Abstract: A turbine nozzle for an aircraft turbine engine, the nozzle including at least one vane and a base having a platform. The nozzle is fitted with a passive system for reintroducing blow-by gas into the primary jet, the passive system including gas extraction ports on the base as well as gas reinjection ports on the radially outer surface of the platform and/or on a suction-side surface of the vanes, the gas reinjection ports being designed to redirect the gas flow in a reinjection direction having a circumferential orientation.

Abstract: A turbocharger includes a turbine housing defining a turbine housing interior, a turbine wheel disposed within the turbine housing interior, a shaft coupled to and rotatable by the turbine wheel, a compressor housing defining a compressor housing interior and a flow path, and a compressor wheel disposed within the compressor housing interior and coupled to the shaft. The compressor wheel has a hub coupled to the shaft, and a plurality of impeller blades extending radially from the hub. The plurality of impeller blades define an inducer end having an inducer diameter, and an exducer end having an exducer diameter greater than the inducer diameter. The inducer diameter and the exducer diameter establish a compressor trim. The compressor wheel also has a compressor wheel shroud disposed about the plurality of impeller blades. The compressor wheel shroud encloses the plurality of impeller blades to define a shroud interior.

Abstract: A recirculation flow collector for a fan includes an arcuate housing; a first face with a first circular opening to receive flow; a second face with a second circular opening to allow flow in a normal fan operating condition; and an outlet in a bottom of the arcuate housing to allow recirculation flow.

Abstract: A housing for a turbomachine includes a peripheral wall delimiting an annular space and a fluid conveying system for redirecting a partial flow of a main flow, which has an axial channel, a front annular channel and a rear annular channel in fluid connection with the axial channel and having a front annular space opening and a rear annular space opening. The fluid conveying system has a front valve device and a rear valve device controllable independently of the front valve device, for opening and closing the annular space openings, and an outlet opening for tapping the partial flow from the fluid conveying system. In the closed state of the rear annular space opening, the partial flow is directable through the rear annular channel and, in the closed state of the front annular space opening, the partial flow is directable through the front annular channel.

Abstract: A compressor section for use in a gas turbine engine has a plurality of compressor stages. Each compressor stage is provided with a rotor hub, and each rotor hub mounts a plurality of compressor blades. A rotor drum extends between adjacent rotor hubs. A plurality of stator stages have an outer ring and a radially inner ring. A plurality of vanes extend between the outer and inner rings. An inner surface of the inner ring is spaced by a gap from an outer surface of the rotor drum. The rotor drum is provided with a plurality of blades having a general airfoil shape to resist leakage across the gap.

Abstract: A frame assembly of a ring-type fan with a pressure-releasing function includes a fan wheel, a pressuring-releasing portion, and a frame body. The fan wheel is received in an accommodating space of the frame body. The fan wheel has a hub and a plurality of blades. The pressure-releasing portion is formed on free ends of the blades and has a stopping wall and a flange extending from one end of the stopping wall. A pressure-releasing channel is formed between the stopping wall and an inner wall of the frame body. With the pressure-releasing portion being formed on the free ends of the blades, the present invention is capable of delaying the deceleration, improving the fan performance, and reducing its noise.

Abstract: A turbomachine including an intermediate casing including, fastened to the end thereof, an outer casing of a high pressure compressor, and an air bleed mechanism bleeding air downstream from the stream through the compressor and including an outlet connected to an air reinjection mechanism reinjecting air upstream from the compressor via an annular manifold surrounding the inner wall of the intermediate casing and situated radially between the inner wall and an outer wall defining a secondary flow stream of the turbomachine.

Abstract: A hydroelectric generator includes a body and an electromechanical apparatus cabin. The body has a tube penetrating the body and a first flow channel. The tube has a tapering segment and a throat portion communicating with the first tapering segment. One end portion of the first flow channel is located on a wall surface of the throat portion, so that the first flow channel communicates with the tube. The first flow channel is used to enable a fluid to flow into the tube from the first flow channel or guide a fluid to flow out of the body from the throat portion. The electromechanical apparatus cabin has an energy retrieving apparatus disposed in the throat portion of the tube, and the end portion of the first flow channel communicating with the tube is located at a front side or a back side of the energy retrieving apparatus.

Abstract: An embodiment of the present invention takes the form of an IBH system that has two conduits, which are positioned close to a downstream end of a silencer section. This arrangement may reduce the overall pressure drop associated with the inlet system. This arrangement may also promote a substantially uniform mixing between the cooler ambient air and the warmer heated air.

Abstract: An embodiment of the present invention takes the form of an IBH system that has a single conduit, which is positioned close to a downstream end of a silencer section. This arrangement may reduce the overall pressure drop associated with the inlet system. This arrangement may also promote a substantially uniform mixing between the cooler ambient air and the warmer heated air.

Abstract: A circulation structure for a turbo compressor, in particular for a compressor of a gas turbine, is disclosed. The circulation structure includes at least one annular chamber that can be traversed in a circumferential direction, is concentric with a shaft of the turbo compressor in the region of the free blade ends of a blade ring, and radially borders a main flow channel. Several chambers that can be traversed in an axial direction are situated upstream of the or each annular chamber, when viewed from the main flow direction of the main flow channel.

Abstract: A turbomachine or high pressure compressor including a stator casing housing a plurality of compression stages that are spaced apart in an axial direction along the central axis of the turbomachine, each compression stage including a row of rotor blades followed by a row of stator vanes. The compressor further includes an air injection system including at least one air injection passage through the casing and including an outlet segment that opens out in an inclined manner upstream from and directed towards a row of rotor blades into a set-back zone of the inside face of the casing.

Abstract: The invention relates to a compressor for a turbine engine including a casing (4), at least one compressor stage consisting of a stationary blade (2) impeller and a mobile blade (1) impeller positioned upstream from said stationary blade (2) impeller, and cavities (5) made in said casing opposite the through-path of the mobile blades (1), said cavities having a length L2 measured axially and being shifted upstream relative to the blades (1) so as to generate an overlap with a length L1, characterized in that the lengths L1 and L2 are respectively between 35% and 50% and between 80% and 90% of the axial chord Cax measured at the outer end of the blades (1), and in that the cavities (5) do not in communication with one another.

Abstract: A compressor typically for use in a turbocharger comprises a downstream radial compressor impeller wheel, an upstream axial compressor impeller wheel and an intermediate stator. The compressor housing has an inlet with inner and outer walls that define between them an MWE gas flow passage. An upstream opening defined by the flow passage provides communication between the passage and the intake and at least one first slot downstream of the upstream opening provides communication between the passage and the inner surface of the inner wall. The stator comprises a plurality of fixed vanes and is disposed in the inner wall of the inlet between the radial and axial impeller wheels. The position of the slot can be at one of several positions along the gas flow passage, in other embodiments there are second and third slots and the flow passage is divided into two parts. All the arrangements are designed to improve the compressor map width.

Abstract: A turbocharger includes: a suction passage into which a fluid is sucked from outside of a compressor housing; an outlet passage that guides the fluid, which is sucked through the suction passage and compressed, to the outside of the compressor housing; an opening portion formed in a wall surface of the compressor housing and serving as an opening of the suction passage; a return passage which makes the outlet passage and the suction passage communicate with each other through the opening portion, thereby returning the compressed fluid from the outlet passage to the suction passage; and an air bypass valve which opens and closes the opening portion. A level of a bottom surface of the return passage located on a vertically lower side therein declines from the outlet passage toward the suction passage without ever rising.

Abstract: A compressor typically for use in a turbocharger comprises a downstream radial compressor impeller wheel, an upstream axial compressor impeller wheel and an intermediate stator. The compressor housing has an inlet with inner and outer walls that define between them an MWE gas flow passage. An upstream opening defined by the flow passage provides communication between the passage and the intake and at least one first slot downstream of the upstream opening provides communication between the passage and the inner surface of the inner wall. The stator comprises a plurality of fixed vanes and is disposed in the inner wall of the inlet between the radial and axial impeller wheels. The position of the slot can be at one of several positions along the gas flow passage, hi other embodiments there are second and third slots and the flow passage is divided into two parts. All the arrangements are designed to improve the compressor map width.

Abstract: A wind generating device employs modules each having two turbines. Each of the turbines employs two rotors coaxially aligned by a shaft associated with an in-line generator. Alternatively, the turbine employs only one rotor for low wind areas. The arrangement includes a proximal channel with a leading portion having decreasing radius toward the first rotor which acts as a collector and a following portion connecting fluidly the first and second rotor and a distal channel which is separate from the proximal channel and opens into the following portion thereby adding to the airflow to the second rotor. Downstream from the second rotor is a diffuser with a radius increasing with distance from the rotor. The modules may be stacked vertically stacked which allows for yaw responsive to wind. The modules may be mounted on a tower.

Abstract: A gas turbine compressor is disclosed. The compressor includes a compressor housing, guide vanes, rotor blades, and valve-controlled blow-in openings for stabilizing the compressor flow by air that is blown in. The air flow is detected by pressure sensors and the valves are controlled as a function thereof.

Abstract: Apparatus for reducing air mass flow through the compressor in a single shaft gas turbine engine having an extended operating range including part load conditions, to provide low emissions combustion. The apparatus includes one or more nozzles positioned for injecting compressed air into the inlet region of the compressor. The nozzles are oriented to direct the compressed air tangentially to, and in the same angular direction as, the direction of rotation to create a swirl in the inlet air flow to the compressor inducer. The apparatus also includes conduits in flow communication between the compressor diffuser and the nozzles, one or more valves operatively connected to control the flow of compressed air from the diffuser to the nozzles, and a controller operatively connected to the valves to cause compressed air flow to the nozzles during operation at part load conditions.

Abstract: A rotating turbomachine component includes a base portion and an airfoil portion extending from the base portion. The airfoil portion includes a first end connected to the base portion and a tip end portion that is cantilevered from the base portion. A tip leakage flow guide is provided at the tip end portion of the airfoil portion. The tip leakage flow guide includes one or more turning vane members configured and disposed to guide a leakage flow from the tip end portion at a flow angle that substantially coincides with a flow angle of gases flowing downstream from the rotating turbomachine component.

Abstract: A ring fan and shroud guide system which includes a rotating fan member with a conical outer ring and a cylindrical shroud member overlapping at least a portion of the outer ring. A plurality of guide vanes are provided in the shroud which minimize the tangential velocity component of the air flow entering the tip-gap region and provide improved air flow through the system. The guide vanes can have a curved configuration.

Abstract: To make manifest the above noted desire, a revelation of the present invention is brought forth. A fan assembly (7) is provided including a hub (10) with a plurality of projecting fan blades (12). A recirculating flow element (18) is provided which is generally forward adjacent an outer diameter of the fan blades (12). A plurality of guide vanes (22) are positioned within the recirculating flow element (18). The guide vanes (22) have an inlet angle (24) that is nearly tangential with an outer diameter surface (15) of the recirculating flow element (18). The guide vanes (22) have an outlet angle (26) which is nearly radial along an inner diameter surface (17) of the recirculating flow element (18).

Abstract: A compressor typically for use in a turbocharger comprises a downstream radial compressor impeller wheel, an upstream axial compressor impeller wheel and an intermediate stator. The compressor housing has an inlet with inner and outer walls that define between them an MWE gas flow passage. An upstream opening defined by the flow passage provides communication between the passage and the intake and at least one first slot downstream of the upstream opening provides communication between the passage and the inner surface of the inner wall. The stator comprises a plurality of fixed vanes and is disposed in the inner wall of the inlet between the radial and axial impeller wheels. The position of the slot can be at one of several positions along the gas flow passage, in other embodiments there are second and third slots and the flow passage is divided into two parts. All the arrangements are designed to improve the compressor map width.

Abstract: A fluid flow machine has a main flow path 2 which is confined by a hub 3 and a casing 1 and in which at least one row of blades 5 is arranged. A gap 11 is provided on at least one blade row 5 between a blade end and a main flow path confinement, with the blade end and the main flow path confinement performing a rotary movement relative to each other. At least one reversing duct 7 is provided in the area of the blade leading edge in the main flow path confinement at a discrete circumferential position. The reversing duct 7 connects two openings 12, 13 arranged on the main flow path confinement.

Abstract: A turbomachine includes at least one rotor 1 featuring a hub and one stator 2, with a casing 5 confining the flow through the rotor 1 and the stator 2 to the outside. It also includes running-gap adjacent hub and casing surfaces LNGO, with openings being provided along the circumference on at least one running-gap adjacent hub and casing surface LNGO which form at least one dynamically operating supply point DAV which is connected via a least one line 6 to at least one opening on a blade-passage confining surface SKO.

Abstract: Disclosed is a method of producing a stator blade for use in a turbo-molecular pump. The method includes subjecting a metal plate to a slitting process to form a blade element having an upstream edge surface and a downstream edge surface, wherein a laser beam is emitted onto the metal plate at an incident angle oblique to a principal surface of the metal plate. Thus, the upstream edge surface and/or the downstream edge surface can be formed to extend obliquely relative to the principal surface of the metal plate, in a simple manner, while eliminating a need for a burr removal operation which would otherwise be necessary in a punching-based slitting process.

Abstract: A multistage compressor for a gas turbine, having a compressor housing, guide vanes, impeller vanes, a hub area, discharge ports, and injection ports for stabilizing the compressor flow, wherein the discharge ports are situated at least one stage downstream from the injection ports, the injection ports being fashioned as nozzles, and the geometry of these nozzles is designed such that the flow speed of the injected air stream is significantly greater than the speed of the flow in a critical cross-section.

Abstract: A fluid flow machine has a flow duct confined by a wall of a casing, with a fluid supply chamber being arranged in an area of the wall, which is in flow connection with an injector insert. The injector insert is provided with an injector nozzle for supplying fluid from the fluid supply chamber into the flow duct. The injector insert is closely connected to the wall of the fluid supply chamber.

Abstract: A fluid flow machine includes an annulus duct formed between a casing and a rotor drum, which is rotatable about a machine axis. At least one row of rotor blades is arranged in the annulus duct, with the latter forming a main flow path and with at least one fluid injector nozzle being arranged in the area of a wall of the casing and/or of the rotor drum. At least part of the injector nozzle protrudes into the main flow path and is provided for the generation of a jet which is tangentially directed to the wall of the main flow path.

Abstract: A gas turbine having at least one compressor, at least one combustion chamber, and at least one turbine, the or each compressor and/or the or each turbine having a rotor that includes rotor blades surrounded by a stationary housing, and a run-in coating being assigned to the housing is disclosed. The gas turbine includes at least one channel which is configured to apply a pressure prevailing on the high-pressure side of the blades of a rotor to a low-pressure side of the same in the area of a gap between the radially outer ends of the blades and the housing and thereby prevent a flow through the gap.

Abstract: Disclosed is an annular flow duct for a turbomachine, the flow duct arranged concentrically about a machine axis running in the axial direction and defined by a boundary wall of circular cross section for directing a main flow, wherein the boundary wall has a plurality of return flow passages distributed over its circumference and through which in each case a partial flow is detached from the main flow at a bleed position and returned to the main flow at a feed position situated upstream of the bleed position, and having aerofoils, arranged radically in the flow duct, of a blade ring, the aerofoil tips of which lie opposite the boundary wall, with a gap formed in each case, wherein the aerofoils are movable in a predetermined rotation direction along the circumference of the boundary wall. Furthermore, a compressor which is insensitive to pumping and flow separations, as viewed in rotation direction, the bleed position of each return flow passage lies upstream of the corresponding feed position.

Abstract: Disclosed is a seal for turbomachinery including a seal face locatable between a first turbomachinery component and a second turbomachinery component. At least one fluid channel extends through the seal. The at least one fluid channel is capable of injecting fluid flow between the first turbomachinery component and the second turbomachinery component at the seal face thereby disrupting a leakage flow between the first turbomachinery component and the second turbomachinery component. Further disclosed is a turbomachine utilizing the seal.

Abstract: A system for controlling the operating lines of a gas turbine engine comprising a compression system which compresses an incoming flow of a gas, a bleed system which extracts gas from a bleed location in the compression system prior to the gas entering a throttling orifice, a recirculation system which reintroduces at least a portion of the gas extracted by the bleed system into a feed location in the compression system or upstream from it, a control system which controls the recirculated gas such that the operating lines of the compression system are changed such that the stall margin of the compression system is increased.

Abstract: The wind generating device employs modules each having two turbines. Each of the turbines employs two rotors, coaxially aligned and arranged one downstream from the other. The arrangement includes a proximal channel with a leading portion having decreasing radius toward the first rotor which acts as a collector and a following portion connecting fluidly the first and second rotor and a distal channel which is separate from the proximal channel and opens into the following portion thereby adding to the airflow to the second rotor. Downstream from the second rotor is a diffuser with radius increasing with distance from the rotor. The device includes mounting modules vertically stacked which allows for yaw responsive to wind. The device further includes mounting the modules on a tower.

Abstract: A vertical axis multi-phased wind turbine power generating system is disclosed. An adjustable air scoop directs air from a first phase of the prevailing wind into an air turbine for efficient power generation. An exit section, which uses a second phase of the prevailing wind in combination with an optional and adjustable exit section drag curtain or barrier, provides for efficient re-entrainment of this first stage of power generating air back into the downstream prevailing wind. The adjustable air scoop and adjustable exit drag curtain or barrier, where utilized, is automatically rotated in a self correcting manner to be suitably and optimally oriented to the prevailing wind direction. The design provides for a second stage of power generation to be accomplished by additionally utilizing a portion of the second phase of prevailing wind to directly or indirectly drive the turbine in a second stage of power production.

Abstract: A fluid flow machine has a main flow path 2 which is confined by a hub 3 and a casing 1 and in which at least one row of blades 5 is arranged. A gap 11 is provided on at least one blade row 5 between a blade end and a main flow path confinement, with the blade end and the main flow path confinement performing a rotary movement relative to each other. At least one reversing duct 7 is provided in the area of the blade leading edge in the main flow path confinement at a discrete circumferential position. The reversing duct 7 connects two openings 12, 13 arranged on the main flow path confinement.

Abstract: A fluid flow machine includes a main flow path in which at least one row of blades (3, 4) is arranged, and a blade shroud (2) which forms a confinement of the main flow path in the area of a blade row (3, 4) and is arranged in a recessed cavity (10) of a surrounding physical structure (11). The cavity (10) so formed between the shroud (2) and the surrounding physical structure (11) is provided with an annular connection (14) to the main flow path at least on the outflow side of the blade shroud (2), and with the blade shroud (2) being penetrated by at least one secondary flow path (16) which, commencing at a location of high pressure on the shroud (2), issues at a surface wetted by the main flow.

Abstract: Disclosed is an annular flow duct for a turbomachine, the flow duct arranged concentrically about a machine axis running in the axial direction and defined by a boundary wall of circular cross section for directing a main flow, wherein the boundary wall has a plurality of return flow passages distributed over its circumference and through which in each case a partial flow is detached from the main flow at a bleed position and returned to the main flow at a feed position situated upstream of the bleed position, and having aerofoils, arranged radically in the flow duct, of a blade ring, the aerofoil tips of which lie opposite the boundary wall, with a gap formed in each case, wherein the aerofoils are movable in a predetermined rotation direction along the circumference of the boundary wall. Furthermore, a compressor which is insensitive to pumping and flow separations, as viewed in rotation direction, the bleed position of each return flow passage lies upstream of the corresponding feed position.

Abstract: A turbocompressor flow structure comprises a ring chamber which is arranged concentrically to an axis of a turbocompressor in an area of free blade/vane ends of a rotor blade ring/vane ring and is adjacent radially to a main flow channel. A ring chamber is provided which is bordered by a front upstream wall, a rear downstream wall and a wall that runs essentially axially. Baffle elements are arranged in the ring chamber and the ring chamber permits flow penetration in a circumferential direction in a front and/or rear area. At least one opening is provided in the area of the wall that runs essentially axially or in the area of the upstream wall and permits flow penetration out of the ring chamber, at least one compressor chamber being provided to accommodate this outgoing flow.

Abstract: A multistage compressor for a gas turbine, having a compressor housing, guide vanes, impeller vanes, a hub area, discharge ports, and injection ports for stabilizing the compressor flow, wherein the discharge ports are situated at least one stage downstream from the injection ports, the injection ports being fashioned as nozzles, and the geometry of these nozzles is designed such that the flow speed of the injected air stream is significantly greater than the speed of the flow in a critical cross-section.

Abstract: To provide a turbofan jet engine which is capable of increasing the bypass ratio without increasing the fan diameter, and of reducing air resistance acting on the engine, a front fan duct that discharges air compressed by a front fan to the atmosphere and an aft fan duct that introduces air into an aft fan are disposed such as to change cross-sectional shapes thereof by rotating around a core engine in a counterclockwise direction, so that the cross-sectional geometric relationship between the front fan duct and the aft fan duct at a position immediately posterior to the front fan and a cross-sectional geometric relationship between the front fan duct and the aft fan duct at a position immediately anterior to the aft fan are inverted.

Abstract: A compressor includes a casing defining a generally cylindrical flow passage, a rotor carrying at least one set of rotor blades, at least one set of stator blades, and anti-stall casing treatment. The casing treatment includes an annular recess in the casing for removing low momentum flow adjacent the tips of the rotor blades, and returning the flow to the generally cylindrical flow passage upstream of the point of removal. A plurality of curved guide vanes are located within the annular recess so as to define an annular inlet downstream of the vanes and/or an annular outlet upstream of the vanes. Each guide vane projects radially inwardly from the casing towards a free end which is exposed at or near the mouth of the recess to define a series of curved channels within the recess adjacent the annular inlet and/or the annular outlet.

Abstract: A compressor for compressing a gas comprises an impeller wheel mounted within a housing (2) defining an inlet and an outlet. The inlet comprises a map-width enhanced structure with an annular flow passage (11) defined between inner (9) and outer (7) tubular walls. The flow passage (11) is in fluid communication with the impeller wheel by virtue of a slot (13) in the inner wall (9). A flow-conditioning member (14) is positioned in the annular flow passage (11) and serves to remove swirl from the gas flow that recirculates through the passage. The flow-conditioning member (14) comprises a body penetrated by a plurality of bores (15). The arrangement provides for a significant improvement in the surge margin of the compressor and is particularly suitable for use in a turbocharger.

Abstract: A flow control arrangement (30; 50; 70) is described in which an inlet slot 35, 55, 85 is positioned prior to a stationary structure (33; 43; 53; 73; 83) such as a stator or pylon in order that air flow is bled or removed from a main flow 31, 51, 81. The removed air passes through a passage duct 36, 56 and is re-injected through an outlet nozzle 37, 57, 87 with an askew angle consistent with rotor blades 32, 52, 72, 82 of a turbine. In such circumstances, distortion in the flow due to the stationary structure 33, 43, 53, 83 is relieved such that there is less instability downstream from that structure 33, 43, 53, 83.

Abstract: Reinjecting air to the inlet of a compressor in order to improve its pumping margin. The inlet stator of the compressor includes injection holes passing through at least some of the vanes in the vicinity of their pivots.

Abstract: A recirculation structure for turbo-compressors has an annular chamber that is positioned in the area of the free blade ends of a rotating blade ring and that radially borders the main flow channel, and has a multitude of guide vanes arranged in the annular chamber and distributed around its circumference. The annular chamber enables the passage of air flow in the forward and/or rear areas, and the guide vanes are firmly fixed to at least one wall of the annular chamber and otherwise are designed to be free-standing. The tips of the guide vanes that face the annular chamber extend along and/or near the contour of the main flow channel, and axially overlap the free blade ends or axially border the area of the free blade ends.

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: A fluid-flow machine includes at least one rotor and a free number of stators flown by a fluid, with at least one blade thereof positioned on throat-confining surfaces provided with both a device for fluid removal from the flow path and a device for fluid supply into the flow path (bi-functionality). The machine includes at least one line associated with the device for fluid removal for returning the removed fluid to an upstream position in the flow path and at least one further line associated with the device for fluid supply for supplying the fluid from a further downstream position in the flow path.

Abstract: An endwall treatment for a gas turbine engine having at least one rotor blade extending from a rotatable hub and a casing circumferentially surrounding the rotor and the hub, the endwall treatment including, an inlet formed in an endwall of the gas turbine engine adapted to ingest fluid from a region of a higher-pressure fluid, an outlet formed in the endwall and located in a region of lower pressure than the inlet, wherein the inlet and the outlet are in a fluid communication with each other, the outlet being adapted to inject the fluid from the inlet in the region of lower pressure, and wherein the outlet is at least partially circumferentially offset relative to the inlet.

Abstract: A compressor casing structure in the region of a rotor blade ring through which there is an axial flow, having a multiplicity of axial grooves which extend from a first radial plane upstream of the blade-tip inlet edges into a second radial plane between the blade-tip inlet edges and the blade-tip outlet edges and have groove cross sections with parallel side walls. The center axes of the groove cross sections have, at the upstream groove ends, from the opening to the groove base, an angle of inclination with a circumferential component counter to the direction of movement of the blade. The center axes of the groove cross sections have, at the downstream groove ends, an angle of inclination with a circumferential component in the direction of movement of the blade.