Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/26—Rotors specially for elastic fluids
  • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
  • F04D29/38—Blades
  • F04D29/384—Blades characterised by form
  • F04D29/386—Skewed blades
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/26—Rotors specially for elastic fluids
  • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
  • F04D29/325—Rotors specially for elastic fluids for axial flow pumps for axial flow fans
  • F04D29/326—Rotors specially for elastic fluids for axial flow pumps for axial flow fans comprising a rotating shroud

Definitions

• the field of the present invention is that of the automobile, and more particularly that of the circulation of air for the cooling of the engine equipment.
• the vehicles with thermal engine need to evacuate the calories that generates their operation and are for that equipped with heat exchangers, in particular cooling radiators, which are generally placed in the front of the vehicle and crossed by outside air .
• a fan is placed upstream or downstream.
• the ventilation fan which serves to force the flow of air has an axially oriented flow. It comprises blades which are connected by their foot to a central hub, and generally held together in their heads by a rotating shell (as illustrated in Figure 1).
• the curvature has beneficial effects for acoustics, it also modifies the aerodynamic properties because it produces forces perpendicular to the blade surface, these forces creating in turn radial flows.
• a rear curvature will produce a flow extending radially outward, while a forward curvature will produce a contraction effect of the flow (as will be explained further in detail in relation to Figure 2).
• a rear curvature will work more head, and promote high-speed performance, while a forward curvature will promote low flow by working more in foot.
• the subject of the invention is a ventilation propeller comprising a hub and blades extending radially outwardly from the hub between a blade root and a blade head, the blades of said propeller having a curvature back-front due to a reversal of curvature on their wingspan.
• said blades comprise at least one abrupt variation of their wedging extending over a limited range of span, said calibration variation being located near a point of inversion of curvature of the blades.
• abrupt variation it is preferentially to say at least 2 ° more or less than with respect to a linear wedging on said span gap.
• limited span spread is preferably meant a maximum span spread of 25%, the total span of the blade.
• Variation located "close” to a point of inversion of the curvature of the blades is preferably between 20 and 80% of their wingspan.
• the calibration variation is between 3 and 5 °.
• a peak of the calibration variation is positioned, with respect to the point of inversion of curvature, at a distance less than or equal to 30% of the span of the blade.
• the proximity of this peak of the inversion point of the curvature makes it possible to make it act as close as possible to the place where the detachments occur, and thus improve its efficiency.
• More preferably said distance is less than or equal to 10% of the span of the blade.
• the pitch variation is positive, the value of the wedging being greater than said linear wedge over the entire span gap.
• the pitch variation is said to be negative, the value of the wedging being less than said linear wedge over the entire span gap.
• the calibration variation has a positive slope, respectively negative, up to its peak, followed by a negative slope, respectively positive. This peak form represents an optimum in terms of efficiency for the removal of flux detachments which are generally observed on the extrados.
• At least one of the slopes of the staggering variation has, in absolute value, a value greater than 1 ° by 10% of span variation. And, more preferably, the other slope has, in absolute value, a value of less than 1 ° by 10% of span variation.
• curvature of the blades at the point of inversion of its curvature is between -4 and -25 °.
• the variation in curvature between the inversion point and the blade heads is between 4 and 25 °.
• the curvatures of the blades in the foot and at the head different from less than 10 °. And more preferably said bends are both less than 10 °.
• the invention also relates to a motor-fan unit comprising a propeller as described above and a cooling system comprising such a motor-fan unit.
• a motor-fan unit comprising a propeller as described above and a cooling system comprising such a motor-fan unit.
• Such a system may include one or more heat exchangers traversed by the air flow generated by the propeller.
• FIG. 1 is a front view of a helix, according to the prior art
• FIG. 2 is a schematic view giving the shape of the flow of air passing through a helix according to FIG. 1, in the cases, respectively, of a rear curvature, a front curvature and a mixed curvature back-front of his blades,
• FIG. 3 is a front view of a propeller with a rear-front mixed curvature
• FIG. 4 is a perspective view of a blade of the helix of FIG. 3, according to the prior art
• FIG. 5 is a perspective view of a blade of the helix of FIG. 3, modified according to the invention.
• FIG. 6 is a schematic view showing the evolution of the curvature of the blade of FIG. 5 along its span
• FIG. 7 is a schematic view showing the evolution of the wedging of the blade of FIG. 5 along its span, respectively according to a first embodiment of the invention and according to a reference embodiment
• FIG. 8 is a schematic view showing the evolution of the wedging of the blade of FIG. 5 along its span, respectively according to a second embodiment and according to a reference embodiment,
• FIG. 9 is a front view of a helix, in a first implementation of the invention.
• FIG. 10 is a front view of a helix, in a second implementation of the invention.
• FIG. 1 1 a front view of a helix, in a third implementation of the invention.
• FIG. 1 shows a helix 1 of the prior art, which is mounted in rotation about an axis passing through its center O and oriented here orthogonal to the plane of the figure.
• the direction of rotation of the helix 1 is designated by the arrow F.
• the propeller 1 brews the air passing through it. The air flow then flows in a direction of flow oriented substantially axially.
• upstream and downstream are understood with reference to the direction of flow of the air flow.
• axial radial
• tangential are themselves used with reference to the axis of rotation of the helix.
• This helix 1 comprises:
• a central hub 2 advantageously intended to cap the drive motor of the propeller
• blades 3 (here six in number), with their first ends, or feet 3a, which are fixed on the hub 2 and which extend radially from this hub,
• peripheral ring 4 of cylindrical annular shape, to which the second ends, or heads 3b, are connected with blades 3.
• the blades 3 are generally identical to each other and may have a substantially airfoil cross section, with an extrados and a lower surface. They thus extend transversely between, respectively, a leading edge which first comes into contact with the air flow during the rotation of the propeller 1, and a trailing edge which is opposite to it.
• the line connecting the leading edge to the trailing edge is called a rope line, while the The line connecting the equidistant points of the upper and lower surfaces of the blade is called the camber line.
• the aerodynamic characteristics of a blade are defined by the following parameters, which are evolutive all along the blade:
• a fourth characteristic, which influences its aerodynamic performance is the curvature of the line which connects, in projection on a radial plane, the mid-rope points of the blade.
• the curvature of the blade is said before if, for the rope considered, the tangent to this line is oriented, moving from the foot to the head, in the direction of rotation F; it is said to be backwards in the opposite direction.
• the curvature, at each mid-cord point along the span, is expressed by the value in degrees of the angle made by the radius at this point with the radius of the half-rope point at the foot of the blade.
• FIG. 2 shows the deviation experienced by a fluid passing through the helix 1 in the case, respectively, of a rear curvature, a front curvature and a mixed rear-front curve of its blades 3.
• the rear curvature produces a flow that extends radially outwards while the central figure shows that a forward curvature produces a centripetal deviation of the flow.
• the two preceding effects cancel each other out and together produce a maintenance of an axial direction, with a contraction of the flow that is centered about mid-span.
• the pressure gradient between the trailing edge and the leading edge is modified and a marked detachment can be observed on the upper surface of the blade 3, which then takes birth substantially mid-span. It is this detachment effect that the invention proposes to reduce, by playing in particular on the timing distribution along the span of the blade, and in particular around this point mid-span.
• Figure 3 shows a propeller 1 whose blades 3 have a curvature is mixed, rear foot 3a and then from the mid-span and up to the head 3b.
• FIG. 4 shows, for its part, a blade, according to the prior art, of the helix of FIG. 3. The wedging of the blade 3 varies continuously along the span, without abrupt variation of this. this.
• FIG. 5 shows a propeller blade 3 according to the invention which has an inflection peak 5 for its wedging at the point of the span where the curvature reverses, that is to say there where is the contraction effect of the flow.
• the positioning, the shape and the intensity of this peak 5 are given in FIGS. 6 to 8.
• FIG. 6 shows the evolution of the curvature in the case of a mixed rear-front curvature.
• the curvature is zero at the bottom of the blade 3a, which means that the line of the points located mid-rope away from the hub 2 being perpendicular thereto.
• the curvature increases in the backward direction until reaching a maximum rear value equal, in the example shown, to -13 ° and positioned mid-span.
• FIGS. 7 and 8 show the evolution of the wedging along the span of a blade 3, in a reference helix version (so-called initial pitching) and, respectively, in two embodiments of the invention ( calibration said modified).
• the invention is characterized by an inflection of the wedge forming a wedging spike; this peak is here at 50% of the span, that is to say precisely around the point of inversion of the curvature.
• This inflection is either positive ( Figure 7) or negative ( Figure 8). But in both cases its amplitude is important, the slope of the inflection being greater or equal, in absolute value, at 1 ° by 10% of variation of curvature.
• the preferred values used in the version shown in the figures and provided by way of example are 3 and 5 ° for 10% of variation of setting, according to whether the slope is upward or downward and according to which the initial calibration curve is it. - even decreasing or increasing around the point of inversion of the curvature.
• the curvature may have slopes of the same absolute value on either side of the inversion point.
• Figures 9 to 1 1 show three cases of implementation of the invention on mixed curvature propellers.
• the curvature is back-front with zero curvatures in the foot 3a and head 3b and a curvature reversal located at 75% of the span. At this point the curvature is equal to -4 °.
• the curvature is back-front with zero curvatures in the foot 3a and equal to 7 ° head 3b.
• the inversion of curvature is located at 20% of the span, and at this point the curvature is equal to -30 °.
• the invention namely the positioning of an inversion, or peak, wedging 5
• the invention can be implemented on any type of propeller with a back-to-front mixed curvature, with a wide range of possible values for the curvature at the foot, the curvature at the head and the position of the inversion of curvature along the span.
• the invention relates to a rear-front curvature:
• the curvature at the foot and in the head are close to one another, that is to say with a difference of less than or equal to 10 ° and more preferably they are both close to zero, that is, less than 10 °.
• the wedging of the blade 3 has a sudden variation, and limited in scale, of its value. This results in a wedge which deviates, on a given span segment of the blade, the linear wedging existing between the two end points of this segment.
• This variation of wedging is defined, according to the invention, advantageously as follows.
• the calibration variation is in span in an area close to the maximum rear curvature point.
• the span difference between the maximum point of curvature and the inflection peak 5 is less than or equal to 30% of the span, more preferably less than or equal to 10%.
• the inflection peak 5 is constituted by a sudden variation of the setting, of at least 2 ° on a variation at most of 25% of the span. Preferably this variation is between 3 and 5 °.
• the wedging is located on the same side with respect to said linear wedging, over the entire span gap, whether above or below.
• the abrupt pitch variation has a positive slope greater than 1 ° by 10% of variation of ca lage, until a peak of inflection 5 is reached, and then, from this point of view, peak, a negative slope less than -1 ° by 10% of calibration variation.
• it has, first of all, a negative slope less than -1 ° by 10% of calibration variation, then a positive slope greater than 1 ° by 10% calibration variation.
• blades 3 having only one inflection peak 5; in alternative versions several peaks may be present along the span of the blade 3, at least one of them having the minimum characteristics described above.
• the geometry proposed for the blade 3 by the present patent application tends to find an optimum from both the aerodynamic and the acoustical point of view.
• the objectives pursued are a good performance, a minimization of the acoustic effects and a minimization of the deflection at the top of the blade 3b.
• the geometry relies firstly on a mixed back-front curvature, and on a distribution distribution law along the span which is adapted to the three-dimensional nature of the flow. Improved performance is achieved through a shape flexion that is positioned near the span where the curvature reverses. This inflection has the effect of locally modifying the angle of attack of the incident flow on the aerodynamic profile and thus improve the flow on its upper surface and minimize detachments. Thanks to this improved design, the drag of the profile is reduced for the same lift, and the suppression of the detachments improves the acoustics by minimizing the interaction noise of the propeller with its support. In terms of aerodynamic performance there is an improvement with, in the example of the propeller of Figure 3, a yield that passes from 43.8 to 45.2% at the same speed and same flow rate.
• the invention has been described in the case of a helix having a ferrule 4 connecting the outer end 3b of the blades. It is obvious that it can just as easily be carried out in the absence of ferrule, provided that the shape given to the blades 3 is that described above.
• the invention also relates to a motor-fan unit comprising such a propeller, and its drive motor.
• Said group may comprise a nozzle provided with an air passage orifice inside which the helix rotates about its axis, said drive motor being carried by the nozzle by means of radial arms advantageously forming stator blades.
• the invention also relates to a cooling system or module of a motor vehicle engine block. It then includes, in particular, the fan-motor group mentioned above and a cooling radiator.
• the propeller may be located between the cooling radiator and the engine block or upstream of said radiator.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

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• 2015
  • 2015-03-19 FR FR1552271A patent/FR3033845B1/fr not_active Expired - Fee Related
• 2016
  • 2016-03-21 EP EP16713789.2A patent/EP3271588B1/de active Active
  • 2016-03-21 US US15/559,634 patent/US10584716B2/en not_active Expired - Fee Related
  • 2016-03-21 WO PCT/EP2016/056139 patent/WO2016146850A1/fr active Application Filing

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