Unducted fan for aviation propulsion

Abstract

The invention relates to an unducted propulsion fan (100) comprising at least a first row of blades (110) rotatable about a central axis (X). Each blade (110) of the first row comprises a profile body extending radially with respect to the central axis (X) from an inner radius Ri to an outer radius Re and comprising a pressure side (111) and a suction side (112) connecting the leading edge (BA) to the trailing edge (BF). The trailing edge (BF) of the profile body of each blade (110) of the first row of blades (110) has serrations, and the profile body of each blade (110) of the first row of blades (110) has an activity factor FA between 100 and 225.

Description

Technical Field

[0001] The technical field of this disclosure is the field of propulsion, and more particularly relates to ductless propulsion fans, such as ductless propulsion fans intended to be actuated by a gas turbine engine in aviation propulsion. Background Technology

[0002] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, numerous countries have already implemented, are implementing, or will implement various restrictions on carbon emissions. In particular, ambitious standards apply to both new and currently in-service aircraft, requiring the implementation of technological solutions to ensure compliance with existing regulations. The civil aviation industry has been actively involved in addressing climate change for many years.

[0003] Technological research has yielded significant improvements in aircraft environmental performance. The applicant considers the influencing factors at each stage of design and development to obtain more energy-efficient and environmentally friendly aerospace components and products whose integration and use in civil aviation have moderate environmental consequences, thereby improving the energy efficiency of aircraft.

[0004] Therefore, the applicant continues to reduce climate impact by employing sound development and manufacturing methods and processes to minimize greenhouse gas emissions and reduce the environmental footprint of the activity.

[0005] These ongoing research and development efforts focus on next-generation aircraft engines, aircraft weight reduction, particularly the development of electrical technologies to ensure propulsion through the use of materials and lightweight airborne equipment, and aviation biofuels as an important complement to technological advancements.

[0006] The goal is to minimize pollution emissions related to air transport, particularly by improving the efficiency of propulsion systems, and more specifically, by increasing propulsion efficiency, which characterizes the efficiency of converting the energy used into useful thrust.

[0007] The primary factors influencing propulsion efficiency are the components that directly contribute to thrust generation, especially the propulsion fan. A known guiding principle for improving propulsion efficiency is to reduce the fan's compression ratio, thereby reducing the air velocity at the fan outlet and the associated kinetic energy loss.

[0008] To achieve the same thrust, this reduction in velocity at the propulsion fan outlet must typically be compensated for by a larger air mass flow rate, thus requiring a larger fan diameter. When the fan is actuated by a gas turbine engine, this also usually means a higher bypass ratio (BPR), which is the ratio between the mass flow rate of the fan's secondary flow and the mass flow rate of the mainstream supplied to the gas turbine engine's combustion chamber.

[0009] When the fan is ducted, the increase in fan diameter also involves an increase in the external dimensions of the retaining casing surrounding it, as well as an increase in the dimensions of the nacelle constituting the aerodynamic housing of the casing, thus increasing its drag and mass. To avoid these disadvantages, it is feasible to shorten the axial length of the nacelle and make it thinner, which reduces the space available for acoustic treatments for noise reduction. Furthermore, several types of ductless propulsion fans have been envisioned, including, in particular, those known by the abbreviations USF and CROR. In both types, the propulsion fan comprises two rows of blades arranged radially about one or more central axes, one row upstream and the other downstream; in the context of this disclosure, the terms "upstream" and "downstream" are understood to refer to the generally defined direction of air circulation through the fan. However, in a USF (Unducted Single Fan) propulsion fan, only the upstream row is rotatable about the central axis; while in a CROR (Counter-Rotating Open Rotor) propulsion fan, both rows are rotatable in opposite directions. However, in both types, the blades in each of the two rows can have variable pitch.

[0010] One drawback of ductless propulsion fans is their acoustic emission level. In fact, without a casing or nacelle surrounding the fan, acoustic emissions propagate directly into the environment. Furthermore, the interaction between successive rows of blades exacerbates these emissions, particularly at harmonics of the blade passing frequency (BPF). Therefore, applicants, in particular, have invested significant research and development efforts to reduce these emissions. To this end, especially in international patent applications WO2023 / 007098A1 and WO2019 / 158875A1, it has been proposed to form teeth or corrugations on the trailing edge of the blades of ductless propulsion fans to reduce or disperse their wingtip vortices. This solution has also been proposed for ducted fans, for example, in French patent applications FR2986285A1 and FR3103231A1. In addition, it has been proposed to provide teeth or corrugations on the leading edge for similar reasons, for example in the European patent application EP2760737A1 and U.S. patents US11,560,796 and US11,047,238. Summary of the Invention

[0011] This disclosure originates from technical research aimed at significantly improving the performance of aircraft and contributing to reducing their environmental impact, particularly in terms of acoustic emissions. To this end, a first aspect of this disclosure relates to a ductless propulsion fan comprising at least a first row of blades rotatable about a central axis, each blade in the first row comprising a profile body with an inner radius R relative to the central axis. i Extending radially to outer radius R eIt includes a pressure side and a suction side, which connect the leading edge to the trailing edge. Each blade in the first row has a profile with a motion factor FA between 100 and 225, preferably between 150 and 200, defined by the following formula:

[0012] Where ξ represents the radial distance relative to the central axis divided by the outer radius R. e c(ξ) represents the local chord length between the leading and trailing edges of the profile at the radial distance ξ. Furthermore, the trailing edge of the profile of at least one blade in the first row of blades has serrations.

[0013] A relatively high activity factor (FA) between 100 and 225 is beneficial for better propulsion efficiency, but it means that the chord length is higher on the upper part of the blade, i.e., on its outer radius R. e The effect is relatively significant in the vicinity. Since the boundary layer thickness at the trailing edge typically increases with chord length, this relatively high activity factor FA is generally associated with increased self-noise of the fan with a wide bandwidth, and with an increase in the characteristic width or scale of the blade wake vortex. However, the inventors have discovered that the teeth at the trailing edge can limit acoustic emissions even at such a high activity factor FA, thus combining high propulsion efficiency with moderate acoustic emissions.

[0014] The trailing edge may in particular have a spacing between the cusps of adjacent teeth, which is radially oriented toward the outer radius R. e Monotonically decreasing. In the context of this disclosure, "monotonically" decreasing means that the distance between the tips of the radially outermost adjacent teeth is less than the distance between the tips of the radially innermost adjacent teeth, and that from the distance between the tips of the radially innermost adjacent teeth to the distance between the tips of the radially outermost adjacent teeth, each distance is less than or equal to the previous adjacent distance. However, alternatively, it can be envisioned that the distance between the tips of adjacent teeth decreases radially towards the outer radius R. e Increase.

[0015] Therefore, it can be envisioned that each of the aforementioned spacings between the tips of adjacent teeth is different, i.e., if the spacing between the tips of adjacent teeth is oriented towards the outer radius R. e If reduced, the distance between the tips of the innermost adjacent teeth in the radial direction and the distance between the tips of the outermost adjacent teeth in the radial direction will each distance be smaller than the previous adjacent distance.

[0016] However, alternatively, it is conceivable that at least two, but preferably no more than five, or even no more than three, of the said spacings between the tips of adjacent teeth are substantially the same, preferably at the height of the blade near its outer radius, especially to simplify blade production.

[0017] Each blade in the first row can have an aspect ratio equal to its outer radius R. e Multiply by a factor between 0.8m -1 With 2.4m -1 The coefficient between these values ​​is preferably between 1.2m. -1 With 2.2m -1 The coefficient between, or preferably between, 1.4m -1 With 1.8m -1 The coefficient between them. The outer radius R of the blade. e Therefore, this aspect ratio, normalized to the diameter D of the blades in this row, can achieve a good aerodynamic load distribution.

[0018] If the distance between the tips of adjacent teeth is from the inner radius R i To the outer radius R e As the ratio decreases monotonically, it is conceivable that the ratio between the maximum and minimum spacing of the distances between the tips of adjacent teeth can be less than 15, preferably less than 8, and even more preferably less than 5, to limit the number of teeth and / or the number of different spacings, thereby simplifying blade production. This ratio can also be greater than 1.25.

[0019] The maximum spacing between the tips of adjacent teeth can be within the height of the blade profile, i.e., the outer radius R. e With the inner radius R i The difference is between 0.05 and 0.4 times, preferably between 0.1 and 0.35 times the height, and more preferably between 0.15 and 0.3 times the height. This allows for the attainment of a maximum spacing, the order of magnitude of which is comparable to the wavelength of the second harmonic Γ2 of the blade passing frequency (BPF) during aircraft takeoff, which is particularly important in terms of noise pollution. The wavelength of the second harmonic of the BPF can be estimated using the following formula:

[0020] Where c0 represents the speed of sound (in m / s), B represents the number of blades, and Ω represents the rotational speed of the first row of blades (in revolutions per minute).

[0021] The trailing edge can be formed such that the ratio between any two adjacent spacings in the spacing between the tips of adjacent teeth is between 1 and 2, preferably between 1.03 and 1.5. In particular, the ratio between each adjacent spacing can be approximately equal to 1 plus the reciprocal of a positive integer. "Approximately" means that it can have an error range of ±30%, preferably ±10%. This allows for decreasing adjacent spacings depending on the blade passing frequency (BPF) or the wavelength of its harmonics.

[0022] The trailing edge can be configured such that each tooth of the trailing edge has a tooth height that is between 0.1 and 2 times the distance between the cusp of the same tooth and the cusp of the adjacent tooth, preferably between 0.2 and 1.6 times, and more preferably between 0.3 and 1.2 times. Choosing this ratio allows for better reduction of acoustic emissions while ensuring good mechanical strength.

[0023] The teeth on the trailing edge can be wavy, especially sinusoidal, although other forms are also conceivable. If the teeth are sinusoidal, the trailing edge can be constructed such that the distance between the tips of adjacent teeth is equal to the square of the height of one of the adjacent teeth multiplied by a factor between 0.005 mm. -1 With 1mm -1 The coefficient between these values ​​is preferably between 0.01 mm. -1 With 0.8mm -1 The coefficient between these values ​​is more preferably between 0.02 mm. -1 With 0.6mm -1 The coefficient between them. In fact, when the tooth is sinusoidal, the radius of curvature at the tooth valley between adjacent teeth is proportional to the ratio between the tooth spacing and the square of the tooth height. However, too small a radius of curvature at the tooth valley increases mechanical stress and makes blade manufacturing difficult, while too large a radius of curvature is less effective in reducing acoustic emissions.

[0024] The propulsion fan can have a pitch angle at the radial position of the tooth tip, which is radially oriented towards the outer radius R. e Monotonically decreasing. Additionally or alternatively, the radial position of each tooth tip can substantially correspond to the radial position of the local maximum or local minimum of the pitch angle. In this context, "substantially" means that the deviation between the radial position of the tooth tip and the radial position of the local maximum or local minimum of the pitch angle is within 5% of the blade profile height, preferably within 2% of the blade profile height.

[0025] The trailing edge of at least one blade in the first row of blades may include at least one toothless portion, particularly two toothless portions separated from each other in the radial direction. Specifically, at least the toothless portion may include portions extending to an outer radius R. e The toothless high portion. This toothless high portion may extend only 45% or less, preferably only 20% or less, of the blade height. Therefore, if at least a second row of blades, either rotating or fixed, is provided downstream of the first row, and the diameter of the second row is smaller than that of the first row, which is commonly referred to as clipping, omitting the teeth in the high portion is beneficial for blade manufacturing and mechanical strength without affecting the aerodynamic interaction between the upstream and downstream rows, because the blades in the downstream row may not be affected by the wake and / or vortex at the top of the toothless high portion of the blades in the upstream row.

[0026] However, it is also conceivable to provide a toothless portion of the trailing edge at a location other than the height of the blade. For example, when an air inlet is provided downstream of the first row of blades, particularly for a gas turbine engine, and especially located at the lower part of the first blade section, near its inner radius R. i In this case, it is conceivable to make the portion of the blade located upstream of the air inlet toothless at its trailing edge, so as to prevent one or more broken teeth from entering the air inlet in the event of their breakage. Furthermore, it is conceivable to make the middle portion of the blade toothless at its trailing edge, the middle portion extending, for example, between the lower and upper quarters of the blade height, in order to reduce mechanical stress in this particularly stressed area.

[0027] One or more of the teeth can be tilted radially outward to locally redirect airflow. Specifically, teeth located at the height of the blade, for example, at a distance of radius R from the outer edge... e Teeth with a distance less than 45% of the blade height, preferably less than 20% of the blade height, can be radially outwardly inclined to move outward away from the tip vortex and thereby reduce their interaction with, for example, the second row of blades located downstream of the first row. It is also conceivable that the tooth inclination gradually increases along the radial distance from the tooth pitch center axis.

[0028] As previously mentioned, a second row of blades can be positioned downstream of the first row, particularly in a configuration known as the USF configuration, in which the second row does not rotate about the central axis, although a configuration known as the CROR configuration is also conceivable, in which the second row rotates in the opposite direction to the first row. In either case, at least one blade in the first and / or second row can have a variable pitch. The leading edge of at least one blade in the second row can have a belly, and the trailing edge of at least one blade in the first row can have at least one tooth tip at a radial distance from the central axis, which is approximately equal to the radial distance of the belly relative to the central axis. The term "approximately equal to" in this context means that the radial distance of the tooth tip is equal to the radial distance of the belly, with an allowable deviation of ±20% (or even just ±10%) of the height of the first row of blades.

[0029] A second aspect of this disclosure relates to a propulsion device that may include a ductless propulsion fan according to the first aspect and a gas turbine engine for actuating the ductless propulsion fan. Specifically, the propulsion device may also include a reduction gear inserted between the gas turbine engine and the propulsion fan to reduce the speed of the propulsion fan relative to the output speed of the gas turbine engine. However, other actuation methods are also contemplated, such as a hybrid propulsion device, in which the gas turbine engine is combined with an electric motor, which may be connected in series between the gas turbine engine and the fan, or connected in parallel with the gas turbine engine in the drive line. An electric propulsion device is also contemplated, which includes only an electric motor for actuating the propulsion fan.

[0030] A third aspect of this disclosure relates to an aircraft that includes a thruster as described above. Attached Figure Description

[0031] A better understanding of the invention and its advantages will become more apparent from the following detailed description of embodiments illustrated by non-limiting examples. The description refers to the accompanying drawings, which are schematic and primarily serve to illustrate the principles of this disclosure.

[0032] In these figures, identical or equivalent elements (or parts thereof) are denoted by the same reference numerals. In these figures: [ Figure 1 ] Figure 1 The aircraft is shown schematically.

[0033] [ Figure 2 ] Figure 2 Schematically showing the ability to push Figure 1 The propulsion system of the aircraft is equipped with a propulsion fan according to the first embodiment.

[0034] [ Figure 3A ] Figure 3A A side view of the blades of the propulsion fan according to the first embodiment is shown.

[0035] [ Figure 3B ] Figure 3B Show Figure 3A A cross-sectional view of the middle blade along the BB plane.

[0036] [ Figure 3C ] Figure 3C Show Figure 3A The curve showing the variation of the chord length of the middle blade as a function of the radial distance relative to the central axis of the propulsion fan.

[0037] [ Figure 3D ] Figure 3D Show Figure 3AThe pitch angle of the middle blade is a curve showing the variation of the radial distance relative to the central axis of the propulsion fan.

[0038] [ Figure 3E ] Figure 3E Show Figure 3A Alternative form of the trailing edge of the middle blade.

[0039] [ Figure 4 ] Figure 4 A side view of the blades of a propulsion fan according to a second embodiment is shown.

[0040] [ Figure 5 ] Figure 5 A propulsion fan according to a third embodiment is shown.

[0041] [ Figure 6 ] Figure 6 A propulsion fan according to a fourth embodiment is shown.

[0042] [ Figure 7 ] Figure 7 A propulsion fan according to a fifth embodiment is shown.

[0043] [ Figure 8 ] Figure 8 A side view of the propulsion fan blades according to the sixth embodiment is shown.

[0044] [ Figure 9 ] Figure 9 A side view of the propulsion fan blades according to the seventh embodiment is shown.

[0045] [ Figure 10 ] Figure 10 A side view of the propulsion fan blades according to the eighth embodiment is shown. Detailed Implementation

[0046] To make this disclosure more specific, embodiments will now be described in detail with reference to the accompanying drawings. However, it should be noted that the present invention is not limited to these embodiments.

[0047] like Figure 1 As shown, the aircraft 1 may include one or more thrusters 10 having a ductless propulsion fan 100 according to the present disclosure. These thrusters 10 may be arranged, in particular, below the wing 2 as shown, but other alternative arrangements are also conceivable, such as at the rear of the fuselage of the aircraft 1.

[0048] like Figure 2As shown, the propulsion unit 10 may also include a gas turbine engine 11 and a reduction gear 12. Along the airflow direction, the gas turbine engine 11 may include a low-pressure compressor 13, a high-pressure compressor 14, a combustion chamber 15, a high-pressure turbine 16, a low-pressure turbine 17, and a nozzle 18, all surrounded by a cowl 19 leading to the nozzle 18. The high-pressure turbine 16 can be connected to the high-pressure compressor 14 via a first shaft 21 to drive the high-pressure compressor 14, while the low-pressure turbine 17 can be connected to the low-pressure compressor 18 in a similar manner via a second shaft 22 coaxial with the first shaft 21. The reduction gear 12 can connect the second shaft 22 to the propulsion fan 100 to actuate the fan 100. Although in the illustrated example the propulsion fan 100 is positioned at the front of the propulsion unit 10 in a configuration known as a pull configuration, it is conceivable that it could be positioned at the rear of the propulsion unit in a push configuration.

[0049] As a complement to or alternative to the gas turbine engine 11, the propulsion unit 10 may also include another type of engine, particularly an electric motor, for driving the fan directly and / or via a transmission device such as a reduction gear 12. Therefore, the propulsion unit 10 can be a series or parallel hybrid propulsion unit, or even a purely electric propulsion unit.

[0050] The propulsion fan 100 may include two rows of blades: a first row of blades 110 and a second row of blades 120 located downstream of the first row of blades 110. The two rows may, in particular, be coaxial, with the two rows of blades 110, 120 arranged radially about the same central axis X, but they may also be conceived to have different, in particular, parallel, central axes. Each of the two rows may, for example, contain 8 to 16 blades, particularly 10 to 14 blades. However, to minimize noise emitted by the propulsion fan 100, the first row may have more blades than the second row; for example, the first row may have at least two more blades than the second row.

[0051] like Figure 2 and Figure 3A As shown, each of the two rows of blades 110, 120 may include a profile extending radially from the inner radius to the outer radius relative to the corresponding row. However, the inner radius Ri and / or outer radius R of the first row... e The inner radius R can be different from that of the second row. i 'and / or outer radius R e Specifically, as shown in the figure, the outer radius R of the second row... e It can be smaller than the outer radius R of the first row. e (Cutting the tip) to avoid interference from the tip vortices of the first row of blades with the second row of blades 120. The outer radius R of the first row. e For example, it can be between 0.5 and 3 m, especially between 1.5 and 2.5 m. The inner radius R of the first row of blades 110 i With outer radius Re The ratio R between i / R e For example, it can be between 0.1 and 0.5, especially between 0.25 and 0.35, and even more especially between 0.26 and 0.32.

[0052] Each blade 110, 120 profile can be formed by stacked airfoils along the corresponding radial stacking axes Z, Z', thus as... Figure 3B The diagram shows a pressure side 111 and a suction side 112, each extending from a leading edge BA to a trailing edge BF. For example, for the cross-section or airfoil of blade 110, the leading edge BA can be defined as the upstream end along the fluid flow direction. The leading edge BA can be characterized by defining a local minimum of the radius of curvature of the surface at its upstream portion. The trailing edge BF can be defined as the downstream end along the fluid flow direction. When the trailing edge BF is circular, it can also be characterized by defining a local minimum of the radius of curvature of the surface at its rear portion; however, to simplify the manufacturing process, the trailing edge BF can alternatively be as follows: Figure 3E The diagram shows a truncated form. These sections or airfoils can be cambered in particular. Each stacked surface has a chord length c, defined as the distance between the leading edge BA and the trailing edge BF along the straight line connecting them and relative to a plane perpendicular to the central axis X, with a pitch angle γ. The chord length c and the pitch angle γ can vary as a function of the radial distance r from the central axis X of the propulsion fan.

[0053] Typically, the pitch angle γ of an airfoil corresponds to the angle formed between two points: on one hand, the first axis 150, which is defined by the intersection of the airfoil plane at a radial distance r and the plane perpendicular to the central axis X; and on the other hand, the straight line connecting the leading edge BA and the trailing edge BF of the airfoil at a radial distance r. The pitch angle γ is measured upstream of the plane perpendicular to the central axis X. The pitch angle γ is measured in the positive direction from the first axis 150 to the straight line connecting the leading edge BA and the trailing edge BF, especially in the direction consistent with the direction from the pressure side line 111 to the suction side line 112.

[0054] like Figure 3A As shown, the inner radius R of the first row of blades 110 i and outer radius R e The distance can be measured on the trailing edge BF, corresponding to the minimum and maximum radial positions relative to the central axis X, respectively. When the blade 110 has a variable pitch, the radial distance can be measured when the blade 110 is positioned at any pitch angle that allows air circulation through the fan in its normal direction. For example, when located at R... eWhen the pitch angle γ of the blade 110 section at 75% of its length is equal to 60°, this pitch angle can represent the pitch angle of the blade 110 during cruise. Similarly, the inner radius R of the first row of blades 120... i 'and outer radius R e The distance can be measured at the leading edge BA, corresponding to the minimum and maximum radial positions relative to the central axis X, respectively. When the blade 120 has a variable pitch, the radial distance can be measured when the blade 120 is positioned at any pitch angle that allows air circulation through the fan in its normal direction. For example, when located at R... e When the blade pitch angle γ' at approximately 75% of the blade section 120 is equal to 80°.

[0055] Each of the two rows of blades may have, for example, a solidity of less than 2.5 over the entire height H, H' of the blades 110, 120, or a solidity of less than 2.5 over the outer radius R of that row. e R e The solidity at that point is even less than 0.5. Within the framework of this disclosure, "blade height" refers to the outer radius R of its surface body. e With inner radius R i R i The difference between the two, "realism," refers to the ratio of the chord length c of each blade 110, 120 in a row to the distance between two adjacent blades in the same row at the same radial distance r from the central axis X. Each blade 110 in the first row can have an outer radius R equal to... e Multiply by a factor between 0.8m -1 With 2.4m -1 Between, preferably between 1.2m -1 With 2.2m -1 Between, or even preferably between 1.4m -1 With 1.8m -1 The aspect ratio is the coefficient between the height H and the average chord length C of the blade. Within the framework of this disclosure, the "aspect ratio" refers to the ratio between the height H and the average chord length C of the blade. The average chord length C can be calculated based on the distribution c(r) of the local chord length c with respect to radius distance, according to the following formula:

[0056] The axial distance between the stacking axes Z and Z' of the two rows of blades can be, for example, the outer radius R of the first row of blades 110. eThe pitch is 0.05 to 1.2 times, particularly 0.36 to 0.6 times, and is especially sufficient to prevent interference between the trailing edge BF of the first row of blades 110 and the leading edge of the second row of blades 120. Each of the blades 110 and 120 can rotate about a radial axis or a pitch-changing axis, which can in particular be a corresponding overlapping axis Z, Z', to adjust its pitch according to the flight phase, and thus its angle of attack relative to the direction of airflow. This pitch-changing axis can preferably be perpendicular to the central axis X, or alternatively inclined relative to the central axis X.

[0057] like Figure 2 As shown, at least the first row of blades 110 is rotatable about the central axis X, and is mechanically connected to the gas turbine engine 11, via a reduction gear 12, for the purpose of driving its rotation about the central axis X. Furthermore, to benefit from the increased downstream air pressure of the first row of blades 110, the air inlet 20 of the gas turbine engine 11 can be located between the two rows of blades 110, 120. This air inlet 20 can be, for example, annular, and separated from the cowling 19 by slats 23.

[0058] On the other hand, also as Figure 2 As shown, in the USF-type ductless configuration, the second row of blades 120 is non-rotatable about the central axis X. However, alternatively, it is conceivable that in the CROR-type configuration, it is also rotatable about the central axis X, and is particularly mechanically connected to the gas turbine engine 11, driven to rotate about the central axis X, but in the opposite direction to the rotation of the first row of blades 110. In this case, it is also conceivable that the rotational speed of the second row of blades 120 is less than or equal to the rotational speed of the first row of blades, especially during the takeoff and / or landing phases of the aircraft 1. This allows for a reduction in the flow velocity interacting with the second row of blades 120, thereby reducing interaction noise and limiting (or avoiding) shock wave formation.

[0059] The trailing edge BF of each blade 110 in the first row can have N teeth, and the tooth height of each tooth is h. j , where j=1,2,…N, and from the inner radius R i To outer radius R e The radial direction is ordered in ascending order, and the distance λ between the tips of adjacent teeth of number M is... k Where k = 1, 2, ..., M, and M ≤ N-1, and from the inner radius R i To outer radius R eThe order is ascending in the radial direction. In the context of this disclosure, "tooth tip" refers to the local maximum value of the chord length c in the radial direction, and "tooth height" refers to the difference between the chord length at the tooth tip and the chord length at the tooth valley, which is the local minimum value of the chord length between the tooth tip and the tooth tip of the adjacent tooth. It should be noted that the tooth tip can be characterized by the first derivative of c(r) being zero and the second derivative being negative, while the tooth valley can be characterized by the first derivative of c(r) being zero and the second derivative being positive.

[0060] Due to the camber of the stacked profile of blade 110, the change in chord length c can be accompanied by a change in the pitch angle γ, such as... Figure 3C and Figure 3D As shown, this is to optimize the aerodynamic operation of blade 110. Especially at the radial position r of each tooth tip. j At that point, the pitch angle γ may have a local maximum or a local minimum, with a deviation of, for example, ±5% of the profile height H of the blade 110, preferably ±2%.

[0061] The distance λ between the tips of adjacent teeth k In k=1,2,…M, the maximum spacing λ max With minimum spacing λ min The ratio between them can be less than 15, preferably less than 8, and more preferably less than 5. This maximum spacing λ max With minimum spacing λ min The ratio between them can be greater than 1.25. Maximum spacing λ max It can also be 0.05 to 0.4 times the profile height H of the blade 110, preferably 0.1 to 0.35 times the height, and more preferably 0.15 to 0.3 times the height.

[0062] Each tooth can have a tooth height h. j The tooth height h j λ is the distance between the cusps of the same tooth and the cusps of adjacent teeth. k The distance λ is 0.1 to 2 times that of the tooth tip, preferably the distance λ between the tooth tips of the same tooth and the tooth tips of adjacent teeth. k The distance λ is 0.2 to 1.6 times that of the tooth tip, more preferably the distance λ between the tooth tips of the same tooth and the tooth tips of adjacent teeth. k 0.3 to 1.2 times.

[0063] like Figure 2 and Figure 3A As shown, the teeth can be wavy, especially in a basic sinusoidal shape, although other alternatives, such as triangular teeth, can also be conceived. The trailing edge can be constructed such that the distance λ between the tips of each adjacent tooth is... k It can be equal to the square of the height of one of the adjacent teeth multiplied by a factor between 0.005mm. -1 With 1mm -1The coefficient between these values ​​is preferably between 0.01 mm. -1 With 0.8mm -1 Between, more preferably between 0.02 mm -1 With 0.6mm -1 This is especially true when the teeth are sinusoidal. Therefore, a trade-off can be achieved between aerodynamic efficiency and mechanical strength for the radius of curvature of the teeth.

[0064] like Figure 2 and Figure 3A Similarly, as shown, the continuity of the teeth can be derived from the inner radius R. i Extending to outer radius R e The entire height H of the profile body covering blade 110. In particular, the trailing edge BF can be relative to the outer radius R. e The blade tip has a final tooth valley or tooth tip at a radial distance less than 30% or even 20% of the height H, specifically used to guide the flow of the tip vortex radially outward, thereby avoiding undesirable interaction with the blades 120 in the second downstream row. Furthermore, the trailing edge BF can be positioned relative to the inner radius R. i The first tooth valley or tooth tip is located at a radial distance less than 30% or even 20% of the height H, especially to avoid or limit boundary layer separation near the root of blade 110, which may also have undesirable interactions with the blades 120 of the second downstream row, or reduce the aerodynamic performance of inlet 20.

[0065] Furthermore, when the leading edge BA' of the second row of blades 120 is at a radial distance r from the central axis X... v The abdomen has a V-shape, and the radial distance r is... v Inner radius R of the second row i 'With outer radius R e When ' ', the trailing edge BF of the first row of blades 110 can be at a radial distance r from the central axis X. j The radial distance r has at least one tooth tip. j Equal to radial distance r vThe permissible deviation is a maximum of ±20% or even ±10% of the height H, in order to reduce the undesirable interaction between the wake of the first row of blades 110 and the belly region V of the second row of blades 120. In fact, at the belly region V of blade 120, the axial distance between the trailing edge BF of blade 110 and the leading edge BA' of blade 120 can be reduced, and the leading edge BA' of blade 120 has a reduced or zero sweep angle, which increases interaction noise. From an aerodynamic perspective, the tooth tip allows for a local reduction in velocity deficit in the wake of blade 110; therefore, placing the tooth tip of the trailing edge BF of blade 110 at a radial position at the belly region V of the leading edge BA' of blade 120 helps to reduce interaction noise. In the context of this disclosure, the “belly” of the blade leading edge refers to the point where the leading edge extends most forward in the upstream axial direction.

[0066] The spacing λ k It can vary, especially in the radial direction towards the outer radius R. e Monotonically decreasing, such that λ1≥λ2≥λ3≥…λ M-1 ≥λ M Therefore, any adjacent spacing λ k With λ k+1 The ratio between them can be between 1 and 2, preferably between 1.03 and 1.5. Furthermore, as... Figure 3D As shown, the tooth tip is at a radial position r j The pitch angle γ at that point can also be directed radially toward the outer radius R. e Monotonically decreasing, such that γ(r1)≥γ(r2)≥γ(r3)…γ(r N-1 )≥γ(r N To accommodate the rotation of the blades towards the outer radius R e A reduced relative flow angle. Alternatively, however, a spacing λ can be envisioned. k In the radial direction toward the outer radius R e Increase. For example, Figure 2 and Figure 3A As shown, all spacings can be different, such that when the spacing λ k Towards outer radius R e When decreasing, λ1>λ2>λ3…λ M-1 >λ M In particular, each adjacent spacing λ k With λ k+1 The ratio between them can be approximated as 1 plus the reciprocal of a positive integer.

[0067] Alternatively, it can be envisioned that while all spacings decrease or increase monotonically overall, some spacings remain the same. Therefore, according to Figure 4In the second embodiment shown, at least two spacings, for example two to five spacings, especially two, three, or four spacings, can be substantially the same. The same spacing can be particularly located in the high portion BFh of the trailing edge BF of the blade 110, adjacent to the outer radius R. e And, for example, extending 45% or 20% of the upper portion of the profile height H along the blade 110. However, other characteristics of the propulsion fan can be the same as or equivalent to those of the first embodiment, therefore in Figure 4 The same reference numerals as those used in the aforementioned figures are used in this figure.

[0068] Furthermore, although in the two embodiments described above the teeth extend along the entire height H of the profile of the blade 110, it is conceivable that at least a portion of the trailing edge may be toothless. Therefore, according to Figure 5 In the third embodiment shown, the adjacent outer radius R of the trailing edge BF of blade 110 is... e The high portion BFh can be toothless. In this embodiment, the toothless high portion BFh can, for example, extend from a radial distance r, which is related to the outer radius R of a row of smaller diameter blades 120 disposed downstream. e 'Basically the same. However, other features of the propulsion fan can be the same as in the aforementioned embodiments, therefore in Figure 5 The same reference numerals as those used in the aforementioned figures are used in this figure.

[0069] Although in the third embodiment the toothless portion is the high portion of the trailing edge, it is also conceivable alternatively or complementaryly to have one or more different toothless portions of the trailing edge BF of the blade 110. Therefore, according to Figure 6 In the fourth embodiment shown, the lower portion BFb of the trailing edge BF may also be toothless. Specifically, the lower portion BFb of this trailing edge BF can be formed from the inner radius R. i Extending to a radial distance r, which can be equal to or greater than the radial position Rb of the slat 23 of the air inlet 20 located downstream of the blade 110, this is particularly useful for preventing teeth from entering the air inlet 20 in the event of tooth breakage, thereby avoiding a reduction in the propeller's operating performance. However, other characteristics of the propulsion fan can be the same as in the aforementioned embodiment, therefore in Figure 5 The same reference numerals as those used in the aforementioned figures are used in this figure.

[0070] Alternatively, however, at least one toothless portion may be the middle BFc of the trailing edge BF of the blade 110, which does not extend to the inner radius R. i It does not extend to the outer radius R. e ,like Figure 7 and Figure 8 The fifth and sixth embodiments are shown respectively. The toothless central portion BFc can extend, in particular, between the two tooth tips, as... Figure 7 The fifth embodiment shown, or alternatively, extends between the two tooth valleys, as... Figure 8The sixth embodiment shown.

[0071] The teeth can be radially outward tilted. With this tilt, even if the spacing between the cusps of adjacent teeth decreases monotonically, the radial distance Δr between at least one cusp and the adjacent outward-facing tooth valley remains constant. a It can be less than the radial distance Δr between the adjacent tooth valley and its next outward tooth tip. b It can be imagined that only the teeth located on the high part BFh at the trailing edge are inclined outward, such as... Figure 9 As shown in the seventh embodiment, it may have a transition region with a gradually increasing slope. However, it is also conceivable that... Figure 10 In the eighth embodiment shown, all teeth are tilted outwards.

[0072] Although the invention has been described with reference to specific exemplary embodiments, it will be apparent that various modifications and changes can be made to these examples without departing from the overall scope of the invention as defined by the claims. Furthermore, various features of the mentioned embodiments may be combined in additional embodiments. Therefore, the specification and drawings should be considered in an illustrative rather than restrictive sense.

Claims

1. A ductless propulsion fan (100) comprising at least a first row of blades (110) rotatable about a central axis (X), each blade (110) in the first row comprising a profile body with an internal radius R relative to the central axis (X). i Extending radially to outer radius R e It includes a pressure side (111) and a suction side (112) that connect the leading edge (BA) to the trailing edge (BF). in, Each blade (110) in the first row of blades (110) has a surface profile with a motion factor FA between 100 and 225, preferably between 150 and 200, the motion factor FA being defined according to the following formula: Where ξ represents the radial distance relative to the central axis (X) divided by the outer radius R. e c(ξ) represents the local chord length between the leading edge (BA) and the trailing edge (BF) of the surface body at the radial distance, and The feature is that it further includes a second row of blades (120) disposed downstream of the first row of blades (110), wherein the trailing edge (BF) of the profile of at least one blade (110) in the first row of blades (110) has serrations, and the leading edge (BA') of at least one blade (120) in the second row of blades (120) has a belly (V), and the trailing edge (BF) of at least one blade (110) in the first row of blades (110) is at a radial distance (r) from the central axis (X). j At least one tooth tip is present at the radial distance (r). j The distance (r) is approximately equal to the radial distance of the abdomen (V) relative to the central axis (X). v ).

2. The ductless propulsion fan (100) according to claim 1, characterized in that, The trailing edge (BF) has a spacing (λ) between the cusps of adjacent teeth. k The spacing is radially oriented towards the outer radius R. e It decreases monotonically.

3. The ductless propulsion fan (100) according to claim 2, characterized in that, The distance (λ) between the tips of adjacent teeth k Each spacing (λ) in ) k They are different.

4. The ductless propulsion fan (100) according to claim 2, characterized in that, The distance (λ) between the tips of adjacent teeth k At least two adjacent spacings in the equation are substantially the same.

5. The ductless propulsion fan (100) according to any one of claims 2 to 4, characterized in that, The distance (λ) between the tips of adjacent teeth k The ratio between the maximum and minimum spacing in the () is less than 15, preferably less than 8, more preferably less than 5 and greater than 1.

25.

6. The ductless propulsion fan (100) according to any one of claims 2 to 5, characterized in that, The distance (λ) between the tips of adjacent teeth k The maximum spacing in the outer radius R is between e With the inner radius R i The difference is between 0.05 and 0.4 times, preferably between the outer radius R. e With the inner radius R i The difference is between 0.1 and 0.35 times, more preferably between the outer radius R. e With the inner radius R i The difference is between 0.15 and 0.3 times.

7. The ductless propulsion fan (100) according to any one of claims 2 to 6, characterized in that, The distance (λ) between the tips of adjacent teeth k The minimum spacing in the outer radius R is between e With the inner radius R i The difference is between 0.01 and 0.2 times, preferably between the outer radius R. e With the inner radius R i The difference is between 0.02 and 0.15 times, more preferably between the outer radius R. e With the inner radius R i The difference is between 0.04 and 0.12 times.

8. The ductless propulsion fan (100) according to any one of claims 2 to 7, characterized in that, The distance (λ) between the tips of adjacent teeth k The ratio between any two adjacent spacings in the equation is between 1 and 2, preferably between 1.03 and 1.

5.

9. The ductless propulsion fan (100) according to any one of claims 2 to 8, characterized in that, At the radial position of the tooth tip (r j The pitch angle (γ) is located at ) j The pitch angle (γ) j ) in the radial direction toward the outer radius R e It decreases monotonically.

10. The ductless propulsion fan (100) according to any one of the preceding claims, characterized in that, Each blade (110) in the first row of blades (110) has an aspect ratio equal to the outer radius R. e Multiply by a factor between 0.8m -1 With 2.4m -1 The coefficient between these values ​​is preferably between 1.2m. -1 With 2.2m -1 The coefficient between these values ​​is preferably between 1.4m. -1 With 1.8m -1 The coefficients between them.

11. The ductless propulsion fan (100) according to any one of the preceding claims, characterized in that, Each tooth of the trailing edge (BF) has a tooth height (h) j The tooth height (h) j The distance (λ) between the cusp of the same tooth and the cusp of the adjacent tooth. k The distance is between 0.1 and 2 times that of the tooth tip, preferably between the distance (λ) between the tooth tip of the same tooth and the tooth tip of the adjacent tooth. k The distance between 0.2 and 1.6 times that of the tooth tip, more preferably between the distance between the tooth tip of the same tooth and the tooth tip of an adjacent tooth (λ). k The value is between 0.3 and 1.2 times that of ) 12. The ductless propulsion fan (100) according to any one of the preceding claims, characterized in that, The radial position of each tooth tip (r) j The radial position that basically corresponds to the local maximum or local minimum of the pitch angle.

13. The ductless propulsion fan (100) according to any one of the preceding claims, characterized in that, Each distance (λ) between the cusps of adjacent teeth k ) equals the tooth height (h) of one of the adjacent teeth. j The square of ) multiplied by a factor between 0.005mm -1 With 1mm -1 The coefficient between these values ​​is preferably between 0.01 mm. -1 With 0.8mm -1 The coefficient between these values ​​is more preferably between 0.02 mm. -1 With 0.6mm -1 The coefficients between them.

14. The ductless propulsion fan (100) according to any one of the preceding claims, characterized in that, The trailing edge (BF) of at least one blade (110) of the first row of blades (110) includes at least one toothless portion, particularly including two toothless portions separated from each other in the radial direction.

15. The ductless propulsion fan (100) according to claim 14, characterized in that, The at least one toothless portion includes a portion extending to the outer radius R. e The high part (BFh).

16. The ductless propulsion fan (100) according to any one of the preceding claims, characterized in that, One or more of the teeth are radially outward inclined.

17. The ductless propulsion fan (100) according to any one of the preceding claims, characterized in that, The second row of blades (120) is non-rotatable about the central axis (X).

18. A propulsion unit (10) comprising a ductless propulsion fan (100) according to any of the preceding claims and a gas turbine engine (11) for actuating the ductless propulsion fan (100).

19. An aircraft (1) comprising a thruster according to claim 18.

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