Provided is an impeller including a first portion including a first hub and a plurality of primary blades each extending while being spaced an equal distance from each other along an outer circumference of the first hub and a second portion including a second hub coupled to a lower side of the first hub by using a projection-groove coupling manner and a plurality of secondary blades each extending while being spaced apart from each other along an outer circumference of the second hub. Here, when a projection angle between a leading edge (L.E.) and a trailing edge (T.E.) of each of the primary blades is .sub.1, and a projection angle between a leading edge (L.E.) and a trailing edge (T.E.) of each of the secondary blades is 1, the projection angle .sub.1 and .sub.1 includes an upstream angle .sub.1u and .sub.1u and a downstream angle .sub.1d and .sub.1d, at which the primary blade and the secondary blade overlap each other, and an angle .sub.1m and .sub.1m at which the primary blade and the secondary blade do not overlap each other, and the projection angle .sub.1 is less than the projection angle .sub.1 to satisfy an equation 0<.sub.1<.sub.1 as a radius of each of the primary blade and the secondary blade goes from the hub to the edge.

The present disclosure relates to a blade structure and a fan and a generator having the same. In accordance with the present disclosure, there is the effect that can ultimately enhance efficiency of the generator by forming the sweep structure or the spline structure on the blade in the inflow direction side of fluid to reduce a low-speed region around the tip of the blade.

A series-connected fan includes a first fan and a second fan. The first fan includes a first frame, a first base, first static blades and a first impeller. The second fan includes a second frame, a second base, second static blades and a second impeller. A first underframe of the first frame is connected to a second underframe of the second frame. The first static blades are disposed around the first base and connected to the first base and the first underframe. The second static blades are disposed around the second base and connected to the second base and the second underframe. The first impeller includes a first hub and first rotor blades. The second impeller includes a second hub and second rotor blades. The cross-sectional area of the first hub increases along a direction from the top of the first hub to the bottom of the first hub.

A rotary heat exchanger includes a hub configured to be rotatably driven by a shaft, a fan including a plurality of fan blades integrally coupled to the hub and extending radially outwardly therefrom, and a heat exchanger including a plurality of heat exchanger sections. The heat exchanger includes a plurality of cooling fins for receiving air from the fan. Each of the plurality of heat exchanger sections is located between two of the plurality of fan blades. The hub, the fan, and the heat exchanger are integrally formed as a single body by a three-dimensional printing process.

A propeller fan includes a shaft portion disposed on a rotation axis, and a blade disposed on an outer peripheral side of the shaft portion and including a leading edge and a trailing edge. The blade includes a negative pressure surface in which a plurality of recesses are formed, and the plurality of recesses include a first recess and a second recess disposed on the trailing edge side than the first recess in a circumferential direction about the rotation axis as a center. The first recess has a depth larger than a depth of the second recess.

In a blade of a propeller fan, an inclination angle () is made by a straight line passing through an outer circumferential side end and an inner circumferential side end of a radial cross section of the blade with a second plane orthogonal to a center axis of a hub. In a blade end of the blade, one end in front of the other end viewed in the rotation direction of the propeller fan is a leading blade end, while the other end behind the leading blade end is a trailing blade end. The blade is shaped such that the inclination angle () monotonically increases, in the direction from the intermediate position toward the trailing blade end, in an area extending from an intermediate position between the leading blade end and the trailing blade end to the trailing blade end.

A manufacturing method of an axial air moving device. A model of the axial air moving device includes a hub and blades. The axial projection of blades is partially overlapped in the axial direction of the hub. The model of the axial air moving device is parted in the axis direction of the hub. The blades are divided into multiple parting models non-overlapped in the axial projection. A mold manufacture using axial demolding and an injection molding are performed and the parting models are connected. Therefore, the axial air moving device with overlapped blades and better fluid performance is achieved through the axial demolding method.

A wind wheel including a plurality of blades and a hub. The plurality of blades each includes an inner edge, an outer edge, a leading edge, and a trailing edge. In a top view of the orthographic projection of the wind wheel, the maximum distance between the center O of the hub and the outer edge of the plurality of blades refers to the outer diameter R; the distance between the center O and the cross point A1 of the inner edge and the leading edge is named R1; the outer edge is connected to the leading edge via an arc; the distance between the center O and a joint A2 of the arc and the leading edge is named R2; and the distances R1, R2, and the outer diameter R satisfy the following conditions: 0.35RR10.45R; 0.8RR20.9R.

Rotor of a gas turbine engines having a rotor hub and a plurality of blades extending from the rotor hub, wherein each blade has a full-span forward sweep along a leading edge of the blade that starts at an airfoil root of the blade at the hub and extends to a blade tip, wherein a sweep of a blade is a percentage of a root axial chord length of the respective blade.

Provided is an axial fan including multiple forward-swept blades. An angle of advance of a trailing edge of the forward-swept blade is larger than an angle of advance of a leading edge of the forward-swept blade. An outer portion of the trailing edge, being positioned further in an outer periphery of the trailing edge than an intermediate portion of the trailing edge with respect to a rotary shaft of the axial fan, advances as the trailing edge advances radially outward of a ventilation channel of the axial fan.