Dosing and mixing assemblies for exhaust aftertreatment system

A conduit arrangement for use in an exhaust aftertreatment assembly, the conduit arrangement extending along a conduit axis and comprising:

• a first flow path extending along the conduit axis of the conduit arrangement, the first flow path having a first entrance;
• a second flow path at least partially surrounding the first flow path, the second flow path having a second entrance that is located downstream from the first entrance, the second flow path having a cross-sectional area that is smaller than a cross-sectional area of the first flow path;
• a common flow path being fed from both the first flow path and the second flow path;
• a mixing zone at which turbulence is applied to exhaust flowing through the first flow path such that the turbulence within the first flow path is greater than any turbulence within the second flow path;
• an impact zone downstream of the mixing zone and upstream of the common flow path, the impact zone defined within the first flow path;
• a merge zone at which the first and second flow paths combine to form the common flow path, the merge zone being downstream of the impact zone,
• a doser mounting location configured to receive a reactant injector, the doser mounting location being oriented to face into the first flow path at or upstream of the mixing zone;
• and
• a first conduit defining the mixing zone, the first conduit including tangential velocity imparting members disposed at the mixing zone, the first conduit defining a constant internal cross-dimension along the mixing zone.