DE102018130298A1 - Assembly with an output stator for a turbofan engine and turbofan engine with such an assembly - Google Patents

Abstract

The invention relates to an assembly with an output stator for a turbofan engine, which has a radial inner flow path boundary (65), a radially outer flow path boundary (21) and an outlet stator (25) with a plurality of guide blades (250), 253), two guide blades (250) each form a blade channel (3) between them in the circumferential direction. It is provided that the guide vanes (250) are each assigned a separate vortex generator element (7), which is arranged on the radially inner flow path boundary (21) and / or the radially outer flow path boundary (65) and extends radially into the secondary flow duct from this (4) extends. The vortex generator element (7) each has a front edge (71), a rear edge (72) and an average radial height (h), which is a maximum of 20% of the radial height (H) of the guide vanes (250). The vortex generator element (7) generates a vortex flow in the blade channel (3) directed against the secondary flow in the blade channel (3). In further aspects of the invention, a turbofan engine with such an assembly and a method for influencing the flow in a blade duct between two guide blades are provided.

Description

The invention relates to an assembly with an output stator for a turbofan engine according to the preamble of claim 1 and a turbofan engine with such an assembly.

It is known to arrange an output guide wheel behind the fan in the secondary flow channel of a turbofan engine, which is also referred to as a fan output guide wheel, fan guide wheel or OGV (“Outlet Guide Vane”). Such a stator serves to take the swirl generated by the fan out of the air flow.

By reducing the number of blades and the blade-to-height ratio of the guide blades of an output guide wheel, it is possible for the guide blades to also take on structural tasks and to be integrated into the intermediate casing of the engine. An advantage is that no separate struts of the intermediate housing that protrude through the secondary flow channel are required. The changed blade shape, however, leads to a highly three-dimensional flow from the outlet stator and thus to an increased interference with installation components in the secondary flow channel. This is associated with losses that have a negative impact on the thrust and the specific fuel consumption of the engine.

The present invention has for its object to provide an assembly with an output stator for a turbofan engine, a corresponding turbofan engine and a method in which the three-dimensionality of the flow is reduced even with a reduced number of blades and a low blade-to-height ratio of the guide blades.

This object is achieved by an assembly with the features of claim 1, a turbofan engine with the features of claim 20 and a method with the features of claim 22. Embodiments of the invention are specified in the dependent claims.

The invention then considers an assembly with an output stator for a turbofan engine. The assembly includes a radially inner flow path boundary and a radially outer flow path boundary that delimit the secondary flow channel of a turbofan engine radially inside and radially outside. Furthermore, an output stator is provided with a plurality of guide vanes which extend in the radial direction between the radially inner flow path boundary and the radially outer flow path boundary in the secondary flow duct of the turbofan engine. The guide vanes each have a pressure side, a suction side, a front edge and a rear edge. Two guide blades each form a blade channel between them in the circumferential direction, in which a secondary flow flows from the pressure side of one guide blade to the suction side of the adjacent guide blade during operation of the turbofan engine.

It is provided that at least some of the guide vanes are each assigned a separate vortex generator element, which is arranged on the radially inner flow path boundary and / or the radially outer flow path boundary and extends radially into the secondary flow duct starting from the latter. The vortex generator element provided in each case has a leading edge, a trailing edge and an average radial height, which is a maximum of 20% of the radial height of the guide vanes, i. H. the vortex generator elements have a substantially lower radial height than the guide vanes. The vortex generator element in each case produces a vortex flow in the blade channel that is directed against the secondary flow in the blade channel, so that the flow in the blade channel is oriented more two-dimensionally.

The present invention first takes into account the fact that a so-called secondary flow is present in the blade duct between two guide blades of an output stator or generally of a guide vane ring, which acts from the pressure side to the suction side. The existence of a secondary flow in the blade channel is generally known and scientifically described. This secondary flow leads to a three-dimensionality of the flow or a strong curvature of the flow emerging from the stator. The three-dimensionality of the flow increases in the case of output guide wheels which have a low blade-height ratio and a low number of blades.

The present invention is based on the knowledge that by providing a vortex generator element, which is assigned to a guide vane, it is possible to generate a vortex flow in the vane channel that is directed opposite the secondary flow in the vane channel. This vortex flow is thus executed from the suction side to the pressure side. It thus counteracts the secondary flow, which is directed from the pressure side to the suction side. As a result, the effect of the secondary flow is reduced and the flow in the blade channel is oriented more two-dimensionally, or the area of a two-dimensional flow increases.

A two-dimensional flow is a flow in which the vectors of the Flow speed are arranged parallel to each other. The fact that the flow in the vane channel is aligned more two-dimensionally by the provision of vortex generator elements means that the vectors of the flow velocity are at least partially aligned more parallel without necessarily being parallel.

According to one embodiment of the invention, a vortex generator element is assigned to each of the guide vanes of the output guide wheel or each blade channel between two guide vanes, so that the flow in all circumferential areas is influenced in the same way by the vortex generator elements in an advantageous manner.

According to one embodiment of the invention, the vortex generator element is designed as a vortex generator plate. It can thus be designed in particular as a metal plate with a leading edge and a trailing edge.

One embodiment of the invention provides that the vortex generator elements are each arranged adjacent to the suction side of a guide vane. For this purpose, an exemplary embodiment provides that the distance in the circumferential direction between the front edge of the vortex generator element and the front edge of the guide vane lies in the range between 0% and 30% of the grid division of the guide vanes.

Alternatively, it can be provided that the vortex generator elements are each arranged adjacent to the pressure side of a guide vane. For this purpose, an exemplary embodiment provides that the distance in the circumferential direction between the front edge of the vortex generator element and the front edge of the guide vane lies in the range between 0% and -15% of the grid division of the guide vanes.

Another embodiment of the invention provides that the vortex generator elements are each arranged upstream of the front edge of the guide blades. As a result, a vortex flow which counteracts the secondary flow in the blade duct is generated in a particularly effective manner. One exemplary embodiment provides that the axial distance between the rear edge of the vortex generator element and the front edge of the guide vane is in each case between 0% and 80% of the chord length of the vortex generator element.

Alternatively, it can be provided that the vortex generator elements are arranged at least with their rear edge downstream of the front edge of the guide blades in the blade channel. One exemplary embodiment provides that the axial distance between the rear edge of the vortex generator element and the front edge of the guide vane is in each case between 0% and -15% of the chord length of the vortex generator element. The general rule here is that an arrangement of the vortex generator elements within the vane passage is possible up to the area from which the streamlines close to the wall experience a high degree of curvature.

A further embodiment of the invention provides that the ratio of the grating pitch to the chord length is between 0.6 and 1 in the guide vanes of the output guide wheel.

According to a further embodiment variant, the chord length of the vortex generator elements is selected such that the chord length is in the range between 5% and 15% of the chord length of the guide blades.

The vortex generator elements have a tip that protrudes into the secondary flow channel. This tip can be designed in the sense that the front edge and the rear edge of the vortex generator elements have the same radial height. Alternatively, it can be provided that the tip of the vortex generator element protruding into the secondary flow channel extends obliquely and extends further towards the rear edge into the secondary flow channel, so that the rear edge has a greater radial height than the front edge. This defines a tip edge angle at the tip which, according to one embodiment variant, is in the range between 4 ° and 10 °. The sum of the radial height of the front edge and the radial height of the rear edge divided by two is defined as the mean radial height of the vortex generator elements.

According to a further embodiment variant, the thickness of the vortex generator elements is selected such that the maximum thickness is in the range between 25% and 50% of the maximum thickness of the guide vanes.

It can further be provided that the mean radial height of the vortex generator elements is in the range between 5% and 15% of the radial height of the guide vanes.

According to a further embodiment variant, the staggering angle of the vortex generator elements is selected such that the staggering angle is larger than the blade entry angle of the guide blades, so that the vortex generator elements are rotated into the flow more than the guide blades. As a result, vortex formation is promoted by the vortex generator elements. An exemplary embodiment provides that the stagger angle of the vortex generator elements differs from the blade entry angle of the guide blades by 10 ° to 40 °, in particular by 20 ° to 28 °.

According to a further embodiment of the invention, the vortex generator elements each have a rounded leading edge and a rounded trailing edge, the radius of curvature of the leading edge and trailing edge being, for example, in each case in the range between 25% and 70% of the maximum thickness of the vortex generator element.

The vortex generator elements can be designed as aerodynamically shaped elements, in particular as aerodynamically shaped sheets, or as non-aerodynamically shaped elements, in particular as non-aerodynamically shaped sheets.

In another aspect of the invention, the present invention relates to a turbofan engine comprising: a core engine, a fan positioned upstream of the core engine, a primary flow channel that passes through the core engine, and a secondary flow channel that passes the core engine. It is provided that the turbofan engine comprises an assembly according to claim 1, the assembly being arranged in the flow direction behind the fan in the secondary flow duct.

It can be provided that the output guide wheel is designed as a structural output guide wheel and is accordingly suitable for this purpose and serves to absorb structural loads. In this way, struts that radially cross the secondary flow channel can be dispensed with in the area of the output stator in any case. It is provided, for example, that the number of guide vanes of the output guide wheel is below 30th , especially under 25th and the blade-to-height ratio of the guide blades of the output stator is in the range between 0.8 and 1.3, in particular in the range between 0.9 and 1.2.

In a further aspect of the invention, the invention relates to a method for influencing the flow in a blade channel between two guide blades of an assembly which extend between a radially inner flow path boundary and a radially outer flow path boundary. The method provides that a vortex flow is generated in the vane channel by means of a vortex generator element assigned to the guide vanes, which is directed against a secondary flow in the vane channel, so that the flow in the vane channel is oriented more than a two-dimensional flow.

It is pointed out that the present invention is described with reference to a cylindrical coordinate system which has the coordinates x, r and φ. X indicates the axial direction, r the radial direction and φ the angle in the circumferential direction. The axial direction is identical to the machine axis of the turbofan engine in which the invention is implemented.

As stated elsewhere herein, the present disclosure may relate to a gas turbine engine. Such a gas turbine engine may include an engine core that includes a turbine, a combustion chamber, a compressor, and a core shaft connecting the turbine to the compressor. Such a gas turbine engine may include a fan (with fan blades) positioned upstream of the engine core.

Arrangements of the present disclosure may be particularly, but not exclusively, advantageous for fans that are driven by a transmission. Accordingly, the gas turbine engine may include a transmission that receives an input from the core shaft and drives the fan to drive the fan at a lower speed than the core shaft. The input for the transmission can take place directly from the core shaft or indirectly from the core shaft, for example via a spur shaft and / or a spur gear. The core shaft may be rigidly connected to the turbine and compressor so that the turbine and compressor rotate at the same speed (with the fan rotating at a lower speed).

The gas turbine engine described and / or claimed herein can have any suitable general architecture. For example, the gas turbine engine may have any desired number of shafts connecting turbines and compressors, for example one, two or three shafts. For example only, the turbine connected to the core shaft may be a first turbine, the compressor connected to the core shaft may be a first compressor, and the core shaft may be a first core shaft. The engine core may further include a second turbine, a second compressor, and a second core shaft connecting the second turbine to the second compressor. The second turbine, the second compressor, and the second core shaft may be arranged to rotate at a higher speed than the first core shaft.

With such an arrangement, the second compressor may be positioned axially downstream of the first compressor. The second compressor may be arranged to receive flow from the first compressor (e.g., take up directly, e.g. via a generally annular channel).

The transmission may be arranged to be driven by the core shaft configured to rotate at the lowest speed (e.g., in use) (e.g., the first core shaft in the example above). For example, the transmission may be arranged to be driven only by the core shaft configured to rotate at the lowest speed (for example, in use) (for example, only the first core shaft and not the second core shaft in the example above) will. Alternatively, the transmission may be arranged to be driven by one or more shafts, for example the first and / or the second shaft in the example above.

In a gas turbine engine described and / or claimed herein, a combustion chamber may be provided axially downstream of the blower and the compressor (s). For example, the combustion chamber can be located directly downstream of the second compressor (for example at the outlet thereof) if a second compressor is provided. As another example, the flow at the outlet of the compressor can be supplied to the inlet of the second turbine if a second turbine is provided. The combustion chamber can be provided upstream of the turbine (s).

The or each compressor (for example the first compressor and the second compressor as described above) can comprise any number of stages, for example several stages. Each stage can include a series of rotor blades and a series of stator blades, which can be variable stator blades (in that their angle of attack can be variable). The row of rotor blades and the row of stator blades can be axially offset from one another.

The or each turbine (e.g., the first turbine and the second turbine as described above) may include any number of stages, for example multiple stages. Each stage can include a series of rotor blades and a series of stator blades. The row of rotor blades and the row of stator blades can be axially offset from one another.

Each fan blade may be defined with a radial span that extends from a foot (or hub) at a radially inner gas-flowed location or at a 0% span position to a tip at a 100% span position. The ratio of the radius of the fan blade on the hub to the radius of the fan blade on the tip may be less than (or on the order of): 0.4, 0.39, 0.38, 0.37, 0.36, 0, 35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, 0.27, 0.26 or 0.25. The ratio of the radius of the fan blade at the hub to the radius of the fan blade at the tip can be in an inclusive range limited by two of the values in the previous sentence (i.e. the values can form upper or lower limits). These ratios can generally be referred to as the hub-to-tip ratio. The radius at the hub and the radius at the tip can both be measured at the front edge portion (or the axially most forward edge) of the blade. The hub-to-tip ratio, of course, refers to the portion of the fan blade over which gas flows, i.e. H. the section that is radially outside of any platform.

The radius of the fan can be measured between the center line of the engine and the tip of the fan blade at its front edge. The diameter of the blower (which can simply be twice the radius of the blower) can be greater than (or on the order of): 250 cm (about 100 inches), 260 cm, 270 cm (about 105 inches), 280 cm (about 110 inches), 290 cm (about 115 inches), 300 cm (about 120 inches), 310 cm, 320 cm (about 125 inches), 330 cm (about 130 inches), 340 cm (about 135 inches), 350 cm, About 360 cm (about 140 inches), 370 cm (about 145 inches), 380 cm (about 150 inches) or 390 cm (about 155 inches). The fan diameter can be in an inclusive range limited by two of the values in the previous sentence (i.e. the values can be upper or lower limits).

The speed of the fan can vary in use. In general, the speed is lower for fans with a larger diameter. For example only, as a non-limiting example, the fan speed may be less than 2500 rpm, for example less than 2300 rpm, under constant speed conditions. Just as another, non-limiting example, the speed of the fan under constant speed conditions for an engine with a fan diameter in the range from 250 cm to 300 cm (for example 250 cm to 280 cm) in the range from 1700 rpm to 2500 rpm, for example in the range from 1800 rpm to 2300 rpm, for example in the range from 1900 rpm to 2100 rpm. Just as another non-limiting example, the speed of the fan under constant speed conditions for an engine with a fan diameter in the range from 320 cm to 380 cm can be in the range from 1200 rpm to 2000 rpm, for example in the range from 1300 rpm. min to 1800 rpm, for example in the range from 1400 rpm to 1600 rpm.

When using the gas turbine engine, the blower (with associated blower blades) rotates about an axis of rotation. This rotation causes the tip of the fan blade to move at a speed U _top emotional. The work performed by the fan blades on the flow results in an increase in the enthalpy dH of the flow. A blower _peak load can be defined as dH / U _peak ² , where dH is the enthalpy increase (e.g. the average 1-D enthalpy increase) across the blower and U _top is the (translation) speed of the fan tip, for example at the front edge of the tip (which can be defined as the fan tip radius at the front edge multiplied by the angular speed). The blower peak load under constant speed conditions can be more than (or on the order of): 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38 , 0.39 or 0.4 are (lie) (all units in this section being Jkg ^-1 K ^-1 / (ms ^-1 ) ² ). The blower peak load can be in an inclusive range limited by two of the values in the previous sentence (ie the values can be upper or lower limits).

Gas turbine engines in accordance with the present disclosure may have any desired bypass ratio, the bypass ratio being defined as the ratio of the mass flow rate of flow through the bypass channel to the mass flow rate of flow through the core at constant speed conditions. In some arrangements, the bypass ratio can be more than (on the order of): 10th , 10th , 5 , 11 , 11 , 5 , 12 , 12 , 5 , 13 , 13 , 5 , 14 , 14 , 5 , 15 , 15 , 5 , 16 , 16 , 5 or 17th amount (lie). The bypass ratio can be in an inclusive range limited by two of the values in the previous sentence (ie the values can form upper or lower limits). The bypass channel can be essentially ring-shaped. The bypass channel can be located radially outside of the engine core. The radially outer surface of the bypass duct can be defined by an engine nacelle and / or a blower housing.

The total pressure ratio of a gas turbine engine described and / or claimed herein can be defined as the ratio of the back pressure upstream of the fan to the back pressure at the output of the supercharger (prior to entering the combustion chamber). As a non-limiting example, the total pressure ratio of a gas turbine engine described and / or claimed herein at constant speed may be more than (or on the order of): 35 , 40 , 45 , 50 , 55 , 60 , 65 , 70 , 75 amount (lie). The total pressure ratio can be in an inclusive range limited by two of the values in the previous sentence (ie the values can be upper or lower limits).

The specific thrust of an engine can be defined as the net thrust of the engine divided by the total mass flow through the engine. Under constant speed conditions, the specific thrust of an engine described and / or claimed herein may be less than (or on the order of): 110 Nkg ^-1 s, 105 Nkg ^-1 s, 100 Nkg ^-1 s, 95 Nkg ^-1 s, 90 Nkg ^-1 s, 85 Nkg ^-1 s or 80 Nkg ^-1 s. The specific thrust can be in an inclusive range limited by two of the values in the previous sentence (ie the values can be upper or lower limits). Such engines can be particularly efficient compared to conventional gas turbine engines.

A gas turbine engine described and / or claimed herein can have any desired maximum thrust. By way of non-limiting example only, a gas turbine described and / or claimed herein can produce a maximum thrust of at least (or on the order of): 160kN, 170kN, 180kN, 190kN, 200kN, 250kN, 300kN, 350kN, 400kN , 450kN, 500kN or 550kN. The maximum thrust can be in an inclusive range limited by two of the values in the previous sentence (ie the Values can form upper or lower limits). The thrust referred to above can be the maximum net thrust under standard atmospheric conditions at sea level plus 15 degrees C (ambient pressure 101.3 kPa, temperature 30 degrees C) for static engines.

In use, the temperature of the flow at the inlet of the high pressure turbine can be particularly high. This temperature, which can be referred to as TET, can be measured at the exit to the combustion chamber, for example immediately upstream of the first turbine blade, which in turn can be referred to as a nozzle guide blade. At constant speed, the TET can be at least (or in the order of magnitude): 1400K, 1450K, 1500K, 1550K, 1600K or 1650K. The constant velocity TET can be in an inclusive range limited by two of the values in the previous sentence (i.e. the values can be upper or lower limits). For example, the maximum TET in use of the engine may be at least (or on the order of): 1700K, 1750K, 1800K, 1850K, 1900K, 1950K or 2000K. The maximum TET can be in an inclusive range limited by two of the values in the previous sentence (i.e. the values can be upper or lower limits). The maximum TET can occur, for example, in a condition of high thrust, for example an MTO condition (MTO - maximum take-off thrust - maximum start thrust).

A fan blade and / or a blade portion of a fan blade described and / or claimed herein can be made from any suitable material or combination of materials. For example, at least a part of the fan blade and / or the blade can be made at least in part of a composite, for example a metal matrix composite and / or a composite with an organic matrix, such as, for example. B. carbon fiber. As another example, at least a portion of the fan blade and / or the blade may be at least partially made of a metal, such as. B. a titanium-based metal or an aluminum-based material (such as an aluminum-lithium alloy) or a steel-based material. The fan blade may include at least two areas made using different materials. For example, the fan blade may have a protective front edge that is made using a material that is more resistant to impact (e.g., birds, ice, or other material) than the rest of the blade. Such a leading edge can be produced, for example, using titanium or a titanium-based alloy. Thus, as an example only, the fan blade may include a carbon fiber or aluminum based body (such as an aluminum-lithium alloy) with a titanium leading edge.

A fan described and / or claimed herein may include a central portion from which the fan blades may extend, for example in a radial direction. The fan blades can be attached to the central section in any desired manner. For example, each fan blade can include a fixation device that can engage a corresponding slot in the hub (or disc). Such a fixing device in the form of a dovetail, which can be inserted into and / or brought into engagement with a corresponding slot in the hub / disc for fixing the fan blade, can be present only as an example. As another example, the fan blades can be integrally formed with a central portion. Such an arrangement can be referred to as a blisk or a bling. Any suitable method can be used to make such a blisk or bling. For example, at least some of the fan blades can be machined out of a block and / or at least some of the fan blades can be welded, e.g. B. linear friction welding, attached to the hub / disc.

The gas turbine engines described and / or claimed herein may or may not be provided with a VAN (Variable Area Nozzle - nozzle with a variable cross-section). Such a variable cross-section nozzle can allow the output cross-section of the bypass channel to be varied in use. The general principles of the present disclosure may apply to engines with or without a VAN.

The blower of a gas turbine described and / or claimed herein can be any desired number of blower blades, for example 16 , 18th , 20th or 22 Blower blades have.

As used herein, constant speed conditions may mean constant speed conditions of an aircraft to which the gas turbine engine is attached. Such constant speed conditions can conventionally be defined as the conditions during the middle part of the flight, for example the conditions to which the aircraft and / or the engine is exposed between (in terms of time and / or distance) the end of the climb and the start of the descent. will.

For example only, the forward speed at the constant speed condition at any point may range from Mach 0.7 to 0.9, for example 0.75 to 0.85, for example 0.76 to 0.84, for example 0.77 to 0 , 83, for example 0.78 to 0.82, for example 0.79 to 0.81, for example in the order of Mach 0.8, in the order of Mach 0.85 or in the range of 0.8 to 0, 85 lie. Any speed within these ranges can be the constant travel condition. For some aircraft, constant speed conditions may be outside of these ranges, for example below Mach 0.7 or above Mach 0.9.

For example only, the constant speed conditions may be standard atmospheric conditions at an altitude that is in the range of 10,000 m to 15,000 m, for example in the range of 10,000 m to 12,000 m, for example in the range of 10,400 m to 11,600 m (approximately 38,000 feet), for example in Range of 10,500 m to 11,500 m, for example in the range of 10,600 m to 11,400 m, for example in the range of 10,700 m (approximately 35,000 feet) to 11,300 m, for example in the range from 10,800 m to 11,200 m, for example in the range from 10,900 m to 11,100 m, for example in the order of 11,000 m. The constant velocity conditions can correspond to standard atmospheric conditions at any given altitude in these areas.

As an example only, the constant speed conditions may correspond to: a forward Mach number of 0.8; a pressure of 23,000 Pa and a temperature of -55 degrees C.

As used throughout, "constant speed" or "constant speed conditions" can mean the aerodynamic design point. Such an aerodynamic design point (or ADP - Aerodynamic Design Point) can correspond to the conditions (including, for example, the Mach number, ambient conditions and thrust requirement) for which the fan operation is designed. This can mean, for example, the conditions in which the blower (or the gas turbine engine) has the optimal efficiency by design.

In use, a gas turbine engine described and / or claimed herein may be operated at the constant speed conditions defined elsewhere herein. Such constant speed conditions can be determined from the constant speed conditions (e.g., mid-flight conditions) of an aircraft to which at least one (e.g., 2 or 4) gas turbine engine may be attached to provide thrust.

It will be understood by those skilled in the art that a feature or parameter described in relation to one of the above aspects can be applied to any other aspect, unless they are mutually exclusive. Furthermore, any feature or parameter described here can be applied to any aspect and / or combined with any other feature or parameter described here, if they are not mutually exclusive.

• 1 eine vereinfachte schematische Schnittdarstellung eines Turbofantriebwerks, in dem die vorliegende Erfindung realisierbar ist;
• 2 schematisch eine perspektivische Darstellung eines Ausführungsbeispiels einer Baugruppe, die ein Fan-Ausgangsleitrad mit Leitschaufeln und den Leitschaufeln jeweils zugeordnete Wirbelgenerator-Bleche umfasst;
• 3 schematisch eine Ansicht von oben und eine Seitenansicht eines Wirbelgenerator-Blechs;
• 4 schematisch die axialen Abstände und die Abstände in Umfangsrichtung zwischen einem Wirbelgenerator-Blech und einer zugeordneten Leitschaufel;
• 5 schematisch einen Längsschnitt durch eine Baugruppe gemäß der 2 unter Darstellung der Schaufelhöhe und der Profilsehnenlänge der Leitschaufeln des Ausgangsleitrads;
• 6 eine perspektivische Darstellung eines weiteren Ausführungsbeispiels einer Baugruppe mit einem Ausgangsleitrad und Wirbelgenerator-Blechen, die jeweils den Leitschaufeln des Ausgangsleitrads zugeordnet sind, wobei die Wirbelgenerator-Bleche auf einer eigenen Nabenstruktur angeordnet sind;
• 7 an einem Ausführungsbeispiel die Stromlinien einer Strömung durch einen Schaufelkanal zwischen zwei Leitschaufeln eines Ausgangsleitrads, wobei die Strömung durch ein Wirbelgenerator-Blech beeinflusst und dadurch stärker zweidimensional ausgebildet ist;
• 8 als Vergleich zur 7 die Stromlinien einer Strömung durch einen Schaufelkanal zwischen zwei Leitschaufeln eines Ausgangsleitrads, wobei die Strömung nicht durch ein Wirbelgenerator-Blech beeinflusst ist;
• 9 schematisch ein Ausführungsbeispiel eines Wirbelgenerator-Blechs, das aerodynamisch geformt ist; und
• 10 schematisch ein Ausführungsbeispiel eines Wirbelgenerator-Blechs, dass nicht aerodynamisch geformt ist.

The invention is explained in more detail below with reference to the figures of the drawing using several exemplary embodiments. Show it:

• 1 a simplified schematic sectional view of a turbofan engine in which the present invention can be implemented;
• 2nd schematically shows a perspective view of an embodiment of an assembly comprising a fan output stator with guide vanes and vortex generator plates respectively assigned to the guide vanes;
• 3rd schematically a view from above and a side view of a vortex generator sheet;
• 4th schematically the axial distances and the distances in the circumferential direction between a vortex generator plate and an associated guide vane;
• 5 schematically shows a longitudinal section through an assembly according to the 2nd showing the blade height and chord length of the guide vanes of the output guide wheel;
• 6 a perspective view of another embodiment of an assembly with an output stator and vortex generator sheets, each associated with the guide vanes of the output stator, the vortex generator sheets being arranged on their own hub structure;
• 7 in one exemplary embodiment, the streamlines of a flow through a vane channel between two guide vanes of an output stator, the flow being influenced by a vortex generator plate and thus being more two-dimensional;
• 8th as a comparison to 7 the streamlines of a flow through a vane channel between two guide vanes of an output stator, the flow not being influenced by a vortex generator plate;
• 9 schematically an embodiment of a vortex generator sheet, which is aerodynamically shaped; and
• 10th schematically an embodiment of a vortex generator sheet that is not aerodynamically shaped.

The 1 shows schematically a turbofan engine 100 having a fan level with a fan 10th as a low pressure compressor, a medium pressure compressor 20th , a high pressure compressor 30th , a combustion chamber 40 , a high pressure turbine 50 , a medium pressure turbine 60 and a low pressure turbine 70 having.

The medium pressure compressor 20th and the high pressure compressor 30th each have a plurality of compressor stages, each comprising a rotor and a stator. The turbofan engine 100 the 1 also has three separate shafts, a low pressure shaft 81 that the low pressure turbine 70 with the fan 10th connects, a medium pressure wave 82 that the medium pressure turbine 60 with the medium pressure compressor 20th connects and a high pressure wave 83 that the high pressure turbine 50 with the high pressure compressor 30th connects. However, this is only to be understood as an example. For example, if the turbofan engine had no medium pressure compressor and no medium pressure turbine, there would only be a low pressure shaft and a high pressure shaft.

The turbofan engine can alternatively be designed as a gear fan, the fan being coupled to the turbine shaft via a reduction gear, typically a planetary gear.

The turbofan engine 100 has an engine nacelle 1 on (also known as engine cowling), which has an inlet lip 14 includes and an engine inlet on the inside 11 trains the inflowing air to the fan 10th feeds. The fan 10th has a plurality of fan blades 101 on that with a fan disk 102 are connected. The annulus of the fan disc 102 forms the radially inner boundary of the flow path through the fan 10th . The flow path is radially outside through a fan housing 2nd limited. Upstream of the fan disc 102 is a nose cone 103 arranged.

Behind the fan 10th forms the turbofan engine 100 a secondary flow channel 4th and a primary power channel 5 out. The total air mass flow sucked in by the engine is behind the fan 10th - but before its guide system - by a so-called splitter 61 into the secondary flow channel 4th and the primary power channel 5 split up. There is a guide wheel 15 into the core engine at the entrance of the primary flow channel 5 . Furthermore there is behind the fan 10th in the secondary flow channel 4th a fan output stator 25th .

The primary power channel 5 leads through the core engine (gas turbine), which is the medium pressure compressor 20th , the high pressure compressor 30th , the combustion chamber 40 , the high pressure turbine 50 , the medium pressure turbine 60 and the low pressure turbine 70 includes. Here are the medium pressure compressors 20th and the high pressure compressor 30th from a peripheral housing 6 surround that forms an annular space on the inside, which forms the primary flow channel 5 limited radially outside. Radially inside is the primary flow channel 5 limited by corresponding ring surfaces of the rotors and stators of the respective compressor stages or by the hub or elements of the corresponding drive shaft connected to the hub.

In operation of the turbofan engine 100 a primary current flows through the primary current channel 5 , which is also called the main flow channel. The secondary flow channel 4th , also referred to as a bypass duct, bypass duct or bypass duct, conducts during operation of the turbofan engine 100 from the fan 10th Air drawn in past the core engine.

The components described have a common axis of rotation or machine 90 . The axis of rotation 90 defines an axial direction of the turbofan engine. A radial direction of the turbofan engine is perpendicular to the axial direction.

In the context of the present invention, the configuration is at the beginning of the secondary flow channel 4th arranged fan output stator 25th or an assembly that includes this is important.

The 2nd shows a perspective view based on an embodiment of the components of the assembly according to the invention.

The assembly includes an output stator 25th that have a plurality of guide vanes 250 comprises, each in the radial direction and equidistant distance between a radially inner, hub-side flow path boundary 65 and a radially outer flow path boundary on the housing side. It is the case that two guide vanes 250 one blade channel in the circumferential direction 3rd train between themselves. Every vane 250 includes a suction side 251 and a print page 252 . The scoop channel 3rd extends between the printed page 252 a guide vane 250 and the suction side 251 of the neighboring guide vane 250 .

The assembly also includes a plurality of vortex generator elements, which act as vortex generator sheets 7 are trained and are referred to below as such. The vortex generator sheets 7 However, they do not necessarily consist of metal and can alternatively consist of a ceramic, for example.

The in the 2nd shown vortex generator sheets 7 extend from the hub-side flow path boundary 65 in the radial direction to the outside. The chord length, the radial height and the alignment of the vortex generator sheets 7 are different compared to the chord length, the radial height and the alignment of the guide vanes 250 . In particular, the radial height of the vortex generator sheets 7 significantly less than the radial height of the guide vanes 250 and is a maximum of 20% of the radial height of the guide vanes 250 . Also the chord length of the vortex generator sheets 7 is significantly less than the chord length of the guide vanes 250 and is included maximum 20% of the chord length of the guide vanes 250 . The alignment of the generator sheets 7 is such that they are rotated more into the flow than the leading edges of the guide vanes 250 . These differences are shown in the 3rd to 6 further explained.

In the embodiment of the 2nd the vortex generator sheets extend 7 from the hub-side flow path limitation 65 into the secondary flow channel 4th . In a corresponding manner, it is alternatively or additionally possible for vortex generator sheets to radially inward from the flow path boundary on the housing side into the secondary flow channel 4th extend. Provided below the design of the vortex generator sheets 7 is described using an arrangement on the hub-side flow path delimitation, these explanations apply in a corresponding manner to vortex generator sheets which are arranged on the housing-side flow path delimitation.

The vortex generator sheets 7 are each a guide vane 250 assigned and each generate a vortex flow in the blade channel 3rd . This vortex flow acts on a secondary flow that is always present in the vane duct, that from the pressure side 252 the one vane 250 that the scoop channel 3rd limited, to the suction side 251 of the neighboring guide vane 250 that the scoop channel 3rd limited, flows, towards.

The vortex generator sheets thus produce 7 one against the secondary flow in the blade channel 3rd directed vortex flow. This is based on the 7 and 8th further explained.

It should be noted that the vortex generator sheets 7 in the embodiment of 2nd based on the flow direction in front of the through the connecting line of the leading edges of the guide vanes 250 formed line and lie to the suction side 251 the guide vanes 250 are arranged. This is the case in embodiments of the invention, with other arrangements of the vortex generator sheets also 7 possible are.

According to the 2nd is every blade channel 3rd or each guide vane 250 a vortex generator sheet 7 assigned. In alternative exemplary embodiments it can be provided that the blade channels 3rd more than a vortex generator sheet 7 assigned. Furthermore, it can be provided in alternative exemplary embodiments that not every blade channel 3rd or each guide vane 250 a vortex generator plate is assigned, but only some of the blade channels 3rd or guide vanes 250 , for example, groups of vane channels and guide vanes are defined in which such a configuration is present.

Based on 3rd to 6 are several parameters that determine the formation of the vortex generator sheets 7 and their positioning and alignment with respect to the guide vanes 250 define, explained. The 3rd shows a top view of a vortex generator plate in the figure above 7 and in the figure below a side view of a vortex generator sheet 7 . The vortex generator sheet 7 includes a rounded front edge 71 , a rounded rear edge 72 , a front 74 and a back 73 . The leading edge 71 has a radius of curvature R1 and the trailing edge has a radius of curvature R2 on. The vortex generator sheet also points 7 a maximum thickness dmax. It is provided in exemplary embodiments that the radius of curvature R1 , R2 each have a value in the interval between 25% and 50% of the maximum thickness dmax of the vortex generator sheet 7 lies.

With regard to the maximum thickness dmax of the vortex generator sheet 7 applies that in exemplary embodiments this is between 10% and 50%, in particular between 25% and 50% of the maximum thickness of the guide vane 250 is.

At the front edge 71 the vortex generator sheet has a radial height h _LE and a radial height at the rear edge h _TE on. In the illustrated embodiment, but not necessarily, these two heights are different, so the top 75 forms a tip edge angle α which is greater than 0 °. The angle is considered in the mathematically positive sense of rotation, so that an angle greater than 0 ° means that the radial height h _TE at the rear edge 72 is greater than the radial height h _LE at the front edge 71 . It is provided in exemplary embodiments that the tip edge angle α lies in the interval between 4 ° and 10 °.

Based on 3rd is also the average height h _m recognizable, which is equal to the sum of the radial height at the leading edge 71 and the radial height at the rear edge 72 divided by two is: $${\text{H}}_{\text{m}}=\left({\text{H}}_{\text{LE}}+{\text{H}}_{\text{TE}}\right)/\mathrm{2nd}$$

The average height applies h _m of the vortex generator sheet 7 in exemplary embodiments between 5% and 15% of the radial height H the guide vanes 250 is. The radial height H the guide vanes 250 is in the 5 shown schematically. It corresponds to the radial extension of the guide vanes 250 in the secondary flow channel 4th .

The 3rd also illustrates the length of the chord c of the vortex generator sheet 7 , the chord length c is defined by the connecting line between the front edge 71 and the trailing edge 72 of the vortex generator sheet 7 .

The chord length applies c of the vortex generator sheet 7 in the range between 5% and 15% of the tendon length S _k the guide vanes 250 of the output idler. The tendon length S _k the guide vanes 250 the output stator is schematically in the 5 shown. Provided the tendon length S _k the guide vanes 250 varies depending on the radial height, the length that the guide vanes have in the middle between the two flow path boundaries is regarded as the chord length. The same applies to other parameters that depend on the radial height.

The 4th illustrates the axial distance between the vortex generator plate 7 and the associated guide vane 250 and on the other hand the offset in the circumferential direction between the vortex generator plate 7 and the associated guide vane 250 .

This will be a line extending in the circumferential direction 91 as a connecting line between the front edges 253 the guide vanes 250 Are defined. In the 4th is this connecting line 91 not exactly to the front edge 253 of the guide vane shown 250 created. However, this is only due to the schematic representation. It should be assumed that the perimeter 91 on the front edges 253 the guide vane 250 is present.

The axial offset between the rear edge 72 of the vortex generator sheet 7 and the circumference 91 will with L designated. Provided L is greater than zero, the rear edge is 72 of the vortex generator sheet 7 related to the axial direction in front of the circumference 91 . Provided L is less than zero, the rear edge is 72 and possibly also the leading edge 71 of the vortex generator sheet 7 based on the axial direction behind the circumference 91 and thus in the blade channel 3rd or the flow passage between two guide vanes 250 .

According to a first embodiment L positive and lies in the range between 0 and 80% of the tendon length c the vortex generator sheets 7 . Such a position of the vortex generator sheets 7 show the 2nd . Alternative is L negative and is, for example, in the range between 0% and minus 15% of the chord length of the vortex generator sheets 7 . It applies that the vortex generator plates only up to the area in the blade channel 3rd into which the streamlines close to the wall experience a high degree of curvature.

For the distance in the circumferential direction p between the leading edge 71 of the vortex generator sheet 7 and the leading edge 253 the guide vane 250 it also applies that this can take positive or negative values. The distance p in the circumferential direction is also referred to as "pitch". If the distance in the circumferential direction p is greater than zero, the vortex generator sheet is 7 adjacent to the suction side 251 the guide vane 250 arranged. Such a position of the vortex generator sheets 7 show the 2nd . In exemplary embodiments p in the range between 0% and 30% of the grating pitch t of the guide vanes 250 of the output stator 25th . The grating pitch t of the output stator 25th is schematically in the 6 shown.

Alternative is p less than 0 and has, for example, a value that is in the range between 0% and minus 15% of the grating pitch t of the guide vanes 250 of the output stator 25th lies.

In the 4th is also shown schematically that the orientation of the vortex generator plate 7 can vary. Such are the vortex generator sheets 7 at a graduation angle γ arranged. The graduation angle γ gives the inclination of the vortex generator sheets 7 at. The graduation angle γ is defined as the angle between the chord of the vortex generator plate and the vertical on an imaginary line, on which the leading edges 71 the vortex generator sheets 7 lie.

Also drawn in the 4th is the blade entry angle Ä of the guide blade 250 , which is defined as the angle between a tangent to the skeletal line of the guide vane 250 and the perpendicular on the line 91 that the leading edges 153 the guide vanes connect. It can be seen that the graduation angle γ of the vortex generator sheet 7 is larger than the blade entry angle λ the guide vane 250 . Refinements provide that the graduation angle γ between 10 ° and 40 °, in particular between 20 ° and 28 °, is greater than the blade entry angle λ the guide vane 250 .

The 5 shows the front edge in a sectional view 253 , the trailing edge 254 , the radial height H and the chord length S _k the guide vane 250 that in the secondary flow channel 4th is arranged and between a hub-side flow path boundary 65 and a flow path limitation on the housing side 21st extends radially.

The 6 shows an embodiment in which the vortex generator sheets 7 on a separate hub-side structure 7 are arranged in the axial direction in front of the output stator 25th is arranged. This is associated with the advantage that the vortex generator sheets 7 regardless of the output idler 25th can be produced. The 6 also shows parts of a housing 22 , the inside of the radially outer flow path limitation 21st trains.

The 7 illustrates the advantages associated with the present invention. Through the vortex generator sheets 7 is achieved that the flow S in the blade channel 3rd between two guide vanes 250 is less curved. This reduces the risk that the flow with built-in components in the secondary flow channel 4th interferes. The lower curvature is achieved in that the vortex generator sheets 7 each generate a vortex flow that is the secondary flow in the blade channel 3rd is directed against.

The 8th shows for comparison the corresponding flow conditions at an output stator to which no vortex generator plates are assigned. The current S0 in the blade channel 3rd between two guide vanes 250 is much more curved.

The 9 and 10th show two embodiments of vortex generator sheets 7a , 7b . The vortex generator sheet 7a of the embodiment of the 9 is aerodynamically shaped. This means that air flowing in from direction Z has an angle of incidence β ₁ which differs from the angle of deviation β ₂ differs. The angle of incidence is the angle between the inflow direction and the tangent to the skeleton line SL of the vortex generator sheet 7a at the front edge 71 . The angle of deviation is the angle between the outflow direction E and the tangent to the skeletal line SL at the rear edge 72 of the vortex generator sheet 7a . Due to the aerodynamic shape of the vortex generator sheet 7 the incidence angle differ β ₁ and the angle of deviation β ₂ .

In contrast, the 10th an embodiment in which the vortex generator sheet 7b is not aerodynamically shaped. Accordingly, the angle of incidence β ₁ and the angle of deviation β ₂ identical.

It is understood that the invention is not limited to the embodiments described above and various modifications and improvements can be made without departing from the concepts described here. Furthermore, any of the features may be used separately or in combination with any other features, unless they are mutually exclusive, and the disclosure extends to and includes all combinations and subcombinations of one or more features described herein. If areas are defined, they include all values within these areas as well as all sub-areas that fall within one area.

Claims (22)

Assembly with an output stator for a turbofan engine, which has: - a radial inner flow path boundary (65) and a radially outer flow path boundary (21) which delimit the secondary flow channel (4) of a turbofan engine radially inside and radially outside, - an output stator (25) with a plurality of guide vanes (250) which extend in the radial direction between the radially inner flow path boundary (65) and the radially outer flow path boundary (21) in the secondary flow duct (4) of the turbofan engine, and which each have a pressure side (252), a suction side ( 251), a front edge (253) and a rear edge (254), - two guide blades (250) each forming a blade channel (3) between them in the circumferential direction, in which a secondary flow from the pressure side (252) during operation of the turbofan engine Guide vane (250) flows to the suction side (251) of the adjacent guide vane (250), characterized in that - at least e In some of the guide vanes (250), a separate vortex generator element (7) is assigned, which is arranged on the radially inner flow path boundary (21) and / or the radially outer flow path boundary (65) and extends radially into the secondary flow duct (4) , wherein the vortex generator element (7) each has a front edge (71), a rear edge (72) and an average radial height (h _max ), which is a maximum of 20% of the radial height (H) of the guide vanes (250), and - the vortex generator element (7) generates a vortex flow directed against the secondary flow in the blade channel (3) in the blade channel (3). Assembly after Claim 1 , characterized in that the vortex generator elements (7) are each arranged adjacent to the suction side (251) of a guide vane (250). Module according to 2, characterized in that the distance (p) in the circumferential direction between the front edge (71) of the vortex generator element (7) and the front edge (253) of the guide vane (250) in the range between 0% to 30% of the grid pitch (t) the guide vanes (250) are located. Assembly after Claim 1 , characterized in that the vortex generator elements (7) are each arranged adjacent to the pressure side (252) of a guide vane (250). Assembly according to 4, characterized in that the distance (p) in the circumferential direction between the front edge (71) of the vortex generator element (7) and the leading edge (253) of the guide vane (250) is in the range between 0% and -15% of the grid pitch (t) of the guide vanes (250). Assembly according to one of the preceding claims, characterized in that the vortex generator elements (7) are each arranged upstream of the front edge (253) of the guide vanes (250). Assembly according to 6, characterized in that the axial distance (L) between the rear edge (72) of the vortex generator element (7) and the front edge (253) of the guide vane (250) each between 0% and 80% of the chord length of the vortex generator element (7) is. Assembly according to one of the Claims 1 to 5 , characterized in that the vortex generator elements (7) are arranged at least with their rear edge (72) downstream of the front edge (253) of the guide blades (250) in the blade channel. Assembly after Claim 8 , characterized in that the axial distance between the rear edge (72) of the vortex generator element (7) and the front edge (253) of the guide vane (250) is in each case between 0% and -15% of the chord length of the vortex generator element (7). Assembly according to one of the preceding claims, characterized in that the chord length (c) of the vortex generator elements (7) is in the range between 5% and 15% of the chord length (S _k ) of the guide blades (250). Assembly according to one of the preceding claims, characterized in that the tip (75) of the vortex generator element (7) projecting into the secondary flow channel (4) extends obliquely and extends further towards the rear edge (72) into the secondary flow channel (4), the Point edge angle (α) is in the range between 4 ° and 10 °. Assembly according to one of the preceding claims, characterized in that the maximum thickness (dmax) of the vortex generator elements (7) is in the range between 25% and 50% of the maximum thickness of the guide vanes (250). Assembly according to one of the preceding claims, characterized in that the mean radial height (h _m ) of the vortex generator elements (7) is in the range between 5% and 15% of the radial height (H) of the guide vanes (250). Assembly according to one of the preceding claims, characterized in that the staggering angle (γ) of the vortex generator elements (7) is greater than the blade entry angle (λ) of the guide blades (250), so that the vortex generator elements (7) are stronger than the guide blades (250) in the flow is turned. Assembly after Claim 14 , characterized in that the stagger angle (γ) of the vortex generator elements (7) differs by 10 ° to 40 °, in particular by 20 ° to 28 °, from the blade entry angle (λ) of the guide blades (250). Assembly according to one of the preceding claims, characterized in that the vortex generator elements (7) each have a rounded leading edge (71) and a rounded trailing edge (72), the radius of curvature (R1, R2) of the leading edge and trailing edge each in the range between 25% and 70% of the maximum thickness (dmax) of the vortex generator element (7). Assembly according to one of the preceding claims, characterized in that the vortex generator elements (7a) are designed as aerodynamically shaped vortex generator elements. Assembly according to one of the preceding claims, characterized in that the vortex generator elements (7b) are designed as non-aerodynamically shaped vortex generator elements. Assembly according to one of the preceding claims, characterized in that the vortex generator elements (7) are designed as vortex generator sheets. A turbofan engine comprising: a core engine (20, 30, 40, 50, 60, 70), a fan (10) positioned upstream of the core engine (20, 30, 40, 50, 60, 70), a primary flow duct (5) leading through the core engine (20, 30, 40, 50, 60, 70), and - a secondary flow duct (4) connected to the core engine (20, 30, 40, 50, 60, 70) leads past, characterized by an assembly according to Claim 1 , which is arranged in the flow direction behind the fan (10) in the secondary flow channel (4). Turbo engine after Claim 20 , characterized in that the output guide wheel (25) is designed as a structural output guide wheel, the number of guide vanes (250) of the output guide wheel being less than 30 and the blade-height ratio of the guide vanes (250) of the output guide wheel in the range between 0.8 and 1 , 3 lies. Method for influencing the flow in a blade channel (3) between two guide blades (250) of an outlet guide wheel (25), which extend between a radially inner flow path boundary (65) and a radially outer flow path boundary (21), characterized in that A vortex flow is generated in the blade channel (3) by means of a vortex generator element (7) respectively assigned to the guide blades (250), which is directed against a secondary flow in the blade channel (3), so that the flow in the blade channel is oriented more strongly than a two-dimensional flow.

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