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.

The invention is about a foldable portable fan, which relates to the technical field of a fan, including an entity; the bottom of the entity is fixedly arranged with a connecting part, the connecting part is connected with a rotating part, one side of the rotating part is connected with a bolt, one end of the bolt is connected with a bolt column; the fan can conveniently connect the entity and the base together by setting a connecting part, a rotating part, a bolt and a bolt column, avoiding the use of screws, and the connection is very convenient; in addition, the entity can be folded between the base, which can save packaging materials, occupy less transportation space and save costs in logistics packaging; and the entity can be matched with different bases, thus providing higher selectivity and more flexible sale.

The gas turbine engine can have an air mover configured for generating a flow of air around a rotation axis; a surface extending around the rotation axis delimiting a passage for the flow of air downstream of the air mover; an electric machine disposed within the passage and coupled to the air mover; a coolant circuit having: an evaporator circumferentially disposed around at least part of the electric machine and in thermal communication therewith; a condenser having a surface cooler circumferentially disposed at least partially around the surface and in thermal communication therewith; a first conduit fluidly connecting an upper region of the evaporator to an upper region of the condenser; and a second conduit fluidly connecting a lower region of the condenser to a lower region of the evaporator; and a coolant fluid in the coolant circuit.

A method and device is provided for increasing the efficiency of jet drives by recuperating effective power from the propulsion flow. A ducted propeller in the propeller housing, driven by a driving engine via a drive shaft, conveys the fluid for the jet drive out of the interior V.sub.i of a radial turbine. The fluid is accelerated axially and ejected backwards against the direction of travel. This creates thrust. Because the pressure in the interior of the turbine decreases, new fluid from the environment flows directly via the blades of the rotating radial turbine from the outside to the inside, thereby driving them. A guide apparatus is missing. The power of the radial turbine is transmitted via a transmission to the drive shaft of the propeller, which relieves the driving engine and increases the efficiency of the jet drive. The invention is particularly suitable for electric drives.

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 fan, and a silencer that silences a sound generated by the fan are provided, in which the silencer has a resonance characteristic, the silencer is disposed at a position connected to a sound field space of the sound generated by the fan, and a sum of an absorbance and a reflectivity of the silencer at a resonance frequency is 10% to 43% and a standardized half-width of the silencer is more than 0.05 and 0.25 or less.

A fan, and a silencer that silences a sound generated by the fan are provided, in which the silencer has a resonance characteristic, the silencer is disposed at a position connected to a sound field space of the sound generated by the fan, and a sum of an absorbance and a reflectivity of the silencer at a resonance frequency is 10% to 43% and a standardized half-width of the silencer is more than 0.05 and 0.25 or less.

An axial fan that includes a casing having an inner space that penetrates in one direction, and a rotor blade disposed in the inner space of the casing, and a silencer that is disposed at a position connected to the inner space of the axial fan are provided, in which the axial fan has a sound pressure distribution having a position at which a sound pressure is high and a position at which the sound pressure is low in a circumferential direction in the inner space during driving, and the silencer is disposed at the position of the axial fan in the circumferential direction at which the sound pressure is high and is not disposed at the position at which the sound pressure is low.

An attachable air filter medium for attachment to a conventional circulation fan is disclosed comprising a netting fabric filter medium being adapted to fit over the rear half of the conventional circulation fan's housing for filtering dust particles in air coming into the circulation fan preventing dust buildup on the fan blade thus eliminate the need to periodically clean the fan.

A convertible ducted fan engine and mounting system. The convertible ducted fan engine has a shroud encircling a mechanical fan. The convertible ducted fan engine includes a fluid-propulsion configuration in which the mechanical fan rotates freely with respect to the shroud to produce thrust through fluid flow, and a drive-wheel configuration in which the shroud rotates about the rotational axis. The mounting system includes at least one gimbal ring and may include a circular track system thereby enabling the convertible engine to be oriented in any direction.