Aerodynamic measuring grid

Abstract

The present invention relates to an aerodynamic measuring grid (14), comprising: a guide frame (20) with longitudinal struts (34) and transverse struts (36), Kiel probes (22) arranged parallel to each other or substantially parallel to each other on the guide frame (20) and having a tubular main body (56) with a fluid inlet (28), a lance (44) with an inner channel (54), the lance (44) being arranged in the tubular main body (56) and an outer channel (70) being located between the lance (44) and the tubular main body (56), the inner channel (54) having an inner channel inlet (58) and an inner channel outlet (62) and the outer channel (70) having an outer channel inlet (67) and an outer channel outlet (68), a pressure measuring device (32), and air pressure lines which are each arranged between the inner channel outlet (62) of one of the Kiel probes (22) and the pressure measuring device (32) and at least partially in the longitudinal struts (34) and / or the transverse struts (36).

Description

[0001] Aerodynamic measuring grid

[0002] The present invention relates to an aerodynamic measuring grid, an aerodynamic measuring system and a method for carrying out aerodynamic measurements with such an aerodynamic measuring system.

[0003] It is known that aerodynamic measurements on vehicles are a necessary but complex task for reducing air resistance, which often requires the use of a wind tunnel.

[0004] The availability of wind tunnels is limited and their use is expensive. Wind tunnel measurements are also time-consuming and expensive. Furthermore, they have limited ability to realistically replicate the conditions a vehicle is exposed to during driving. For example, cornering and other complex maneuvers frequently encountered in real-world driving situations cannot be accurately simulated. This represents a significant hurdle for conducting comprehensive and accurate aerodynamic measurements.

[0005] As an alternative to wind tunnel measurements, it is known to use local measuring devices on vehicles, such as keel probes, which measure air pressure. However, known aerodynamic measuring devices based on keel probes have the disadvantage that they are not standardized, and measurements taken with them are prone to errors. Keel probes with common designs have only a very limited angle of attack, which means that an incoming airflow direction to be measured that lies outside the angle of attack leads to inaccurate or erroneous measurements. Such deviations regularly occur during driving maneuvers such as cornering, but can also occur when certain weather conditions prevail, such as strong crosswinds. Furthermore, keel probes are also expensive and are therefore only used in special applications such as racing.However, the precise functionalities, mechanics, and technologies of racing applications are largely unpublished individual solutions and therefore do not represent the general state of the art in the details necessary for general application. As a result, aerodynamic measurement techniques are only available to a limited extent, are associated with high costs, and often require considerable effort to implement.

[0006] This creates a gap in our understanding of the aerodynamic properties of vehicles under real-world conditions.

[0007] It is an object of the present invention to solve the above-mentioned problems.

[0008] In particular, it is an object of the present invention to provide a measuring device that enables reliable, simple, and cost-effective aerodynamic measurements to be performed in real-world driving situations. This measuring device should be capable of performing accurate and reliable measurements under a wide range of conditions, including complex maneuvers such as cornering. Furthermore, it should be cost-effective and easy to operate to enable widespread application.

[0009] The object of the present invention is to at least partially remedy the disadvantages described above in a cost-effective and simple manner. In particular, the object of the present invention is to provide a device for performing aerodynamic measurements on vehicles in a cost-effective and simple manner.

[0010] It is a further object of the invention to measure aerodynamic data of vehicles more accurately in real driving situations.

[0011] The above objects are achieved by an aerodynamic measurement grid having the features of claim 1, an aerodynamic measurement system according to claim 15, and a method for performing an aerodynamic measurement having the features of claim 16. Further features and details of the invention emerge from the subclaims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the aerodynamic sensor according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0012] A first aspect of the present invention provides an aerodynamic measurement grid.

[0013] The aerodynamic measurement grid is designed to feature a guide frame with longitudinal and transverse bracing. The guide frame serves as a structural base and allows the various components to be arranged on it. The guide frame also forms a stable and robust structure capable of withstanding the stresses and strains encountered during a test drive.

[0014] Furthermore, the aerodynamic measurement grid comprises keel probes arranged parallel to one another or substantially parallel to one another and on the guide frame, each having a tubular base body with a fluid inlet and a lance with an inner channel. The lance is arranged in the tubular base body such that an outer channel is formed between the lance and the tubular base body. The inner channel has an inner channel inlet and an inner channel outlet. The outer channel has an outer channel inlet and an outer channel outlet.

[0015] This arrangement of the keel probes enables accurate and reliable measurement of the air pressure at the measuring positions defined by them.

[0016] The aerodynamic measuring grid further comprises a pressure measuring device and air pressure lines, wherein the air pressure lines are each arranged between the inner channel outlet of one of the keel probes and the pressure measuring device and at least partially in the longitudinal struts and / or the transverse struts. The air pressure present at the inner channel inlet is transmitted to the pressure measuring device through the air pressure lines arranged in this way. The air pressure lines are in particular designed, at least partially, as 3D-printed channels within the longitudinal struts and / or the transverse struts. Individual channels conduct the air pressure from each of the keel probes separately to a channel outlet, which can be connected to a measuring inlet of the pressure measuring device, in particular via a flexible pressure hose. The longitudinal struts and transverse struts are arranged essentially perpendicular to one another.Longitudinal struts and transverse struts are preferably designed in a straight form, as this often enables the shortest paths for pressure transmission, but can also be at least partially curved.

[0017] An advantage of this arrangement is that the tubular base body with fluid inlet and the outer channel with outer channel inlet and outer channel outlet ensures a uniform flow around the lance with the inner channel and thus high measurement accuracy at the inner channel, even at a large flow angle of 50° or more.

[0018] The core idea of ​​the aerodynamic measuring grid according to the invention is that an aerodynamic measurement can be carried out easily and with high accuracy even during road measurements, since the design of the aerodynamic measuring grid can be produced by means of additive manufacturing, its keel probes have a large angle of attack and the aerodynamic measuring grid is therefore universally applicable, an accurate pressure transmission between the inner duct inlet and the pressure measuring device is made possible by the air pressure lines and potential measurement errors due to turbulence generated by the measuring device itself due to the routing of the air pressure lines in the longitudinal struts and / or transverse struts of the guide frame are reduced compared to alternative designs.

[0019] The aerodynamic measurement grid is a device designed to measure the aerodynamic behavior of bodies in air or other gases at multiple locations using point-based pressure measurements. An aerodynamic measurement refers to the quantification of air turbulence, forces, and local pressures that occur during the movement of a body through a fluid, especially air. A vehicle is a structure equipped with wheels, runners, or wings, with its own or external propulsion, for the transport of people and loads and can in particular be a car, preferably a passenger car or a truck. The guide frame is a structure that serves to hold other components, especially the keel probes, in a specific orientation and position and to guide the air pressure lines at least partially within its interior.Keel probes are a further development of the Pitot tube and are used to measure the total pressure in moving flows. They have the advantage over the normal Pitot tube of being less sensitive to the angle of attack. The fluid inlet for receiving air pressure is an opening in the keel probe through which air enters the interior of the probe to measure the air pressure. After the air enters the fluid inlet, the air channels split into an inner channel in the lance and an outer channel between the lance and the tubular base body. After entering the keel probe via the fluid inlet, the air can either be guided via the inner channel inlet, through the inner channel to the inner channel outlet and then via the air pressure lines to the pressure measuring device, where a pressure measurement is taken, or it can flow around the lance via the outer channel inlet, the outer channel and the outer channel outlet.

[0020] An arrangement of the keel probes parallel to each other means that their fluid inlets point in the same direction and the central axes of the tubular base bodies run parallel to each other or have only small angular deviations of up to ±5° from each other. An arrangement substantially parallel to each other means that the central axes of the tubular base bodies can have angular deviations from a central axis of up to ±45°, preferably up to ±22.5°, and particularly preferably up to ±10°.

[0021] The tubular base body can have a round or square cross-section. Preferably, the cross-section of the tubular base body is round, thus giving the tubular base body a cylindrical shape, or oval; alternatively, however, it can also have the shape of a polygon, in particular a regular polygon, preferably a regular quadrilateral, pentagon, hexagon, or octagon.

[0022] The pressure measuring device is a device that measures the physical pressure of a liquid or gaseous medium. The air pressure lines are, in particular, ducts, preferably pressurized ducts, but can also be pipes or hoses used to transport air from one location to another with little or no significant pressure change. They are sufficiently dimensioned to ensure efficient air flow and / or efficient air pressure transfer. The lance with an internal channel is a long, slender component that has a continuous channel or opening along its length. The lance can, in particular, be or comprise a Pitot tube.

[0023] It can be advantageous if the aerodynamic measuring grid according to the invention is provided with the aerodynamic measuring grid itself and / or the keel probes being manufactured at least partially by additive manufacturing. Additive manufacturing, also known as 3D printing, is a process for producing three-dimensional solid objects from a digital model. In additive manufacturing, components are built up layer by layer rather than by removing material. One advantage of additive manufacturing is that it enables fast and cost-effective production. The additive manufacturing method preferably comprises one or more of the following processes: stereolithography, selective elastomer melting, and fused deposition modeling.

[0024] Further advantages are achieved if the tubular base body is tapered at the fluid inlet. Tapering refers to a change in the diameter of the tubular base body along its length. With tapering, the diameter of the tubular base body at the fluid inlet is increased in relation to an outer channel diameter, in particular by at least 40%, preferably by at least 50%, particularly preferably by at least 60%. An advantage of this particular embodiment of the invention is that air flows from a larger angular range with no or only slight changes in air pressure can be recorded and transmitted for measurement without causing relevant flow changes. This reduces the sensitivity of the aerodynamic sensor to the orientation, wind direction, and / or driving maneuvers performed. Different air flows can also be measured precisely.

[0025] Preferably, the pressure measuring device comprises a multi-channel pressure sensor. A multi-channel pressure sensor is capable of performing pressure measurements in multiple channels simultaneously. An advantage of this particular embodiment of the invention is that it enables simultaneous measurement at multiple points with a single device, thus eliminating or at least reducing errors caused by malfunctions or incorrect settings, such as calibration errors, of different sensors.

[0026] Further advantages are achieved when the guide frame has interconnected longitudinal bracing, transverse bracing, and / or diagonal bracing. An advantage of this particular embodiment of the invention is that it ensures high stability and strength of the guide frame, which can lead to more reliable measurements, and some of the air pressure lines can be shortened, thus reducing pressure transmission fluctuations.

[0027] It is particularly advantageous if the cross-sectional area of ​​the outer channel outlet is at least 50% larger than the cross-sectional area of ​​the fluid inlet. The cross-sectional area of ​​the outer channel outlet is typically composed of the cross-sectional areas of several individual outlets, particularly holes, that together form the outer channel outlet. In other words, the ratio of the cross-sectional area of ​​the outer channel outlet to the cross-sectional area of ​​the fluid inlet is at least 1.5. A ratio of this magnitude greatly reduces the dependence of the measured values ​​on the angle of flow.

[0028] Further advantages are achieved when the fluid inlet has a diameter of at least 5 mm, in particular at least 7 mm. An advantage of this particular embodiment of the invention is that it ensures sufficient air supply for the measurements and, in combination with an additive manufacturing process, can be manufactured with better relative manufacturing tolerances. Both lead to more accurate measurement results.

[0029] In particular, it can be provided that the inner channel has an inner diameter of at least 1.2 mm, preferably of at least 1.4 mm. An advantage of this particular embodiment of the invention is that it enables precise measurement of the air pressure within the channel, which also leads to more accurate measurements. According to a further preferred embodiment of the invention, it can be provided that the lance has a wall thickness of at least 0.8 mm, preferably of at least 1.0 mm. This enables or facilitates additive manufacturing, in particular.

[0030] Further preferably, the ratio between the diameter of the inner channel and the diameter of the tubular base body can be between 0.25 and 0.5. In this context, the "diameter" refers to the inner diameter. An advantage of this particular embodiment of the invention is that it offers an optimal balance between the size of the inner channel and the stability of the tubular base body, which enables more reliable measurements.

[0031] It is further advantageous if the inner channel inlet of the lance is spaced from the fluid inlet of the tubular base body by at least 2 mm, preferably at least 3 mm, in the longitudinal direction of the keel probe. An advantage of this particular embodiment of the invention is that it enables precise measurement of the air pressure at a specific point within the channel, which can lead to more accurate measurements.

[0032] The keel probes can be attached to the guide frame via a screw thread. An advantage of this particular embodiment of the invention is that it allows for simple and secure attachment of the keel probes to the guide frame, which can also lead to more reliable measurements and allows for interchangeability of the keel probes in the event of a fault or for special types of measurements, for example, for testing different keel probe designs.

[0033] It can be provided that the guide frame has an adapter device for connecting the guide frame to other identical or similar guide frames. An advantage of this particular embodiment of the invention is that it enables flexible adaptation of the measuring system to different requirements, which enables more versatile measurements and can cover larger measuring ranges. It can be provided that the guide frame and at least one of the keel probes, in particular all keel probes, are manufactured using additive manufacturing. An advantage of this particular embodiment of the invention is that it enables rapid and cost-effective production of components, in particular complex or customized components.

[0034] It can be provided that the keel probes span a measuring field and are arranged on the measuring field at equal distances from one another in at least one direction. An advantage of this particular embodiment of the invention is that it enables comprehensive and uniform coverage of the measuring field, which leads to a more detailed and accurate measurement of the aerodynamic properties. In particular, the keel probes can also be arranged on the measuring field at equal distances from one another in two directions. This way, the keel probes form square rectangular grids.

[0035] According to a second aspect, the invention provides an aerodynamic measuring system comprising an aerodynamic measuring grid according to any one of claims 1 to 14, and a wind measuring device for measuring wind direction and wind strength independently of the aerodynamic measuring grid.

[0036] The aerodynamic measuring system may further comprise an evaluation device to evaluate the measured data, in particular in an automated manner.

[0037] According to a third aspect, the invention provides a method for performing an aerodynamic measurement on a vehicle with an aerodynamic measuring system according to claim 15.

[0038] The method comprises the steps of: a) providing a vehicle with an aerodynamics measuring system according to claim 15, wherein the wind measuring device is arranged at a wind measuring position on the vehicle and the aerodynamics measuring grid is arranged at an aerodynamics measuring position on the vehicle, b) performing a driving maneuver on a roadway, c) measuring the wind direction and wind strength relative to the vehicle with the wind measuring device and the static air pressure at the positions of the keel probes with the aerodynamics measuring grid during the driving maneuver, and d) calculating a pressure coefficient at the positions of the keel probes using the associated static air pressure, the measured wind direction, and the wind strength. An advantage of this method is that it enables accurate and reliable measurement of the aerodynamic properties of a vehicle under real driving conditions.

[0039] In this method, the pressure coefficient c pbe determined by

[0040] Where p is the measured static pressure, p sta t the static pressure in the free flow is independent of the vehicle, p tot describes the pressure at the stagnation point of the free flow, p represents the fluid density, and LL represents the fluid velocity of the free flow. For this purpose, the value of ptot is measured using the keel probes. The values ​​of LL and pstat are measured using the wind measurement device, i.e., the reference sensor, independently of the keel probes. The value of p is calculated from known environmental conditions and / or from data from the reference sensor on the test day using the barometric altitude formula. For this purpose, a reference sensor can also calculate the values ​​of relative humidity, air temperature, altitude above sea level, and / or atmospheric pressure.

[0041] The method may further include the step of adjusting an aerodynamically relevant component of the vehicle based on the pressure coefficient measured in step d). With this additional step, the method serves, in particular, to aerodynamically optimize the vehicle. It is possible to use the obtained data to specifically optimize the aerodynamic properties of the vehicle and / or a component of the vehicle.

[0042] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. They schematically show: Fig. 1 shows a vehicle with an aerodynamic sensor according to the invention in accordance with a particular embodiment of the invention,

[0043] Fig. 2 is a perspective view of an aerodynamic measuring grid of a particular embodiment of the invention,

[0044] Fig. 3 is another perspective view of the aerodynamic measuring grid according to Fig. 2,

[0045] Fig. 4 is a further perspective view of the aerodynamic measuring grid according to Figs. 2 and 3,

[0046] Fig. 5 is a plan view of an aerodynamic measuring grid of another particular embodiment of the invention,

[0047] Fig. 6 is a perspective view of the aerodynamic measuring grid of Fig. 5,

[0048] Fig. 7 is another perspective view of the aerodynamic measurement grid of Fig. 6, and

[0049] Fig. 8 a technical drawing of a keel probe with dimensions.

[0050] Figure 1 shows a vehicle 10 configured to perform an aerodynamic measurement using an aerodynamic measurement system 12 according to a particular embodiment of the invention. For this purpose, an aerodynamic measurement grid 14 is arranged on the vehicle 10 at an aerodynamic measurement position behind the left exterior mirror 16. The position behind the left exterior mirror 16 is of aerodynamic interest, since the exterior mirror 16 generates turbulence while driving and makes a significant contribution to the vehicle's air resistance. The type and magnitude of the turbulence, and thus the air resistance, can also be significantly altered by the design of the exterior mirror 16.

[0051] Furthermore, a wind measuring device 18 is arranged at a wind measuring position on the roof of the vehicle 10. The wind measuring device 18 serves to measure the wind direction and wind strength independently of the aerodynamic measuring grid 14. The wind measuring device can, in particular, also be arranged at a wind measuring position elevated above the roof of the vehicle 10. This allows the values ​​measured by the wind measuring device 18 to be measured independently of the vehicle 10 and the turbulence it generates. The wind measuring device 18 is preferably arranged at least 50 cm above the roof of the vehicle 10, particularly preferably at least 100 cm above the roof of the vehicle 10.

[0052] Figure 2 shows an aerodynamic measuring grid 14 according to a particular embodiment of the invention, which is a component of the aerodynamic measuring system 12. The aerodynamic measuring grid 14 has a guide frame 20 with longitudinal struts 34 and transverse struts 36. A total of 16 keel probes 22 are arranged parallel to one another in a rectangular matrix on the guide frame 20. Each of the keel probes has a lance 44 with an internal channel in a tubular base body 56. The tubular base body 56, in turn, has an eluent inlet 28. Further details on the specific design of the keel probes are explained in connection with Figure 8.

[0053] In addition to the longitudinal struts 34 and the transverse struts 36, the guide frame 20 also has diagonal struts 38. Air pressure lines are arranged in each of the longitudinal struts 34, transverse struts 36, and diagonal struts 38, each of which connects an inner channel outlet 62 of one of the keel probes 22 to a measuring inlet 40 of the pressure measuring device 32. The inner channel outlets 62 of the keel probes 22 preferably end in the passages and are therefore in fluid communication with the air pressure lines directly in the passages. In the embodiments shown, the air pressure lines are designed as 3D-printed channels, with the inner channel outlets 62 leading directly into the channels.

[0054] Figure 3 shows the aerodynamic measurement grid 14 of Figure 2 from a perspective rear view. Also shown here are the keel probes 22, the guide frame 20, the longitudinal struts 34, the transverse struts 36, and the diagonal struts 38. The pressure measuring device 32 is arranged centrally in the guide frame. From this perspective, it can be seen in particular that the pressure measuring device 32 has several pressure measuring inlets 40, to which the air pressure lines are connected during operation. Furthermore, the perspective of Figure 3 clearly shows that the longitudinal struts 34 and the transverse struts 36 extend further in the longitudinal direction of the keel probes 22 than transversely to them.This creates, on the one hand, enough space in the longitudinal struts 34, transverse struts 36 and diagonal struts 38 of the guide frame 20 to arrange the air pressure lines therein and, on the other hand, to design the shape of the guide frame 20 in such a way that it itself has low air resistance.

[0055] Adapter devices 42 are arranged on the longitudinal struts 34 and the transverse struts 36 of the guide frame 20. Using the adapter devices 42, the guide frame 20 can be connected to other identical or similar guide frames 20. This allows the measurement area covered by the aerodynamic measurement grid 14 to be expanded virtually as desired.

[0056] Figure 4 shows the aerodynamic measurement grid 14 already shown in Figures 2 and 3 from a third perspective. This perspective view shows, in particular, the lances 44 of the keel probes 22 inside the tubular base body 56. The tubular base body 56 of each of the keel probes 22 is tapered at the fluid inlet.

[0057] Figure 5 shows a schematic plan view of an alternative embodiment of the aerodynamic measuring grid 14. In this alternative embodiment of the aerodynamic measuring grid 14, the guide frame 20 has, in addition to the longitudinal struts 34, the transverse struts 36, and the diagonal struts 38, additional struts 48 in the longitudinal and transverse directions. These also have air pressure lines and connect internal keel probes 22 to the diagonal struts 38, thus shortening the distances traveled by the air pressure lines in the longitudinal struts 34 and transverse struts 36 between the keel probe 22 and the pressure measuring device 32. Furthermore, the additional struts 48 ensure increased mechanical stability of the guide frame 20 and thus of the aerodynamic measuring grid 14.

[0058] Figures 6 and 7 show the aerodynamic system shown schematically in Figure 5.

[0059] Measuring grid 14 is shown in different perspectives. In addition to the features already described, a measuring head 50 is arranged on the pressure measuring device 32, which is in signal communication with the pressure measuring device 32. A data transfer cable 52 leads from the measuring head 50 to an evaluation device (not shown), which is configured to evaluate the data measured by the pressure measuring device 32.

[0060] Figure 8 shows a technical drawing of a section through a keel probe 22, in which essential dimensions of individual elements of the keel probe 22 are indicated by dashed lines and double arrows. The section plane is located along a central axis 46 of the keel probe 22. All dimensions are given in mm.

[0061] The keel probe 22 has a tubular base body 56 with a fluid inlet 28 and a lance 44 with an inner channel 54. The inner channel 54 has an inner channel inlet 58 and an inner channel outlet 62. The lance 44 is arranged radially centered in the tubular base body 56, so that an outer channel 70 is formed between the lance 44 and the tubular base body 56. The outer channel 70 has an outer channel inlet 67 and an outer channel outlet 68.

[0062] The tubular base body 56 forms the outer shell of the keel probe 22.

[0063] During operation, the air flows through a fluid inlet 28 into the keel probe 22 and flows there partly through the inner channel inlet 58 into the inner channel 54 and partly via the outer channel inlet 67 into the annular outer channel 70, past the inner channel 54 to the outer channel outlet 68 formed by a plurality of holes 66. The holes 66 are added to the sectional view of Figure 8 to illustrate and explain the design and function of the keel probe 22 in more detail. The keel probe 22 has a total of three circumferential rows of eight holes 66 each, which form the outer channel outlet. They serve to prevent congestion in the keel probe 22, within the tubular base body 56. The tubular base body 56 is tapered at the fluid inlet 28, thus forming a funnel-shaped opening.With the dimensions of the keel probe 22 shown in Figure 8 and explained below, a particularly large angle of attack of up to 50° or more can be achieved and the keel probe 22 can be manufactured entirely by additive manufacturing.

[0064] The keel probe 22 has a length of 1K=42.0 mm. Its diameter is dK=7.0 mm. The fluid inlet 28 has a length of 3.5 mm and also a diameter of 7.0 mm, thus forming the maximum radial extent of the keel probe 22. Preferably, the fluid inlet 28 has a diameter of at least 5 mm, particularly preferably at least 6 mm. The inner channel 54 has a diameter of di=1.54 mm at its inner channel inlet 58. Preferably, the diameter of the inner channel inlet 58 is at least di=1.2 mm, particularly preferably at least di=1.4 mm. The lance 44 has an outer diameter of di,A=2 mm and an inner diameter of du=0.91 mm in a central region and thus a wall thickness of 1.09 mm. The inner channel inlet 58 of the lance 44 is spaced from the fluid inlet 28 of the tubular base body 56 by 3.5 mm in the longitudinal direction of the keel probe.This results in a flow around the inner channel inlet 58 during operation, which has a positive effect on the accuracy of the measurement results.

[0065] An outer channel 70 is formed between the lance 44 and the tubular base body 56 for flow around the lance 44. During operation, the outer channel 70 guides the air from the fluid inlet 28 toward the holes 66 to the outer channel outlet 68. The radius of the outer channel 70 increases from 4.14 mm to 5.38 mm toward the outer channel outlet 70. This improves the flow characteristics.

[0066] It should be noted that the cross-sectional area of ​​the fluid inlet 28 with a diameter corresponding to that of dK=7.0 mm is approximately 38.48 mm 2For a particularly favorable ratio of at least 1.5 between the cross-sectional area of ​​the fluid inlet 28 and the cross-sectional area of ​​the outer channel outlet 68, the latter being equal to the sum of the cross-sectional areas of the holes 66, each of the 24 identically designed holes 66 with a round cross-section must have a diameter of at least 1.75 mm. In the example shown, the diameter of each of the holes 66 is 1.8 mm. It is also possible to provide holes 66 of different sizes and / or holes with differently shaped cross-sections as the outer channel outlet 68, as long as the ratio between the cross-sectional area of ​​the fluid inlet 28 and the cross-sectional area of ​​the outer channel outlet 68 is at least 1.5. Further dimensions of the keel probe 22 can be found in Fig. 8.

[0067] With the dimensions of the keel probe 22 shown in Eigur 8 and described here, it is possible to manufacture the keel probe 22 by means of additive manufacturing while maintaining the mechanical and aerodynamic properties, whereby the objects underlying the invention are achieved.

[0068] The above explanations of the embodiments describe the present invention exclusively by way of examples.

[0069] List of reference symbols

[0070] 10 vehicles

[0071] 12 Aerodynamics measuring system

[0072] 14 Aerodynamic measuring grid

[0073] 16 exterior mirrors

[0074] 18 Wind measuring device

[0075] 20 Guide frame 22 Keel probe 28 Fluid inlet 30 Fluid outlet 32 ​​Pressure measuring device

[0076] 34 Longitudinal bracing

[0077] 36 Cross bracing

[0078] 38 Diagonal bracing

[0079] 40 Pressure measurement input

[0080] 42 Adapter device 44 Lance 46 Center axis 48 Additional bracing 50 Measuring head

[0081] 52 data transfer cables

[0082] 54 inner channel

[0083] 56 tubular base body

[0084] 58 internal channel inlets

[0085] 62 internal duct outlet

[0086] 66 holes

[0087] 67 External duct inlet 68 External duct outlet

[0088] 70 external channel

[0089] 1K Length of the keel probe 0K Diameter of the keel probe di Diameter of the inner channel inlet dLA Outer diameter of the lance du Inner diameter of the lance

Claims

Patent claims 1 to 17 1. Aerodynamic measuring grid (14), comprising: a guide frame (20) with longitudinal struts (34) and transverse struts (36), keel probes (22) arranged parallel to one another or substantially parallel to one another on the guide frame (20), comprising a tubular base body (56) with a fluid inlet (28), a lance (44) with an inner channel (54), wherein the lance (44) is arranged in the tubular base body (56) and an outer channel (70) is located between the lance (44) and the tubular base body (56), wherein the inner channel (54) has an inner channel inlet (58) and an inner channel outlet (62) and the outer channel (70) has an outer channel inlet (67) and an outer channel outlet (68), a pressure measuring device (32), and Air pressure lines, each arranged between the inner channel outlet (62) of one of the keel probes (22) and the pressure measuring device (32) and at least partially in the longitudinal struts (34) and / or the transverse struts (36).

2. Aerodynamic measuring grid (14) according to claim 1, wherein the tubular base body (56) is tapered at the fluid inlet (28).

3. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein the pressure measuring device (32) comprises a multi-channel pressure sensor.

4. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein the guide frame (20) has interconnected longitudinal struts (34), transverse struts (36) and / or diagonal struts (38).

5. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein a cross-sectional area of ​​the outer channel outlet (68) is at least 50% larger than a cross-sectional area of ​​the fluid inlet (28).

6. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein the fluid inlet (28) has a diameter of at least 5 mm, in particular of at least 7 mm.

7. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein the inner channel (54) has an inner diameter (du) of at least 1.2 mm, preferably of at least 1.4 mm.

8. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein the lance (44) has a wall thickness of at least 0.8 mm, preferably of at least 1.0 mm.

9. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein a ratio between the diameter (du) of the inner channel (54) and the diameter of the tubular base body (56) is between 0.25 and 0.

5.

10. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein the inner channel inlet (58) of the lance (44) is spaced from the fluid inlet (28) of the tubular base body (56) by at least 2 mm, preferably at least 3 mm in the longitudinal direction of the keel probe (22).

11. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein the keel probes (22) are fastened to the guide frame (20) via a screw thread.

12. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein the guide frame (20) has an adapter device for connecting the guide frame (20) to other identical or similar guide frames (20).

13. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein the guide frame (20) and at least one of the keel probes (22), in particular all keel probes, are manufactured using additive manufacturing.

14. Aerodynamic measuring grid (14) according to one of the preceding claims, wherein the keel probes (22) span a measuring field and are arranged on the measuring field at equal distances from one another in at least one direction.

15. Aerodynamics measuring system (12), comprising an aerodynamics measuring grid (14) according to one of the preceding claims, and a wind measuring device (18) for measuring the wind direction and wind strength independently of the aerodynamics measuring grid (14).

16. A method for carrying out an aerodynamic measurement on a vehicle (10) with an aerodynamic measuring system (12) according to claim 15, comprising the steps: a) providing a vehicle (10) with the aerodynamic measuring system (12) according to claim 15, wherein the wind measuring device (18) is arranged at a wind measuring position on the vehicle (10) and the aerodynamic measuring grid (14) is arranged at an aerodynamic measuring position on the vehicle (10), b) carrying out a driving maneuver on a roadway, c) measuring the wind direction and the wind strength relative to the vehicle (10) with the wind measuring device (18) and the static air pressure at the positions of the keel probes (22) with the aerodynamic measuring grid (14) during the driving maneuver, and d) calculating a pressure coefficient at the positions of the keel probes (22) using the associated static air pressure, the measured wind direction and the wind strength.

17. The method of claim 16, further comprising the step: e) adjusting an aerodynamically relevant component of the vehicle (10) based on the pressure coefficient measured in step d).

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