Multifunctional sensor of FADS and total temperature estimation method

Abstract

The invention discloses a multifunctional sensor of an FADS and a total temperature estimation method. The multifunctional sensor comprises a pressure sensor, an adapter, a temperature sensor and a heat flow sensor. The air entraining cover is arranged at the upper end of the base, and an inner cavity is formed between the air entraining cover and the base; a pressure measuring hole is formed in the outer surface of the air entraining cover and is communicated with the inner cavity; a T-shaped air guide hole is formed in the base; an air entraining channel is arranged in the adapter, and the upper end of the air entraining channel is connected with the lower end of the air entraining hole; the lower end of the air entraining channel is connected with an external air path and is used for transmitting pressure; the sensing ends of the temperature sensor and the heat flow sensor are located in the inner cavity and used for measuring the regional temperature in the inner cavity and measuring the heat flow of the pressure sensor. The device has a dustproof and anti-blocking structural design, and integrates the functions of measuring pressure, total temperature, heat flow and static temperature. The device is simple in structure, convenient to install and low in manufacturing cost, and can be applied to an embedded atmosphere data system of a high-speed aircraft.

Description

Technical Field

[0001] The invention relates to the field of atmospheric parameter measurement, and in particular to a multifunctional sensor of FADS and a total temperature estimation method. Background Art

[0002] The Flush Airdata Sensing (FADS) is a system used to measure atmospheric parameters on high-speed aircraft. The FADS system solves the problem of traditional probe-type atmospheric data systems surviving the complex aerodynamic thermal environment generated by shock waves at high Mach numbers by opening holes in the aircraft fuselage.

[0003] Embedded atmospheric data sensing technology is currently the most advanced atmospheric sensing technology. During its development, the layout of pressure points, air bleed structure, pressure sensor, atmospheric data computer and system algorithm are the key research areas. As an atmospheric data sensor, the air bleed structure is one of the key components of the system. In particular, the problems of ablation and deformation of the air bleed structure caused by aerodynamic heat in high-speed aircraft and pressure hysteresis caused by long pipes are technical difficulties in the structural design and material selection of the air bleed structure. The existing air bleed method is usually to directly open a hole in the fuselage and lead the pressure to the computer. Although this method is simple, it has the following problems:

[0004] 1) Insufficient design margin. Direct openings are usually single air inlet holes. If they are blocked under high temperature and high pressure, the pressure measuring point will become invalid, affecting the calculation of atmospheric parameters.

[0005] 2) As a distributed pressure measuring hole, the single function cannot meet the design concept of reducing weight and cost of existing high-speed aircraft;

[0006] 3) For aircraft with a waverider structure, it is impossible to install a pressure measuring structure at the stationary position, which makes it difficult to measure the total temperature. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the present invention provides a multifunctional sensor and a total temperature estimation method for FADS, which solve the problems of easy failure and poor adaptation effect of the existing bleed air structure.

[0008] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0009] A multifunctional sensor for FADS is provided, which comprises a pressure sensor, an adapter, a temperature sensor and a heat flow sensor; the pressure sensor comprises an air bleed cover and a base;

[0010] The air bleed cover is arranged at the upper end of the base, and an inner cavity is formed between the air bleed cover and the base; a pressure measuring hole is arranged on the outer surface of the air bleed cover, and the pressure measuring hole is communicated with the inner cavity;

[0011] A T-shaped air inlet hole is provided inside the base; the upper lateral part of the air inlet hole is communicated with the inner cavity;

[0012] An air bleed channel is provided inside the adapter, the upper end of the air bleed channel is connected to the lower end of the air bleed hole; the lower end of the air bleed channel is connected to the external air path for pressure transmission;

[0013] The sensing end of the temperature sensor is located in the inner cavity and is used to measure the regional temperature in the inner cavity;

[0014] The sensing end of the heat flow sensor is located inside the air bleed cover and is used to measure the heat flow of the pressure sensor.

[0015] The beneficial effects of the present invention are as follows: the multifunctional sensor of the FADS is equipped with a pressure measuring hole, and the internal gas path is led out by an adapter and transmitted to the atmospheric machine using an external gas path (hose), so as to realize the FADS atmospheric parameter solution; the pressure measuring sensor is integrated with a temperature sensor and a zero-point calorimeter, and has a heat flow measurement function. At the same time, the total temperature and static temperature of the free flow can be calculated according to the proposed total temperature estimation method. The multifunctional sensor of the FADS has a compact structure and high integrity, and can be applied to various aircraft. The multifunctional sensor of the FADS is equipped with an inner cavity (blocking cavity) and an air bleed cylinder, which increases the deposition of redundant materials and greatly reduces the risk of blockage of the air bleed pipe.

[0016] Furthermore, the air bleed cover and the base are melt-welded, and the air bleed cover and the base as a whole are a cylinder with a flange; the outer surface of the air bleed cover is consistent with the curvature of the aircraft skin; there are three pressure measuring holes, each with a diameter of 1mm, and the interior of the pressure measuring hole is an inverted cone with an angle of 100°; the diameter of the inner cavity is 10mm.

[0017] The beneficial effect of adopting the above further solution is: compared with the traditional air bleed structure that directly punches holes on the fuselage, this design sets multiple air intake holes in a single pressure measurement area to prevent the pressure point from failing due to blockage. The inverted cone setting can prevent particulate matter from accumulating at the air intake hole.

[0018] Furthermore, the upper lateral portion of the air bleed hole is a cylinder with a diameter of 3 mm; the vertical portion of the air bleed hole has a diameter of 2 mm; and the lower end of the air bleed hole is fixed to the adapter via an M8 thread.

[0019] The beneficial effect of adopting the above further solution is that it can achieve smooth air induction of the cylinder while greatly reducing the risk of blockage of the air induction pipeline.

[0020] Furthermore, the diameter of the air duct in the adapter is 2 mm, and the upper end of the adapter is an M8 threaded section; a fluorosilicone rubber ring for sealing is provided between the adapter and the base; the middle part of the adapter is located outside the base and is provided with a hexagonal disk; the lower end of the adapter is a pagoda structure.

[0021] The beneficial effects of adopting the above further scheme are: the M8 threaded section can make the adapter closely connected with the air duct hole to ensure the stability of the structure; the fluorosilicone rubber ring can achieve effective sealing between the adapter and the base, thereby improving the accuracy of pressure measurement; the hexagonal disk facilitates the disassembly and assembly of the adapter; the pagoda structure facilitates the disassembly and assembly and sealing of the adapter and the external air path, thereby improving the ease of use of the multifunctional sensor of the FADS.

[0022] Furthermore, the temperature sensor includes a wound platinum resistor located in the inner cavity, a first mica gasket is arranged between the wound platinum resistor and the base; the circuit of the wound platinum resistor passes through the base, and a first ceramic tube is arranged outside the circuit of the wound platinum resistor; the first ceramic tube and the base are sealed by high temperature resistant insulating glue.

[0023] Furthermore, the heat flow sensor is a zero-point calorimeter, including a heat transfer body, a thermocouple, a second ceramic tube, a second mica gasket, a ceramic gasket and a fastening screw; the heat transfer body is located in the air bleed cover; the thermocouple is located in the heat transfer body; the ceramic gasket is arranged between the thermocouple and the base; the thermocouple line passes through the base, and the second ceramic tube is arranged outside the thermocouple line; the second mica gasket is arranged at the place where the thermocouple line passes through the base, and is fixed to the base by a fastening screw.

[0024] The beneficial effects of adopting the above further solution are: the mica gasket and the ceramic tube can achieve fastening and heat insulation, and improve the measurement accuracy and life of the temperature sensor and the heat flow sensor. The packaging process of the temperature sensor and the heat flow sensor is consistent, so that the thermal resistance and thermal conductivity of the lateral heat transfer are basically consistent, thereby improving the accuracy of the total temperature estimation.

[0025] Furthermore, the air bleed cover and the base are both made of high temperature resistant nickel-based alloy material.

[0026] The beneficial effect of adopting the above further solution is: making the pressure sensor resistant to high temperatures and increasing its service life.

[0027] A method for estimating total temperature of a multifunctional sensor based on FADS is provided, which comprises the following steps:

[0028] S1. Obtain temperature T through temperature sensor m ;

[0029] S2. Obtain temperature T through heat flow sensor b ;

[0030] S3. Obtain the incoming flow Mach number M s ;

[0031] S4. According to the formula:

[0032]

[0033] Calculate the total temperature of the incoming flow T t ; where γ is the specific heat of the incoming flow.

[0034] The beneficial effects of the present invention are: the total temperature of the incoming flow can be calculated quickly and accurately, and the efficiency and accuracy of FADS atmospheric parameter solution can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the appearance and structure of the multifunctional sensor of FADS;

[0036] Figure 2 It is an overall cross-sectional view of the pressure sensor and the adapter;

[0037] Figure 3 The figure is a cross-sectional view of the multifunctional sensor of FADS;

[0038] Figure 4 It is a top view of the pressure sensor;

[0039] Figure 5 The heat transfer schematic diagram of the multifunctional sensor of FADS;

[0040] Wherein: 1. air bleed cover; 2. base; 3. adapter; 4. temperature sensor; 5. heat flow sensor; 101. pressure measuring hole; 102. inner cavity; 201. cylinder; 202. air bleed hole; 301. M8 threaded section; 302. fluorosilicone rubber ring; 401. wound platinum resistor; 402. first ceramic tube; 403. first mica gasket; 501. heat transfer body; 502. thermocouple; 503. second ceramic tube; 504. second mica gasket; 505. ceramic gasket; 506. fastening screw. DETAILED DESCRIPTION

[0041] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0042] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the multifunctional sensor of the FADS includes a pressure sensor, an adapter 3, a temperature sensor 4 and a heat flow sensor 5; the pressure sensor includes an air bleed cover 1 and a base 2;

[0043] The air bleed cover 1 is arranged at the upper end of the base 2, and an inner cavity 102 is formed between the air bleed cover 1 and the base 2; a pressure measuring hole 101 is arranged on the outer surface of the air bleed cover 1; and the inner cavities 102 and 102 are communicated with each other;

[0044] A T-shaped air inlet hole 202 is provided inside the base 2; the upper lateral portion of the air inlet hole 202 is communicated with the inner cavity 102;

[0045] An air bleed channel is provided inside the adapter 3, the upper end of the air bleed channel is connected to the lower end of the air bleed hole 202; the lower end of the air bleed channel is connected to the external air path for pressure transmission;

[0046] The sensing end of the temperature sensor 4 is located in the inner cavity 102 and is used to measure the regional temperature in the inner cavity 102;

[0047] The sensing end of the heat flow sensor 5 is located in the air bleed cover 1 and is used to measure the heat flow of the pressure sensor.

[0048] The air bleed cover 1 and the base 2 are melt-welded. The air bleed cover 1 and the base 2 are cylindrical with flanges. The flanges are provided with through holes and can be connected to the aircraft by screws. The outer surface of the air bleed cover 1 is consistent with the curvature of the aircraft skin. There are three pressure measuring holes 101, each with a diameter of 1 mm. The inside of the pressure measuring hole 101 is an inverted cone with an angle of 100°. The diameter of the inner cavity 102 is 10 mm. The air bleed cover 1 and the base 2 are made of high-temperature resistant nickel-based alloy materials.

[0049] The upper lateral portion of the air ducting hole 202 is a cylinder 201, and the diameter of the cylinder 201 is 3 mm; the diameter of the air ducting hole 202 is 2 mm; the lower end of the air ducting hole 202 is fixed to the adapter 3 through an M8 thread.

[0050] The diameter of the air duct in the adapter 3 is 2 mm, and the upper end of the adapter 3 is an M8 threaded section 301; a high-temperature resistant fluorosilicone rubber ring 302 for sealing is provided between the adapter 3 and the base 2; the middle part of the adapter 3 is located outside the base 2 and is provided with a hexagonal disk; the lower end of the adapter 3 is a pagoda structure.

[0051] In a specific implementation process, the M8 thread segment 301 may also be a thread segment of other specifications.

[0052] The temperature sensor 4 includes a wound platinum resistor 401 located in the inner cavity 102, and a first mica gasket 403 is arranged between the wound platinum resistor 401 and the base 2; the circuit of the wound platinum resistor 401 passes through the base 2, and a first ceramic tube 402 is arranged outside the circuit of the wound platinum resistor 401; the first ceramic tube 402 and the base 2 are sealed by high-temperature resistant insulating glue.

[0053] The heat flux sensor 5 is a zero-point calorimeter, comprising a heat transfer body 501, a thermocouple 502, a second ceramic tube 503, a second mica gasket 504, a ceramic gasket 505 and a fastening screw 506; the heat transfer body 501 is located in the air bleed cover 1; the thermocouple 502 is located in the heat transfer body 501; the ceramic gasket 505 is arranged between the thermocouple 502 and the base 2; the line of the thermocouple 502 passes through the base 2, and the second ceramic tube 402 is arranged on the outer sleeve of the line of the thermocouple 502; the second mica gasket 504 is arranged at the position where the line of the thermocouple 502 passes through the base 2, and is fixed to the base 2 by the fastening screw 506.

[0054] In this embodiment, the pressure sensor is only an air bleed structure and does not include a pressure measurement module. It is consistent with the pipeline in function, takes in air through the pressure hole 101, and transmits the air path through the adapter 3 under the transmission of the internal pipeline, and measures the pressure through the external pressure measurement module, thereby calculating the total pressure, differential pressure, angle of attack, sideslip angle and Mach number. The entire pressure sensor is positioned and connected to the fuselage through the four through holes on the flange, and the outer surface of the pressure hole 101 is consistent with the curvature of the aircraft skin surface.

[0055] In one embodiment of the present invention, the multifunctional sensor of FADS integrates a pressure sensor, a heat flow sensor 5 and a temperature sensor 4, has the functions of pressure measurement and heat flow measurement, and estimates the total temperature during high Mach number flight by using the characteristics of the zero-point calorimeter and the temperature measured by the temperature sensor 4. Figure 5 The heat transfer between the free flow of the multifunctional sensor of this FADS in a high-speed environment can be described as the skin area with a smaller curvature, causing the fluid layer where the structure is located to be approximated as laminar flow around a flat plate. The temperature of the free flow is the static temperature T s , Mach number M s Calculated by the FADS system. Figure 5 Under the heat transfer schematic diagram shown, the total temperature measurement method is:

[0056] High-speed flow will generate shock waves at the head of the aircraft, and the airflow will generate high temperature due to compression and viscous dissipation. According to the Carnot cycle theorem in the laws of thermodynamics, for an ideal gas, its free flow has the following relationship with the temperature, pressure and specific volume at any position in the boundary layer:

[0057]

[0058] Where T s Indicates the temperature of the incoming flow. For the free incoming flow outside the boundary layer, its temperature is the static temperature; T e represents the temperature at any point in the boundary layer; p and v represent the pressure and specific volume in the incoming flow direction; P e 、v e It represents the pressure and specific volume at any point in the boundary layer.

[0059] For the FADS system, the pressure between each pressure measuring point is i The incident angle θ can be measured, and the sideslip angle β and the angle of attack α can be obtained by arranging the pressure measuring points, that is, the Mach number has a functional relationship with the sideslip angle, the incident angle, the angle of attack and the pressure:

[0060] M s =f(p i ,θ,α,β) (2)

[0061] The specific functional relationship f(.) is the prior art, and the specific principle can refer to the pneumatic principle of embedded five-hole pressure measurement.

[0062] For compressible flow, there is the following relationship between the total atmospheric temperature, static temperature and Mach number:

[0063]

[0064] Among them, T t represents the total temperature of the incoming flow; γ represents the specific heat of the incoming flow. From formula (1), it can be seen that the total temperature is related to the temperature, pressure and specific volume of a certain point in the boundary layer. When T e At the edge of the boundary layer, the pressure and specific volume at this location are basically consistent with the incoming flow, so T e =T s .

[0065] For the aerodynamic layout of the pressure sensor, the preference is to select an external flow field close to laminar flow with less influence from the aircraft boundary layer. For aircraft skin with small curvature, the flow field at the pressure measuring point can be approximated as compressible laminar flow around a flat plate. For this flow, there is an engineering approximation method: the reference temperature T at any point in the boundary layer is * and free flow temperature T e The following relationship exists:

[0066]

[0067] Among them, T w represents the wall temperature; M e represents the Mach number of the free stream. Since the zero-point calorimeter has the characteristic that the temperature of the internal measuring point is approximately equal to the wall temperature, that is,

[0068] When the reference temperature T * When T is the average temperature at the pressure measuring hole, * Measure the temperature T with the temperature sensor m The following relationship exists:

[0069] T m =T * +T E+T c (5)

[0070] Among them, T E Indicates the temperature produced by gas momentum retardation; T c is the temperature of lateral heat transfer. For laminar flow around a flat plate, the flow velocity at the pressure measuring hole is small, and the airflow entering the pressure measuring sensor is considered incompressible, and the temperature T generated by the retardation E Temperature T relative to lateral heat transfer c It is a small amount and can be corrected by subsequent calibration.

[0071] Since the temperature sensor 4 and the heat flux sensor 5 have the same insulation process and the same material of the heat transfer body, the temperature T b During the effective working time of the heat flux sensor, the lateral heat transfer can be ignored. The effective working time is Where L is the length of the heat transfer body and σ is the thermal diffusivity of the heat transfer body. Therefore, during the effective working time, T m =T * , T b =T w The free flow temperature is obtained from equation 4:

[0072]

[0073] When freedom comes to flow e =T s When , the total temperature is obtained by formula (3):

[0074]

[0075] Therefore, the total temperature estimation method of the multifunctional sensor based on FADS includes the following steps:

[0076] S1. Obtain temperature T through temperature sensor 4 m ;

[0077] S2. Obtain temperature T through heat flow sensor 5 b ;

[0078] S3. Obtain the incoming flow Mach number M s ;

[0079] S4. According to the formula:

[0080]

[0081] Calculate the total temperature of the incoming flow T t ; where γ is the specific heat of the incoming flow.

[0082] In conclusion, the present invention has a dust-proof and anti-blocking structural design, and integrates the measurement functions of pressure, total temperature, heat flow and static temperature. It has a simple structure, is easy to install, and has a low manufacturing cost, and can be applied to the embedded atmospheric data system of high-speed aircraft.

Claims

1. A multifunctional sensor for FADS, characterized in that: It comprises a pressure sensor, an adapter (3), a temperature sensor (4) and a heat flow sensor (5); the pressure sensor comprises an air bleed cover (1) and a base (2); The air bleed cover (1) is arranged at the upper end of the base (2), and an inner cavity (102) is formed between the air bleed cover (1) and the base (2); a pressure measuring hole (101) is arranged on the outer surface of the air bleed cover (1), and the pressure measuring hole (101) is communicated with the inner cavity (102); A T-shaped air intake hole (202) is provided inside the base (2); the upper lateral portion of the air intake hole (202) is in communication with the inner cavity (102); An air bleed channel is provided inside the adapter (3), the upper end of the air bleed channel is connected to the lower end of the air bleed hole (202); the lower end of the air bleed channel is connected to an external air path for pressure transmission; The sensing end of the temperature sensor (4) is located in the inner cavity (102) and is used to measure the regional temperature in the inner cavity (102); The sensing end of the heat flow sensor (5) is located inside the air bleed cover (1) and is used to measure the heat flow of the pressure sensor.

2. The multifunctional sensor of FADS according to claim 1, characterized in that: The air bleed cover (1) and the base (2) are melt-welded, and the air bleed cover (1) and the base (2) are cylindrical with flanges as a whole; the outer surface of the air bleed cover (1) is consistent with the curvature of the aircraft skin; three pressure measuring holes (101) are provided, each with a diameter of 1 mm; the interior of the pressure measuring hole (101) is inverted cone shape with an angle of 100 degrees; and the diameter of the inner cavity (102) is 10 mm.

3. The multifunctional sensor of FADS according to claim 2, characterized in that: The upper lateral portion of the air ducting hole (202) is a cylinder (201), and the diameter of the cylinder (201) is 3 mm; the diameter of the vertical portion of the air ducting hole (202) is 2 mm; and the lower end of the air ducting hole (202) is fixed to the adapter (3) via an M8 thread.

4. The multifunctional sensor of FADS according to claim 3, characterized in that: The diameter of the air duct in the adapter (3) is 2 mm, and the upper end of the adapter (3) is an M8 threaded section (301); a fluorosilicone rubber ring (302) for sealing is provided between the adapter (3) and the base (2); the middle part of the adapter (3) is located outside the base (2) and is provided with a hexagonal disk; and the lower end of the adapter (3) is a pagoda structure.

5. The multifunctional sensor of FADS according to claim 1, characterized in that: The temperature sensor (4) comprises a wire-wound platinum resistor (401) located in the inner cavity (102); a first mica gasket (403) is arranged between the wire-wound platinum resistor (401) and the base (2); a circuit of the wire-wound platinum resistor (401) passes through the base (2); a first ceramic tube (402) is arranged outside the circuit of the wire-wound platinum resistor (401); and the first ceramic tube (402) and the base (2) are sealed by high-temperature resistant insulating glue.

6. The multifunctional sensor of FADS according to claim 1, characterized in that: The heat flow sensor (5) is a zero-point calorimeter, comprising a heat transfer body (501), a thermocouple (502), a second ceramic tube (503), a second mica gasket (504), a ceramic gasket (505) and a fastening screw (506); the heat transfer body (501) is located in the air bleed cover (1); the thermocouple (502) is located in the heat transfer body (501); the ceramic gasket (505) is arranged between the thermocouple (502) and the base (2); the line of the thermocouple (502) passes through the base (2), and the second ceramic tube (402) is arranged on the outer sleeve of the line of the thermocouple (502); the second mica gasket (504) is arranged at the position where the line of the thermocouple (502) passes through the base (2), and is fixed to the base (2) by the fastening screw (506).

7. The multifunctional sensor of FADS according to claim 1, characterized in that: The air bleed cover (1) and the base (2) are both made of high temperature resistant nickel-based alloy material.

8. A total temperature estimation method of a multifunctional sensor based on FADS according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Obtain temperature T through temperature sensor (4) m ; S2. Obtain temperature T through heat flow sensor (5) b ; S3. Obtain the incoming flow Mach number M s ; S4. According to the formula: Calculate the total temperature of the incoming flow T t ; where γ is the specific heat of the incoming flow.

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