Patent ID: 11897027

Abstract:
The cross-sectional shape of a flow passage 31 is circular in a first portion 3; the shape of a flow passage 51 is a flat shape in a second portion 5; in a connecting portion 4, the shape of a flow passage 41 is a shape continuously connecting the flow passage 31 of the first portion 3 and the flow passage 51 of the second portion 5; an opening 52 is provided on the distal end side of the second portion 5 and extends along a plane direction of the flat shape; and assuming that a maximum value of a cross-sectional area of the flow passage 31 in the first portion 3 is given by S1, that a maximum value of a cross-sectional area of the flow passage 51 in the second portion 5 is given by S2, and that a minimum value of a cross-sectional area of the flow passage 31 within a range of 20% of a length L1 of the first portion 3 from a boundary portion 42 between the first portion 3 and the connecting portion 4 toward the upstream side is given by S3, S2 is greater than S1, the ratio S1/S3 between S1 and S3 is 1.10 or more and 2.00 or less, and the ratio S2/S3 between S2 and S3 is 1.20 or more and 2.50 or less.