Fan for aircraft propulsion

Abstract

A propeller fan for aircraft propulsion. A propulsive fan (100) comprising at least one first row of blades (110) capable of rotating about a central axis (X). Each of the blades (110) in the first row comprises a streamlined body extending radially from an inner radius Ri to an outer radius Re with respect to the central axis (X) and comprising an intrados (111) and an extrados (112) connecting a leading edge (BA) to a trailing edge (BF). The trailing edge (BF) of the streamlined body of each blade (110) in the first row of blades (110) has saw teeth, and the streamlined body of each blade (110) in the first row of blades (110) has an activity factor FA between 225 and 300. Figure for the abstract: Fig. 2.

Description

Title of the invention: Fan for aeronautical propulsion Technical field

[0001] The technical field of the present disclosure is that of propulsion and in particular that of propulsive fans, such as those intended in particular to be driven by a gas turbine engine in aeronautical propulsion. Prior art

[0002] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft and those in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0003] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0004] Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0005] This sustained research and development work covers new generations of aircraft engines, the lightening of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as essential complements to technological progress, aeronautical biofuels.

[0006] The search for minimizing polluting emissions linked to air transport involves in particular improving all the efficiencies of propulsion systems, and more particularly the propulsive efficiency which characterizes the efficiency with which the energy used is converted into useful thrust.

[0007] The elements influencing this propulsive efficiency to the first order are those which contribute immediately to the generation of thrust, including propulsive fans. The known guiding principle for improving propulsive efficiency is to reduce the compression ratio of the fan, thereby reducing the airflow velocity at the fan outlet and the associated kinetic energy losses.

[0008] To obtain the same thrust, this reduction in flow velocity at the outlet of the propulsive fan must normally be compensated by a greater mass flow rate of air, and therefore a larger diameter of the fan. When this fan is driven by a gas turbine engine, this normally also implies a greater dilution ratio (in English, "bypass ratio", abbreviated "BPR"), which is the ratio between the mass flow rate of the cold flow of the fan (secondary flow) and that feeding the combustion chamber of the gas turbine engine (primary flow).

[0009] When the fan is shrouded, the increase in the diameter of the fan also implies an increase in the external dimensions of the retention casing surrounding it, as well as of the nacelle constituting the aerodynamic envelope of the casing in question, and therefore its drag, as well as that of their mass. In order to avoid these drawbacks, it is possible to shorten the axial length of the nacelle and to thin it, which reduces the space available for the acoustic treatments which serve to reduce noise.

[0010] Furthermore, the interactions between successive rows of blades and vanes can aggravate these noise emissions, in particular at the harmonics of the blade passing frequency (BPF). Significant research and development efforts have therefore been directed, in particular by the Applicant, towards reducing these noise emissions. To this end, it has been proposed, in particular in the publications of international patent applications WO 2023 / 007098 A1 and WO 2019 / 158875 A1, to form teeth or undulations on the trailing edge of the blades of unducted propulsive fans, so as to reduce or distribute their marginal vortices. This solution has also been proposed for ducted fans, for example in the publications of French patent applications FR 2 986 285 A1 and FR 3 103 231 A1.Furthermore, it has also been proposed to incorporate teeth or undulations into the leading edge for similar reasons, for example in European patent application publication EP 2 760 737 A1 and in US patents 11,560,796 and US 11,047,238. Statement of the invention

[0011] This disclosure is the result of technological research aimed at significantly improving the performance of aircraft and, in this sense, contributes to reducing their environmental impact, particularly in terms of noise emissions. For this purpose, a first aspect of this disclosure concerns a fan propulsive, comprising at least one row of blades capable of rotating about a central axis, each of the blades of the row of blades comprising a profiled body extending radially from an inner radius R; to an outer radius Re relative to the central axis and comprising a lower surface and an upper surface connecting a leading edge to a trailing edge. The profiled body of each blade of the row of blades has an activity factor FA between 225 and 300, preferably between 240 and 300, said activity factor FA being defined according to the equation: 100,000 f1 >°where f represents a radial distance from the axis central, divided by the outer radius Re, and c(f) represents a local chord between the leading and trailing edges of the profiled body at said radial distance f. Furthermore, the trailing edge of the profiled body of at least one blade of the row of blades has saw teeth.

[0012] The relatively high activity factor FA between 225 and 300 is conducive to better propulsive efficiency, but implies that the chord is relatively large in the upper part of the blade, i.e. near its outer radius Re. Since the thickness of the boundary layer at the trailing edge normally increases with the chord, such a relatively high activity factor FA is normally associated with an increase in the inherent, broad-band noise of the fan, and in the characteristic width or scale of the wake vortices of the blades. The inventors have, however, found that the teeth at the trailing edge make it possible to limit noise emissions even with such a high activity factor FA, so as to combine high propulsive efficiency with moderate noise emissions.

[0013] The trailing edge may in particular have spacings between the apexes of adjacent teeth which decrease monotonically in the radial direction towards the outer radius Re. By “monotonic” decrease, in the context of the present disclosure, it is meant that the spacing between the apexes of the adjacent teeth located most radially to the outside is less than that between the apexes of the adjacent teeth located most radially to the inside and that, from the spacing between the apexes of the adjacent teeth located most radially to the inside to the spacing between the apexes of the adjacent teeth located most radially to the outside, each spacing is equal to or less than the preceding adjacent spacing. However, it is alternatively conceivable that the spacings between the apexes of adjacent teeth are increasing in the radial direction towards the outer radius Re.

[0014] Thus, it is conceivable that each spacing among said spacings between tops of adjacent teeth is different, that is to say that, from the spacing between the tops of the adjacent teeth located most radially on the inside to the spacing between the tops of the adjacent teeth located most radially on the outside, each spacing is less than the previous adjacent spacing if the spacings between adjacent tooth tips decrease towards the outer radius Re.

[0015] However, it is alternatively conceivable that at least two adjacent spacings, but preferably not more than five, or even three, among said spacings between adjacent tooth tips, preferably in an upper part of the blade, close to its outer radius, are substantially identical, in particular in order to simplify the production of the blades.

[0016] Each of the blades in the row of blades may have an elongation equal to the outer radius Re multiplied by a coefficient between 1.2 m1 and 2.6 m1, preferably between 1.6 m1 and 2.2 m1. Such an elongation, normalized by the outer radius Re of the blade, and therefore the diameter D of the row of blades, makes it possible to obtain a good distribution of the aerodynamic load.

[0017] Although the spacings between adjacent tooth apexes decrease monotonically from the inner radius R; to the outer radius Re, it is conceivable that a ratio between a maximum spacing and a minimum spacing among said spacings between adjacent tooth apexes is less than 15, preferably less than 8, and even more preferably less than 5, so as to limit the number of teeth and / or the number of different spacings and thus simplify the production of the blades. This ratio between the maximum spacing Xmax and the minimum spacing / .,nm may also be in particular greater than 1.25.

[0018] A maximum spacing among said spacings between adjacent tooth tips may be between 0.05 and 0.4 times the height of the profiled body of the blade, i.e., the difference between said outer radii Re and inner radii R;, preferably between 0.1 and 0.35 times said height, more preferably between 0.15 and 0.3 times said height. It is thus possible to obtain a maximum spacing which may be of the order of magnitude of the wavelength of the second harmonic r2 of the blade passage frequency (“BPF”) during the takeoff phase of the aircraft, which may be particularly important in terms of acoustic nuisance. This wavelength of the second harmonic of the BPF may be estimated according to the equation: „ _ 3Oco in which c0 represents the speed of sound (in m / s), B the number of blades and Q the rotational speed of the first row of blades (in revolutions per minute). Furthermore, a minimum spacing among said spacings between adjacent tooth tips is between 0.01 and 0.2 times a difference between said outer radii Re and inner radii R;, preferably between 0.02 and 0.15 times the difference between said outer radii Re and inner radii R;, more preferably between 0.04 and 0.12 times the difference between said outer radii Re and inner radii R;.

[0019] The trailing edge may be formed such that any ratio between adjacent spacings among said spacings between adjacent tooth tips is between 1 and 2, preferably between 1.03 and 1.5. In particular, each ratio between adjacent spacings may be approximately equal to one plus the inverse of a positive integer. By "approximately" is meant that it may be subject to a margin of error of ±30%, or preferably ±10%. This makes it possible to have adjacent spacings decreasing according to the wavelength of the blade passing frequency ("BPF") or its harmonics.

[0020] The trailing edge may be configured such that each of the teeth of the trailing edge has a height between 0.1 and 2 times a spacing between the top of the same tooth and the top of an adjacent tooth, preferably between 0.2 and 1.6 times the spacing between the top of the same tooth and the top of the adjacent tooth, more preferably between 0.3 and 1.2 times the spacing between the top of the same tooth and the top of the adjacent tooth. The choice of this ratio makes it possible to better reduce noise emissions, while ensuring good mechanical strength.

[0021] Said teeth of the trailing edge may take the form of undulations, in particular sinusoidal, although other forms are also conceivable. The trailing edge may be configured such that each spacing between the tops of adjacent teeth is equal to the square of the height of one of the adjacent teeth, multiplied by a coefficient between 0.005 mm1 and 1 mm ', preferably between 0.01 mm1 and 0.8 mm ', more preferably between 0.02 mm1 and 0.6 mm ', in particular if the teeth are sinusoidal. Indeed, when the teeth are sinusoidal, the radius of curvature at the hollows between adjacent teeth is proportional to the ratio between the spacing and the square of the height. However, a radius of curvature that is too small at the hollows increases the mechanical stresses and makes the manufacture of the blade difficult, while a radius of curvature that is too large would be less effective for reducing noise emissions.

[0022] The propulsive fan may have pitch angles, at the radial positions of the tooth apexes, which decrease monotonically in the radial direction towards the outer radius Re. In addition to or alternatively to this, the radial position of each tooth apex may correspond substantially to a radial position of a local maximum or a local minimum of the pitch angle. In this context, the term "substantially" may be understood to mean that the radial positions of the tooth apexes and the radial positions of local maxima or minima of the pitch angle correspond to within 5%, preferably within 2%, of the height of the profiled body of the blade.

[0023] Said trailing edge of the at least one blade of the row of blades may comprise at least one part without teeth, and in particular two parts without teeth separated from each other in the radial direction.

[0024] For example, when an air inlet, in particular a gas turbine engine air inlet, is arranged downstream of the row of blades, and in particular of a lower part of the blades of the part of the blades, adjacent to their inner radius R;, it is possible for this part of the blades arranged upstream of the air inlet to be devoid of teeth, thus preventing them from being able to enter the air inlet in the event of breakage of one or more teeth. In addition, it is also possible for a middle part of the blades, extending for example between the lower quarter and the upper quarter of the height of the blades, to be devoid of teeth on the trailing edge, in order to reduce the mechanical stresses in this particularly stressed area.

[0025] As indicated previously, a row of outlet guide vanes or OGVs (from the English "Outlet Guide Vanes") may be arranged downstream of the row of blades, in particular according to a configuration in which this row of guide vanes is not rotatable about the central axis. At least one blade of the row of blades and / or one guide vane of the row of guide vanes may be of variable pitch. A leading edge of at least one guide vane of the row of guide vanes may have a belly, and the trailing edge of at least one blade of the row of blades may then have at least one tooth tip at a radial distance from the central axis approximately equal to a radial distance of said belly relative to the central axis. By "approximately equal", it may be understood, in this context, that the radial distance of the tooth tip is equal to that of the belly, ±20% (or even only ±10%) of the height of the blade of the first row.

[0026] The propulsive fan may in particular be a ducted propulsive fan, further comprising a nacelle surrounding at least the row of blades.

[0027] A second aspect of the present disclosure relates to a thruster which may comprise the propulsive fan according to the first aspect and a gas turbine engine for actuating the propulsive fan. The thruster may in particular also comprise a reduction gear interposed between the gas turbine engine and the propulsive fan, in order to reduce the rotational speed of the propulsive fan relative to an output speed of the gas turbine engine. However, other actuation means are also conceivable, such as for example a hybrid thruster in which the gas turbine engine would be combined with an electric motor, which could be interposed in series between the gas turbine engine and the fan, or be arranged in parallel with the gas turbine engine in a transmission line. An electric thruster, comprising only an electric motor for actuating the propulsive fan, is also conceivable.

[0028] A third aspect of the present disclosure relates to an aircraft comprising a propellant as described above. Brief description of the drawings

[0029] The invention will be well understood and its advantages will appear better, on reading the detailed description which follows, of embodiments represented as non-limiting examples. The description refers to the appended drawings which are schematic and aim above all to illustrate the principles of the disclosure.

[0030] In these drawings, from one figure to another, identical or equivalent elements (or parts of elements) are identified by the same reference signs. In these attached drawings:

[0031] [Fig-1] [Fig.l] schematically illustrates an aircraft.

[0032] [Fig.2] [Fig.2] schematically illustrates a propeller, suitable for the propulsion of the aircraft of [Fig.l], equipped with a ducted propulsive fan according to a first embodiment.

[0033] [Fig.3A] [Fig.3A] represents a side view of a blade of the propulsive fan of the first embodiment.

[0034] [Fig.3B] [Fig.3B] represents a sectional view of the blade of [Fig.3A] along plane BB.

[0035] [Fig.3C] [Fig.3C] illustrates an evolution of the chord of the blade of [Fig.3A] as a function of the radial distance from the central axis of the propulsive fan.

[0036] [Fig.3D] [Fig.3D] illustrates the evolution of the pitch angle of the blade of [Fig.3A] as a function of the radial distance from the central axis of the propulsive fan.

[0037] [Fig.3E] [Fig.3E] illustrates an alternative shape of the trailing edge of the blade of the [Fig.3A].

[0038] [Fig.4] [Fig.4] represents a side view of a blade of a propulsive fan according to a second embodiment.

[0039] [Fig.5] [Fig.5] illustrates a propulsive fan according to a third mode of realization.

[0040] [Fig.6] [Fig.6] illustrates a propulsive fan according to a fourth mode of realization.

[0041] [Fig.7] [Fig.7] illustrates a propulsive fan according to a fifth mode of realization. Description of the embodiments

[0042] In order to make the disclosure more concrete, embodiments are described in detail below, with reference to the accompanying drawings. It is recalled, however, that the invention is not limited to these embodiments.

[0043] As illustrated in [Fig.l], an aircraft 1 may incorporate one or more propellers 10 with a propulsive fan 100 according to the present description. These propellers 10 may in particular be arranged, as illustrated, under the wings 2, but other alternative arrangements, for example at the rear of the fuselage of the aircraft 1, are also possible.

[0044] As illustrated in [Fig. 2], the propellant 10 may also comprise a gas turbine engine 11 and a reduction gear 12. In the direction of air flow, this gas turbine engine 11 may comprise 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, surrounded by a fairing 19 terminating in the nozzle 18. The high-pressure turbine 16 may be connected to the high-pressure compressor 14 by a first rotary shaft 21 for driving the latter, while the low-pressure turbine 7 may be connected to the low-pressure compressor 3 by a second rotary shaft 22 coaxial with the first rotary shaft 21, in a similar manner. The reduction gear 12 may connect the second rotary shaft 22 to the propulsive fan 100 for actuating the latter.

[0045] In addition to or replacing the gas turbine engine 11, the thruster 10 could however comprise another type of motor, and in particular an electric motor, for actuating the fan, directly and / or through a transmission such as the reduction gear 12. The thruster 10 could therefore be a hybrid thruster, in series or parallel, or even purely electric.

[0046] The propulsive fan 100 may comprise a row of blades 110 and a row of guide vanes 120, downstream of the row of blades 110. The two rows may in particular be coaxial, with the blades 110 and the guide vanes 120 arranged radially around the same central axis X, but it is also conceivable that they have different central axes, and in particular parallel ones. The row of blades 110 may contain, for example, between 8 and 24 blades, in particular between 10 and 22. The row of guide vanes 120 may contain, for example, between 10 and 44 blades, in particular between 12 and 40. The blades 110 may be fewer in number than the blades 120 to comply with the rules of acoustic cut-off in the duct and therefore to minimize the noise emitted by the propulsive fan 100. For example, the number of guide vanes 120 may be greater than twice the number of blades 110.

[0047] The propulsive fan 100 may in particular be a ducted fan, also comprising a nacelle 130 surrounding at least the blades 110. This nacelle 130 may also comprise a retention casing 140 around the blades 110, with an abradable material to limit damage in the event of contact between the radially external end of the blades 110 and the casing, and / or acoustic treatments for noise reduction.

[0048] Each of the blades 110 and the vanes 120 may comprise a profiled body extending radially, relative to a profiled body, from an inner radius to an outer radius of the corresponding row, as illustrated in FIGS. 2 and 3A. However, the inner radii R; and / or outer radii Re of the first row may be different from the radii interior R / and / or exterior Re' of the second row.

[0049] The profiled body of each blade 110 and of each vane 120 may be formed by aerodynamic profiles stacked along a corresponding radial stacking axis Z, Z', so as to form, as illustrated in [Fig.3B], a lower surface 111 and an upper surface 112, each extending from a leading edge BA to a trailing edge BF. For example, for a section or aerodynamic profile of the blade 110, the leading edge BA may be defined as the upstream end along the direction of flow of the fluid. The leading edge BA may be characterized by a local minimum on the radius of curvature defining the profile in its upstream part. The trailing edge BF may be defined as the downstream end along the direction of flow of the fluid.The trailing edge BF can also be characterized by a local minimum on the radius of curvature defining the profile in its rear part when the trailing edge BF is rounded, although, to simplify the manufacturing process, the trailing edge BF can alternatively be truncated, as illustrated in [Fig.3E]. These sections or aerodynamic profiles can in particular be cambered. Each of the stacked profiles has a chord c which is defined as the distance between the leading edge BA and the trailing edge BF on a straight line connecting them and having a pitch angle y with respect to a plane perpendicular to the central axis X. The chord c and the pitch angle y can be variable depending on the radial distance r from the central axis X of the propulsive fan.

[0050] Conventionally, the pitch angle y of an aerodynamic profile corresponds to the angle formed between, on the one hand, a first axis 150 which is defined by the intersection between the plane of the aerodynamic profile at the radial distance r and a plane perpendicular to the central axis X, and on the other hand, a straight line connecting the leading edge BA and the trailing edge BF of the aerodynamic profile at the radial distance r. The pitch angle y is measured on the upstream side of the plane perpendicular to the central axis X. The pitch angle y is measured positively in a direction going from the first axis 150 to the straight line connecting the leading edge BA and the trailing edge BF, and more particularly in a direction coinciding with the direction going from the intrados line 111 to the extrados line 112.

[0051] As illustrated in [Fig.3A], the inner radii R; and outer radii Re of a blade 110 can be measured on the trailing edge BF and correspond, respectively, to the minimum and maximum radial positions relative to the central axis X. When the blade 110 is of variable pitch, the radial distances can be measured with the blade 110 placed at any pitch angle allowing the usual direction of air circulation through the fan. For example when the pitch angle y is equal to 60° for a section of the blade 110 located approximately 75% of Re, which can be representative of the pitch angle of the blades 110 in cruise. Similarly, the inner radii Ri' and outer radii Re' of a blade 120 can be measured on the leading edge BA' and correspond, respectively, to the minimum and maximum radial positions relative to the central axis X. When the blade 120 is variable pitch, the radial distances can be measured with the blade 120 placed at any pitch angle allowing the usual direction of air circulation through the fan. For example when the pitch angle y' is equal to 80° for a section of the blade 120 located approximately 75% of Re'.

[0052] At least one of the two rows may have a strength less than, for example, 3.0 over the entire height H, H' of the respective blades 110, or vanes 120, or even less than 1.2 and greater than 0.5 than the outer radius Re, Re' of the row. By "height", is meant, in the context of the present disclosure, the difference between the outer radius Re, and the inner radius R;, R / of the profiled body, and by "strength", the ratio between the chord c of each blade 110 or vane 120 of a row and the distance between two adjacent blades or vanes in the same row at the same radial distance r from the central axis X. Each of the blades 110 may have an elongation equal to the outer radius Re multiplied by a coefficient between 1.2 m 1 and 2.6 m1, preferably between 1.6 m1 and 2.2 m1. In the context of this presentation, the term "elongation" means the ratio between the height H and the average chord C of the blade.As for the mean chord C, it can be calculated from the distribution c(r) of the local chord c as a function of the radial distance, according to the equation: ,Re .

[0053] The axial distance between the stacking axes Z, Z' of the two rows may be, for example, between 0.05 and 1.2, in particular between 0.36 and 0.6 times the outer radius Re of the first row of blades 110, and above all sufficient to prevent interference of the trailing edges BF of the blades 110 with the leading edges of the vanes 120. Each of the blades 110 and vanes 120 may be rotatable about a radial axis or pitch change axis, which may in particular be the corresponding stacking axis Z, Z', in order to adjust its pitch and therefore its incidence relative to the direction of air flow according to the flight phase. This pitch change axis may preferably be perpendicular to the central axis X, alternatively inclined relative to the central axis X.When the blades 110 and the vanes 120 are fixed-pitch, the axial distance between the trailing edge BF of the blades 110 and the leading edge BA' of the vanes 120 may be between 1 and 4 times the chord c of the blade 110 at the radial position 0.95*Re relative to the central axis X, preferably between 1.5 and 3 times the chord c of the blade at the radial position 0.95*Re relative to the central axis X.

[0054] As illustrated in [Fig.2], the row of blades 110 may be able to rotate around the central axis X, and in particular be mechanically connected, for its rotational drive around the central axis X, to the gas turbine engine 11, possibly by via a reducer 12. Furthermore, in order to take advantage of the increase in the dynamic pressure of the air downstream of this first row of blades 110, an air inlet 20 of the gas turbine engine 11 may in particular be arranged between the blades 110 and the vanes 120. This air inlet 20 may for example be annular, with a nozzle 23 separating the air inlet 20 from the fairing 19.

[0055] On the other hand, the blades 120 may be, as also illustrated in [Fig.2], non-rotating around the central axis X.

[0056] The trailing edge BF of the profiled body of each blade 110 of the may have a number N of teeth with tooth heights hj where j=1,2,...N in increasing order in the radial direction from the inner radius R; to the outer radius Re, and a number M of spacings Xk between adjacent tooth apexes, where k=1,2,...M and M < Nl in increasing order in the radial direction from the inner radius R; to the outer radius Re. In the context of the present disclosure, the term "tooth apex" means a local maximum of the chord c in the radial direction and the term "tooth height" means the difference between the chord at the tooth apex and the chord at a trough, i.e. a local minimum of the chord, located between the apex of this tooth and that of the adjacent tooth.It is worth noting that a tooth crest can be characterized by a zero derivative of c(r) and a negative second derivative of c(r), while a trough can be characterized by a zero derivative of c(r) and a positive second derivative of c(r).

[0057] Following the camber of the stacked profiles of the blade 110, the variations of the chord c may be accompanied by variations of the pitch angle y, as illustrated in [Fig.3C] and 3D, in order to optimize the aerodynamic operation of the blade 110. In particular, the pitch angle y may have a local maximum or a local minimum at the radial position q of each tooth tip, more or less up to, for example, 5%, preferably 2%, of the height H of the profiled body of the blade 110.

[0058] The ratio between a maximum spacing Xmax and a minimum spacing Xmin among said spacings Xk for k=1,2,.. .M between adjacent tooth apices may be less than 15, preferably less than 8, and more preferably less than 5. This ratio between the maximum spacing Xmax and the minimum spacing may furthermore be in particular greater than 1.25. The maximum spacing Xmax may furthermore be between 0.05 and 0.4 times the height H of the profiled body of the blade 110, preferably between 0.1 and 0.35 times said height, more preferably between 0.15 and 0.3 times said height.

[0059] Each of the teeth may have a height hj between 0.1 and 2 times a spacing Xk between the top of the same tooth and the top of an adjacent tooth, preferably between 0.2 and 1.6 times the spacing Xk between the top of the same tooth and the top of the adjacent tooth, more preferably between 0.3 and 1.2 times the spacing Xk between the top of the same tooth and the top of the adjacent tooth.

[0060] As illustrated in Figures 2 and 3A, the teeth may take the form of undulations, and in particular substantially sinusoidal undulations, even if other alternative shapes such as for example triangular teeth are also conceivable. The trailing edge may be configured such that each spacing Xk between the apexes of adjacent teeth may be equal to the square of the height of one of the adjacent teeth, multiplied by a coefficient between 0.005 mm1 and 1 mm ', preferably between 0.01 mm 1 and 0.8 mm ', more preferably between 0.02 mm1 and 0.6 mm ', in particular if the teeth are sinusoidal. Thus, a compromise can be obtained, for the radius of curvature of the teeth, between aerodynamic efficiency and mechanical strength.

[0061] As also illustrated in Figures 2 and 3A, the succession of teeth may extend over the entire height H of the profiled body of the blade 110, from the inner radius R; to the outer radius Re. In particular, the trailing edge BF may have a last hollow or tooth apex at a radial distance, relative to the outer radius Re, of less than 30%, or even 20%, of the height H, in particular to redirect the flow of blade tip vortices radially outwards and thus avoid undesirable interactions with the blades 120 of the second row downstream.Furthermore, the trailing edge BF may have a first hollow or tooth apex at a radial distance, relative to the inner radius R, of less than 30%, or even 20%, of the height H, in particular to avoid or limit boundary layer separation near the root of the blade 110 which could also have an undesirable interaction with the blades 120 downstream or degrade the aerodynamic performance of the air inlet 20.

[0062] Furthermore, when the leading edge BA' of the blades 120 of the present a belly V at a radial distance rv from the central axis X, between the inner radius R / and the outer radius Re' of this second, the trailing edge BF of the blades 110 of the first row may present at least one tooth tip at a radial distance q from the central axis X equal to the radial distance rv, plus or minus at most 20%, or even 10%, of the height H, in order to reduce the undesirable interactions between the wake of the blades 110 and the belly zone V of the blades 120. Indeed, at the belly zone V of the blades 120, the axial distance between the trailing edge BF of the blades 110 and the leading edge BA' of the blades 120 may be reduced, and the leading edge BA' of the blades 120 has a reduced or zero sweep angle, which may increase interaction noise.From an aerodynamic point of view, the tips of the teeth make it possible to reduce the speed deficit locally in the wake of the blades 110, hence the interest in placing a tip of a tooth of the trailing edge BF of the blades 110 at the level of the radial position of the belly V of the leading edge B A' of the blades 120 to reduce the interaction noise. By "belly" of the leading edge of a blade or vane, is meant, in the context of the present disclosure, the most advanced point of the leading edge in the upstream axial direction.

[0063] The spacings Xk may vary, and in particular decrease monotonically in the radial direction towards the outer radius Re, such that Xi > X2 > X3 >... XM_i > XM. Thus, any ratio between adjacent spacings Xk and Xk+i may be between 1 and 2, preferably between 1.03 and 1.5. Furthermore, as illustrated in [Fig.3D], the pitch angles y at the radial positions q of the vertices may also decrease monotonically in the radial direction towards the outer radius Re, such that y(ri) > y(r2) > y(r3)... y(rN_i) > y(rN), in order to adapt them to a relative flow angle which decreases towards the outer radius Re due to the rotation of the blades. As illustrated in Figures 2 and 3A, all spacings may be different, such that Xi> X2 > X3... XM_i>XM. In particular, every ratio between adjacent spacings Xk and Xk+i can be approximately equal to one plus the inverse of a positive integer.

[0064] Alternatively, it is nevertheless conceivable that some of the spacings are identical, while maintaining a monotonic decrease, or increase, over all of the spacings. Thus, according to a second embodiment illustrated in [Fig. 4], at least two, for example two to five, in particular two, three or four spacings may be substantially identical. The identical spacings may in particular be located in an upper part BFh of the trailing edge BF of the blade 110, adjacent to the outer radius Re, and extending for example over the upper 45% or 20% of the height H of the profiled body of the blade 110. The other characteristics of the propulsive fan may however be identical or equivalent to those of the first embodiment and consequently receive the same references in [Fig. 4] as in the preceding figures.

[0065] Furthermore, although in the two previous embodiments the teeth extend over the entire height H of the profiled body of the blade 110, it is also conceivable that at least a portion of the trailing edge is devoid of teeth. Thus, according to a third embodiment illustrated in [Fig. 5], a lower portion BFb of the trailing edge BF may also be devoid of teeth. This lower portion BFb of the trailing edge BF may in particular extend from the inner radius R; and up to a radial distance r which may be, for example, equal to or greater than the radial position Rb of the spout 23 of an air inlet 20 arranged downstream of the blades 110, and this in order in particular to prevent the teeth from being able to enter the air inlet 20 in the event of tooth fracture, which could degrade the operation of the thruster.The other characteristics of the propulsive fan may however remain identical to those of the previous embodiments, and consequently receive the same references in [Fig.5] as in the previous figures.

[0066] Alternatively, however, at least one toothless portion may be a central portion BFc of the trailing edge BF of the blade 110, extending neither to the inner radius R; nor to the outer radius Re, as on the fourth and fifth embodiments respectively illustrated in figures 6 and 7. This central part BFc without teeth can in particular extend between two tooth tops, as in the fifth embodiment illustrated in [Fig.6], or alternatively between two hollows, as in the sixth embodiment illustrated in [Fig.7].

[0067] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that various modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. Furthermore, individual features of the various embodiments discussed may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

Claims

1. A propulsive fan (100) comprising at least one row of blades (110) capable of rotating about a central axis (X), each of the blades (110) comprising a profiled body extending radially from an inner radius R; to an outer radius Re relative to the central axis (X) and comprising a lower surface (111) and an upper surface (112) connecting a leading edge (BA) to a trailing edge (BF), wherein the profiled body of each blade (110) has an activity factor FA between 225 and 300, preferably between 240 and 300, said activity factor FA being defined according to the equation: ! on non f1 df) >3 ■ °where f represents a radial distance by FA= j relative to the central axis (X), divided by the outer radius Re, and c(£) represents a local chord between the leading (BA) and trailing (BF) edges of the profiled body at said radial distance, and in which the trailing edge (BF) of the profiled body of at least one blade (110) has saw teeth.

2. A propulsive fan (100) according to claim 1, wherein the trailing edge (BF) has spacings (Xk) between adjacent tooth apexes which decrease monotonically in the radial direction towards the outer radius Re.

3. A propellant fan (100) according to claim 2, wherein each spacing (Xk) of said spacings (Xk) between adjacent tooth apices is different.

4. A propellant fan (100) according to claim 2, wherein at least two adjacent spacings among said spacings (Xk) between adjacent tooth apices are substantially identical.

5. A propellant fan (100) according to any one of claims 2 to 4, wherein a ratio of a maximum spacing to a minimum spacing among said spacings (Xk) between adjacent tooth apices is less than 15, preferably less than 8, and more preferably less than 5 and greater than 1.

25.

6. A propellant fan (100) according to any one of claims 2 to 5, wherein a maximum spacing among said spacings (Xk) between adjacent tooth apexes is between 0.05 and 0.4 times a difference between said outer radii Re and inner radii R;, preferably between 0.1 and 0.35 times the difference between said outer radii Re and interior R;, still preferably between 0.15 and 0.3 times the difference between said exterior radii Re and interior R;.

7. A propellant fan (100) according to any one of claims 2 to 6, wherein a minimum spacing among said spacings (Xk) between adjacent tooth apexes is between 0.01 and 0.2 times a difference between said outer radii Re and inner radii R;, preferably between 0.02 and 0.15 times the difference between said outer radii Re and inner radii R;, more preferably between 0.04 and 0.12 times the difference between said outer radii Re and inner radii R;.

8. A propellant fan (100) according to any preceding claim, wherein any ratio between adjacent spacings among said spacings (Xk) between adjacent tooth tips is between 1 and 2, preferably between 1.03 and 1.5

9. A propellant fan (100) according to any one of claims 2 to 8, having pitch angles (Yj), at the radial positions (q) of the apexes of the teeth, which decrease monotonically in the radial direction towards the outer radius Re.

10. A propulsive fan (100) according to any preceding claim, wherein each of the blades (110) has an elongation equal to the outer radius Re multiplied by a coefficient between 1.2 m1 and 2.6 m1, preferably between 1.6 m1 and 2.2 m1.

11. A propellant fan (100) according to any preceding claim, wherein each of the trailing edge teeth (BF) has a height (hj) between 0.1 and 2 times a spacing (Xk) between the top of the same tooth and the top of an adjacent tooth, preferably between 0.2 and 1.6 times the spacing (Xk) between the top of the same tooth and the top of the adjacent tooth, more preferably between 0.3 and 1.2 times the spacing (Xk) between the top of the same tooth and the top of the adjacent tooth.

12. A propulsive fan (100) according to any preceding claim, wherein the radial position (q) of each tooth tip substantially corresponds to a radial position of a local maximum or a local minimum of pitch angle.

13. Propulsive fan (100) according to one of the preceding claims, in which each spacing (Xk) between tops of adjacent teeth is equal to the square of a tooth height (hj) of one of the adjacent teeth, multiplied by a coefficient between 0.005 mm 1 and 1 mm ', preferably between 0.01 mm 1 and 0.8 mm ', more preferably between 0.02 mm1 and 0.6 mm'.

14. A propulsive fan (100) according to any preceding claim, wherein said trailing edge (BF) of the at least one blade (110) comprises at least one toothless portion, in particular two toothless portions separated from each other in the radial direction.

15. A propulsive fan (100) according to any one of the preceding claims, comprising a row of guide vanes (120), non-rotating around the central axis (X), arranged downstream of the row of blades (110).

16. A propulsive fan (100) according to claim 14, wherein a leading edge (BA') of at least one blade (120) of the row of blades (120) has a belly (V) and the trailing edge (BF) of at least one blade (110) of the row of blades (110) has at least one tooth tip at a radial distance (q) from the central axis (X) approximately equal to a radial distance (rv) of said belly (V) relative to the central axis (X).

17. A propulsive fan (100) according to any preceding claim, which is a ducted propulsive fan, further comprising a nacelle (130) surrounding at least the row of blades (110).

18. A thruster (10) comprising the propulsive fan (100) according to any preceding claim and a gas turbine engine (11) for driving the propulsive fan (100).

19. An aircraft (1) comprising the propellant of claim 18.

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