A propeller fan includes a hub that has a side surface around a central axis, and blades that are provided on the side surface, wherein a blade of the blades includes an inner peripheral portion located on a side of a base, and an outer peripheral portion located on a side of an outer edge, the outer peripheral portion is formed as one blade, the inner peripheral portion includes blade elements arranged at a predetermined interval, a ratio r/R of a radius r which is a distance from the central axis to the outer peripheral portion and a radius R which is a distance from the central axis to the outer edge is 0.4 or less, and when a wind speed at the outer peripheral portion is V1 and a wind speed at the inner peripheral portion is V2, a relational formula of V1≤V2×2.0 is established.

A propeller fan includes a hub that has a side surface around a central axis, and blades that are provided on the side surface, wherein a blade of the blades includes an inner peripheral portion located on a side of a base, and an outer peripheral portion located on a side of an outer edge, the outer peripheral portion is formed as one blade, the inner peripheral portion includes blade elements arranged at a predetermined interval, a ratio r/R of a radius r which is a distance from the central axis to the outer peripheral portion and a radius R which is a distance from the central axis to the outer edge is 0.4 or less, and when a wind speed at the outer peripheral portion is V1 and a wind speed at the inner peripheral portion is V2, a relational formula of V1≤V2×2.0 is established.

This disclosure is related to a thin type counter-rotating axial air moving device. The ratio of the front hub diameter to the front blade diameter is about 0.3 to about 0.85. The front average pitch angle of the front blades is greater than about 46 degrees. The ratio of the rear hub diameter to the rear blade diameter is about 0.3 to about 0.85. The rear average pitch angle of the rear blades is less than about 38 degrees. The ratio of the total thickness to the greater one between the front blade diameter and the rear blade diameter is less than or equal to about 0.75.

A refractory metal core (RMC) finishing method according to an exemplary aspect of the present disclosure includes, among other things, performing a plurality of finishing operations on a plurality of RMC samples, analyzing one or more properties of at least a portion of the plurality of RMC samples and selecting a combination of finishing operations for generating an RMC having desirable properties for manufacturing a part free from defects.

A fan including a hub and a plurality metal blades is provided. Each of the blades extends from the hub and is inclined relative to a radial direction of the hub. Each blade has a distal edge away from the hub, and has a pair of wingtips at the distal edge.

An axial fan has an inner-rotor motor which includes a drive end, a non-drive end and a shaft which extends axially from the drive end; and an impeller which includes a cylindrical impeller cup and a number of impeller blades that extend radially from the impeller cup. The impeller cup has an open upstream end and a closed downstream end which is connected to the shaft. In operation, the motor spins the impeller to generate an airflow in a direction from the non-drive end of the motor to the drive end of the motor. The impeller cup is configured to receive the motor therein and surround the drive end of the motor but not the non-drive end of the motor. As a result, the non-drive end of the motor is exposed to the airflow during operation of the fan.

A vacuum pump comprises: a rotor rotatable in a predetermined rotation direction; and a case housing the rotor; and a fixed component arranged facing an inner wall of the case. A clearance is formed between the inner wall of the case and the fixed component, and a groove allowing communication between the clearance and an exhaust path in the case is formed at either the inner wall of the case or the fixed component.

A vacuum pump comprises: a rotor rotatable in a predetermined rotation direction; and a case housing the rotor; and a fixed component arranged facing an inner wall of the case. A clearance is formed between the inner wall of the case and the fixed component, and a groove allowing communication between the clearance and an exhaust path in the case is formed at either the inner wall of the case or the fixed component.

A rotating thrust-producing apparatus having a control system includes a rotatable foil having opposite first and second faces and a plurality of spaced apart fins occupying a periphery thereof. A pressure control assembly includes a first adjustable control surface disposed adjacent to a first face of the foil so as to be selectively movable over the fins of the foil. The pressure control assembly may include a second control surface disposed adjacent to the second face of the foil and which may be adjustable. As the foil is rotated, and the at least one adjustable control surface is moved over fins of the foil, a fluid pressure imbalance is created, causing a thrust in the direction of the pressure deficit.

A self-rotation graphene heat-dissipation device for a direct-drive electro-hydrostatic actuator, that includes inner and outer walls of a shell eccentrically arranged relative to each other, the shell sleeves on an outer side of a self-rotation mechanism. The self-rotation mechanism is arranged on an outer side of a shaft; the shaft is coaxial with the inner wall of the shell and connected with outer and inner end covers. The self-rotation mechanism includes a rotor and blades, the rotor sleeves on the shaft and is connected with the outer and inner end covers. The rotor is slidably connected with the blades, and outer walls of the blades are closely attached to the inner wall of the shell. Graphene heat-dissipation layers are coated on outer walls of all of the shell, blades, the rotor, the inner and outer end covers respectively.