A blower assembly including a motor, an impeller and a volute that is configured such that an inlet chamber of the volute and an outlet chamber of the volute are divided from one another by an airtight membrane and the membrane is configured to allow the transmission of pressure waves between the inlet and outlet chambers.

A fan frame turbulence structure includes a frame body having a wind incoming side and a wind outgoing side respectively on two sides of the frame body. The frame body defines an airflow passage which passes through the frame body from the wind incoming side to the wind outgoing side. The wind incoming side has an inlet in communication with the airflow passage. The inlet has a breaking section between the wind incoming side and the passage inner wall. The breaking section includes densely distributed breaking units. The breaking units define therebetween gaps in communication with the airflow passage. The breaking units serve to break and fracture airflow sucked in from the wind incoming side, whereby part of the airflow passes through the gaps between the breaking units and is broken and fractured into multiple gap turbulences to flow into the air passage so as to lower the wideband noise.

Provided is a circuit that eliminates harmonics generated in a synchronous detection circuit to achieve low vibration and low noise, along with a position detection device, a magnetic bearing device, and a vacuum pump. An odd-order harmonic of a sensor carrier frequency can be eliminated from a displacement signal by setting a duty of a switch of the synchronous detection circuit to a specified value. Conditions for a pulse generation method are adjusted to generate a pulse at a phase angle of 180 degrees + 360 degrees x n. A duty of a pulse for a synchronous detection switch is set such that a positive-side area and a negative-side area of a harmonic waveform are equal to each other. Moreover, the pulse duty is adjusted to center the phase angle at which a sensor signal has a highest sensitivity.

An aircraft system includes, among other things, an aircraft and a gas turbine engine coupled to the aircraft. The gas turbine engine includes a propulsor section including a propulsor, a compressor section, a turbine section including a first turbine and a second turbine, and a gear reduction between the propulsor and the second turbine. The second turbine includes a number of turbine blades in each of a plurality of rows of the second turbine. The second turbine blades operating at least some of the time at a rotational speed. The number of blades and the rotational speed being such that the following formula holds true for a majority of the blade rows of the second turbine: 5500 Hz≤(number of blades×speed)/60 sec≤10000 Hz. The gas turbine engine is rated to produce 15,000 pounds of thrust or more.

A gas turbine engine according to an aspect of the present disclosure includes, among other things, a propulsor section, a compressor section including a first compressor and a second compressor, and a turbine section including a first turbine and a second turbine. The first compressor includes a plurality of arrays of airfoils defining a plurality of compressor stages. A number of airfoils in each downstream array of the plurality of arrays is a factor (F) of a number of airfoils in a respective immediately upstream array of the plurality of arrays. The factor (F) is between 1.19 and 1.55 for each of the downstream arrays of the first compressor.

An air conditioning apparatus includes a centrifugal fan and a heat exchanger disposed in a position facing a discharge port of the centrifugal fan. The centrifugal fan includes: a fan, blades; and a scroll casing housing the fan, the scroll casing including a discharge portion, and a scroll portion including a side wall, a circumferential wall, and a tongue portion. In the circumferential wall, at a first end between the circumferential wall and the tongue portion, and at a second end between the circumferential wall and the discharge portion, a distance between an axis of the rotational shaft and the circumferential wall is equal to a distance between the axis of the rotational shaft and a standard circumferential wall, and is greater than or equal to the distance between the first end and the second end of the circumferential wall, the circumferential wall including an extended portion between the first end and the second end of the circumferential wall and bulging out, at a position facing the circumferential portion of the main plate, in a direction parallel to the rotational shaft.

An acoustic treatment grid intended to be mounted inside or at the outlet of a duct of a bleed valve of a turbomachine of an aircraft intended to convey a gas flow, the grid comprising a perforated plate and circular orifices traversing the perforated plate along a first direction, the orifices having a diameter and a geometrical center.

Each orifice is separated from an adjacent orifice by a space, the length of which is equal to the product of the diameter of said orifice and a spacing coefficient of a value between 1.1 and 6.

Provided are a blower, capable of suppressing noise occurring in a stator while significantly improving blowing efficiency, and an outdoor unit using the same. The present disclosure comprises: a bell mouth part spaced apart at a predetermined distance in the radial direction with respect to an outer circumferential end of a propeller fan; and a diffuser part installed on the downstream side of the bell mouth part, and having a flow path area which is enlarged from the upstream side toward the downstream side with a larger magnification rate than the magnification rate of the flow path area in the downstream end of the bell mouth part; and a stator part having a plurality of stators, wherein the stator part is arranged within the diffuser part.

A fan assembly including a fan frame and an impeller. The fan frame includes a frame body and a first peripheral protruding plate and has an air inlet and an air outlet. The first peripheral protruding plate protrudes from a side of the frame body and forms an air channel together with the frame body. The first peripheral protruding plate is configured to reduce a noise made by the fan assembly. The air inlet is in fluid communication with the air outlet via the air channel. The impeller is rotatably disposed on the frame body and located in the air channel. The protruding height of the first peripheral protruding plate relative to the frame body ranges from 50 to 100 percent of an overall axial thickness of the impeller.

A fan frame with noise muffling structure includes a frame having a top and a bottom and defining a centered air flow passage that extends from the top to the bottom. The air flow passage has an air inlet and an air outlet formed on the top and the bottom, respectively. The frame further has a noise muffling zone in at least one area of the frame located between the air flow passage and an outer periphery of the frame. In the noise muffling zone, there is provided at least one noise muffling unit, which is located between the top and the bottom without communicating with the air flow passage. The noise muffling unit internally defines a hollow cavity, which is closed between but not extended through the top and the bottom. The hollow cavity isolates air flow noise and absorbs frame vibration and noise produced by the frame vibration.