An axial ventilator has multiple fan wheel blades (2) arranged around an axis of rotation (RA) in a blade ring. At least one of the fan wheel blades (2) has an inner section (3) located on the radial inside. A blade edge section (4) directly adjoins the inner section (3) and borders a blade edge (5). The at least one fan wheel blade (2) has a local projection (6) over a radial extension of the blade edge section (4). The local projection (6) is formed as an extension of the chord length of the fan wheel blade. The projection locally enlarges the fan wheel blade (2) in the blade edge section (4). An average angle of attack (α) of the fan wheel blade (2), in relation to a plane of rotation (RE), of the fan wheel (1), is larger than an average angle of attack (β) of the projection (6), in relation to the plane of rotation (RE).

A centrifugal blower assembly includes a housing having an inner surface and an outer surface. The inner surface of the housing defines in part an interior space. The centrifugal blower also includes a first portion of texture applied to at least a first portion of at least one of the inner surface and the outer surface of the housing. The first portion of texture has a first height based at least in part on a local boundary layer height of an airflow moving across at least one of the inner surface and the outer surface respectively. The first portion of texture is configured to generate a turbulent flow within the airflow moving across the first portion of texture.

In order to reduce the rotating stall onset flowrate, this centrifugal compressor comprises: a vaneless diffuser (12) provided on a discharge outlet (6B) side of an impeller (6); and a fluid circulation flow path (21) having an inlet (21A) that opens into a first wall section (22) of a hub casing (2B) forming the vaneless diffuser (12) and also having an outlet (21B) that opens into a second wall section (23) of the hub casing (2B) facing a hub disk (6C) rear surface in the impeller (6). As a result of causing the first wall section (22) to protrude on to a wall section (31) side of the shroud casing (2A), the flow path width (D) of the vaneless diffuser (12) is smaller than the width (W) of the discharge outlet (6B) in the impeller (6). In addition, the hub casing (2B) comprises an inclined wall section (24) having a protruding end (24A) between the discharge outlet (6B) of the impeller (6) and the inlet of the vaneless diffuser (12), said inclined wall section (24) connecting the second wall section (23) and the first wall section (22).

The impeller provides that when an angle made by a projection line 33 that is obtained by projecting a camber line 32 of the blade 22 onto a predetermined meridional cross section and the camber line 32 is defined as an inclination angle γθ and an inclination in a direction opposite to a rotating direction of the rotary shaft is defined to be positive, the blade 22 is formed in such a manner that the inclination angle γθ of a leading edge 22A is zero or positive on the hub 20 side and gradually increasing toward the shroud 21 and the inclination angle is gradually decreasing from the leading edge toward a trailing edge in a flow direction of the fluid.

A blower includes a fan that has blades and generates an air flow by rotating. Each of the blades has a front edge and a serration provided at least in a part of the front edge. The serration has tip portions and recessed portions arranged alternately with each other. Each of the blades has a negative pressure surface and one or more ribs protruding from the negative pressure surface. Each of the ribs extends from a corresponding one of the recessed portions, which is designated as a starting point, toward a rear edge of a corresponding one of the blades.

A multi-stage axial compressor with an inner wall including a step portion for each of the compressor stages. Each step portion is defined along a respective stage. Each step portion may extend over at least a majority of an axial length of the stage. Each step portion may optionally include a point aligned with a maximum thickness of the airfoil portions of the rotor blades and a point aligned with a maximum thickness of the stator vanes. Adjacent step portions are connected by a transition portion converging toward a central axis of the compressor from the upstream step to the downstream step. Each transition portion has a steeper slope than that of the adjacent step portions. A method of directing flow through a multi-stage axial flow compressor is also discussed.

Multiple projections are provided at a flow-change portion, which corresponds to such a portion of a wall surface of an A/C casing, at which velocity gradient of air current becomes larger in an area adjacent to the wall surface, in order to decrease aerodynamic sound generated by disturbed air current.

A turbine engine compressor blade includes a leading edge, a trailing edge, a suction surface, and a pressure surface. In addition, the blade includes at least one irregularity in the form of a projecting protuberance of the suction surface or the pressure surface or in the form of a recess nested in the suction surface or the pressure surface. The irregularity may have a direction of longest dimension substantially parallel to the leading edge or substantially axial.

The invention relates to a profiled structure, elongated in a direction in which the structure has a length exposed to an airflow, and transversely to which the structure has a leading edge (164) and/or a trailing edge, at least one of which is profiled and has, in said direction of elongation, serrations (28a) defined by successive teeth (30) and depressions (32).

Along the profiled leading edge and/or profiled trailing edge, the successive teeth (30) and depressions (32) extend only over a part of said length exposed to the flow over which the amplitude and/or spacing of the teeth varies monotonically except for the few teeth nearest each end of said part, a remaining part (280) of said length being smooth.

A novel mechanism for reducing boundary layer friction and inhibiting the effects of uncontrolled fluid turbulence and turbulent layer separation, thus reducing the body drag, kinetic energy losses and lowering engine and pump fuel consumption is proposed. It steps on the type of turbulence observed in the so-called in fluid dynamics “drag crisis”. Plurality of device shapes and plurality of devices producing the wanted pure form of even plurality of counter-rotating vortices extending into the flow, i.e. tubes, are presented and discussed in detail, contrasting with the prior art. Configurations of multiple devices for the purposes of drag and fuel reduction, including their simulations and experimental results are put forward. Additional embodiments of the resulting tubes disclose use on aircraft or vessel control surfaces as stall inhibitors, use in wind turbines as dynamic range extenders, as well as use in turbines in efficient cooling mechanisms.