FR2803816A1 - Control for selective air flow through moving subsonic vehicle comprises body with convex front placed in front of conduit through which air is delivered - Google Patents

Abstract

The vehicle comprises a fixed and rigid body (13), placed in front of a conduit (11) through which the air supply is controlled selectively according to the flow speed of the incident air (2). Above a certain speed limit a wake is formed behind the body which prevents the fluid from penetrating into space located behind the body. The body has a convex front and a totally non-profiled rear.

Description

The invention relates to a vehicle intended to move at subsonic speed, the use of which implies that it interacts with a fluid in relative motion, this movement possibly being external and / or internal to this vehicle, the fluid being essentially of the 'air.

To allow and prohibit the access of an air flow, selectively according to the relative speed of said moving flow with respect to a vehicle, to a zone of space defined with respect to this vehicle, obstacles are used, you can change the shape and / or position.

The present invention aims to propose a new category of vehicles capable of performing the functions of permission and prohibition of access in areas of space, using obstacles whose shapes and positions relative to the vehicles. of reference remain constant over time. Consequently, the invention also aims to propose such vehicles provided with means for variable control of the trajectories of the air flows in contact with them, simplified compared to vehicles provided with the same function but using mobile mechanisms.

The invention particularly aims to provide a vehicle such as a car, certain air inlets of which can be made totally or partially ineffective beyond a speed limit.

The invention also aims to propose a vehicle such as a car whose access to the air flow to certain functions of the vehicle can be canceled or altered beyond a speed limit.

To do this, the invention relates to a vehicle intended to move at subsonic speed in the air, characterized in that for each of its air inlets or functions whose access is to be controlled by the fluid in relative motion, selectively according to its speed, without using a movable mechanism: - it comprises a rigid body placed in a fixed manner in front of the area of space whose fluid supply is to be controlled, - said body receives the fluid in motion by its front, and sees the fluid bypassing it from above, below, right, left or by several of these possibilities at the same time, depending on its position relative to the rest of the vehicle, - said body has a shape provided for its wake, linked to the detachment of the current lines from the surface of the body, can vary from a minimum, is the total absence of wake, to a maximum, which can be a wake whose largest cross section is at m oins substantially equal to the largest cross section of the wake body.

- the creator body of the wake has at least one of its series of longitudinal sections parallel to each other which are similar to sections, or to half-sections, of an almost totally profiled body, that is to say of a body whose convex front part, with forward convexity, has a progressive variation in its curvature in the direction of flow, and whose rear part has at least a rapid variation in its curvature, in addition to that corresponding to its end, or at least a portion of steep inclination relative to the direction of the incident fluid in front of the body; the connection between the front and the rear being without discontinuity in the variation in curvature. It is accepted that for a rear part, an inclination of the order of 15 relative to the direction of the incident fluid is a strong inclination.

Throughout this description, a reference mark is used which is fixed relative to the object equipped with the invention. The front and the rear are defined therein in a conventional manner, that is to say that the fluid in relative movement with respect to the invention arrives from the front of the invention and leaves from the rear of the invention.

The fluid to which we want to control access to a zone of space is approximately reduced to the fluid passing through a projection of the body on a plane perpendicular to the speed of the fluid before it is disturbed by the invention, plane being located in front of the body, in an area where the fluid is animated by the translational movement which it has just before reaching the body.

The speed of the fluid is variable from a minimum to a maximum. Below a certain speed limit, the current lines of the fluid close to the body follow the shape of the body. Above this speed the current lines take off in one or more places of the body and a wake is formed, that is to say an area of space where the movement of the fluid is strongly different from its original relative movement characterized by the dominance of the translational movement of the front to rear. Approximately, in the wake the fluid is animated by vortices or else stagnates. Throughout the present description, we do not consider as a wake a simple disturbance of the air flow behind the body, but much like a volume of fluid having its own characteristics, the wake is a zone of space where the movement of the fluid has a component of translation from the front to the back greatly reduced or even eliminated. By approximation, it is considered that the fluid outside the wake does not enter this wake, access to which is prohibited, at least in its original state characterized by the dominance of its translational movement from front to rear. in reality, there is an exchange of matter between the wake and the outside, but it can be overlooked.

The variation in size of the wake may be discontinuous, that is to say that the shape of the body may be provided so that around a certain speed limit there is an almost instantaneous passage from the absence of wake to the existence of a wake.

According to the invention, the creator body of the wake is adapted so that the limit speed of appearance of the wake is a significant fraction of the total range of variation of the vehicle speeds.

Several variants of the shape of the longitudinal sections of the wake body are possible. In a first variant, the wake body has at least one of its series of longitudinal sections parallel to each other, the rear part of which has an inflection point, on one or two of its opposite sides, so that following the direction of flow, the center of curvature which is first on a half-line starting from the surface then passing inside the body, is found on a half-line starting from the surface then going towards the outside of the body.

In a second variant, the creator body of the wake has at least one of its series of longitudinal sections parallel to each other, the rear part of which has, on one or two of its opposite sides, a portion whose curvature is at least substantially zero, which is connected tangentially to the beginning of the rear part and which goes to its end.

In an advantageous embodiment, the creator body of the wake has at least one of its series of longitudinal sections parallel to each other, the rear part of which has, on one or two of its opposite sides, a projection. separation of the fluid on the surface of the body. Beyond a certain speed limit, this separation bubble increases and results in a total separation of the fluid behind this portion. Thus, such an irregularity of the surface makes it possible to better control the position of the separation lines on the body. This position is variable on the bodies whose curvature varies only gradually.

For the same principles as for a projection, the creator body of the wake may have at least one of its series of longitudinal sections parallel to each other, the rear part of which has, on one or two of its opposite sides, an angular portion, corresponding to a abrupt narrowing of these sections.

The part of the object carrying the invention intended to receive fluid in a variable manner according to the behavior of the invention, that is to say to receive fluid whose movement is roughly similar to what it was before to undergo the effect of the invention, or else the fluid whose dominant movement of translation from front to rear is greatly reduced or even eliminated, is placed just behind the invention, that is to say say in the area where the wake appears, or else this part can receive the fluid undergoing the action of the invention through a conduit.

The area of space to which we want to control access, therefore includes the maximum volume that the wake can occupy. In the case where a duct, supplied when the wake is not present or is not at its maximum size by the fluid arriving from the front of the invention, at one of its ends present in the volume occupied by the wake, the area of space whose access is to be controlled by the fluid in motion is increased by the volume to which the drove.

Such a conduit may be composed of one or more parts which may or may not be distinct from the object carrying the invention and or from the body creating the wake. Thus, such a conduit may for example have one of its walls constituted by one of the walls of the object carrying the invention.

In the case where the fluid bypasses the creator body of the wake by two of its opposite sides, it is preferable that the body has a symmetry of its two faces each corresponding to one of the two sides, so that there is no not creating circulation around the creator body of the wake.

Other characteristics and advantages of the invention will appear on reading the following description which refers to the appended figures in which - FIG. 1 is a diagrammatic elevation view partially broken away of a vehicle according to the invention, - FIG. 2 is an enlarged view in section through a longitudinal vertical plane of one of the devices for controlling the air flow trajectory of the vehicle in FIG. 1, FIG. 3 is a view of a device adapted to a particular form of conduit, - Figure 4 is a schematic sectional view similar to Figure 2 showing a variant of the invention.

Figures 1 and 2 show an example of a vehicle according to the invention consisting of a motor car.

Throughout the text of this application, vehicle 1 is assumed to move horizontally and the relative air flow 2 created by the movement of the vehicle is assumed to be horizontal. Throughout the text of this application, the terms "before" and "rear" are used with reference to the direction of movement of the vehicle 1.

The longitudinal direction of the vehicle 1 is the horizontal direction parallel to the horizontal movement of the vehicle. The transverse direction is the horizontal direction perpendicular to the longitudinal direction of movement of the vehicle.

In the example shown, the vehicle 1 comprises two lateral pontoons 3 each located on one side of its body 4, and between its wheels 5. These pontoons 3 contain inter alia radiators 6 and 7 for cooling the engine. At each radiator 6 or 7, corresponds to part 8 or 9 respectively, of the relative air flow 2.

The part 8 of the relative air current 2 is brought, whatever the speed of the vehicle 1 to reach the radiator 6 after being engulfed in the upper part 10 of the pontoon 3 which has an opening 18 on its front. then discharged through the rear part 12 of the pontoon which is open.

Part 9 of the relative air stream 2 is made to undergo the action of the body 13. This part 9 of the relative air stream 2 corresponds at least substantially to the fraction of the relative air stream 2 which passes through a projection. of the body 13 on a vertical transverse plane located in front of the body 13.

Below a certain speed limit, the body 13 is bypassed by the part 9 of the relative air flow 2 which can therefore penetrate into the lower part 11 of the pontoon 3 to then reach the radiator 7 and then exit through the rear part 12 of the pontoon 3. The lower part 11 has an opening 15 between the lower wall 16 of the pontoon 3 and the body 13. The upper 10 and lower parts I1 of the pontoon 3 are separated by a horizontal flat plate 14.

Above the aforementioned speed limit, a wake appears behind the body 13 and it prevents part 9 of the air stream 2 from entering the lower part 11 through the opening 15 of the pontoon 3. Thus, the volume of which the body 13 makes it possible to control the air supply comprising the entire lower part 11 of the pontoon 3.

Above the speed limit, the radiator 7 is therefore not supplied with fresh air. The ratio between the vertical cross sections of the upper 10 and lower 11 parts of the pontoon 3 is provided so that beyond the speed limit the air flow in the upper part 10 is sufficient to cool the engine The shapes of the pontoon 3 and of the body 13 are provided so that the drag due to the wake of the body 13 and the bypass of the pontoon 3 by the part 9 of the current d relative air is less than the pressure drop which would be induced by the passage of this part 9 of the relative air current 2 in the lower part 11 then in the rear part of the pontoon 3 for the same vehicle speeds 1.

In the example presented of the vehicle 1 in FIGS. 1 and 2, the wake-creating body 13 and the flat plate 14 are produced in a single piece of carbon which is fixed by screws to the pontoon 3 itself made of carbon. in a vehicle according to the invention, a wake creator body may be a separate part from the other parts of the vehicle, or it may be confused with one or more other parts of the vehicle.

The wake-forming body 13 is characterized by longitudinal vertical sections, the front part 19 of which is convex with convexity oriented towards the front, and the lower rear part 20 of which tapers towards the rear has an inflection point of so that following the direction of flow, the center of curvature which is first on a half-line starting from the lower surface 21 then passing inside the body 13, is found on a half-line starting from the lower surface 21 then going downwards and towards the outside of the body 13.The upper surface 22 of the body 13 is planar.

In the example of vehicle 1, the body 13 has a width, defined in a transverse direction of the vehicle, of 300 mm. Its front part 19 has a radius of curvature of 125 mm, the center of curvature being located on the upper part 22. Its lower rear part 22, which first has the same radius of curvature as the front part 19, then has a portion of curvature at least substantially zero with an inclination equal to 14, then a point of inflection. body 13 is 690 mm. From the point of inflection, the curvature decreases and becomes zero at the rear end 24 of the body 13. The maximum cross section of the body 13 corresponds to one third of the cross section of the opening 18.

In the example of vehicle 1, the body 13 is extended from the rear by the flat plate 14 which separates the upper 10 and lower ducts 11. The body 13 is flanked on its right and its left by longitudinal vertical walls which are on the one hand constituted by the part of the bodywork 4 between the pontoons 3, and on the other hand constituted by a portion of the side wall 17 of the pontoon 3.These vertical walls allow good control of the transverse extension of the wake. More generally, a wake-creating body 13 according to the invention can be flanked on one or two of its opposite sides by such longitudinal walls, but not necessarily vertical.

The volume for which the body 13 makes it possible to control the supply of fluid is not limited to the zone where the wake appears, but thanks to the walls of the pontoon 3 and to the flat plate 14 which form a conduit, it is increased in particular of the lower part 11 of the pontoon 3.

In this example of the vehicle 1, the longitudinal sections of the body 13 all have the same projection on a longitudinal vertical plane. For a vehicle according to the invention it could be otherwise, a wake creator body could for example have a front part placed at an angle to part 9 of the incident air stream 2.11 it should be noted that in this case, an angle Too high an incidence would affect the functioning of the wake creator body. A wake creator body could, for example again, have longitudinal vertical sections whose projections on a longitudinal vertical plane would be offset in height. Such sections could be of size different, ... A wake creator body according to the invention could also have longitudinal sections of similar shapes but not parallel to each other.

Only one of the pontoons 3 is seen here, but the vehicle 1 according to the invention is generally symmetrical with respect to a median longitudinal vertical plane. Thus the vehicle 1 comprises two devices according to the invention.

FIG. 3 shows a variant of the invention in which the wake-creating body 13 has a general half-crown shape. It is located in front of an air inlet 25 in the form of a semi-disc, and of the same axis. This configuration allows, for the same affected front surface, to reduce the length of the body 13. Its radial longitudinal sections are identical between they.

FIG. 4 shows a variant of the invention in which the wake-creating body 13 is characterized by longitudinal sections, the rear part 23 of which, on each of its two opposite sides, has an angular portion 26 projecting outwards. Such projections cause the appearance of separation bubbles 27 of the incident fluid 2 on the surface of the body 13. The bubbles 27 are presented here in the case of a speed of the incident fluid 2 lower than the limit speed of appearance of the wake. , and there is therefore presence of gluing points 28 of the fluid on the surface of the body 13.

The invention is applicable not only to a motor car, but also to other categories of vehicles such as motorcycles, aircraft, ...

In addition, the invention may be subject to other variants than those shown in the figures, depending on the type and shape of each category of vehicle.

The invention is also applicable for other functions of a vehicle than the cooling of its engine, it can be so also for the air supply of its propulsion system, the ventilation of its passenger compartment, ...

Claims (1)

 CLAIMS 1 / - Vehicle intended to move at subsonic speed in the air, characterized in that for each of its air inlets or functions whose access is to be controlled by the fluid in relative motion, selectively according to its speed, without using a movable mechanism: - it comprises a rigid body (13) fixedly placed in front of the area of space for which the supply of fluid is to be controlled, - said body (13) receives the moving fluid (2) by its front, and sees the fluid bypassing it from the top, bottom, right, left or by several of these possibilities at the same time, depending on its position relative to the rest of the vehicle, - said body (13 ) has a shape designed so that its wake, linked to the separation of the streamlines from the surface of the body (13), can vary from a minimum, which is the total absence of wake, to a maximum, which can be a wake with the largest cross section t at least substantially equal to the largest cross section of the body (13) creating the wake. - the body (13) creating the wake has at least one of its series of longitudinal sections parallel to each other which are similar to sections, or to half-sections, of an almost completely profiled body, that is to say to say of a body whose front part (19) convex, with convexity oriented towards the front, presents a progressive variation of its curvature in the direction of flow, and of which the rear part (23) presents at least a variation rapid curvature, in addition to that corresponding to its end (24), or at least a portion of steep inclination relative to the direction of the incident fluid in front of the body (13); the connection between the front (19) and the rear (23) being without discontinuity in the variation in curvature. 2 / - Vehicle according to claim 1, characterized in that each body (13) creating the wake is adapted so that its wake is a zone of space where the movement of the fluid has a component of translation from the front to the rear greatly reduced or even eliminated. 3 / - Vehicle according to one of claims 1 and 2, characterized in that for each of its bodies (13) creating the wake, the limit speed of appearance of the wake is a significant fraction of the total range of variation of the speeds of the vehicle. 4 / - Vehicle according to one of claims 1 to 3, characterized in that at least one of its wake-creating bodies (13) has at least one of its series of longitudinal sections which are parallel to each other, the rear part (23) has an inflection point, on one or two of its opposite sides, so that following the direction of flow, the center of curvature which is first on a half-line starting from the surface then passing to the inside the body, is found on a half-line starting from the surface then going towards the outside of the body (13). <I> 5I - </I> Vehicle according to one of claims 1 to 4, characterized in that at least one of its wake-creating bodies (13) has at least one of its series of longitudinal sections which are parallel to one another. the rear part has, on one or two of its opposite sides, a portion whose curvature is at least substantially zero, which is tangentially connected to the start of the rear part (23) and which extends to its end (24). 6 / - Vehicle according to one of claims 1 to 5, characterized in that at least one of its wake-creating bodies (13) has at least one of its series of longitudinal sections which are parallel to one another, the rear part (23) has, on one or two of its opposite sides, a projection (26). 7 / - Vehicle according to one of claims 1 to 6, characterized in that at least one of its wake-creating bodies (13) has at least one of its series of longitudinal sections which are parallel to each other, the rear part (23) has, on one or two of its opposite sides, an angular portion, corresponding to a sudden narrowing of these sections. 8 / - Vehicle according to one of claims 1 to 7, characterized in that for at least one of its wake-creating bodies (13), a duct placed behind the body (13) increases the corresponding area of space, we want to control the supply of fluid to the volume to which the conduit leads. 9 / - Vehicle according to one of claims 1 to 8, characterized in that at least one of its wake-creating bodies (13) is flanked on two of its opposite sides by longitudinal walls. 10 / - Vehicle according to one of claims 1 to 9, characterized in that at least one of its wake-creating bodies (13) is merged with one or more other parts of the vehicle.