BRPI1003810A2 - Textured Surface Application Method for Aerodynamic or Hydrodynamic Drag Reduction on a Vehicle Surface and Textured Surface - Google Patents

Abstract

TEXTURIZED SURFACE APPLICATION METHOD FOR AERODYNAMIC OR HYDRODYNAMIC DRAG REDUCTION ON A VEHICLE SURFACE AND TEXTURIZED SURFACE. A cover and a method for obtaining textured surfaces are described with the main objective of reducing the drag coefficient, whether aerodynamic or hydrodynamic, enabling a performance gain and a reduction in fuel consumption. This surface is applied to vehicle exterior surfaces and has basically three distinct layers. A first distinct layer is characterized by a binder (100), a second layer is characterized by a screen (14) and the last distinct layer is characterized by an ink (53). The method basically consists of four distinct steps. In a first step, a binder layer is applied to the smooth surface of the vehicle. In a second step, the web is applied to the surface and in a third step preferably three more layers of binder are applied. In the last step a layer of paint is applied which will be used for sealing the textured surface and for aesthetic purposes.

Description

Report of the Invention Patent for "TEXTURIZED SURFACE APPLICATION METHOD FOR AERODYNAMIC OR HYDRODYNAMIC TRAFFIC REDUCTION ON A TEXTURIZED VEHICLE SURFACE".

The present invention relates to a textured surface and to a

a method to obtain it with the main objective of reducing the drag coefficient, whether aerodynamic or hydrodynamic, allowing a performance gain and a reduction in fuel consumption.

Description of the state of the art There is currently a major concern regarding the conservation

Because of this, the overwhelming majority of objects produced have some kind of social and environmental commitment. As an example of this statement, currently developed vehicle engines have higher efficiency and less aggregate pollution compared to the well-known internal combustion engines. As is well known, much of the energy developed by the vehicle engine is wasted due to friction or drag, which generates counter forces in the fluid's interface with the vehicle during travel.

The first solution found by the designers was based on the modification of the vehicle's external shape to reduce this loss, but there are limitations to these designs, as they should at the same time provide user comfort, ergonomics, functionality, aesthetic design. market efficiency and drag reduction efficiency (aerodynamic and / or hydrodynamic). In this sense, three strands were developed to help reduce these losses; A first strand concerns the development of ever smoother surfaces that would give a false feeling of greater fluidity, reducing drag loss. A second is the development of aerodynamic shapes, many in wind tunnels, which facilitate air flow over surfaces and better dissipation of vortices in low pressure areas, which reduces drag.

Contrary to the first strand, when processing increasingly smooth and polished surfaces, there is a third strand that advocates textured surfaces for drag reduction and utilizes knowledge developed by the second. Contrary to what was initially believed, smooth or polished surfaces have a higher drag coefficient compared to textured surfaces. Naturally, the surface texturing should be defined in such a way as to allow a reduction of the aerodynamic and / or hydrodynamic coefficient. If the texturing is done correctly, it is necessary to talk about significant gain over smooth surfaces. As will be seen below, this statement has a vast explanation of the physical phenomenon that occurs. As stated, the study of transport phenomena

the movement or movement of a body through fluids, added to a series of experiments in this field over time, allowed a new insight into the practical consequences of the various types of surface finishes, guiding the development of textured surfaces. These surfaces are considered more efficient in reducing drag due to the fact that they have cavities or convexities resulting from high and low reliefs. In these cavities there is the formation of vortices, which consist of a rotating flow, where the current flow lines present a circular or spiral pattern, where their movement occurs around a center of rotation. These vortices, also called stationary vortices, will provide advantages such as: decreasing the pressure gradient along the surface of the object, delaying the point of change from laminar to turbulent flow and, as a consequence, the region low pressure becomes narrower but longer. This principle had already been detected and applied previously, as can be observed on the golf ball. But the application of this same physical principle to vehicles is still in full development by a number of factors. One of the main factors preventing practical application is the cost of producing textured surfaces for their application in large areas. Such texturing could, for example, be applied when making a plate of a vehicle. By stamping the plate in a pre-textured mold it would already have the stamped properties as a consequence of the mold, but most likely this could only be applied to relatively flat surfaces such as a car hood. Already in the creases of greater or lesser curvature or angulation, or areas of concave or convex shape of such surfaces, it would still be possible to generate the cavities, but these manufacturing processes would present very high costs, which would in many cases make the process become handmade. Consequently, the cost does not allow for a possible series production, which is one of the main explanatory factors for the non-existence of large-scale vehicles with such texturing on their surface.

There are some attempts to make texturing applications viable as described below.

US 1976 / 3,973,510 describes a drag reduction submersible object and a method for obtaining it comprising applying a bonding agent which features a base layer and impermeable silica which is overlaid with the characteristic base layer. - rendering a top layer. The function of the binding agent is merely to promote the fixation of the impermeable silica layer with the object.

The ultimate goal of this method is to obtain a non-uniform outer coating that contributes to drag reduction. However, there are some disadvantages that can be cited, such as: the textured surface is for the exclusive use of marine vehicles; the final coating is necessarily non-uniform and the base layer formed of at least 50% impermeable silica. The potential environmental impacts associated with the use of silica are high, so the costs for safe application of this material are high. In addition, the very high cost of silica in this format makes it disadvantageous. This makes the final object produced expensive and not in accordance with current environmental laws.

WO 2009 / 083,622 discloses a system and method for reducing the frictional resistance of fluids applied in air or sea vehicles. This occurs from a screen that is held in a desired position by cables, clamps and / or other types of fasteners that retard the boundary layer separation point. This has the consequence of reduced turbulence and frictional resistance of the fluids.

The screens may have different distributions and shapes (pointed, concave or convex) according to the desired applications and the conditions of "attack" of the fluid.

A disadvantage of this process is that the user is required to maintain surface adjustment through tightening mechanisms or other types of mechanisms, which inevitably results in a loss of surface effectiveness over the long term. Another disadvantage is the possible theorization of the screen as it has no protective coating. Due to this fact, there is a possibility that with the deterioration of the screen, it may come loose. This would lead to an increase in the drag coefficient, which would meet its main purpose of drag reduction, as the hanging fabric would function on the same principle as an anchor. In addition, the object cannot be applied to land vehicles.

Finally, US 2009 / 0,256,385 describes a method for reducing aerodynamic and hydrodynamic drag in a vehicle comprising the steps of: providing a textured surface on the vehicle body such that it includes a structure of spaced cavities that induce to a turbulent zone. This zone causes the delay of the boundary layer along the body length and as a consequence promotes drag reduction. The textured surface is made up of two distinct layers,

where a first distinct layer is called a perforated layer and contains in its lower portion an adhesive. The second distinct layer is called a laminate layer, and also has an adhesive distributed throughout its lower portion. The perforated layer is fixed to the smooth surface of the vehicle and after its complete adhesion, the laminate layer is fixed, which promotes the definition of the final shape of the textured surface. This surface covers about 20 to 30% of the outer surface of the vehicle. The dimensions and shapes of the perforations and their concavities are not precisely defined and may take square, hexagonal, octagonal, oval or circular shapes. In a preferred embodiment, some dimensions are defined such as the diameter of the perforations which is approximately 4.8 mm and the center-to-center spacing of the concavities which is about 25.4 mm.

The fact that the nature of the layers is adhesive makes it difficult to fix them in living corner regions and / or regions with other geometric complexities. This is due to the lack of flexibility of these layers, which are so deformed in their application to geometrically complex regions, which significantly compromise their drag reduction properties.

Still with respect to the same document, there are voids (air bubbles) for two different reasons: the first occurs when the laminated layer is fixed over the perforated layer in the concavity region due to the difference in final shapes between the two beds. - and the second occurs due to the attempt to overlap two or more laminate layers. Due to this difficulty in fixing the layers, their final dimensioning is compromised. An example of this is that the dimensions of the concavities are directly determined by the thickness of the perforated layer.

Brief Description of the Invention

The present invention, in a preferred embodiment, discloses a method for aerodynamic and hydrodynamic drag reduction applied to vehicle exterior surfaces having basically three distinct layers. In a first step, preferably a resin layer (epoxy or polyester) acting as a binder is superimposed on the smooth surface of the vehicle to facilitate attachment of the subsequent layers. In a second step, a layer consisting of a web (woven polyester or other flexible material) is overlaid with the existing resin layer. The joining of these two layers gives rise to an upward absorbing flow from the still semi-liquid resin layer and initiates the process of naturally absorbing the fabric, merely guaranteed by a physical property. In a third stage, above said web are applied, having already absorbed part of the initial resin, in a preferred embodiment, preferably two or more layers of resin, whose material is identical to the first resin layer. This step defines the formation of a downward flow, also by natural / capillary absorption and gravitational action that will meet the upward flow, generating a definitive settlement of the resin layers in the bowel of the screen. This will serve to fix the screen to the smooth surface and set the final diameter of the concavities ranging from 2 to 10 mm. In the last step, layers of paint, which will be used for sealing the textured surface and for aesthetic purposes, are applied to the two distinct layers mentioned above.

One of the advantages of textured surfaces obtained from this method is that, after its application, there is no need for adjustments to maintain the drag reduction characteristics, ie it is a fully passive device.

Another advantage of this method is that the textured surface has no "air bubbles" since the resin applied to the canvas is composed of a thermosetting material, which at the moment of application is in the liquid phase and due to its physical characteristics. (viscosity, acting stresses, among others) is distributed over the entire surface of the screen, allowing no voids or latent stresses.

The nature of the layers that make up the textured surface and the method for obtaining them makes the final surface obtained to be considered as one. In other words, the textured surface is added in such a way to the smooth surface of the vehicle that one (textured surface) becomes an extension of the other (smooth surface), resulting in complete integration between them. This causes the textured surface to become a structural reinforcement and the resulting material to have some enhanced properties such as increased impact resistance and increased corrosion resistance. This last feature is due to the fact that the textured surface is preferably polymeric in nature. This results in the "shielding" of the raw materials constituting the smooth surfaces of vehicles which are preferably made of ferrous sheet metal.

In addition, the fact that the canvas is made of a material that only

can be fixed to the smooth surface of the vehicle from the application of a first layer of resin facilitates the maneuverability and attachment of the fabric to regions of sharp corners and / or regions having curved, concave, convex or other shaped areas. geometric complexities. Brief Description of the Drawings

The present invention will hereinafter be described in more detail based on an exemplary embodiment shown in the drawings. The figures show:

Figure 1 - is the visualization of some concepts arising from the state of the art;

Figure 2 - is the application of these concepts arising from the state

of technique;

Figure 3 is a cross-sectional view through which a mode of application of a first layer of resin featuring a distinct first layer can be viewed on the smooth surface of the vehicle;

Figure 4 is a top view of the screen featuring a second distinct layer;

Figure 5 is a view of how the screen is applied to a smooth surface of a vehicle;

Figure 6 - is a screen view applied to a surface

flat;

Figure 7 - is a visualization of the screen application mode on a surface of significant geometric complexity; Figure 8 is a cross-sectional view of a cross section

allows the visualization of the application of a second layer of resin on the canvas; Figure 9 is a view of the mode of application, in a preferred embodiment, of a third resin layer on the surface formed so far;

Figure 10 is a view of the mode of application, in a preferred embodiment, of a fourth layer of resin on the surface formed so far; Figure 11 is a view of the mode of application of an ink layer on the surface formed so far;

Figure 12 is a cross-sectional view taken after the paint is applied to the canvas and resin layers; Figure 13 is a top view of the final textured surface;

Figure 14 is a detail view of a living corner after being subjected to said method.

Detailed Description of the Figures

Figure 1 is a cross-sectional view showing the profile of a wing of a motor vehicle in contact with a fluid. Flow lines 1 are parallel to each other until the contact between the fluid and the wing profile begins.

It is important to note that the boundary layer defines the degree to which regions are affected by the fluid interface - wing cross profile, also called the airfoil. In view of this concept, three main flow lines are defined and measured using the Reynolds number, which is used to measure the flow level and classify it basically into three distinct types: laminar flow, transition flow and flow. turbulent. The first line 5, whose flow is laminar, is practically parallel to the flow lines 1, since they are in a region significantly away from the wing profile. The geometry of the wing profile causes a flow at its upper part which, from a certain point, generates vortices 3 along its length, which, depending on the velocity and angle of attack, characterizes a turbulent flow represented by second flow line 2. Due to the nearly flat shape of the underside of the wing profile, the characteristic flow of this region remains laminar as initial, which characterizes a third flow line 4. The turbulent flow shown by the second flow line 2 features a drag zone, which in this case represents the abrupt reduction in speed of the aircraft in flight, resulting in the so-called stall. If there were no such "detachment" of the layer laminar air flow, maintaining this flow following the fixedly fixed path along the entire extension of the upper surface, since the curvature has a longer path to In the upper part, a region of low pressure (vacuum) is obtained by the physical property of air expansion, which tends to "suck" the entire wing upwards. In the lower surface, this less curved, generates an area of high pressure by "attack" to the fluid, by the physical property of compressibility of air. This simultaneous combination causes a pressure gradient that allows the air vehicle to float. This pressure gradient is called thrust or hold. This figure illustrates how drag is formed on a moving body through the air and how, by the physical property of that same air, that of expansion, creates an area of low pressure that creates a force contrary to that of the body's direction of movement. , acting as a brake, ie the definition of drag.

Figure 2 illustrates another application of the concepts discussed above, where a hypothetical smooth surface golf ball 6 is subjected to an air movement. The interface region 12 whose flow is laminar becomes reduced due to the location of the boundary layer separation point 10. It is important to highlight that in this region, before the laminar flow detachment along the surface, the friction forces applied to the sphere are in reduced area. The "air mat" 7 formed after the surface laminar flow layer has detached for this configuration is wider, occupying a large relative area in section, where the low air pressure (vacuum) forces act, exerting great brake, that is, drag effectiveness. The textured surface golf ball 8 is subjected to the

same movement, but its cavities allow an increase in the laminar space region 13 due to the delay of the boundary layer separation point 151, this means an increase in the region subjected to reduced frictional forces. Another development of this configuration is the formation of an "air mat" 9 characterized by a narrower but longer shape.

This comparison allows us to conclude that objects whose surfaces

are textured, they have a greater region of exposure to reduced pressure gradients which allows a smaller action of the vacuum (expanded air) that forms in the outlet (leakage) part of the body, since its area of action Reduced air reduces the effectiveness of the drag, allowing longer air fluctuation in the case of the golf ball.

Another feature that emerges from this action of the air layers over the textured surface of the moving golf ball is that the formation of the point microturbillion in each "cavity" of the texturing becomes proportionally intense, which, being compressed, causes a detachment of the laminar layers from the rigid surface of the ball, causing friction to pass air over the rigid surface of the golf ball to air over microturbillions, ie air to air friction, which further reduces the resulting drag coefficients in the moving ball.

In light of all the concepts discussed by the state of the art,

It is necessary to develop objects that, when subjected to movement (dislocations), present a reduced drag loss. Some methods for obtaining textured surfaces that reduce drag applied to vehicles have been developed but, as discussed, all these methods have disadvantages that hinder their implementation and functionality. This is due to the fact that despite the vast use of textures for the formation of cavities, such as the use of golf balls, it has not been employed to date in industrial scale such application to large objects such as vehicles or boats.

The object and method for aerodynamic and hydrodynamic drag reduction on a vehicle surface of the present invention is then presented, where Fig. 3 is a cross-sectional view of the first application mode. Resin layer 100, which features a distinct first layer and acts as a binder on the smooth surface of vehicle 200.

The first distinct layer facilitates the process of fixing the

later layers as it makes the smooth surface of the vehicle more adherent.

Figure 4 is a top view of the screen 14 where it is possible to view the alignment and orientation of the holes 15. The spacing between the holes / future concavities is initially defined between 1 and 10 mm and the diameter of the holes may vary between 0 , 5 and 20 mm.

Figure 5 shows the exact moment when screen 16 is applied to a surface 17 of a vehicle. Importantly, the fixation of the mesh occurs after half cure of the first resin layer. This application causes an upward flow from the resin layer to begin and the process of filling the screen. In addition, the application is made in such a way that the screen remains movable along the entire smooth surface of the vehicle as there is no type of adhesive attached to it. The screen, in a preferred embodiment, is placed on the entire surface of the vehicle at one time. If there are regions that do not need the textured surface, due to the small "attack" of fluid, the application of screens will be done by regions. Other areas that will be avoided for obvious reasons are transparent glass.

Figure 6 is presented to make it easier to understand how screen 16 is made available after its application in a wide region. Because of this, a flat surface of the vehicle 17 with screen applied is presented. Note that the screen does not obstruct the view of the vehicle surface 17 due to its shape and composition.

Figure 7 shows the step of securing screen 18 in a sharp corner region 19 of an object 20. The fact that screen 18 is flexible facilitates operator or process handling in regions of significant geometric complexity. . Another important fact to note is that the high degree of flexibility of the screen does not allow permanent deformation of the screen regardless of the region of application, which ensures the maintenance of drag reduction characteristics. This high degree of flexibility, on the other hand, allows the screen to be applied to any external surface region of the vehicle. This allows, if necessary, a coating of 100% of the external area of the vehicle.

Importantly, the flexibility of the screen is due to the fact that it is a warp and weft fabric composed of several segments (micro-filaments) which allows, in cases of very complex surfaces, very close application without that bubbles or material is left over. Some types of surfaces could not be coated, but by the object of the present invention this became possible, such as convex surfaces and concave surfaces.

Figure 8 is a cross-sectional view showing how to apply a second layer of resin 31 onto screen 16. The second layer of resin 31, due to the presence of capillary tensions and the fact that it is a thermosetting material that is in the liquid phase at the time of application is distributed throughout the entire region of the mesh, even being absorbed by it, as indicated by the downflow arrows 33. Another important fact is The highlight is that the upward flow 150 meets the downward flow 33, which causes the formation of various resin regions which will be discussed below. A first resin region 29 formed lies between the underside 35 of the screen 16 and the smooth surface 17 of the vehicle. This first formation occurs after the passage of the first resin layer described in figure 3. Simultaneously two subsequent layers are formed from the junction of flow lines 33 and 150, which are: the absorbed resin layer by the screen 16 and the resin layer 27 lining the sidewall. This last cited layer presents critical points that are those of live corners (26, 28). Bottom 28 has a higher resin layer thickness due not only to the weight of the layer itself but also to the flow direction. As a result, point 27 has a median resin layer thickness due to the aforementioned layer characteristics, and lastly, point 26 has a lower resin layer thickness than the 3 points mentioned. The second resin layer 31 may form a higher base than screen 16. This dependence is linked to the amount of resin deposited in the first and second applications.

Figure 9 illustrates the mode of application, in a preferred embodiment, of a third resin layer 36 on the surface formed thereafter. This third layer may perform a coating as shown in Figure 8 or it may terminate the process of filling the screen 16 and begin forming a layer of resin overlapping the screen. If the coating is made as shown in Figure 8, the second resin layer 36 will overlap the first resin layer 31 such that the resin now applied will no longer have direct physical contact with the fabric. Thus, this layer 36 will already serve to start the process of defining the final dimensions of the concavities.

Figure 10 shows the mode of application, in a preferred embodiment, of the fourth resin layer 42 on the two previous layers (40, 41) which will, in a preferred embodiment, define the final dimensions of the concavities and the textured surface thickness as a However, the latter is usually 0.5 to 3 mm.

The application of the third and fourth resin layers will depend on a number of characteristics inherent in the vehicle to which the textured surface will be applied, such as: vehicle region, degree of fluid attack and the like. Therefore, the application of the third and fourth layers becomes optional.

Figure 10 is a cross-sectional view taken on the surface after applying all four resin layers and the screen 16 on the smooth surface of the vehicle 17. Note that in another preferred embodiment of the invention it is possible to apply only three layers of resin, but this is a function of the material employed and even the type of surface being treated. This practically characterizes the final dimensions of the coating, both in the flat region and in the concavity or convexity region.

Figure 11 shows the manner of applying an ink layer 60 on the surface formed so far. The paint is applied, in a preferred embodiment, by a blasting technique, where the formed layer has significant thickness in the final "fit" to optimize the dimensions of the texturizing elements, of course, the sealing and final finishing. desired aesthetic.

Figure 12 illustrates a cross-sectional view 60 in which it is possible to view all the layers that make up the textured surface, including the newly applied paint layer 53.

Figure 13 is a top view of the final textured surface 62, where it is possible to view the formed concavities 63. These concavities 63 make it possible to form vortices (micro-swirls) that will characterize the separation point delay process. As a consequence of this, there is a reduction of the drag loss in vehicles coated by the textured surface. The spacing between the concavities can also be viewed from this figure.

Figure 14 is a detail view of a complete surface, such as a corner or convex surface 64 with sharp corners, after undergoing said method. It is possible to notice that the concavities 63, signifi- cantly close to 65 to these regions of high geometric complexity, do not present distortions in their form due to the characteristics mentioned above such as: the flexibility of the screen and the way of its application on the surface of the object. .

Having described an example preferred embodiment, it is to be understood that the scope of the present invention encompasses other possible variations and is limited only by the content of the appended claims, including the possible equivalents thereof. In addition, the figures presented above have a purely illustrative character, thus not characterizing a real proportion between the elements constituting the textured surface described above.

Claims (16)

1. Method of applying a textured surface for aerodynamic or hydrodynamic drag reduction to a vehicle surface comprising the steps of: - applying a mesh (14) with spaced holes over the surface to be coated; characterized in that: - after applying the screen (14) on the surface, coating the screen with a Binding Agent (100); - the binding agent is applied until it penetrates the screen (14) and provides a retention of it to the surface to be coated; - agent (100) is applied as many times as necessary until it covers the screen (14), generating an outer layer that promotes the formation of concavities (63) in its interaction with said spaced holes (15) . Method according to Claim 1, characterized in that the step of securing the web (14) may be preceded by applying a layer of Binder (100) such as to provide a prefixing of the web. screen (14) and make it easier to apply it. Method according to either claim 1 or claim 2, characterized in that the textured surface further receives an ink layer (53). Method according to any one of claims 1 to 3, characterized in that the web (14) comprises a polyester or other flexible material. Method according to any one of claims 1 to 4, characterized in that the binding agent (100) is composed of a resin whose material may be epoxy or polyester. Method according to any one of claims 1 to 5, characterized in that a layer of paint (53) is applied to the textured surface. Method according to any one of claims 1 to 6, characterized in that the concavities (63) shown on the textured surface have a diameter ranging from 1 to 20 mm. Method according to any one of claims 1 to 7, characterized in that the spacing of the concavities (63) shown on the textured surface ranges from 2 to 10 mm. Method according to any one of claims 1 to 8, characterized in that the thickness of the textured surface at the end of the process is 0.5 to 3mm. Method according to any one of claims 1 to 9, characterized in that the textured surface has application to the outer surface of the vehicle which may vary from 10% to 100% coverage. Textured surface which allows the reduction of aerodynamic or hydrodynamic drag as defined in any one of the preceding claims, characterized in that it has two distinct layers where the first distinct layer is composed of a screen (14) and the second bed. - of the distinct one is composed of a ligand agent (100). Surface according to Claim 11, characterized in that the textured surface further receives a layer of paint (53). Surface according to claim 11 or 12, characterized in that it is attached to the original smooth surface of the vehicle forming a single continuous surface. Surface according to any one of claims 11 to 13, characterized in that the continuous textured surface is polymeric and corrosion resistant, which makes the final surface to be more corrosion resistant in vehicles where She is present. Surface according to any one of Claims 11 to 14, characterized in that the smooth surface of the vehicle is covered against corrosion. Surface according to any one of Claims 11 to 15, characterized in that the smooth surface of the covered vehicle is structurally reinforced.