WO2025195755A1 - Fan impeller - Google Patents

Abstract

The invention relates to a fan impeller (1) comprising a hub (2) having an axis of rotation (XR) and blades (3) extending generally radially outwards from the hub (2), each blade (3) being defined by a span, a leading edge and a trailing edge, the blade (3) being further defined by a stack of aerodynamic profiles constructed with a law of thickness about a neutral axis connecting the leading edge to the trailing edge of the blade (3), the neutral axis being characterized by a parameter called chord length representing the distance between the two ends of the neutral axis, the law of thickness representing the variation in the thickness of the profile along the neutral axis, at least one of the blades (3) having the law of thickness on the neutral axis which forms on the blade (3), along the neutral axis, at least one corrugation (5) having an amplitude of between 0.1% and 2% of the chord length.

Description

Fan propeller

[1] The present invention relates to a fan propeller, in particular an axial type fan. The fan is in particular configured to be integrated into a front cooling module of a thermal or electric vehicle.

[2] The present invention aims in particular to reduce the noise in such a fan, without impacting the aeraulic performance of the fan.

[3] The invention thus relates to a fan propeller comprising a hub having an axis of rotation and blades extending generally radially outwards from the hub, each blade being defined by a span, a leading edge and a trailing edge, the blade being further defined by a stack of aerodynamic profiles constructed with a thickness law around a neutral fiber connecting the leading edge to the trailing edge of the blade, the neutral fiber being characterized by a parameter called chord length representing the distance between the two ends of the neutral fiber, the thickness law representing the evolution of the thickness of the profile along the neutral fiber, at least one of the blades having the thickness law on the neutral fiber which forms on the blade, along the neutral fiber, at least one undulation having an amplitude of between 0.1% and 2% of the chord length.

[4] The applicant has found that the undulation(s) on the blade provide an acoustic and aerodynamic gain. In particular, the invention allows a reduction in the acoustic level without impact on the aeraulic performance and without modification of the manufacturing process. In particular, the undulations provide flow consistency by reducing the aeraulic radial effects. The explanation for the performance gain can be explained in particular by the fact that the boundary layer can be better maintained on the profile, which causes less separation likely to cause a loss of aeraulic performance and which reduces the acoustic fluctuations generating noise.

[5] It is recalled that the neutral fiber passes through the center of the blade profile, between the leading edge and the trailing edge. The aerodynamic profile corresponds in particular to a circular section of the blade at a given radius, a section obtained by intersection at a given radius with a geometric cylinder of the same axis as the axis of rotation of the propeller.

[6] The aerodynamic profiles of the stack can be identical or variable.

[7] The term "blade span" refers in particular to the length of the blade measured in a plane perpendicular to the axis of rotation of the propeller, on a straight line passing through the axis of rotation and expressed as a percentage. The value 0% corresponds in particular to a point of contact of the blade with the hub (point called blade root) and the value 100% corresponds to a point of contact of the blade with a rim (point called blade head).

[8] The thickness law on the neutral fiber is taken here with the following conventions, in the case where the intrados and the extrados are symmetrical to each other: on the abscissa, is the position of the point considered along the neutral fiber expressed as a percentage of the length of the neutral fiber, with 0% when it is the point on the leading edge and 100% when it is the point on the trailing edge, and on the ordinate, we read the thickness of the blade, on one side of the neutral fiber, expressed as a percentage of the chord length, namely the ordinate is determined by a ratio of the chord length to a given radius. The thickness is measured by taking the neutral fiber as Zero reference. For example, the profile of the extrados is defined by the evolution of the thickness along the neutral fiber, this thickness being the distance measured between the neutral fiber and the extrados.

[9] It is possible to have a thickness law to define the intrados of the blade. The thickness is, in this case, the distance between the neutral fiber and the intrados.

[10] It is possible to have a thickness law for the extrados and another thickness law for the intrados.

[11] According to one aspect of the invention, the corrugation has at least one high point and at least one low point, the high point being the point of the corrugation furthest from the neutral fiber (this high point thus defining the maximum distance of the corrugation from the neutral fiber) and the low point being the point of the corrugation closest to the neutral fiber (this low point thus defining the minimum distance of the corrugation from the neutral fiber). The low point is at a distance from the leading edge and the trailing edge, which means that the low point is not on the leading edge or on the trailing edge. The corrugation can be defined, along the neutral fiber, by a low point surrounded by two high points. Each corrugation extends locally along the neutral fiber, namely over only a fraction of the length of the neutral fiber.

[12] The amplitude of the corrugation is the difference in thickness between the low point and the high point of the corrugation, at a given length of the neutral fiber in a given circular section.

[13] According to one aspect of the invention, the thickness law on the neutral fiber defines on at least one of the main faces of the blade (the extrados and/or the intrados) a plurality of undulations along the neutral fiber, from the trailing edge to the leading edge. Thus several undulations can follow one another along the neutral fiber, from the trailing edge to the leading edge. A pitch relative to the undulations in a given circular section can be defined. This pitch can vary for example between 4% and 20% of the chord length. [14] According to one aspect of the invention, this plurality of undulations on the main face (extrados or intrados) has identical thickness amplitudes at least for some of the undulations.

[15] According to another aspect of the invention, the plurality of undulations on the main face (extrados or intrados) have completely different thickness amplitudes.

[16] According to one aspect of the invention, at least some of the undulations on the main face (extrados or intrados) have thickness amplitudes which increase as they approach the trailing edge.

[17] According to one aspect of the invention, the thickness law on the neutral fiber is based on a main evolution curve, along the neutral fiber, which is constant or decreasing in its part where the undulations are formed.

[18] According to one aspect of the invention, the undulations are substantially centered on this main evolution curve.

[19] In other words, the thickness law on the neutral fiber is obtained by adding to the main evolution curve, one or more undulations of relatively low amplitude (undulation(s) having an amplitude of at most 1%, in particular at most 0.1%, of the chord length).

[20] The undulations are notably contained between two envelope curves separated by at most 1% of the chord length.

[21] According to one aspect of the invention, the undulation(s) have, along the neutral fiber, a sinusoidal or pseudo-sinusoidal shape.

[22] According to one aspect of the invention, the undulation develops along at least a portion of the blade span. In other words, the undulation has a certain extension when traveling along the blade from the blade root to the blade tip. Thus the undulation is similar to a furrow which extends over at least a portion of the span.

[23] The undulation, or groove, may have a thickness amplitude that varies as one moves along the undulation from the blade root to the blade tip.

[24] Alternatively, the corrugation, or groove, may have a thickness amplitude that is constant as one moves along the corrugation from the blade root toward the blade tip.

[25] According to one aspect of the invention, the undulation, or the groove, may be parallel to the leading edge and/or the trailing edge.

[26] Alternatively, the corrugation, or groove, may be inclined relative to the leading edge, with a non-zero angle. More generally, the leading edge/ undulation can be variable from one section to another, in particular while guaranteeing continuity of the undulation along the span or part of the span.

[27] According to one aspect of the invention, the undulations are parallel to each other, insofar as they remain distant from each other when traveling along the blade from the blade root to the blade head.

[28] According to one aspect of the invention, the undulation(s) extend from the blade root to the blade head, over the entire span of the blade.

[29] Alternatively, the undulation(s) extend over only a portion of the span, between the blade root and the blade tip.

[30] According to one aspect of the invention, the undulation(s) extend over only a portion of the span, starting from the blade head and stopping for example before the middle of the total span or before three-quarters of the total span of the blade.

[31] According to one aspect of the invention, only the extrados or the intrados has one or more undulations. The other main face is free of undulations.

[32] Alternatively, both the extrados and the intrados have one or more undulations.

[33] In this case, the undulations on the extrados and intrados may be symmetrical to each other with respect to the neutral fiber, or alternatively, be asymmetrical.

[34] According to one aspect of the invention, the number of undulations on a main face is between 5 and 25, for example between 7 and 20.

[35] According to one aspect of the invention, all the blades of the propeller are provided with undulations according to the invention.

[36] According to one aspect of the invention, the blades join, at their blade head, a rim which is axisymmetrical with the hub.

[37] The invention also relates to an electric fan, in particular for a motor vehicle, comprising a propeller as mentioned above.

[38] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several examples of embodiment given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which:

[39] [Fig. 1] Figure 1 is a representation of a propeller according to an exemplary embodiment of the invention;

[40] [Fig. 2] Figure 2 is a sectional view of a blade of the propeller of Figure 1; [41] [Fig. 3] Figure 3 shows a curve illustrating the thickness law applied to the blades of the propeller of Figure 1;

[42] [Fig. 4] Figure 4 is a representation of a blade with its characteristic elements;

[43] [Fig. 5] Figure 5 is a sectional representation of a blade with these characteristic elements;

[44] [Fig. 6] Figure 6 shows a curve illustrating a simple thickness law;

[45] [Fig. 7] Figure 7 shows a pseudo thickness law that can be applied in an example of the present invention.

[46] The features, variants and different embodiments of the invention may be combined with each other in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and/or to differentiate the invention from the prior art.

[47] Figure 1 shows a propeller 1 which equips an axial-type fan 100. The fan 100, driven by an electric motor, is configured to be integrated into a front cooling module of a thermal or electric vehicle. Other applications are of course conceivable.

[48] The propeller 1 comprises a hub 2 having an axis of rotation XR and blades 3 extending generally radially (along a radius Ra) outwards from the hub 2 to a rim 4. The number of blades is for example between 5 and 20, being here 7. The blades 3 are regularly distributed (with a regular angular pitch) around the hub 2, or distributed in a non-regular manner around the axis XR, thus creating an asymmetrical distribution.

[49] As illustrated in Figure 4, each blade 3 is defined by a span EN, a leading edge BA and a trailing edge BF. The blade 3 is further defined by a stack of airfoils PA constructed with a thickness law around a neutral fiber FN connecting the leading edge BA to the trailing edge BF of the blade 3 (see Figure 5). The neutral fiber FN is characterized by a parameter called chord length LC representing the distance between the two ends BA and BF of the neutral fiber FN. [50] Figure 6 shows, on the bottom curve, an example of a simple thickness law (without the undulations described below) which represents the evolution of the thickness of the PA profile along the neutral fiber FN.

[51] As can be seen in Figure 3, the blades 3 have a thickness law LEP on the neutral fiber FN which forms on each blade 3, along the neutral fiber FN, undulations 5 having an amplitude between 0.1% and 2% of the chord length LC. The thickness law LEP according to an example of the invention is the result of the simple thickness law illustrated in Figure 6 to which the undulations 5 have been added.

[52] It is recalled that the neutral fiber FN passes through the center of the profile PA of the blade 3, between the leading edge BA and the trailing edge BF. The aerodynamic profile PA corresponds in particular to a circular section of the blade 3 at a given radius Rd (see figure 4), section obtained by intersection at a given radius with a geometric cylinder of the same axis as the axis of rotation of the propeller XR.

[53] The PA aerodynamic profiles of the stack can be identical or variable.

[54] The term “blade span EN” refers in particular to the length of blade 3 measured in a plane perpendicular to the axis of rotation XR of propeller 1, on a straight line passing through the axis of rotation XR and expressed as a percentage. The value 0% corresponds to a point of contact of blade 3 with hub 2 (point called blade root PP) and the value 100% corresponds to a point of contact of blade 3 with rim 4 (point called blade head TP).

[55] The LEP thickness law on the neutral fiber FN is taken here with the following conventions (see figures 3 and 6): on the abscissa, is the position of the point considered along the neutral fiber FN expressed as a percentage of the length of the neutral fiber, with 0% when it is the point on the leading edge BA and 100% when it is the point on the trailing edge BF, and on the ordinate, we read the thickness of the blade, on one side of the neutral fiber FN, expressed as a percentage of the chord length, namely the ordinate is determined by a ratio of the chord length to a given radius. The thickness is measured by taking the neutral fiber FN as reference Zero. For example, the profile of the extrados EXT is defined by the evolution of the thickness along the neutral fiber FN, this thickness being the distance measured between the neutral fiber FN and the extrados EXT.

[56] The curves in Figures 3 and 6 show the thickness law applied to the neutral fiber FN of a circular section at a given radius to define the extrados curve at this same radius. For example, an ordinate value equal to zero means that the thickness of blade 3 is zero, and an ordinate value of 2% means that, at this point on the fiber neutral FN of the section, the thickness measured by relying on the neutral fiber FN of blade 3, is 2% of the chord length LC.

[57] It is also possible to have a thickness law to define the intrados INT of blade 3. The thickness is, in this case, the distance between the neutral fiber FN and the intrados INT.

[58] It is possible to have a thickness law for the extrados EXT and another thickness law for the intrados INT. In this case, the neutral fiber is offset from the center of the profile PA.

[59] The ripple 5 is defined, along the neutral fiber FN, by a low point PoB surrounded by two high points PoH. Each ripple 5 extends locally along the neutral fiber FN, namely over only a fraction of the length of the neutral fiber FN.

[60] The amplitude AMP of the corrugation 5 is the difference in thickness between the low point PoB and the high point Poh of the corrugation, at a given length of the neutral fiber FN in a given circular section.

[61] The LEP thickness law on the neutral fiber FN defines on the main faces INT and EXT of the blade 3 (the extrados and/or the intrados) a plurality of undulations 5 along the neutral fiber FN, from the leading edge BA to the trailing edge BF, as illustrated in Figure 2. Thus several undulations 5 can follow one another along the neutral fiber FN, from the leading edge BA to the trailing edge BF. A pitch relative to the undulations 5 can be defined in a given circular section. This pitch can vary for example between 4% and 20% of the chord length.

[62] This plurality of undulations 5 on the main face (extrados EXT or intrados INT) has amplitudes AMP of identical thickness at least for some of the undulations, or amplitudes of thickness which are completely different.

[63] For example, at least some of the undulations 5 on the main face (extrados EXT or intrados INT) have thickness amplitudes which increase as they approach the trailing edge BF.

[64] The LEP thickness law on the neutral fiber is based on a main evolution curve LE1 (dotted in figure 3), along the neutral fiber FN, which is constant or decreasing in its part where the undulations 5 are formed.

[65] The 5 waves are substantially centered on this main evolution curve LE1.

[66] In other words, the LEP thickness law on the neutral fiber is obtained by adding to the main evolution curve LE1, several undulations of relatively low amplitude (undulation(s) having an amplitude of at most 2%, in particular at most 0.1%, of the chord length). [67] The 5 undulations are contained between two envelope curves LEV1 and LEV2 separated by at most 1% of the chord length LC.

[68] The 5 undulations present, along the neutral fiber FN, a sinusoidal or pseudo-sinusoidal shape.

[69] The undulation 5 develops along at least a portion of the blade span 3. In other words, the undulation 5 has a certain extension when one travels along the blade 3 from the blade root PP to the blade tip TP. Thus the undulation 5 is similar to a furrow which extends over at least a portion of the span EN, as can be seen in Figure 2.

[70] The corrugation 5, or the groove, may have a thickness amplitude which varies when moving along the corrugation from the blade root PP towards the blade head TP.

[71] Alternatively, the undulation 5, or the groove, may have a thickness amplitude which is constant when moving along the undulation from the blade root PP towards the blade head TP.

[72] The undulation 5, or the groove, can be parallel to the leading edge BA and/or to the trailing edge BF.

[73] Alternatively, the corrugation 5, or the groove, may be inclined relative to the leading edge, with a non-zero angle. This is called a twist. More generally, the leading edge/corrugation distance may vary from one section to another, while ensuring continuity of the corrugation along the span or part of the span.

[74] The blade 3 may have a certain pitch angle CAL, as illustrated in Figure 5.

[75] The undulations 5 are parallel to each other, insofar as they remain distant from each other when one travels along the blade 3 from the blade root PP to the blade head TP.

[76] The undulations 5 extend from the blade root to the blade head, over the entire span of the blade 3.

[77] Alternatively, the undulations 5 extend over only a portion of the span, between the blade root PP and the blade head TP.

[78] The undulations 5 extend over only a portion of the span EN, starting from the blade head TP and stopping for example before the middle of the total span EN or before three-quarters of the total span EN of the blade 3. [79] In one example, only the extrados EXT or the intrados INT has the undulations 5. The other main face is devoid of undulations.

[80] When both the extrados INT and the intrados EXT have the undulations 5, the undulations 5 on the extrados EXT and the intrados INT may be symmetrical to each other with respect to the neutral fiber FN, or alternatively, be asymmetrical.

[81] In the example described, all the blades 3 of the propeller are provided with undulations 5 according to the invention.

[82] In a variant of the invention illustrated in Figure 7, the thickness law may be a pseudo thickness law. [83] In a variant not illustrated, the thickness law is applied to a flat plate

(the thickness law then being a fixed value) and we add to this thickness law undulations 5.

Claims

[Claim 1] Fan propeller (1) comprising a hub (2) having an axis of rotation (XR) and blades (3) extending generally radially outward from the hub (2), each blade (3) being defined by a span (EN), a leading edge (BA) and a trailing edge (BF), the blade (3) being further defined by a stack of aerodynamic profiles (PA) constructed with a thickness law (LEP) around a neutral fiber (FN) connecting the leading edge (BA) to the trailing edge (BF) of the blade (3), the neutral fiber (FN) being characterized by a parameter called chord length (LC) representing the distance between the two ends of the neutral fiber (FN), the thickness law (LEP) representing the evolution of the thickness of the profile along the neutral fiber (FN), at least one of the blades (3) having the thickness law on the neutral fiber (FN) which forms on the blade (3), along the neutral fiber (FN), at least one undulation (5) having an amplitude (AMP) between 0.1% and 2% of the chord length (LC). [Claim 2] Propeller (1) according to the preceding claim, in which the thickness law (LEP) on the neutral fiber (FN) defines on at least one of the main faces of the blade (3), the extrados (EXT) and/or the intrados (INT), a plurality of undulations (5) along the neutral fiber (FN), from the trailing edge (BF) to the leading edge (BA). [Claim 3] Propeller (1) according to one of the preceding claims, in which the thickness law (LEP) on the neutral fiber (FN) is based on a main evolution curve (LE1), along the neutral fiber (FN), which is constant or decreasing in its part where the undulations (5) are formed. [Claim 4] Propeller (1) according to one of the preceding claims, in which the undulations (5) are in particular contained between two envelope curves (LEV1, LEV2) separated by at most 1% of the chord length (LC). [Claim 5] Propeller (1) according to one of the preceding claims, in which the undulation(s) (5) have, along the neutral fiber (FN), a sinusoidal or pseudo-sinusoidal shape. [Claim 6] Propeller (1) according to one of the preceding claims, in which the undulation (5) develops along at least a portion of the blade span (EN) so that the undulation (5) has a certain extension when traveling along the blade from the blade root (PP) towards the blade head (TP). [Claim 7] Propeller (1) according to one of the preceding claims, in which the corrugation (5) is parallel to the leading edge (BA) and/or the trailing edge (BF). [Claim 8] Propeller (1) according to the preceding claim, in which the undulation(s) (5) extend from the blade root (PP) to the blade head (TP), over the entire span (EN) of the blade (3). [Claim 9] Propeller (1) according to one of the preceding claims, in which the number of undulations (5) is between 5 and 25, for example between 7 and 20. [Claim 10] Fan (100), in particular for a motor vehicle, comprising a propeller according to one of the preceding claims.