flow path. The mixing arrangement radially and angularly rearranges segments of two different portions of flow to mix the different portions of flow. The mixing arrangement initially converts a generally radially stratified temperature profile into an angularly stratified temperature profile to increase surface area between cool segments of exhaust gas and hot segments of exhaust gas. The aftertreatment system may also include a combustion chamber, a combustor housing and a combustor liner. The mixing arrangement is downstream from the combustion chamber to direct radially outward hot gas passing through the combustor liner and to direct radially outer cool gas passing between the liner and the combustor housing radially inward in an interleaving fashion.

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1. A method of mixing a flow of exhaust flowing along a flow axis including the step(s) of: rearranging the flow of exhaust along the flow axis via a mixer arrangement coaxial to the flow axis, the exhaust made up entirely of combusted gases, wherein rearranging the flow of exhaust includes the step

1. A method of mixing a flow of exhaust flowing along a flow axis including the step(s) of: rearranging the flow of exhaust along the flow axis via a mixer arrangement coaxial to the flow axis, the exhaust made up entirely of combusted gases, wherein rearranging the flow of exhaust includes the steps of: directing a first portion of the flow radially outward away from the flow axis by passing the first portion of the flow only over a plurality of first flow directing tabs, of the mixer arrangement, that are convex to the flow axis, anddirecting a second portion of the flow radially inward toward the flow axis by passing the second portion of the flow only over a plurality of second flow directing tabs, of the mixer arrangement, that are concave to the flow axis; andwherein the steps of directing the first and second portions includes separating the first portion into a plurality of first segments and directing the first segments radially outward and separating the second portion into a plurality of second segments and directing the second segments radially inward, wherein the step of rearranging includes increasing the surface area between the first and second portions. 2. The method of claim 1, wherein the steps of directing the first and second portions of the flow includes changing a cross-sectional shape of the first segments of the first portion of the flow and changing the cross-sectional shape of the second segments of the second portion of the flow. 3. The method of claim 2, wherein: the steps of directing the first and second portions of the flow includes changing the radial distribution of the first portion of the flow relative to the second portion such that the first portion of the flow has a first mean distance from the flow axis prior to the step of rearranging and the first portion of flow has a second mean distance from the flow axis after the step of rearranging, the second mean distance being greater than the first mean distance and wherein the second portion of the flow has a third mean distance from the flow axis prior to the step of rearranging and the second portion of flow has a fourth mean distance from the flow axis after the step of rearranging, the fourth mean distance being less than the third mean distance. 4. The method of claim 3, wherein the cross-sectional area of the first segments remains substantially constant during the step of rearranging and the cross-sectional area of the second segments remains substantially constant during the step of rearranging. 5. The method of claim 1, wherein the first portion of the flow and the first segments are radially inward of and substantially circumscribed by the second portion of flow and the second segments when the step of rearranging begins, after the step of rearranging, the first segments are a plurality of first angular segments and the second segments are a plurality of second angular segments, the exhaust flow being formed by alternating first and second angular segments after the step of rearranging. 6. The method of claim 5, wherein: the exhaust flow has a temperature profile that is radially stratified having high temperatures at the radially inner flow and having lower temperatures at the radially outer flow, relative to the inner flow, prior to the step of rearranging; andafter the step of rearranging, the temperature profile of the exhaust flow is angularly stratified by the alternating first and second angular segments of high and low temperatures relative to one another. 7. The method of claim 1, wherein: the steps of directing the first and second portions of the flow includes changing the radial distribution of the first portion of the flow relative to the second portion such that the first portion of the flow has a first mean distance from the flow axis prior to the step of rearranging and the first portion of flow has a second mean distance from the flow axis after the step of rearranging, the second mean distance being greater than the first mean distance and wherein the second portion of the flow has a third mean distance from the flow axis prior to the step of rearranging and the second portion of flow has a fourth mean distance from the flow axis after the step of rearranging, the fourth mean distance being less than the third mean distance. 8. The method of claim 7, wherein the first portion of the flow is radially inward of and substantially circumscribed by the second portion of flow when the step of rearranging begins, the step of directing the second portion of flow radially inward includes directly directing the second portion of portion of flow radially inward and directing the first portion of flow radially outward is performed indirectly and is facilitated by the introduction of the increased amount of the second portion of the flow radially inward. 9. An exhaust gas mixer for interleaving portions of a flow of exhaust gas from an internal combustion engine comprising: a plurality of first flow directing tabs;a plurality of second flow directing tabs;the first and second flow directing tabs arranged to circumscribe a flow axis; andthe first flow directing tabs arranged to direct radially inward exhaust flow radially outward; andthe second flow directing tabs arranged to direct radially outer exhaust flow radially inward; andwherein:the first flow directing tabs have an upstream inlet end and a downstream outlet end;the second flow directing tabs have an upstream inlet end and a downstream outlet end;the inlet ends of the first flow directing tabs are radially inward of the outlet ends of the first flow directing tabs;the inlet ends of the second flow directing tabs are radially outward of the outlet ends of the first flow directing tabs;the inlet ends of the first flow directing tabs are radially inward of the inlet ends of the second flow directing tabs; andthe outlet ends of the first flow directing tabs are radially outward of the outlet tends of the second flow directing tabs and the inlet ends of the first flow directing tabs. 10. The exhaust gas mixer of claim 9, wherein: each of the first and second flow directing tabs have an upstream surface facing upstream;the upstream surface of the first flow directing tabs being concave from the inlet end to the outlet end such that an angle between a tangent of the upstream surface and the flow axis increases in magnitude when moving in a direction from the inlet end toward the outlet end; andthe upstream surface of the second flow directing tabs being concave from the inlet end to the outlet end such that an angle between a tangent of the upstream surface and the flow axis increases in magnitude when moving in a direction from the inlet end toward the outlet end. 11. The exhaust gas mixer of claim 10, wherein: the angle between the upstream surface of the first flow directing tabs and flow axis proximate the inlet end is between about zero (0) and twenty (20) degrees and the angle between the tangent and the upstream surface of the first flow directing tab proximate the outlet end is between about thirty (30) and seventy (70 degrees); andthe angle between the upstream surface of the second flow directing tabs and flow axis proximate the inlet end is between about zero (0) and twenty (20) degrees and the angle between the tangent and the upstream surface of the second flow directing tabs proximate the outlet end is between about thirty (30) and seventy (70) degrees. 12. The exhaust gas mixer of claim 10, wherein the upstream surface of the first flow directing tabs faces radially outward and the upstream surface of the second flow directing tabs faces radially inward. 13. The exhaust gas mixer of claim 10, wherein: each of the first flow directing tabs are scoop shaped including a trough bottom and two generally radially extending sidewalls extending outward from the trough bottom and radially outward; and each of the second flow directing tabs are scoop shaped including a trough bottom and two generally radially extending sidewalls extending outward from the trough bottom and radially inward. 14. The exhaust gas mixer of claim 9, wherein the plurality of first and second flow directing tabs are formed from a single body being a continuous piece of material formed into a generally annular shape, the body having an upstream end that is generally circular inlet and downstream end that is formed from a plurality of generally triangularly shaped angularly spaced legs extending outward from the flow axis, the tabs not being formed from independent pieces of material and then subsequently connected together. 15. An exhaust gas mixer for interleaving portions of a flow of exhaust gas from an internal combustion engine comprising: a plurality of first flow directing tabs;a plurality of second flow directing tabs;the first and second flow directing tabs arranged to circumscribe a flow axis; andthe first flow directing tabs arranged to direct radially inward exhaust flow radially outward;the second flow directing tabs arranged to direct radially outer exhaust flow radially inward; andwherein:the first flow directing tabs have an upstream inlet end and a downstream outlet end;the second flow directing tabs have an upstream inlet end and a downstream outlet end;the inlet ends of the first flow directing tabs are radially inward of the outlet ends of the first flow directing tabs;the inlet ends of the second flow directing tabs are radially outward of the outlet ends of the first flow directing tabs;the inlet ends of the first flow directing tabs are radially inward of the inlet ends of the second flow directing tabs; andthe outlet ends of the first flow directing tabs are radially outward of the outlet tends of the second flow directing tabs and the inlet ends of the first flow directing tabs; andwherein the inlet end of the plurality of first flow directing tabs is narrower than the downstream outlet end of the plurality of first flow directing tabs, and wherein the inlet end of the plurality of second flow directing tabs is wider than the downstream outlet end of the plurality of second flow directing tabs. 16. A diesel fuel exhaust aftertreatment system for treating diesel fuel exhaust from an internal combustion engine comprising: a heat generating device for heating the exhaust generating a radially stratified temperature profile;a mixer arrangement downstream from the heat generating device, the mixer arrangement including: a plurality of first flow directing tabs configured to direct a radially inward portion of the exhaust flow radially outward by passing the radially inward portion of the exhaust flow only over the plurality of first flow directing tabs; anda plurality of second flow directing tabs, each having an inlet attached to an interior surface of the combustor can, configured to direct a radially outer portion of the exhaust flow radially inward by passing the radially outer portion of the exhaust flow only over the plurality of second flow directing tabs. 17. The aftertreatment system of claim 16, further comprising: a combustor housing;a combustor liner disposed within the combustor housing with the radially inward portion of the exhaust flow passes through the combustor liner;an annulus located between an inner surface of the combustor housing and an outer surface of the combustor liner, the radially outward portion of the exhaust flow passing through the annulus; and wherein the first flow directing tabs draw the radially inward portion of the exhaust passing through the combustor liner radially outward toward the inner surface of the combustor housing and the second flow directing tabs direct the radially outward portion of the exhaust passing through the annulus radially inward, such that the mixer arrangement is configured to form a plurality of angularly stratified segments formed from alternating segments of the inward portion of the exhaust and the outward portion of the exhaust. 18. The aftertreatment system of claim 17, wherein the temperature profile, taken perpendicular to the flow path, of the exhaust passing through the annulus and the combustor liner upstream of the mixer arrangement is generally radially stratified having high temperatures at the radially inner flow and having lower temperatures at the radially outer flow, relative to the inner flow; and wherein the temperature profile, taken perpendicular to the flow path, of the exhaust downstream of the mixing arrangement is generally angularly stratified having alternating high and low temperature portions, respectively. 19. The aftertreatment system of claim 18, wherein the high temperature portions are formed by high temperature exhaust that has been radially outwardly directed by the first flow directing tabs and are aligned with the first flow directing tabs and the low temperature portions are formed by low temperature exhaust that has been radially inwardly directed by the second flow directing tabs and are aligned with the second flow directing tabs. 20. The aftertreatment system of claim 17, wherein the first flow directing tabs are scoop shaped being both radially concave and angularly concave. 21. The aftertreatment system of claim 20, wherein the first flow directing tabs have a main bottom portion and two outward extending sidewalls between which the main bottom portion extends, the main bottom portion and two outward extending sidewalls defining a trough shape that opens in an upstream direction. 22. A diesel fuel exhaust aftertreatment for treating diesel fuel exhaust from an internal combustion engine comprising: a heat generating device for heating the exhaust generating a radially stratified temperature profile;a mixer arrangement downstream from the heat generating device, the mixer arrangement including: a plurality of first flow directing tabs configured to direct a radially inward portion of the exhaust flow radials outward; anda plurality of second flow directing tabs, each having an inlet attached to an interior surface of the a combustor can, configured to direct a radially outer portion of the exhaust flow radially inward;a combustor housing;a combustor liner disposed within the combustor housing with the radially inward portion of the exhaust flow passes through the combustor liner;an annulus located between an inner surface of the combustor housing and an outer surface of the combustor liner, the radially outward portion of the exhaust flow passing through the annulus;wherein the first flow directing tabs draw the radially inward portion of the exhaust passing through the combustor liner radially outward toward the inner surface of the combustor housing and the second flow directing tabs direct the radially outward portion of the exhaust passing through the annulus radially inward, such that the mixer arrangement is configured to form a plurality of angularly stratified segments formed from alternating segments of the inward portion of the exhaust and the outward portion of the exhaust; andwherein the second flow directing tabs have an inlet end that is radially outward of the inner liner and an outlet end that is radially inward of the inner liner. 23. The aftertreatment system of claim 22, wherein the first flow directing tabs have an inlet end that is at least radially aligned with the inner liner and an outlet end that is radially outward of the inner liner. 24. The aftertreatment system of claim 23, wherein at least one of the first flow directing tabs is configured differently than another one of the first flow directing tabs and at least one of the second flow directing tabs is configured differently than another one of the second flow directing tabs. 25. An exhaust gas mixer for interleaving portions of a flow of exhaust gas from an internal combustion engine comprising: a plurality of first flow directing tabs;a plurality of second flow directing tabs;the first and second flow directing tabs arranged to circumscribe a flow axis; andthe first flow directing tabs arranged to direct radially inward exhaust flow radially outward by passing the radially inward exhaust flow only over the plurality of first flow directing tabs; andthe second flow directing tabs arranged to direct radially outer exhaust flow radially inward by passing the radially outer exhaust flow only over the plurality of second flow directing tabs;wherein:the first flow directing tabs have an upstream inlet end and a downstream outlet end;the second flow directing tabs have an upstream inlet end and a downstream outlet end;the inlet ends of the first flow directing tabs are radially inward of the outlet ends of the first flow directing tabs;the outlet ends of the first flow directing tabs are radially outward of the inlet ends of the first flow directing tabs; andthe inlet ends of the second flow directing tabs are radially outward of the outlet ends of the second flow directing tabs. 26. The exhaust gas mixer of claim 25, wherein the outlet ends of the second flow directing tabs are radially inward of the inlet ends of the second flow directing tabs. 27. An exhaust gas mixer for interleaving portions of a flow of exhaust gas from an internal combustion engine comprising: a plurality of first flow directing tabs;a plurality of second flow directing tabs;the first and second flow directing tabs arranged to circumscribe a flow axis; andthe first flow directing tabs arranged to direct radially inward exhaust flow radially outward; andthe second flow directing tabs arranged to direct radially outer exhaust flow radially inward;wherein:the first flow directing tabs have an upstream inlet end and a downstream outlet end;the second flow directing tabs have an upstream inlet end and a downstream outlet end;the inlet ends of the first flow directing tabs are radially inward of the outlet ends of the first flow directing tabs;the outlet ends of the first flow directing tabs are radially outward of the inlet ends of the first flow directing tabs;the inlet ends of the second flow directing tabs are radially outward of the outlet ends of the second flow directing tabs;the inlet ends of the second flow directing tabs are radially outward of the outlet ends of the first flow directing tabs;the inlet ends of the first flow directing tabs are radially inward of the inlet ends of the second flow directing tabs; andthe outlet ends of the first flow directing tabs are radially outward of the outlet tends of the second flow directing tabs. 28. An exhaust gas mixer for interleaving portions of a flow of exhaust gas from an internal combustion engine comprising: a plurality of first flow directing tabs;a plurality of second flow directing tabs;the first and second flow directing tabs arranged to circumscribe a flow axis; andthe first flow directing tabs arranged to direct radially inward exhaust flow radially outward by passing the radially inward exhaust flow only over the plurality of first flow directing tabs; andthe second flow directing tabs arranged to direct radially outer exhaust flow radially inward by passing the radially outer exhaust flow only over the plurality of second flow directing tabs; andwherein: the first flow directing tabs have an upstream inlet end and a downstream outlet end;the second flow directing tabs have an upstream inlet end and a downstream outlet end; andthe inlet ends of the first flow directing tabs are radially inward of the outlet ends of the first flow directing tabs.