Abstract: A once-through pump is provided which is able to improve air-blowing efficiency, reduce operation noise, and achieve a sufficient amount of blast or flow rate even within a limited design space. The once-through pump for accelerating fluid (F) in a flow passage (P) while passing the fluid (F) through the flow passage (P) includes a cylindrical impeller (10) rotatably supported in the flow passage, a plurality of vanes (11) provided on the outer periphery of the impeller (10), and a motor for driving the impeller to rotate. The impeller (10) has a substantially D-shaped cross sectional configuration with a suction side, at which the fluid (F) is sucked into the impeller (10), being formed into a straight portion (10a). Each of the vanes (11) has a positive vane angle with respect to a fluid advancing or flowing direction (A) in the straight portion (10a).

Abstract: A once-through pump is provided which is able to improve air-blowing efficiency, reduce operation noise, and achieve a sufficient amount of blast or flow rate even within a limited design space. The once-through pump for accelerating fluid (F) in a flow passage (P) while passing the fluid (F) through the flow passage (P) includes a cylindrical impeller (10) rotatably supported in the flow passage, a plurality of vanes (11) provided on the outer periphery of the impeller (10), and a motor for driving the impeller to rotate. The impeller (10) has a substantially D-shaped cross sectional configuration with a suction side, at which the fluid (F) is sucked into the impeller (10), being formed into a straight portion (10a). Each of the vanes (11) has a positive vane angle with respect to a fluid advancing or flowing direction (A) in the straight portion (10a).

Abstract: A centrifugal multiblade fan comprises a plurality of curved blades which are circularly arranged about a common rotation axis at evenly spaced intervals defining a curved air flow passage between every neighboring blades. Each curved blade has concave front and convex rear surfaces which extend longitudinally in parallel with the rotation axis. A lower annular end plate is provided for putting thereon lower ends of the circularly arranged blades. A radially outside part of each curved blade has a radius of curvature which is greater than that of a radially inside part of the blade. A slit extends longitudinally parallel with the rotation axis at a radially inside portion of each blade.