An impeller of a centrifugal compressor according to the present disclosure includes: a hub; a plurality of full blades disposed on a peripheral surface of the hub at intervals in a circumferential direction; and a plurality of splitter blades each of which is disposed between adjacent full blades of the plurality of full blades on the peripheral surface of the hub. When a blade height ratio which is a ratio of a blade height (Hf) of each full blade to a blade height (Hs) of each splitter blade on a meridional plane of the impeller is defined as Hs/Hf, the blade height ratio satisfies Hs/Hf<1 at least at a leading edge of each splitter blade.

An impeller of a centrifugal compressor according to the present disclosure includes: a hub; a plurality of full blades disposed on a peripheral surface of the hub at intervals in a circumferential direction; and a plurality of splitter blades each of which is disposed between adjacent full blades of the plurality of full blades on the peripheral surface of the hub. When a blade height ratio which is a ratio of a blade height (Hf) of each full blade to a blade height (Hs) of each splitter blade on a meridional plane of the impeller is defined as Hs/Hf, the blade height ratio satisfies Hs/Hf<1 at least at a leading edge of each splitter blade.

A fan includes a hub and a plurality of fan blades. The hub has an axle center. The fan blades are disposed around the hub. Each of the fan blades has a bent portion, and the bent portions of the fan blades are extended along a surrounding direction surrounding the axle center. The hub is welded with the bent portion of each of the fan blades along the surrounding direction. As a result, the number of fan blades is maximized, the strength is simultaneously ensured to be enough, and the advantages of effectively enhancing the fan characteristics are achieved.

A compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy such as at a pressure between 4-30 cmH2O includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes a set of impeller blades, each impeller blade comprising a leading edge and a trailing edge; and a first shroud and a second shroud, each shroud at least partly defining a flow passage through the impeller, the first shroud comprising a wall defining a periphery of an impeller inlet. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between 4-30 cmH2O at an overall sound power level of less than 50 dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than 50 mm. The first shroud and the second shroud are configured such that the flow passage is narrower in an axial direction at an outer portion of the impeller than at an inner portion of the impeller; and a diameter of the impeller inlet is at least 50% of the diameter of the impeller.

A compact respiratory therapy device suitable for use by a patient during sleep to provide respiratory pressure therapy such as at a pressure between 4-30 cmH2O includes a housing, an inlet, an outlet, a motor including a rotor, and an impeller configured to be rotated by the rotor to deliver a flow of air from the inlet toward the outlet. The impeller includes a set of impeller blades, each impeller blade comprising a leading edge and a trailing edge; and a first shroud and a second shroud, each shroud at least partly defining a flow passage through the impeller, the first shroud comprising a wall defining a periphery of an impeller inlet. The compact respiratory therapy device is configured to deliver the flow of air from the outlet for delivery to the patient at a pressure between 4-30 cmH2O at an overall sound power level of less than 50 dB(A) thereby reducing any disturbance to a quality of sleep for the patient. A diameter of the impeller is less than 50 mm. The first shroud and the second shroud are configured such that the flow passage is narrower in an axial direction at an outer portion of the impeller than at an inner portion of the impeller; and a diameter of the impeller inlet is at least 50% of the diameter of the impeller.

A centrifugal fan includes a main plate, a blade connected to the main plate, and a shroud having an annular shape and connected to a shroud-side end of the blade that is an end opposite a main-plate-side end of the blade connected to the main plate. The centrifugal fan rotates about a rotation axis to suction a fluid through an opening of the shroud and discharge the fluid through the blade in a radial direction. A leading edge of the blade includes a recess located next to a point at which a shroud inner surface of the shroud that faces the main plate is connected to the leading edge and curving inwardly from the point toward a trailing edge and a projection located closer to the main plate than is the recess and projecting in the rotation direction.

A centrifugal fan includes a main plate, a blade connected to the main plate, and a shroud having an annular shape and connected to a shroud-side end of the blade that is an end opposite a main-plate-side end of the blade connected to the main plate. The centrifugal fan rotates about a rotation axis to suction a fluid through an opening of the shroud and discharge the fluid through the blade in a radial direction. A leading edge of the blade includes a recess located next to a point at which a shroud inner surface of the shroud that faces the main plate is connected to the leading edge and curving inwardly from the point toward a trailing edge and a projection located closer to the main plate than is the recess and projecting in the rotation direction.

An assembly is provided for a turbine engine. This assembly includes a static structure and an impeller rotor housed within the static structure. The impeller rotor includes a vane structure and a shroud. The vane structure includes a first sidewall, a second sidewall and a plurality of vanes arranged circumferentially about a rotational axis. The vanes include a first vane. The first vane includes a first portion, a second portion and a third portion. The first portion is axially between the first sidewall and the second sidewall. The second portion is radially between the first sidewall and the shroud. The third portion is radially between the second sidewall and the shroud. The shroud circumscribes the vane structure. A gap is formed by and extends between the shroud and the static structure. A dimension of the gap changes as the gap extends along the shroud.

An assembly is provided for a turbine engine. This assembly includes a static structure and an impeller rotor housed within the static structure. The impeller rotor includes a vane structure and a shroud. The vane structure includes a first sidewall, a second sidewall and a plurality of vanes arranged circumferentially about a rotational axis. The vanes include a first vane. The first vane includes a first portion, a second portion and a third portion. The first portion is axially between the first sidewall and the second sidewall. The second portion is radially between the first sidewall and the shroud. The third portion is radially between the second sidewall and the shroud. The shroud circumscribes the vane structure. A gap is formed by and extends between the shroud and the static structure. A dimension of the gap changes as the gap extends along the shroud.

Provided is a turbofan including a shroud, a main plate, and a plurality of blades. A main plate-side shoulder surface portion is curved so as to be distanced from the rotational center axis while approaching the blade trailing edge as the main plate-side shoulder surface portion is distanced from a main plate-side blade tip portion, and has a convexoconcave shape including a blade tip section and the main plate-side blade tip portion. An inner peripheral-side leading edge section includes the inner peripheral-side blade leading edge section main plate-side portion and an inner peripheral-side blade leading edge section tip-side portion including curves that protrude rearward in the rotational direction.