Five-hole differential pressure type airspeed tube

Abstract

The invention relates to the field of measurement of flight parameters such as airspeed, attitude angle and the like in flight of low-altitude aircrafts, in particular to a five-hole differential pressure type airspeed tube which comprises a probe, and the probe comprises a first conical surface section arranged at the end of the probe and a second conical surface section connected with the first conical surface section in the axial direction of the probe. The taper angle of the first conical surface section is larger than that of the second conical surface section, so that the flow speed of airflow in the area where the first conical surface section is connected with the second conical surface section is increased; a center hole is formed in the end face of the first conical surface section; the center line of the center hole coincides with the axis of the probe; and four side holes are uniformly formed in the conical surface of the second conical surface section in the circumferential direction. According to the invention, under the effect of rapid increase of the airflow speed, mosquitoes, dust and other sundries can rapidly cross over without entering the four side holes in the second conical surface in the process of flowing backwards along the two conical surfaces of the probe, so that the anti-blocking effect is achieved.

Description

Technical Field

[0001] The present invention relates to the field of measuring flight parameters such as airspeed (CAS), attitude angle (AOA, AOS) and the like during the flight of a low-altitude aircraft, and in particular to a five-hole differential pressure pitot tube. Background Art

[0002] Among the many onboard sensors configured on aircraft, the instrument used to measure airspeed is a basic equipment, which provides the most important guarantee for flight control and safety. The pitot tube technology is the most mature and widely used flight airspeed measurement technology, so the pitot tube is still an important means of aircraft airspeed measurement. The types and characteristics of the commonly used pitot tubes are as follows: Pitot tube type: It is composed of a double-layer casing with a hole at the front end. It measures the total airflow pressure through the hole at the front end and the static pressure through the static pressure hole on the tube wall. Then, the airspeed of the aircraft is calculated using an atmospheric data computer. This type of pitot tube has a simple structure and is easy to manufacture, but it has a large measurement error when the aircraft is maneuvering at a large angle.

[0003] External wind vane type: Its main body is the same as the pitot tube type pitot tube, and it is equipped with an external wind vane angle of attack sensor and sideslip angle sensor, which can measure airspeed and attitude angle at the same time. This type of pitot tube can measure the flight attitude angle of the aircraft, but it will be affected by the "cylindrical turbulence" phenomenon, and data jitter will occur when the angle of attack and sideslip angle sensors are maneuvered in the opposite direction.

[0004] Total pressure tube type: It consists of an independent total pressure tube and a static pressure hole array arranged on the fuselage. The independent total pressure tube only measures the total airflow pressure, and cooperates with the static pressure collected by the static pressure hole array arranged on the fuselage to obtain the aircraft's airspeed through the atmospheric data computer. This type of pitot tube has high measurement accuracy, but the design requirements for the static pressure hole array on the fuselage are also very high. At the same time, small aircraft are limited by the size of the fuselage and it is difficult to arrange the static pressure hole array.

[0005] Five-hole differential pressure type: Its head is hemispherical or conical, with five holes on it for measuring airflow speed and pressure in different directions; there are multiple static pressure holes on the tube wall for measuring static pressure, thus providing more comprehensive flight data. This type of pitot tube has fewer limitations and performs well in low-speed, subsonic and even supersonic flight. It can more accurately measure the aerodynamic parameters of the aircraft during flight, but because there are many holes in the head and the aperture needs to be limited due to structural and weight requirements, there is a risk of mosquitoes, dust, etc. blocking the air intake when the aircraft is flying at low altitude and low speed. Summary of the invention

[0006] In view of the defects of the above-mentioned various pitot tubes, especially the existing technology of the five-hole differential pressure pitot tube with comparative advantages, the present invention provides a five-hole differential pressure pitot tube, including a probe first cone angle, a second cone angle, and a different aperture design of the center hole and the four side holes opened on the second cone surface. The focus is on improving the probe of the traditional five-hole differential pressure pitot tube, and the problem of easy blockage of the air intake hole during low-altitude and low-speed flight of the aircraft is solved through the design of variable cone angle and multiple apertures, while ensuring a compact structure, reducing weight, and ensuring measurement accuracy.

[0007] In order to achieve the above-mentioned object, the technical solution provided by the present invention is a five-hole differential pressure pitot tube, which includes a probe, wherein the probe includes a first conical surface section arranged at the end of the probe, and a second conical surface section connected to the first conical surface section along the axial direction of the probe, The cone angle of the first cone surface segment is greater than the cone angle of the second cone surface segment, so that the flow velocity of the airflow in the area where the first cone surface segment and the second cone surface segment meet increases; A center hole is formed on the end surface of the first conical surface segment, and the center line of the center hole coincides with the axis of the probe; The conical surface of the second conical surface segment is evenly provided with four side holes along the circumferential direction.

[0008] Furthermore, the cone angle range of the first cone surface segment is 45°~65°, and the cone angle range of the second cone surface segment is 35°~55°.

[0009] Furthermore, the cone angle of the first cone surface segment is 62°; and the cone angle of the second cone surface segment is 43°.

[0010] Furthermore, a center line of the side hole is perpendicular to the conical surface of the second conical surface segment.

[0011] Furthermore, the diameter of the central hole is larger than the diameter of the side holes.

[0012] Furthermore, the diameter of the central hole is φ4 mm; the diameters of the four side holes are all φ1.5 mm.

[0013] Furthermore, the five-hole differential pressure pitot tube includes a pitot tube body connected to the probe, the interior of the pitot tube body is provided with a front cavity, a middle cavity and a rear cavity in sequence along the direction away from the probe, the center hole is connected to the front cavity, a total pressure collection head and a drainage hole are provided in the front cavity, and a static pressure hole is provided in the middle cavity.

[0014] Furthermore, a base is provided at one end of the pitot tube body away from the probe, a pressure pipe joint and a wire joint are provided on the base, a heating wire is provided on the inner wall of the front cavity, and the heating wire is connected to the wire joint through a wire.

[0015] Furthermore, the side hole is connected to a pressure-guiding pipe, and the pressure-guiding pipe is connected to the pressure-guiding pipe joint.

[0016] Furthermore, the side hole is connected to a pressure-inducing tube, and the diameter of the pressure-inducing tube is equal to the diameter of the side hole.

[0017] The beneficial effects of the present invention are as follows: a probe is provided, and the probe is a variable cone angle structure. Specifically, the probe includes two mutually connected cone sections with different cone angles, and the first cone section with a larger cone angle transitions to the second cone section with a smaller cone angle. With such a configuration, on the one hand, the measurement performance of the five-hole differential pressure pitot tube in a wider speed range of aircraft flight such as low speed, subsonic speed, and supersonic speed can be made better. On the other hand, the aerodynamic principle can be used to make the airflow in flight pass through the cone surface of the first cone section, and the speed at the connection between the first cone section and the second cone section increases rapidly, and the airflow speed reaches the maximum at the connection between the bottom of the second cone section and the pitot tube body. With such a configuration, under the effect of the rapid increase in airflow speed, mosquitoes, dust and other debris can quickly pass through the four side holes on the second cone surface while flowing backward along the two cone surfaces of the probe, and will not enter, thereby playing an anti-blocking role. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a five-hole differential pressure pitot tube in one embodiment of the present invention; Figure 2 It is a schematic diagram of the structure of a probe in one embodiment of the present invention; Figure 3 is a side view of a probe in one embodiment of the present invention; Figure 4 A cross-sectional view of a five-hole differential pressure pitot tube in one embodiment of the present invention; Figure 5 for Figure 4 A partial magnified view of the middle probe area; Figure 6 This is a simulation diagram of the 0.6Ma airflow velocity distribution of three types of probes in an embodiment of the present invention; Figure 7 for Figure 6 A partial enlarged view of part I; Figure 8 for Figure 6 A partial enlarged view of part II; Fig. 9 for Figure 6 A partial enlarged view of part III; Fig.10 This is a simulation diagram of the 0.3Ma airflow velocity distribution of three types of probes in an embodiment of the present invention; Fig.11 for Fig.10A partial enlarged view of part I; Fig.12 for Fig.10 A partial enlarged view of part II; Fig.13 for Fig.10 A partial enlarged view of part III; Fig.14 It is a schematic diagram of the simulation of the surface pressure of the side holes of the combination of two cone angles of 65° and 55° in one embodiment of the present invention; Fig.15 It is a schematic diagram of the simulation of the surface pressure of the side holes of the combination of two cone angles of 45° and 35° in one embodiment of the present invention; Fig.16 It is a schematic diagram of the simulation of the surface pressure of the side holes of the combination of two cone angles of 62° and 43° in one embodiment of the present invention; Fig.17 It is a velocity vector diagram of the combined corner position of two cone angles of 62° and 43° in one embodiment of the present invention; Fig.18 This is a comparison diagram of the boundary layer thickness at key positions after the two cone angles of 62° and 43° are combined into a corner in one embodiment of the present invention; In the figure: 100, probe, 110, first cone surface section, 111, end surface, 1111, center hole, 112, first cone surface, 120, second cone surface section, 121, second cone surface, 1211, side hole, 200, pitot tube body, 210, front cavity, 211, total pressure collection head, 212, heating wire, 213, drainage hole, 220, middle cavity, 221, static pressure hole, 230, rear cavity, 231, wire, 240, pressure pipe, 300, base, 310, pressure pipe joint, 320, wire joint. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0020] like Figure 1As shown, a schematic diagram of the structure of a five-hole differential pressure pitot tube in an embodiment of the present invention includes a probe 100, a pitot tube body 200, and a base 300. The probe 100 is provided at one end of the pitot tube body 200, and the base 300 is provided at the other end of the pitot tube body 200. The probe 100 is a variable cone angle multi-aperture structure for collecting airflow pressure; the pitot tube body 200 is provided with a front cavity 210, a middle cavity 220 and a rear cavity 230, the front cavity 210 is used to collect the total pressure of the airflow (Pt), ablation of mosquitoes, and deicing drainage; the middle cavity 220 is used to collect the static pressure of the airflow (Ps); the rear cavity 230 is connected to the base 300, and the pressure pipe joint 310 and the wire joint 320 at the rear end of the base 300 can be connected to the atmospheric data host.

[0021] See also Figure 2 The probe 100 includes a first conical section 110 disposed at the end of the probe, and a second conical section 120 connected to the first conical section 110 along the axial direction of the probe 100. The cone angle of the first conical section 110 is greater than the cone angle of the second conical section 120, so that the flow velocity of the airflow in the area where the first conical section 110 and the second conical section 120 are connected increases, that is, the airflow pressure suddenly and significantly decreases, and the airflow velocity suddenly and significantly increases. A center hole 1111 is opened on the end surface of the first conical section 110, and the center line of the center hole 1111 coincides with the axis of the probe 100; four side holes 1211 are evenly opened on the conical surface of the second conical section 120 along the circumferential direction.

[0022] The above-mentioned five-hole differential pressure pitot tube is provided with a probe 100, and the probe 100 is a variable cone angle structure. Specifically, the probe 100 includes two mutually connected cone sections with different cone angles, and transitions from the first cone section 110 with a larger cone angle to the second cone section 120 with a smaller cone angle. With such a configuration, on the one hand, the measurement performance of the five-hole differential pressure pitot tube can be better in aircraft flights in a wider speed range such as low speed, subsonic speed, and supersonic speed. On the other hand, the aerodynamic principle can be used to make the airflow in flight pass through the cone surface of the first cone section 110, and the speed at the connection between the first cone section 110 and the second cone section 120 increases rapidly, and the airflow speed reaches the maximum at the connection between the bottom of the second cone section 120 and the pitot tube body 200. With such a configuration, under the effect of the rapid increase in airflow speed, mosquitoes, dust and other debris can quickly pass through the four side holes 1211 on the second cone section 121 while flowing backward along the two cone surfaces of the probe 100, thereby playing the role of the first layer of anti-blocking. See. Figure 4 In a preferred embodiment, the cone angle of the first cone segment 110 is 62°, and the cone angle of the second cone segment 120 is 43°. Fig.16In this embodiment, the results of the side hole pressure simulation show that the 0 pressure line is exactly located at the side hole 1211, and its measurement accuracy is the best. The two cone angles in this embodiment can achieve the anti-blocking effect and ensure the measurement accuracy, so 62° and 43° are the best cone angle combinations.

[0023] See also Figure 2 and Figure 3 In a specific embodiment, the first conical surface section 110 is arranged at the end of the probe 100, which includes an end surface 111 and a first conical surface 112, and a center hole 1111 is opened at the center position of the end surface 111; the second conical surface section 120 includes a second conical surface 121, and four side holes 1211 are opened on the second conical surface 121 and are evenly distributed.

[0024] like Figure 3 As shown, specifically, the center hole 1111 opened at the center of the top of the end surface 111 of the first conical surface section 110 is hole 2, the two side holes 1211 opened in the vertical direction of the second conical surface 121 are holes 1 and 3, and the two side holes 1211 opened in the horizontal direction are holes 4 and 5. The function of the five holes on the probe 100 is to collect the airflow pressure of the aircraft during flight, wherein the total pressure (Pt) collected by hole 2 minus the static pressure (Ps) collected by the static pressure hole 221 on the wall of the middle cavity 220 can be used to calculate the dynamic pressure (Qc), and the flight airspeed (CAS) of the aircraft can be calculated according to formulas such as the Bernoulli equation; the flight angle of attack (AOA) is calculated through the pressure difference collected by holes 1 and 3, and the flight angle of sideslip (AOS) is calculated through the pressure difference collected by holes 4 and 5.

[0025] In order to further enhance the anti-blocking effect, in one embodiment, the center line of the side hole 1211 is perpendicular to the conical surface of the second conical surface section 120. In this way, since the four side holes 1, 3, 4, and 5 are opened in a normal direction, the projection area of ​​the four side holes 1211 facing the incoming flow direction (the axial direction of the five-hole differential pressure pitot tube) will be reduced, thereby playing a second anti-blocking role.

[0026] like Figure 3 As shown, in one embodiment, the diameter of the central hole 1111 is larger than the diameter of the side holes. In specific configuration, in one embodiment, the diameter of the central hole 1111 is φ4 mm; the diameters of the four side holes 1211 are all φ1.5 mm.

[0027] Since the center hole 1111 of the above-mentioned five-hole differential pressure pitot tube is opened in the high-pressure area at the front end of the probe 100, according to the principle of aerodynamics, the air flow velocity will stagnate at 0 at the orifice of the center hole 1111. If the aperture of the center hole 1111 is too small, mosquitoes and other debris will block the hole. In this embodiment, the aperture is designed to be φ4mm, so that mosquitoes can smoothly enter the front cavity 210 of the pitot tube and be discharged by heating, ablation, drainage, etc.; at the same time, a total pressure collection head 211 is set in the front cavity 210 of the pitot tube, and a pressure lead pipe 240 with the same diameter as the four side holes 1211 is used to ensure measurement accuracy. In addition, according to aerodynamic principles and engineering practice, if the hole of the pneumatic probe is small or the projected area facing the incoming flow hole is small, the resolution of the incoming air will be improved, the sensitivity of the measurement will be enhanced, and the measurement accuracy of the attitude angle (AOA, AOS) will be improved; at the same time, a small air inlet hole can be connected to it using a small diameter pressure lead pipe 240, thereby reducing the diameter of the pitot tube as a whole, making the structure more compact and lighter. Therefore, the aperture of the four side holes 1211 is designed to be φ1.5mm, which not only adds a layer of anti-blocking design on the basis of the existing variable cone angle anti-blocking design, but also ensures the measurement accuracy and makes the pitot tube structure more compact and reduces the weight.

[0028] In order to reduce the overall diameter and weight of the pitot tube, the present invention arranges a total pressure collecting head 211 in the front cavity 210 of the pitot tube. The side of the total pressure collecting head 211 has circumferential air inlet holes for collecting the total pressure (Pt) (which also serves to prevent clogging). The diameter of the pressure lead pipe 240 connected to the rear of the total pressure collecting head 211 is consistent with the diameter of the pressure lead pipe 240 connected to the rear of the four side holes 1211. As a result, the overall diameter of the pitot tube will not increase due to the expansion of the diameter of the center hole 1111, thereby ensuring the compactness of the pitot tube structure and the control of weight. At the same time, the control of the aperture also ensures the measurement accuracy of the pitot tube for the aircraft flight airspeed (CAS), angle of attack (AOA), and sideslip angle (AOS).

[0029] See also Figure 1 and Figure 4 In one embodiment, the five-hole differential pressure pitot tube includes a pitot tube body 200 connected to the probe 100, and the interior of the pitot tube body 200 is provided with a front cavity 210, a middle cavity 220 and a rear cavity 230 in sequence along the direction away from the probe, the center hole 1111 is connected to the front cavity 210, a total pressure collection head 211 and a drainage hole 213 are provided in the front cavity 210, and a static pressure hole 221 is provided in the middle cavity 220.

[0030] Specifically, see Figure 4In order to clean and discharge mosquitoes, dust and other debris entering through the central hole 1111, in one embodiment, a base 300 is provided at the end of the pitot tube body 200 away from the probe 100, and a wire connector 320 is provided on the base 300. A heating wire 212 is provided on the inner wall of the front cavity 210, and the heating wire 212 is connected to the wire connector 320 through a wire 231. With this arrangement, mosquitoes can smoothly enter the front cavity 210 of the pitot tube, and be discharged by heating, ablation, drainage, etc. through the heating wire 212. Figure 1 The drainage hole 213 is provided on the pitot tube body 200 and is connected to the front cavity 210. The heating and ablation are completed in the front cavity 210. The mosquitoes entering the pitot tube will be ablated into ashes and then discharged through the drainage hole 213. In addition, in the absence of water, the dust and impurities after ablation can also adhere to the surface of the heating wire.

[0031] Continue to see Figure 4 In one embodiment, a pressure-leading pipe joint 310 is provided on the base 300 , and the side hole 1211 is connected to the pressure-leading pipe 240 , and the pressure-leading pipe 240 is connected to the pressure-leading pipe joint 310 .

[0032] It should be noted that the probe 100 is provided with five holes, which are respectively connected to the pressure-inducing pipe 240 for collecting airflow pressure. In the specific setting, the central hole 1111 is equivalent to the opening of the front cavity 210, and the total pressure collection head 211 is arranged inside the front cavity 210, and the total pressure collection head 211 is connected to the central pressure-inducing pipe 240. The four side holes 1211 are respectively connected to one end of the four pressure-inducing pipes 240, and the other ends of the four pressure-inducing pipes 240 are connected to the pressure-inducing pipe joint 310 arranged on the base 300, and the connection method includes but is not limited to welding.

[0033] In one embodiment, the side hole 1211 is connected to a pressure-inducing tube 240 , and the diameter of the pressure-inducing tube 240 is equal to the diameter of the side hole 1211 .

[0034] See also Figure 7-Figure 9 , Figure 11-13 As shown, in order to explore and verify the feasibility, scientificity and rationality of the variable cone angle improved design of the present invention, two air flow velocities of 0.6Ma and 0.3Ma were selected to perform aerodynamic simulation on three types of probes, among which Figure 7 , Fig.11 It is a single cone angle probe. Figure 8 , Fig.12 It is a variable cone angle probe. Fig. 9 , Fig.13It is a hemispherical probe. From the simulation results of the airflow velocity at 0.6Ma, the high-pressure area of ​​the single-cone angle probe is located at holes 1, 3, 4, and 5, and the low-pressure area is located at the connection between the bottom of the cone and the tube body, that is, the airflow velocity at holes 1, 3, 4, and 5 is low, which makes it easy for mosquitoes, dust and other debris to block the four side holes; the location of the high-pressure area of ​​the hemispherical probe is similar to that of the single-cone angle probe, and its low-pressure area is located in front of the connection between the bottom of the arc and the tube body, and there is also a risk of mosquitoes, dust and other debris blocking the four side holes 1, 3, 4, and 5; the high-pressure area of ​​the variable cone angle probe is located at the connection between the first and second cone surfaces, in front of holes 1, 3, 4, and 5, and the low-pressure area is located at the connection between the bottom of the second cone surface and the tube body, that is, the airflow velocity increases gradually from the connection between the first and second cone surfaces, and mosquitoes, dust and other debris will pass through holes 1, 3, 4, and 5 as the airflow velocity increases, thereby reducing the risk of blocking the four side holes 1211. From the simulation results of the 0.3Ma airflow velocity, the airflow velocity changes of the single cone angle probe, hemispherical probe, and variable cone angle probe are the same as those of the 0.6Ma velocity; the difference is that due to the low airflow velocity, the pressure changes in the high and low pressure areas are small, and the increase in airflow velocity is not as obvious as that of the 0.6Ma velocity. However, the design of the probe variable cone angle also plays an anti-blocking role because the airflow velocity increases in advance due to the forward movement of the high pressure area. In summary, the design of the five-hole differential pressure pitot tube variable cone angle probe meets expectations and can achieve the invention purpose of anti-blocking under low-altitude and low-speed conditions of aircraft.

[0035] The cone angle of the first cone segment and the cone angle of the second cone segment in the present invention include but are not limited to a combination of 62° and 43°, see Fig.14 , Fig.15 and Fig.16 The cone angle range of the first cone surface segment 110 is 45°~65°, and the cone angle range of the second cone surface segment 120 is 35°~55°.

[0036] See also Fig.14 , Fig.15 , Fig.16 As shown, in order to explore and verify the feasibility of the selection of the cone angle range of the two cone segments of the present invention and the rationality of the optimal cone angle, three cone angle combinations of 65° and 55°, 45° and 35°, and 62° and 43° are selected for aerodynamic calculation and simulation. After calculation, the dynamic pressure value ranges of the above three cone angle combinations are as follows: Embodiment 1: The cone angle of the first cone section is 65°, and the cone angle of the second cone section is 55°; the dynamic pressure value range (Pa) is 5469.48~5613.41; Embodiment 2: The cone angle of the first cone section is 45°, and the cone angle of the second cone section is 35°; the dynamic pressure value range (Pa) is 6620.95~6764.88; Embodiment 3: The cone angle of the first cone surface segment is 62°, and the cone angle of the second cone surface segment is 43°; the dynamic pressure value range (Pa) is 6189.15~6333.08.

[0037] See also Fig.17 As shown, in the aerodynamic simulation results when the combination of 62° and 43° is selected, a vortex with a maximum Q criterion value of 0.38 is generated at the corner position, which can use the vortex separation effect to throw heavy impurities and blockages out of the side hole measurement range.

[0038] See also Fig.18 As shown in the aerodynamic simulation results when the combination of 62° and 43° is selected, the original boundary layer thickness is thinned after the corner position and reduced to 15% of the thickness of the single cone structure, effectively reducing the thickness of the low-speed zone and the number of impurities in the low-speed flow.

[0039] In Example 3, the cone angle of the first cone surface segment is greater than the cone angle of the second cone surface segment. The cone angle of the first cone surface segment is 62°, and the cone angle of the second cone surface segment is 43°. By reducing the cone surface angle by 19°, the surface dynamic pressure of the two cone surface segments is increased by 15.2%, which facilitates the light impurities to move out of the side hole measurement position faster with the airflow; There is a corner structure between the first cone surface and the second cone surface, which generates a vortex of controllable range during use and can separate the heavy impurities vortex out of the side hole range. When the first cone surface is 62° and the second cone surface is 43°, the vortex intensity generated is the Q criterion value of 0.38; The cone angle of the first section is greater than that of the second section, so that the low-speed airflow of the center hole of the first section is better concentrated on the surface of the first section, reducing the thickness of the low-speed boundary layer on the surface of the second section, reducing the probability and quantity of light impurities in the boundary layer in the low-speed area, and improving the measurement accuracy of the side holes of the two sections. When the first cone surface is 62° and the second cone surface is 43°, the thickness of the boundary layer after the corner of the two cone surfaces is reduced to 15% of the single cone surface.

[0040] Since the air flow rate on the surface of the four side holes is negatively correlated with the probe angle (i.e., the larger the probe cone angle, the smaller the air flow rate on the side hole surface; conversely, the smaller the probe cone angle, the greater the air flow rate on the side hole surface), taking the dynamic pressure value range (5459.67~5620.25) Pa of the 60° single cone angle commonly used in engineering as a reference, the dynamic pressure value range of Example 1 is equivalent to the dynamic pressure value range of the 60° single cone angle, indicating that even if the cone angle of the first cone section is greater than 60°, due to the design that the cone angle of the second cone section is smaller than the cone angle of the first cone section, a considerable dynamic pressure value can still be achieved, that is, the same effect of increasing the air flow rate on the side hole surface is achieved to achieve an anti-blocking effect; see Fig.14The results of the side hole pressure simulation in Example 1 show that the 0 pressure line begins to partially deviate relative to the side hole, which will have a certain impact on the measurement accuracy. Therefore, the two cone angles in Example 1 can be regarded as the maximum values ​​of the cone angles of the first cone segment and the second cone segment.

[0041] The dynamic pressure value of Example 2 is the largest, that is, the air flow rate on the side hole surface is the largest, and the anti-clogging effect is theoretically the best. Fig.15 From the results of the side hole pressure simulation, the 0 pressure line also began to deviate relative to the side hole, which will also have a certain impact on the measurement accuracy. Therefore, the two cone angles of Example 2 can be regarded as the minimum value of the cone angle of the first cone segment and the cone angle of the second cone segment.

[0042] The dynamic pressure value of Example 3 is between that of Example 1 and Example 2, that is, the air flow rate on the side hole surface is also between the two combinations, and the anti-clogging effect is also very obvious; see Fig.16 The results of the side hole pressure simulation in Example 3 show that the 0 pressure line is located exactly at the side hole, and its measurement accuracy is the best. Therefore, the two cone angles in Example 3 can both achieve the anti-blocking effect and ensure the measurement accuracy, and 62° and 43° are the best value combinations.

[0043] It should be noted that the design of the variable cone angle of the pitot probe of the present invention, as well as the design of the normal openings of holes 1, 3, 4, and 5 on the second cone surface, will increase the difficulty of manufacturing and processing to a certain extent, and will lead to a small increase in manufacturing costs. In addition, although the pitot probe with a variable cone angle can be used to measure the airspeed and attitude angle of the aircraft under low-speed, subsonic and supersonic conditions, the supersonic condition flight is generally a high-altitude environment. At the same time, due to the fast airflow speed, an air film will be formed on the surface of the pitot tube, so the air inlet generally does not have a blockage problem. The use of a single cone angle probe is often a suitable choice. Therefore, the design of the variable cone angle of the pitot probe of the present invention is more suitable for the low-altitude and low-speed flight conditions of the aircraft.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0046] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0048] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

Claims

1. Five-hole differential pressure pitot tube, characterized by: Including probe, The probe comprises a first conical surface section arranged at the end of the probe, and a second conical surface section connected with the first conical surface section along the axial direction of the probe; The cone angle of the first cone surface segment is greater than the cone angle of the second cone surface segment, so that the flow velocity of the airflow in the area where the first cone surface segment and the second cone surface segment meet increases; A center hole is formed on the end surface of the first conical surface segment, and the center line of the center hole coincides with the axis of the probe; The conical surface of the second conical surface segment is evenly provided with four side holes along the circumferential direction; The cone angle range of the first cone surface segment is 45° to 65°, and the cone angle range of the second cone surface segment is 35° to 55°.

2. The five-hole differential pressure pitot tube according to claim 1, characterized in that: The cone angle of the first cone surface segment is 62°; the cone angle of the second cone surface segment is 43°.

3. The five-hole differential pressure pitot tube according to claim 1 or 2, characterized in that: The center line of the side hole is perpendicular to the conical surface of the second conical surface segment.

4. The five-hole differential pressure pitot tube according to claim 1 or 2, characterized in that: The diameter of the central hole is larger than the diameter of the side holes.

5. The five-hole differential pressure pitot tube according to claim 4, characterized in that: The diameter of the central hole is φ4mm; the diameters of the four side holes are all φ1.5mm.

6. The five-hole differential pressure pitot tube according to claim 1 or 2, characterized in that: The five-hole differential pressure pitot tube comprises a pitot tube body connected to the probe, The interior of the pitot tube body is provided with a front cavity, a middle cavity and a rear cavity in sequence in a direction away from the probe. The central hole is connected to the front cavity, and a total pressure collection head and a drainage port are provided in the front cavity. The middle cavity is provided with a static pressure hole.

7. The five-hole differential pressure pitot tube according to claim 6, characterized in that: The end of the pitot tube body away from the probe is provided with a base, and the base is provided with a pressure pipe joint and a wire joint. The inner wall of the front cavity is provided with a heating wire, and the heating wire is connected to the wire connector through a wire.

8. The five-hole differential pressure pitot tube according to claim 7, characterized in that: The side hole is connected with a pressure-guiding pipe, and the pressure-guiding pipe is connected with the pressure-guiding pipe joint.

9. The five-hole differential pressure pitot tube according to claim 1 or 2, characterized in that: The side hole is connected with a pressure-inducing tube, and the diameter of the pressure-inducing tube is equal to the diameter of the side hole.

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