Multiaxial pressure probe and three-dimensional vector calculation method for plasma jet

Abstract

This invention provides a multi-axis pressure probe and a method for calculating the three-dimensional vector of a plasma jet, relating to the field of fluid dynamics measurement technology. The multi-axis pressure probe uses a ceramic substrate extending along the z-direction. A first, second, third, and fourth measuring unit are sequentially connected to the ceramic substrate. The first and third measuring units are positioned opposite each other along the x-direction, and the second and fourth measuring units are positioned opposite each other along the y-direction, with the x, y, and z directions being mutually perpendicular. A fifth measuring unit is installed at one end of the ceramic substrate along the z-direction. The difference in electrical signal intensity between the first and third measuring units characterizes the vector pressure in the x-direction, the difference between the second and fourth measuring units characterizes the vector pressure in the y-direction, and the difference between the fifth measuring unit characterizes the vector pressure in the z-direction, enabling the detection of pressure vector signals in high-speed flowing media.

Description

Technical Field

[0001] This invention relates to the field of fluid dynamics measurement technology, and in particular to a multi-axis pressure probe and a method for calculating the three-dimensional vector of plasma jets. Background Technology

[0002] In the magnetized plasma generated by a magnetoplasmic thruster, the pressure distribution in the plasma flow is not isotropic due to the presence of vortex effects within the device. Therefore, vector analysis in three-dimensional space is required to describe the fluid motion state and the impact force (pressure) of the plasma jet.

[0003] Impact force (pressure), as an important macroscopic parameter of fluids, is usually detected using contact pressure probes. These probes measure the local pressure of a high-speed flowing medium in pulse-like patterns. However, traditional contact pressure probes cannot detect the spatial distribution of pressure, thus making it difficult to accurately describe the fluid's motion state. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-axis pressure probe and a three-dimensional vector calculation method for plasma jets, which can realize the detection of the spatial distribution of pressure in high-speed flowing media.

[0005] In a first aspect, the multiaxial pressure probe provided by the present invention includes: a first measuring unit, a second measuring unit, a third measuring unit, a fourth measuring unit, a fifth measuring unit, and a ceramic substrate;

[0006] The ceramic matrix extends along the z-direction;

[0007] The first measuring unit, the second measuring unit, the third measuring unit, and the fourth measuring unit are sequentially arranged and connected to the ceramic substrate;

[0008] The first measuring unit and the third measuring unit are arranged opposite each other along the x-direction, and the second measuring unit and the fourth measuring unit are arranged opposite each other along the y-direction, wherein the x-direction, y-direction and z-direction are perpendicular to each other;

[0009] The fifth measuring unit is installed at one end of the ceramic substrate in the z-direction.

[0010] In conjunction with the first aspect, the present invention provides a first possible implementation of the first aspect, wherein the first measuring unit, the second measuring unit, the third measuring unit, the fourth measuring unit and the fifth measuring unit each include: a piezoelectric ceramic, a first electrode, a second electrode and a substrate device;

[0011] The first electrode and the second electrode are spaced apart, and the piezoelectric ceramic is connected to the first electrode and the second electrode;

[0012] The substrate device is connected to the ceramic substrate and abuts against the piezoelectric ceramic.

[0013] In conjunction with the first possible implementation of the first aspect, the present invention provides a second possible implementation of the first aspect, wherein the ceramic substrate is provided with a hollow cavity, and the first electrode and the second electrode extend into the hollow cavity respectively.

[0014] In conjunction with the first possible implementation of the first aspect, the present invention provides a third possible implementation of the first aspect, wherein the substrate device comprises: a pressing sheet and a base;

[0015] The pressure plate is bolted to the ceramic substrate, and the base is pressed between the pressure plate and the piezoelectric ceramic.

[0016] In conjunction with the third possible implementation of the first aspect, the present invention provides a fourth possible implementation of the first aspect, wherein the substrate device includes a plurality of said press sheets, and the plurality of said press sheets have different thicknesses and are connected to the ceramic substrate.

[0017] In conjunction with the third possible implementation of the first aspect, the present invention provides a fifth possible implementation of the first aspect, wherein the pressing sheet, the base and the ceramic substrate are respectively made of one of alumina ceramic with a content of 95%, alumina ceramic with a content of 99% and boron nitride ceramic with a content of 99%.

[0018] In conjunction with the third possible implementation of the first aspect, the present invention provides a sixth possible implementation of the first aspect, wherein the base is detachably connected to a baffle.

[0019] In conjunction with the third possible implementation of the first aspect, the present invention provides a seventh possible implementation of the first aspect, wherein the tablet has a central hole, the base passes through the central hole, and the base is connected to a baffle via a threaded connection.

[0020] Secondly, the plasma jet three-dimensional vector calculation method provided by the present invention uses the multi-axis pressure probe described in the first aspect, and includes the following steps:

[0021] When the multi-axis pressure probe is inserted into the fluid medium, the electrical signals of the first measurement unit, the second measurement unit, the third measurement unit, and the fourth measurement unit are acquired;

[0022] The difference in electrical signal strength between the first measuring unit and the third measuring unit is used to characterize the vector pressure in the x-direction;

[0023] The difference in electrical signal strength between the second measuring unit and the fourth measuring unit is used to characterize the vector pressure in the y-direction;

[0024] The vector pressure in the z-direction is characterized by the difference in electrical signal intensity of the fifth measuring unit.

[0025] In conjunction with the second aspect, the method for calculating the three-dimensional vector of plasma jets further includes:

[0026] Calculate the resultant force of the impact;

[0027] Calculate the direction angle in each direction.

[0028] The embodiments of the present invention bring the following beneficial effects: A ceramic substrate extending along the z-direction is used, and a first, second, third, and fourth measuring unit are sequentially arranged and connected to the ceramic substrate. The first and third measuring units are arranged opposite each other along the x-direction, and the second and fourth measuring units are arranged opposite each other along the y-direction. The x, y, and z directions are mutually perpendicular. A fifth measuring unit is installed at one end of the ceramic substrate along the z-direction. The difference in electrical signal intensity between the first and third measuring units characterizes the vector pressure in the x-direction, the difference in electrical signal intensity between the second and fourth measuring units characterizes the vector pressure in the y-direction, and the difference in electrical signal intensity between the fifth measuring unit characterizes the vector pressure in the z-direction. This enables the detection of pressure vector signals in high-speed flowing media.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 A schematic diagram of a multiaxial pressure probe provided in an embodiment of the present invention;

[0032] Figure 2 This is a cross-sectional view of a multiaxial pressure probe provided in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the multi-axis pressure probe provided in an embodiment of the present invention with the baffle removed.

[0034] Figure 4This is a schematic diagram illustrating the evolution of pressure over time in the plasma jet three-dimensional vector calculation method provided in this embodiment of the invention.

[0035] Icons: 100-First measuring unit; 110-Piezoelectric ceramic; 120-First electrode; 130-Second electrode; 140-Substrate device; 141-Pressure plate; 142-Base; 143-Baffle; 150-Bolt; 200-Second measuring unit; 300-Third measuring unit; 400-Fourth measuring unit; 500-Fifth measuring unit; 600-Ceramic substrate; 601-Hollow cavity. Detailed Implementation

[0036] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Physical quantities in formulas, unless otherwise specified, should be understood as basic quantities in the International System of Units (SI), or derived quantities derived from basic quantities through mathematical operations such as multiplication, division, differentiation, or integration.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] like Figure 1 and Figure 2As shown, the multiaxial pressure probe provided in this embodiment of the invention includes: a first measuring unit 100, a second measuring unit 200, a third measuring unit 300, a fourth measuring unit 400, a fifth measuring unit 500, and a ceramic substrate 600; the ceramic substrate 600 extends along the z-direction; the first measuring unit 100, the second measuring unit 200, the third measuring unit 300, and the fourth measuring unit 400 are sequentially arranged and connected to the ceramic substrate 600; the first measuring unit 100 and the third measuring unit 300 are arranged opposite each other along the x-direction, and the second measuring unit 200 and the fourth measuring unit 400 are arranged opposite each other along the y-direction, wherein the x-direction, y-direction, and z-direction are perpendicular to each other; the fifth measuring unit 500 is installed at one end of the ceramic substrate 600 in the z-direction.

[0040] The multi-axis pressure probe described in this embodiment can be inserted into the fluid medium to perform three-dimensional vector detection. The difference in electrical signal intensity between the first measurement unit 100 and the third measurement unit 300 represents the vector pressure in the x-direction, the difference in electrical signal intensity between the second measurement unit 200 and the fourth measurement unit 400 represents the vector pressure in the y-direction, and the difference in electrical signal intensity between the fifth measurement unit 500 represents the vector pressure in the z-direction. This can realize the detection of pressure vector signals of high-speed flowing media, and is therefore suitable for accurately describing the motion state of the fluid medium in three-dimensional space.

[0041] In this embodiment of the invention, the first measuring unit 100, the second measuring unit 200, the third measuring unit 300, the fourth measuring unit 400, and the fifth measuring unit 500 each include: a piezoelectric ceramic 110, a first electrode 120, a second electrode 130, and a substrate device 140; the first electrode 120 and the second electrode 130 are spaced apart, and the piezoelectric ceramic 110 is connected to the first electrode 120 and the second electrode 130; the substrate device 140 is connected to the ceramic substrate 600, and the substrate device 140 abuts against the piezoelectric ceramic 110.

[0042] During testing, fluid impacts the substrate device 140, thereby generating a corresponding compressive force on the piezoelectric ceramic 110, and the potential difference between the first electrode 120 and the second electrode 130 is detected as a test signal.

[0043] Furthermore, the ceramic substrate 600 is provided with a hollow cavity 601, and the first electrode 120 and the second electrode 130 extend into the hollow cavity 601 respectively. The signal line can be introduced through the hollow cavity 601 and connected to the first electrode 120 and the second electrode 130 respectively.

[0044] like Figure 2 and Figure 3 As shown, the substrate device 140 includes a pressing sheet 141 and a base 142; the pressing sheet 141 is connected to the ceramic substrate 600 by bolts 150, and the base 142 is pressed between the pressing sheet 141 and the piezoelectric ceramic 110.

[0045] The axis of bolt 150 is perpendicular to the pressure plate 141. By adjusting the preload of bolt 150, the pressure of pressure plate 141 on base 142 can be adjusted, thereby adjusting the initial pressure on piezoelectric ceramic 110.

[0046] In addition, the substrate device 140 includes multiple pressure plates 141 with different thicknesses and connected to the ceramic substrate 600. The preload applied to the piezoelectric ceramic 110 can be adjusted by replacing the pressure plates 141 with different thicknesses.

[0047] In an optional embodiment, the pressing tablet 141, the base 142, and the ceramic substrate 600 are respectively made of alumina ceramic with a content of 95%, alumina ceramic with a content of 99%, and boron nitride ceramic with a content of 99%.

[0048] In addition, bolt 150 can be made of stainless steel or titanium alloy.

[0049] In this embodiment, the base 142 is detachably connected to the baffle 143, and the baffle 143 of different shapes can be replaced as needed.

[0050] Furthermore, the tablet 141 has a central hole, the base 142 passes through the central hole, and the base 142 is connected to the baffle 143 by a threaded connection.

[0051] The base 142 is locked by a plurality of spaced bolts 150, and the baffle 143 is connected to the base 142. The impact on the baffle 143 is transmitted to the piezoelectric ceramic 110 through the base 142.

[0052] In an optional embodiment, the baffle 143 is made of quartz plate or graphite plate, which has better pressure resistance and wear resistance, and can efficiently transmit the pressure of the fluid medium so that the multi-axis pressure probe can obtain accurate vector signals.

[0053] The plasma jet three-dimensional vector calculation method provided in this embodiment of the invention uses the multi-axis pressure probe described in the above embodiments and includes the following steps:

[0054] When a multi-axis pressure probe is inserted into a fluid medium, electrical signals from the first measurement unit 100, the second measurement unit 200, the third measurement unit 300, and the fourth measurement unit 400 are acquired.

[0055] The vector pressure in the x-direction is characterized by the difference in electrical signal intensity between the first measuring unit 100 and the third measuring unit 300.

[0056] The vector pressure in the y-direction is characterized by the difference in electrical signal strength between the second measuring unit 200 and the fourth measuring unit 400.

[0057] The vector pressure in the z-direction is characterized by the difference in electrical signal intensity of the fifth measurement unit 500.

[0058] The difference between the voltage signals measured from the two opposing piezoelectric ceramics 110 is multiplied by a conversion factor k. i The three-dimensional spatial vector of the pressure value can be obtained, i=x,y,z,P x =k x (U1-U2), P y =k y (U3-U4), P z =k z U5 and U1-U2 are the voltage signal differences between the two piezoelectric ceramics 110 in the x direction, U3-U4 are the voltage signal differences between the two piezoelectric ceramics 110 in the y direction, and U5 is the voltage signal value of the piezoelectric ceramic 110 in the fifth measurement unit 500.

[0059] Impact force vector F in the x direction x =P x A x Impact force vector F in the y direction y =P y A y Impact force vector F in the z direction z =P z A z A i (i=x,y,z) represents the cross-sectional area of ​​the baffle in the three directions.

[0060] Impact force resultant force The direction of the resultant force can be represented by the ratio of the component of the resultant force along each axis to the magnitude of the resultant force, and thus the direction angle in each direction. .

[0061] See Figure 4 As an example of pressure test results, given the cross-sectional area of ​​the baffle, the impact force at t=3μs can be calculated. The pressure can also be integrated to calculate the elementary impulse. The calculation results are shown in the table below:

[0062]

[0063] The above-mentioned multi-axis pressure probe and plasma jet three-dimensional vector calculation method have the following advantages:

[0064] (1) The multi-axis pressure probe has vector signal resolution capability, which can meet the measurement requirements of the three-dimensional spatial distribution of pressure in fluid medium;

[0065] (2) The base 142 is connected to the baffle 143 by threaded connection, and the pressure plate 141 is connected to the ceramic substrate 600 by bolt 150, realizing glue-free connection, which is beneficial to improving the temperature application range of the multi-axis pressure probe;

[0066] (3) The thickness of the pressure plate 141 can be replaced and changed, thereby adjusting the pressure on the piezoelectric ceramic 110 in its initial state, which facilitates sensitivity calibration of each measuring unit.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multiaxial pressure probe, characterized in that, include: The first measuring unit (100), the second measuring unit (200), the third measuring unit (300), the fourth measuring unit (400), the fifth measuring unit (500), and the ceramic substrate (600); The ceramic matrix (600) extends along the z-direction; The first measuring unit (100), the second measuring unit (200), the third measuring unit (300) and the fourth measuring unit (400) are sequentially arranged and connected to the ceramic substrate (600); The first measuring unit (100) and the third measuring unit (300) are arranged opposite each other along the x-direction, and the second measuring unit (200) and the fourth measuring unit (400) are arranged opposite each other along the y-direction, wherein the x-direction, y-direction and z-direction are perpendicular to each other; The fifth measuring unit (500) is installed at one end of the ceramic substrate (600) in the z-direction; The first measurement unit (100), the second measurement unit (200), the third measurement unit (300), the fourth measurement unit (400) and the fifth measurement unit (500) each include: a piezoelectric ceramic (110), a first electrode (120), a second electrode (130) and a substrate device (140). The first electrode (120) and the second electrode (130) are spaced apart, and the piezoelectric ceramic (110) connects the first electrode (120) and the second electrode (130). The substrate device (140) is connected to the ceramic substrate (600), and the substrate device (140) abuts against the piezoelectric ceramic (110).

2. The multiaxial pressure probe according to claim 1, characterized in that, The ceramic substrate (600) is provided with a hollow cavity (601), and the first electrode (120) and the second electrode (130) extend into the hollow cavity (601) respectively.

3. The multiaxial pressure probe according to claim 1, characterized in that, The substrate device (140) includes: a pressing sheet (141) and a base (142). The pressure plate (141) is connected to the ceramic substrate (600) by bolts (150), and the base (142) is pressed between the pressure plate (141) and the piezoelectric ceramic (110).

4. The multiaxial pressure probe according to claim 3, characterized in that, The substrate device (140) includes multiple sheets (141) of different thicknesses and is connected to the ceramic substrate (600).

5. The multiaxial pressure probe according to claim 3, characterized in that, The pressing plate (141), the base (142) and the ceramic substrate (600) are respectively made of one of the following: alumina ceramic with a content of 95%, alumina ceramic with a content of 99%, and boron nitride ceramic with a content of 99%.

6. The multiaxial pressure probe according to claim 3, characterized in that, The base (142) is detachably connected to the baffle (143).

7. The multiaxial pressure probe according to claim 3, characterized in that, The pressure plate (141) has a central hole, the base (142) passes through the central hole, and the base (142) is connected to the baffle (143) by a threaded connection.

8. A method for calculating the three-dimensional vector of a plasma jet, characterized in that, The plasma jet three-dimensional vector calculation method uses the multi-axis pressure probe described in any one of claims 1-7, and includes the following steps: When the multi-axis pressure probe is inserted into the fluid medium, the electrical signals of the first measurement unit (100), the second measurement unit (200), the third measurement unit (300) and the fourth measurement unit (400) are acquired; The impact force vector in the x-direction is characterized by the difference in electrical signal intensity between the first measuring unit (100) and the third measuring unit (300); The difference in electrical signal intensity between the second measuring unit (200) and the fourth measuring unit (400) is used to characterize the impact force vector in the y-direction; The impact force vector in the z-direction is characterized by the difference in electrical signal intensity of the fifth measuring unit (500).

9. The method for calculating the three-dimensional vector of a plasma jet according to claim 8, characterized in that, Also includes: Calculate the resultant force of the impact; Calculate the direction angle in each direction.

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