Axial flow impeller blade and axial flow impeller

摘要

A blade (4) of an axial flow impeller (1), said blade being connectable to a central hub (2) of the impeller, the blade being formed substantially from a plate-like material and having a leading edge ( 5), an exit edge (6), a tip (7), a root (8) that can be fixed to the central hub (2) of the impeller, a first straight bend (9) that extends along the blade in a first direction and dividing the blade into a first profile part (10) located adjacent to the leading edge (5) and a second profile part (11), the first and second profile parts joining the first fold so that the first profile part is angled at a first angle α1 downwards from the second profile part, a second straight bend (12) extending along the blade in a second direction that is different from said first address and located separately from the first fold and which further divides the blade into a third of profile (13) located adjacent to the trailing edge (6), said second and third parts of profile joining in said second fold so that the third part of profile is angled at a second angle α2 downwards with respect to the second part of profile, the second part of profile (11) being angled at a third angle α3 in relation to the horizontal plane, and, in a plan view, the blade has the general shape of an envelope rectangle R × Wb with transition cuts to the less at the corners of the root side of the rectangle, said rectangle having a length R which is the longitudinal dimension from the axis of rotation (x) of the impeller to the tip (7) of the blade (4), and a width Wb that is the width across the blade perpendicular to the longitudinal direction, the inner rectangle having inner corners (14, 15) adjacent to the root (8) and outer corners (16, 17) adjacent to the tip (7), characterized by the contour of the pa the (4) is defined by the dimensions proportional to the transition cuts from the enveloping rectangle, the cuts comprising - a first cut (18) that is adjacent to the root (8) and a first inner corner (14) of the rectangle on the side of the leading edge (5), the first cut (18) having a right triangle with the longitudinal leg (19) having a dimension A = 0.2R, a leg (20) that is wide a dimension B = 0.2Wb, and a hypotenuse that forms a first cutting edge (21) of the blade that extends from the root (8) to the leading edge (5), - a second cut (22) which is adjacent to the root (8) and a second inner corner (15) of the rectangle on the side of the trailing edge (6), the second cut (22) having a right triangle shape with the longitudinal leg (23) having a dimension C = 0.2R, with a leg (24) wide that has a dimension D = 0.2Wb, and a hypotenuse that forms a second cutting edge (25) of the blade extending from the root (8) to the trailing edge (6), - a third cut (26) that is adjacent to the tip (7) and to a first outer corner (16 ) of the rectangle on the side of the leading edge (5), the third cut (26) having a right triangle with the longitudinal leg (27) having a dimension E = 0.5R, a leg (28) at width having a dimension F = (0.1 to 0.2) R, and a hypotenuse that forms a third cutting edge (29) of the blade that extends from the leading edge (5) to the tip ( 7), connecting the third cutting edge (29) to the tip (7) with a rounding (30) having a radius of curvature G = 0.2Wb, and - a fourth cut (31) that is adjacent to the tip (7) and to a second outer corner (17) of the rectangle on the side of the trailing edge (6), the fourth cut (31) having a right triangle shape with the longitudinal leg (32) having a dimension H = 0.25R, one leg (33) wide q It has a dimension I = 0,1R, and a hypotenuse that forms a fourth cutting edge (34) of the blade that extends from the trailing edge (6) to the tip (7), connecting the fourth edge of cut (34) to the tip (7) with a rounding (35) that has a radius of curvature G = 0.2Wb; because the first fold (9) intersects the longitudinal side of the enveloping rectangle at the junction point of the first cutting edge (21) and the leading edge (5) at a distance A = 0.2R from the first inner corner (14), and the first fold (9) intersects the wide side of the surrounding rectangle adjacent to the tip (7) at the distance J = 0.4R from the third corner (17); because the second fold (12) intersects the wide side of the surrounding rectangle adjacent to the root (8) at a distance across the width K = 0.1Wb from the first corner (14), and the second fold (12 ) intersects the side of the surrounding rectangle adjacent to the tip (7) at a distance across the width I = 0.1R from the fourth corner (17); and why the first angle α1 = 6 ° ± 1 °, the second angle α2 = 8 ° ± 1 ° and the third angle α3 = 19 ° at 25 °.