A fluid supply pipe according to an embodiment of the invention includes a first internal structure, a second internal structure, and a pipe body configured to house the first internal structure and the second internal structure, and the pipe body has an inlet and an outlet. The first internal structure includes a head portion comprising a plurality of spiral vanes, and a body portion positioned downstream from the head portion and comprising a plurality of protrusions on its outer circumferential surface. The second internal structure formed in a hollow shaft shape includes a head portion comprising a plurality of spiral vanes, and a body portion positioned downstream from the head portion and comprising a plurality of protrusions on its outer circumferential surface. At least a part of the first internal structure is housed in the hollow of the second internal structure.

A fluid supply pipe according to an embodiment of the invention includes a first internal structure, a second internal structure, and a pipe body configured to house the first internal structure and the second internal structure, and the pipe body has an inlet and an outlet. The first internal structure includes a head portion comprising a plurality of spiral vanes, and a body portion positioned downstream from the head portion and comprising a plurality of protrusions on its outer circumferential surface. The second internal structure formed in a hollow shaft shape includes a head portion comprising a plurality of spiral vanes, and a body portion positioned downstream from the head portion and comprising a plurality of protrusions on its outer circumferential surface. At least a part of the first internal structure is housed in the hollow of the second internal structure.

A fluid supply pipe according to an embodiment of the invention includes a first internal structure, a second internal structure, and a pipe body configured to house the first internal structure and the second internal structure, and the pipe body has an inlet and an outlet. The first internal structure includes a head portion comprising a plurality of spiral vanes, and a body portion positioned downstream from the head portion and comprising a plurality of protrusions on its outer circumferential surface. The second internal structure formed in a hollow shaft shape includes a head portion comprising a plurality of spiral vanes, and a body portion positioned downstream from the head portion and comprising a plurality of protrusions on its outer circumferential surface. At least a part of the first internal structure is housed in the hollow of the second internal structure.

A fluid supply pipe according to an embodiment of the invention includes a first internal structure, a second internal structure, and a pipe body configured to house the first internal structure and the second internal structure, and the pipe body has an inlet and an outlet. The first internal structure includes a head portion comprising a plurality of spiral vanes, and a body portion positioned downstream from the head portion and comprising a plurality of protrusions on its outer circumferential surface. The second internal structure formed in a hollow shaft shape includes a head portion comprising a plurality of spiral vanes, and a body portion positioned downstream from the head portion and comprising a plurality of protrusions on its outer circumferential surface. At least a part of the first internal structure is housed in the hollow of the second internal structure.

An exhaust-gas treatment arrangement for an exhaust system of an internal-combustion engine includes a diesel internal-combustion engine. The arrangement includes a first exhaust-gas treatment unit and, downstream of the first exhaust-gas treatment unit, an exhaust-gas treatment assembly. The first exhaust-gas treatment unit and the exhaust-gas treatment assembly are arranged axially succeeding one another in the direction of a longitudinal axis of a flow path encompassing the first exhaust-gas treatment unit and the exhaust-gas treatment assembly. A hydrocarbon-feeding assembly is provided for feeding hydrocarbon into exhaust gas flowing in the flow path. The hydrocarbon-feeding assembly includes a hydrocarbon-dispensing unit dispensing hydrocarbon into the flow path downstream of the first exhaust-gas treatment unit and upstream of the exhaust-gas treatment assembly. A swirl-flow-generating unit is provided in the flow path upstream of the hydrocarbon-dispensing unit.