Abstract: A fluid flow machine has a main flow path in which at least one row of blades (2) is arranged, with at least one blade end of a blade row (2) being firmly connected to the main flow path confinement and, in an area of this fixed blade end at a sidewall (9), at least one longish, obstacle-type boundary layer barrier (11) is provided which in at least part of its course is oriented obliquely to the main flow direction, thereby deflecting fluid flowing near the sidewall towards the blade pressure side.

Abstract: An downstream plasma boundary layer shielding system includes film cooling apertures disposed through a wall having cold and hot surfaces and angled in a downstream direction from a cold surface of the wall to an outer hot surface of the wall. A plasma generator located downstream of the film cooling apertures is used for producing a plasma extending downstream over the film cooling apertures. Each plasma generator includes inner and outer electrodes separated by a dielectric material disposed within a groove in the outer hot surface. The wall may be part of a hollow airfoil or an annular combustor or exhaust liner. A method for operating the downstream plasma boundary layer shielding system includes forming a plasma extending in the downstream direction over the film cooling apertures along the outer hot surface of the wall. The method may further include operating the plasma generator in steady state or unsteady modes.

Abstract: A ducted fan includes a fan that generates an airflow that flows substantially parallel with the axis of the rotating shaft of the fan; a duct, arranged around the fan, that extends in the direction of the rotating shaft of the fan and includes an airflow inlet defined by the upstream end and an airflow outlet defined by the downstream end, and that has a ramp portion formed in the inner face of the airflow inlet; an airflow guide portion, provided at the airflow outlet, that introduces air from outside of the duct to a position downstream of the airflow outlet; and a negative-pressure forming portion, provided at the downstream end of the airflow guide portion. The negative-pressure forming portion generates a negative pressure near the downstream end of the airflow guide portion when air passes by the negative-pressure forming portion.

Abstract: A turbine outer air seal includes, in a radially inner major surface thereof, at least one circumferential groove accommodating a plurality of holes which supply air for film cooling the radially inner surface of the air seal.

Abstract: A serial fan of the present invention includes a first fan and a second fan, each of which includes a housing and an impeller disposed in the housing. The housings respectively include a plurality of connecting elements, and there are several air-guiding recesses defined on the connecting elements of the first fan or the second fan, which can guide air to smoothly flow out from the housing so as to increase airflow and air pressure and reduce noise.

Abstract: Turbine system including a turbine and a tubular arrangement having an exit opening. The tubular arrangement is arranged on a downstream side of the turbine. At least one flow controlling device at least partially prevents a fluid flow through the tubular arrangement from becoming detached from the tubular arrangement. The at least one flow controlling device is positioned within the fluid flow and in an area of the exit opening. The turbine system is configured to operate efficiently in an environment wherein at least an upper edge of the exit opening is arranged above a downstream liquid level.

Abstract: The nozzles are in the form of blowing-in openings in the housing wall which bounds the flow channel. The blowing-in openings are fed directly by means of air which is extracted from the flow channel downstream from the diffusor. This air is at a higher pressure than the flow in the flow channel upstream of the diffusor. This results in a passive, dynamic stabilization system for a compressor stage in the high pressure-ratio range, which does not require any additional control or actuating elements.

Abstract: Air pressure distribution for airfoil lower and upper surfaces is utilized to divert airflow using ducts formed in space-curve shapes placed inside the airfoil volume, through span-wise located inlets from high pressure areas on the airfoil lower surface near the leading edge and through chord-wise spaced inlets on the side face of the airfoil wing tip correspondingly to the side face of the airfoil wing tip through chord-wise spaced outlets on the side face of the airfoil wing tip and to span-wise located outlets to the low pressure areas on the airfoil upper surface. Triboelectric materials on the wing surfaces are employed to static charge the air in drag. Inside the ducts, the employment of either triboelectric linings and materials, or HV-supplied electrodes, or both, help to static charge the diverted air flow to and from the airfoil wing tip side face to diffuse wing tip vortex core early.

Abstract: A leading edge vortex reducing system includes a gas turbine engine airfoil extending in a spanwise direction away from an end wall, one or more plasma generators extending in the spanwise direction through a fillet between the airfoil and the end wall in a leading edge region near and around a leading edge of the airfoil and near the fillet. The plasma generators being operable for producing a plasma extending over a portion of the fillet in the leading edge region. The plasma generators may be mounted on an outer wall of the airfoil with a first portion of the plasma generators on a pressure side of the airfoil and a second portion of the plasma generators on a suction side of the airfoil. A method for operating the system includes energizing one or more plasma generators to form the plasma in steady state or unsteady modes.

Abstract: A turbine blade cascade structure includes a plurality of blades arranged in series in a circumferential direction on a wall surface, in which a corner portion defined by the wall surface and a front edge portion of each of blade bodies supported by the wall surface, to which a working fluid flows, includes a cover portion (fillet) that extends toward an upstream side of a flow of the working fluid. The turbine blade cascade structure is capable of reducing the secondary flow loss of the secondary flow in spite of the fluctuation of an incident angle of the working fluid flowing to the front edge portion of the blade body.

Abstract: A fan of the present invention includes a fan housing and an impeller disposed in the fan housing. The fan housing includes a plurality of connecting elements at its air outlet. Each connecting element includes a plurality of air-guiding teeth thereon, which can guide the air to flow smoothly out from the fan housing so as to increase airflow and air pressure, and reduce the noise.

Abstract: A method operable to improve pressure recovery and/or distortion within engine inlet is disclosed. A first fluid flow is provided to primary jet vortex generator(s) operable to inject fluid at a first injection rate into a boundary layer of a primary fluid flow within the inlet. A secondary fluid flow is injected by secondary jet vortex generator(s) at a second injection rate into the boundary layer of the primary fluid flow, The fluid injected at the first injection rate and second injection rate is operable to induce secondary flow structures within the boundary layer. These secondary close structures are then operable to improve or manipulate the pressure recovery of the inlet. At specific engine conditions, this method may redistribute the ratio of the first injection rate and second injection rate in order to improve pressure recovery and/or distortion of the inlet when the particular engine conditions.

Abstract: An upstream plasma boundary layer shielding system includes film cooling apertures disposed through a wall having cold and hot surfaces and angled in a downstream direction from a cold surface of the wall to an outer hot surface of the wall. A plasma generator located upstream of the film cooling apertures is used for producing a plasma extending downstream over the film cooling apertures. Each plasma generator includes inner and outer electrodes separated by a dielectric material disposed within a groove in the outer hot surface. The wall may be part of a hollow airfoil or an annular combustor or exhaust liner. A method for operating the upstream plasma boundary layer shielding system includes forming a plasma extending in the downstream direction over the film cooling apertures along the outer hot surface of the wall. The method may further include operating the plasma generator in steady state or unsteady modes.

Abstract: An air circulation method in a turbomachine compressor includes minimizing an inner flowpath between two adjacent blades by providing labyrinths on an inner casing between the two adjacent blades, and sucking in air from the minimized inner flowpath through a radially inner orifice of a vane faced by the labyrinths. The method further includes directing the sucked in air through the vane, bleeding the air from the vane through a radially outer opening of the vane and through an orifice of an outer casing. The air is collected from the vane into a manifold outside the compression stage. A compressor arrangement for circulating air includes a suction device for sucking in air present in the inner flowpath between labyrinths and the vane, and for sending the air into the vane of the stator. The arrangement also includes a device for bleeding air in the vane of the stator and for sending the air outside the compressor.

Abstract: A compressor assembly (404) includes a compressor housing (412) having a main inlet bore (424) and a secondary inlet passage (422) that has an increasing flow cross-sectional area. The secondary inlet passage (422) is positioned in the compressor housing (412) and around the main inlet bore (424). A secondary inlet slot (426) and an outlet slot (420) fluidly connect the secondary inlet passage (422) with the main inlet bore (424). A compressor wheel (418) is in the compressor housing (412) and has a stepped portion (518) formed by at least one plurality of vanes (506). The stepped portion (518) is located adjacent to the outlet slot (420) of the housing (412).

Abstract: An inlet guide vane provides improved, smooth airflow and avoids separation of flow even at high incidence angles. The inlet guide vane includes a strut having opposite side surfaces that are continuously curved to provide a controlled velocity distribution at the trailing edge of the strut. The inlet guide vane further includes a flap having a leading edge aligned behind the trailing edge of the strut. Generally, the strut and the flap are designed together so that low momentum air in the gap between the strut and the flap will be energized and entrained in the boundary layer of the flap. The airflow from the gap will remain attached to the flap to improve the flow from the flap.

Abstract: A turbomachine compressor comprises at least one plurality of moving blades and spaced apart therefrom in an axial direction relative to a central longitudinal axis of the turbomachine, a plurality of stationary vanes, and a stationary casing surrounding said plurality of moving blades and including a plurality of bleed holes centered in the range 5% to 50% of the blade chord length and having a diameter less than or equal to 30% of the blade chord length, each bleed hole sloping at two angles of inclination relative to the central longitudinal axis. Advantageously, each bleed hole has a first axis of inclination presenting an angle ? relative to the central longitudinal axis lying in the range 30° to 90°, and a second axis of inclination perpendicular to the first and presenting an angle ? relative to the central longitudinal axis lying in the range 30° to 90°.

Abstract: A bypass channel for use in an inter-turbine transition duct assembly of a turbine engine is connected to a suction port disposed upstream of a high-pressure turbine and at least two injection openings disposed downstream of the high-pressure turbine. The flow through the bypass channel is motivated by the natural pressure difference across the high-pressure turbine. The flow out of the at least two injection openings is used to energize the boundary layer flow downstream of the high-pressure turbine in order to allow for the use of a more aggressively expanded inter-turbine duct without boundary layer separation. Methods for optimizing the flow through the turbine engine are also disclosed.

Abstract: A blade including a body having a leading edge, a trailing edge, a surface point of maximum camber, and a low pressure surface extending between the leading edge and the trailing edge. The body further includes a high pressure surface extending between the leading edge and the trailing edge on an opposite side of the body relative to the low pressure surface. The low pressure surface includes a leading edge surface extending from the leading edge to the surface point of maximum camber. The blade further includes at least two ridges located on the leading edge surface, each ridge extending generally parallel to the leading edge.

Abstract: A turbocharger system having a compressor housing containing a rotating compressor wheel with a plurality of impellers that define an impeller passageway from an inducer to an exducer. The compressor housing includes an annular upstream housing-portion forming an upstream shroud-wall, and a downstream housing-portion forming a downstream shroud-wall. The a rib supports the upstream housing-portion with respect to the downstream housing-portion such that they are respectively disposed to form an annular bypass port into the impeller passageway between the upstream and downstream shroud-walls. The rib extends along a non-axial path within the bypass passageway.

Abstract: A turbomachine blade row is provided having a hub that includes a non-axisymmetric end wall modified by a transformation function. The blade row further includes a circumferential row of a plurality of airfoil members radially extending from the non-axisymmetric end wall of the hub and forming a plurality of sectoral passages therebetween. A radius of the non-axisymmetric end wall is determined by a transformation function including a plurality of geometric parameters defined by a user based on flow conditions. The plurality of geometric parameters provide for modification of the end wall in both an axial and a tangential direction to include a plurality of concave profiled regions and convex profiled regions.

Abstract: A shroud 15 attached to an air discharge side of a radiator 13 narrows toward a centrifugal-flow-type rotary fan 11 and forms a cylindrical shape. A surrounding portion 17 is provided so as to surround the rotary fan 11, and a guide portion 19 extending in the centrifugal direction of the rotary fan 11 is provided at the end of the surrounding portion 17. The length of the guide portion 19 is about 6% the diameter of the rotary fan 11. Since this mitigates turbulence of centrifugally flowing air 21 flowing out of the rotary fan 11 and suppress a drop in the amount of air passing through the radiator 13, the cooling capacity of the radiator 13 can be enhanced.

Abstract: A wind turbine blade is situated on a wind turbine and includes a side and a tip. The blade is configured to rotate about an axis upon an impact of a wind flow on the blade. An active flow modification device is disposed on the blade. The active flow modification device is configured to receive active flow instructions and to modify the wind flow proximate to the blade. The resulting wind turbine blade uses these active flow modifications to achieve reduced loads, reduced aerodynamic losses, reduced noise, enhanced energy capture, or combinations thereof.

Abstract: A turbomachine includes at least one rotor (6), at least one stator (7), and a casing (1), with the rotor (6) comprising several rotor blades (8) attached to a rotating shaft, and with the stator (7) being provided with stationary stator blades (9), the casing (1) being passed by a fluid flowing through the rotor (6) and stator (7). Provision is made for the removal of fluid on at least one blade (8, 9) of a blade row of the rotor (6) and/or the stator (7) on non-axially symmetrical, aerodynamically critical locations on blade tip and annulus surfaces (SRO).

Abstract: An axial compressor has at least one circumferential row of aerofoil members (30a, 30b, 30c) in which at least one of the two end walls (37) between adjacent blades is given a non-axisymmetric profile, defined by circumferentially-extending sinusoids at a number of axial positions (AA, BB, CC). Corresponding points on the successive sinusoids are joined by spline curves, so that the curvature of the end wall is smooth. This end-wall profiling modifies the boundary layer flow at the wall, reducing or eliminating the corner separation and reversed flow associated with known arrangements.

Abstract: A turbo compressor comprising a driving motor, an impeller to be rotated by the driving motor, a second gas suction part through which gas is introduced into the impeller, and a discharger through which the gas is discharged from the impeller, the turbo compressor comprises a shroud provided between the gas suction part and the gas discharger and spaced from a blade of the impeller; and a plurality of channels provided on the shroud and inclined toward the gas discharger along a rotating direction of the impeller. With this configuration, the present invention provides a turbo compressor in which compression efficiency is increased by eliminating a backflow and a leakage flow.

Abstract: A device and method for conversion of the energy of medium flows are provided. The proposed device and method ensure suppression of the vortex streams in the flow on the leg of its motion along the radially converging trajectories and concentration of the flow energy, which is expressed by the increase of its velocity and decrease of the summary area of the cross section of the converging trajectories. As the flow runs along the first system of helical trajectories the following takes place: the harmful secondary vortex jets continue attenuating, the degree of concentration of the flow energy increases and velocity components form in the flow, which correspond to natural vortex streams, for instance, tornadoes, whirlpools.

Abstract: Turbine system including a turbine and a tubular arrangement having an exit opening. The tubular arrangement is arranged on a downstream side of the turbine. At least one flow controlling device at least partially prevents a fluid flow through the tubular arrangement from becoming detached from the tubular arrangement. The at least one flow controlling device is positioned within the fluid flow and in an area of the exit opening. The turbine system is configured to operate efficiently in an environment wherein at least an upper edge of the exit opening is arranged above a downstream liquid level.

Abstract: The present invention features a fluid flow regulator that functions to influence fluid flow across an airfoil or hydrofoil, as well as various rotating or rotary devices, including propellers, impellers, turbines, rotors, fans, and other similar devices, as well as to affect the performance of airfoils and hydrofoils and these rotary devices subjected to a fluid. The fluid flow regulator comprises a pressure recovery drop that induces a sudden drop in pressure at an optimal pressure recovery point on the surface, such that a sub-atmospheric barrier is created that serves as a cushion between the molecules in the fluid and the molecules at the airfoil's or hydrofoil's surface. More specifically, the fluid flow regulator functions to regulate the pressure gradients that exist along the surface of an airfoil or hydrofoil.

Abstract: A compressor or pump employs principles of unsteady delayed stall to enhance the head increase produced by the compressor or pump. Plural airfoil-shaped lifting elements are spaced from each other in a cascade and the fluid is directed into the cascade by a device that varies a parameter of the flow relative to each lifting element in repeating cycles to cause the flow relative to each lifting element to begin to separate from the lifting element and then reattach thereto during each cycle. The cascade can comprise an axial flow impeller with plural impeller blades arranged around a hub capable of rotating on an axis. The device for varying the flow parameter can be a stator with a plurality of stator blades upstream of the impeller, or a second, counter-rotating axial flow impeller. In either case, the parameter is a flow angle at which the flow is directed to the downstream impeller.

Abstract: A compressor for compressing a gas comprises an impeller wheel (1) mounted within a housing (2) defining an inlet and an outlet (6). The inlet comprises an outer tubular wall (7) extending away from the impeller wheel in an upstream direction and forming a gas intake portion (8) of the inlet, and an inner tubular wall (9) of diameter D extending away from the impeller wheel in an upstream direction within the outer tubular wall (7) and defining an inducer portion (10) of the inlet. An annular gas flow passage (11) is defined between the inner and outer tubular walls (9, 7) and has an upstream end and a downstream end separated by a length L1 measured along its axis. The upstream end of the annular passage (11) communicates with the intake or inducer portions of the inlet through at least one upstream aperture and at least one downstream aperture (13) communicates between a downstream portion of the annular flow passage (11) and the impeller.

Abstract: A turbine stage includes a row of airfoils joined to corresponding platforms to define flow passages therebetween. Each airfoil includes opposite pressure and suction sides and extends in chord between opposite leading and trailing edges. Each platform includes a crescentic ramp increasing in height from the leading and trailing edges toward the midchord of the airfoil along the pressure side thereof.

Abstract: A compressor (16) comprises a rotor (40) having a plurality of circumferentially spaced radially outwardly extending rotor blades (42). A casing (44) surrounds the rotor (40) and rotor blades (42). The casing (44) has an inner surface (48) and a plurality of circumferentially spaced slots (50) are provided in the inner surface (48) of the casing (44). Each slot (50) has a length (L), a depth (D), a width (W), an angle (?) of inclination relative to the radial direction, an axial position (AP) relative to the rotor blades (42) and a circumferential position (CP) relative to an adjacent slot (50). The slots (50) are arranged such that at least one of the length (L), depth (D), width (W), angle (?) of inclination relative to the radial direction, axial position (AP) relative to the rotor blades (42) and circumferential position (CP) relative to an adjacent slot (50) varies circumferentially around the casing (44).

Abstract: An apparatus and method is provided for improving efficiency of a transonic gas turbine engine compressor by bleeding off a shockwave-induced boundary layer from the gas flow passage of the compressor using an array of bleed holes having a downstream edge aligned with a foot of an oblique shock wave which originates on the leading edge of an adjacent transonic rotor blade tip.

Abstract: Embodiments of the invention provide a method, device, and turbopump configured to suppress higher order cavitations at an inducer tip in a turbopump. An inducer having a tip is rotated, and a first flow is induced axially through the inducer at a first velocity. A second fluid flow is introduced toward a tip of the inducer substantially parallel to the first fluid flow at a second velocity that is greater than the first velocity, such that back flow through the tip of the inducer is reduced.

Abstract: The present invention features a fluid flow regulator that functions to significantly influence fluid flow across an airfoil or hydrofoil, as well as various rotating or rotary devices, including propellers, impellers, turbines, rotors, fans, and other similar devices, as well as to significantly effect the performance of airfoils and hydrofoils and these rotary devices subjected to a fluid. The fluid flow regulator comprises a pressure recovery drop that induces a sudden drop in pressure at an optimal pressure recovery point on the surface, such that a sub-atmospheric barrier is created that serves as a cushion between the molecules in the fluid and the molecules at the airfoil's or hydrofoil's surface. More specifically, the present invention fluid flow regulator functions to significantly regulate the pressure gradients that exist along the surface of an airfoil or hydrofoil.

Abstract: The present invention is a system (20) for controlling various fluid flows, e.g., secondary fluid flows including cavitating fluid flows, typically developed along the shroud line and usually in or around a leading edge (21) within a flow channel (22) of a compressor or pump impeller (23) and inducer/impeller (24). System (20) includes a plurality of devices for controlling various flow conditions. In one embodiment, system (20) includes a diffuser device (27) for stabilizing cavitating flows, a bypass device (28) for re-injecting flow upstream, and a flow control device (30) for selectively directing secondary fluid flow to either the diffuser device or the bypass device. In addition, at very high flow rates, bypass device (28) may also serve as a high-flow, forward-bypass device. Devices (27) and (28) form a pathway for secondary fluid flows, including cavitating flows, around a first portion (31) of a housing (32).

Abstract: A centrifugal compressor for high pressure (10) with improved efficiency, of the type comprising a rotor (12), an inner case (14), diffusers (16) and diaphragms (18), wherein the surfaces which are subjected to passage of the flow of gas have been subjected to burnishing working.

Abstract: A flow directing device of a gas turbine engine, comprising: an airfoil having a leading edge, trailing edge, suction side and pressure side; a wall abutting the airfoil; and a fillet between the airfoil and wall. The fillet has an enlarged section at the leading edge, along the suction and pressure sides, and towards the trailing edge. The device could be part of a vane segment. In addition to eliminating a horseshoe vortex, the device also reduces heat load on the airfoil by directing the cooler gas from the proximal end of the airfoil to the hotter gas at the medial section of the airfoil.

Abstract: A rotor blade system with reduced blade-vortex interaction noise includes a plurality of tube members embedded in proximity to a tip of each rotor blade. The inlets of the tube members are arrayed at the leading edge of the blade slightly above the chord plane, while the outlets are arrayed at the blade tip face. Such a design rapidly diffuses the vorticity contained within the concentrated tip vortex because of enhanced flow mixing in the inner core, which prevents the development of a laminar core region.

Abstract: Recirculation structure for turbocompressors, having a ring chamber which is arranged in the area of the free blade ends of a blade ring largely upstream of the latter and adjoins the main flow duct. A plurality of guiding elements are arranged in the ring chamber distributed over its circumference and are arranged and shaped in a fluidically advantageous manner with respect to the recirculation flow, with recesses provided in the leading and/or trailing area of the ring chamber. The side of the ring chamber which adjoins the contour of the main flow duct is open along its axial length as well as along its entire circumference, the free edges of the guiding elements being situated on the or close to the contour of the main flow duct.

Abstract: A buffer chamber and outlet guide provide an air path from an intake passage in a compressor housing to an upstream position relative to an intake port of the compressor. Surging is minimized during low airflow conditions while cyclic forces on the blades of the impeller are minimized during high airflow conditions. By providing an air path through the buffer chamber and outlet guide, ribs or other supporting structures are eliminated within the air pathway through the intake port and intake passage within the compressor housing.

Abstract: An apparatus and method for a slurry pump having improved erosion characteristics. The pump comprises a rotatable impeller having at least one impeller vane, an impeller shroud having an inlet for conveying slurry to the impeller and an outlet for discharging slurry accelerated by the impeller, and a pump housing having a side wall with a recess therein, said recess being deep enough to therein matingly receive said impeller shroud outlet so as to form a joint surface producing a sufficient impingement angle between the impeller shroud outlet and the pump housing side wall to substantially reduce erosion thereon by the accelerated slurry.

Abstract: The invention is an Exit Stay Apparatus for Francis and propeller hydraulic turbines. The purpose of the invention is to eliminate the loss of turbine efficiency and strong pulsations in draft tube caused by the axial circular vortex in all turbine operating regimes other than optimum without a noticeable decrease in maximum efficiency. It can be incorporated not only into newly fabricated hydraulic turbines, but also retrofitted into existing turbines. The Exit Stay Apparatus has a crown and exit stay vanes secured to the the crown. When installed in the turbine, the exit stay crown is located immediately after the runner crown, which is truncated at the bottom by a plane perpendicular to the central axis of the turbine. The exit stay crown together with the truncated runner crown forms water passages after the runner blade crown profile exit.

Abstract: A vortex-reducing fluid guide component is disclosed. The fluid guide component includes a base portion and an upstanding body portion. An internally-cooled blending element extends between the base portion and a leading edge of the body portion. The blending element includes a deflection region that advantageously disrupts horseshoe vortex formation. The fluid guide component includes a supplemental cooling channel between the blending element and the intersection of the body portion leading edge and the base portion. In one embodiment, the supplemental cooling channel captures cooling fluid used to cool the blending member and provides additional cooling to the body portion leading edge/base interface. The component includes a strategically-perforated impingement panel or member that distributes cooling fluid to selected portions of the blending member, thereby ensuring that key regions within the blending member are efficiently cooled in accordance with temperature distribution.

Abstract: A gas turbine with a compressor area has a rotor shaft 2 to carry rotor blades 1 and a casing 4 to carry stator vanes 3, with the related rotor blades 1 and stator vanes 3 forming an axial clearance space 5 between one another, wherein, in the area of the axial clearance space 5, at least one wall of the rotor shaft 2 and/or of the casing 4 is provided with an arrangement of fins 6 which are inclined against the axial direction.

Abstract: Acoustic vibrations generated by von Karman vortex streets are reduced by shaping members interposed in moving air flowstreams, such as fan guards and grilles used in forced flow air conditioning systems, to have either a cylindrical cross section or a non-cylindrical cross-section with non-linear or interrupted leading or trailing edges presented to the air flowstream. Relatively flat rectangular cross-section members with interrupted or non-linear leading or trailing edges formed by somewhat sawtooth or sinusoidal wave forms or connected to spaced apart support members, or cylindrical members formed in the shape of a sawtooth or sinusoidal wave form, or presented with spaced apart rings or grooves interrupting the cylindrical cross-section of the member are typical configurations which exhibit reduced or substantially eliminated acoustic vibrations caused by von Karman vortex shedding.

Abstract: A fan assembly for use in association with an airborne vehicle, the fan assembly comprising a propeller assembly and a shroud. The propeller assembly is rotatably coupled to an output shaft of a motor. The propeller assembly includes at least two blades each having a first end proximate an output shaft of a motor and a second end distally spaced therefrom. The shroud extends circumferentially around the propeller assembly, and includes a groove along the lower surface thereof. In turn, the second end of the at least two blades extends at least partially into the groove.

Abstract: As air passes through the airflow channels (46) between the blades (10) of a compressor impeller, boundary layers build up on the blade (10) surfaces. These low momentum masses of air are considered a blockage and loss generators. Ultimately, the boundary layer on the suction side of the blade (20) will separate, causing stall and reversed flow. Reversed flow will occur until a stable pressure ratio with positive volume flow rate is reached. When the pressure ratio becomes unstable again, the cycle will repeat. Introducing a slit (12) or a series of perforations (28) on the compressor wheel blade (10) allows the air to communicate between the pressure side (18) and the suction side (20) of the blade, which allows the boundary layer to stay attached longer.

Abstract: A system and method is provided for detecting and controlling rotating stall in the diffuser region of a centrifugal compressor. The process begins with the detection or sensing of acoustic energy associated with the onset of rotating stall. A pressure transducer is placed in the gas flow path downstream of the impeller, preferably in the compressor discharge passage or the diffuser, to measure the sound or acoustic pressure phenomenon. Next, the signal from the pressure transducer is processed either using analog or digital techniques to determine the presence of rotating stall. Rotating stall is detected by comparing the detected energy amount, which detected energy amount is based on the measured acoustic pressure, with a predetermined threshold amount corresponding to the presence of rotating stall. Finally, an appropriate corrective action is taken to change the operation of the centrifugal compressor in response to the detection of rotating stall.