A method for profiling blades of an axial turbomachine includes preparing a geometric model of a blade profile; determining an oscillation mode of the geometric model; calculating a time profile of a position-dependent disruptive pressure in a channel between two adjacent blade profiles over an oscillation period of the oscillation belonging to the oscillation mode, changing the geometric model and determining a different oscillation mode for the modified geometric model; and determining the damping of the oscillation using the disruptive pressure profile calculated previously and accepting the modified geometric model for the case that the damping of the oscillation turns out to be greater than calculated, otherwise repeating the last two steps with another modified geometric model.

An axial fan for an outdoor unit of an air conditioner is provided. The axial fan may include at least one blade connected to a hub. The at least one blade may include a blade inner portion, a blade outer portion provided outside of the blade inner portion in a radial direction, and a blade connector that connects the blade inner portion and the blade outer portion as a curved surface, thereby improving noise and increasing an air volume.

A blower for providing a supply of air at positive pressure in the range of approximately 2 cmH.sub.2O to 30 cmH.sub.2O includes a motor, at least one impeller, and a stationary component. The stationary component includes an inlet and an outlet. The motor, the impeller, the inlet and outlet are co-axial.

A fan includes blades and a side plate. The side plate includes a fan ring portion having a cylindrical shape centered on a fan axis. A guide part that is annular is arranged on one side of the fan ring portion in the axial direction and forms a suction port through which the air sucked into the fan passes. A communication path that allows an upstream space located on the one side in the axial direction with respect to the guide part to communicate with a gap between the fan ring portion and the guide part is formed outside the guide part in a radial direction of the fan axis. The fan ring portion is located outside in the radial direction with respect to an innermost peripheral portion of the guide part located on an innermost side in the radial direction.

The present invention relates to a jet structure of a fan rotor, which comprises a fan wheel and at least one connecting channel. The fan wheel has a hub and plural blades disposed on the circumferential side of the hub. The hub has a top portion and a sidewall. Each of the blades has an upper surface and a lower surface which form a high-pressure zone and a low-pressure zone, respectively. The connecting channel is provided with at least one first inlet disposed in the high-pressure zone and at least one first outlet disposed in the low-pressure zone. The first inlet and the first outlet are a first end and a second end of the connecting channel, respectively. By means of the design of the present invention, the effect of noise reduction can be achieved.

In a blade of a propeller fan, a position on a chord line where the camber becomes maximum is set as a maximum camber position A, and a ratio of a distance d between a leading edge and the maximum camber position A to a chord length c is set as a maximum camber position ratio. The end portion on the hub side of the blade is set as a blade root, and the end portion on the outer circumferential side of the blade is set as a blade end. In the blade, the maximum camber position ratio monotonically increases in the direction from the reference blade cross section located between the blade root and the blade end toward the blade end and becomes maximum at the blade end. Thus, fan efficiency of the propeller fan is improved.

A centrifugal blower device includes a rotating shaft, a turbo fan unit and a casing. A shroud ring of the turbo fan unit and a cover portion of the casing form a gap between them. The gap includes a radial gap formed between the cover portion and the shroud ring in a radial direction and an axial gap formed between the cover portion and the shroud ring in an axial direction. The radial gap is located at a position outside of a shroud-side inner peripheral end in the radial direction. The axial gap is located at a position inside of the radial direction in the radial direction. A minimum gap dimension of the radial gap is smaller than a minimum gap dimension of the axial gap. A shortest distance between the shroud-side inner peripheral end and the cover portion is larger than the minimum gap dimension of the radial gap.

In a blade of a propeller fan, an inclination angle (φ) 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 (φ) 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 propeller system combines innovative strategies to create a new methodology to reduce propeller or rotor noise. The propeller is specifically aimed for ultra-quiet electrically powered aircraft for use in high proximity aviation, but its low-noise advantages will extend to other purposes. The propeller blade includes geometries, along with size and operational limitations that minimize rotational and vortex noise, vibration and span-wise air flow on the blade. To further reduce noise, the propeller provides greater relative thrust on the inboard portions of the blade than do conventional propellers and provides less than conventional relative thrust including negative thrust at the outermost portions of the blade. The propeller blade includes stepped changes in local blade stiffness at calculated intervals that can reduce resonant blade vibrations and their resultant noise. This ultra-quiet propeller design can also be used for quieting hovercraft, drones, surveillance aircraft, indoor fans, wind tunnels and other applications.

Disclosed examples include a retrofit fan frame assembly, comprising: a leading edge adjustment component coupleable to an airfoil, the leading edge adjustment component of variable chord length, the variable chord length to increase and then decrease along a radial length from a hub end of the airfoil to an opposite tip end of the airfoil; and an attachment mechanism configured to couple the leading edge adjustment component to a leading edge of the airfoil.