A velocity measurement device for gas vortex flow and a method of using the same

Abstract

The present invention discloses a velocity measurement device for gas vortex flow and a method of using the device, including a pitot tube, a measuring point position control mechanism, a vortex tube and an equipment bracket. The pitot tube is clamped at the bottom of the measuring point position control mechanism and inserted into the vortex tube, the measuring point position control mechanism is located above the vortex tube and fixed at the top of the equipment bracket, and the vortex tube is fixed at the bottom of the equipment bracket. Based on the Seebeck effect and the Bernoulli principle, a back-type pitot tube made of two hollow tubes of different metal materials is used to measure the velocity magnitude and direction of the gas vortex flow in the vortex tube. The present invention takes into account the difference in gas density between the center and the periphery caused by the pressure and temperature gradient in the vortex flow, and uses the measuring point position control mechanism to continuously and accurately move the velocity measurement point to avoid the interference of multiple measuring points on the flow field, thereby reducing the test cost while improving the measurement accuracy of the gas vortex flow velocity, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of air flow velocity measurement, and in particular to a velocity measurement device for gas vortex flow and a use method thereof. Background Art

[0002] Gas vortex flow refers to the flow phenomenon in which gas rotates around a fixed axis to form a vortex structure, and there are significant differences in pressure, velocity and temperature between the center and periphery of the vortex. The central pressure of the gas vortex is low and the peripheral pressure is high. The rotation speed varies with the radius. Usually, the peripheral velocity is higher than the central velocity. When the swirl intensity is high, the gas will undergo energy separation due to multiple factors such as adiabatic expansion, viscous dissipation and heat transfer, which is specifically manifested as a central cold air flow vortex and a peripheral hot air flow vortex. Gas vortex flow is widely used in industry, involving cooling, heating, separation, combustion, chemical reaction, energy utilization and environmental protection, and has significantly improved the performance and efficiency of various industrial equipment. For example, the vortex flow in the vortex tube separator is used to separate the compressed gas into cold and hot parts for equipment cooling, the vortex flow in the cyclone separator is used to separate particulate matter in the gas for industrial waste gas treatment, and the vortex flow in the gas turbine is used to enhance the mixing of fuel and air to improve combustion efficiency, etc.

[0003] Accurately measuring the velocity of gas vortex flow is of great significance in scientific research and engineering applications. It can clarify the flow structure of gas vortex, optimize the design of vortex generating equipment, improve energy efficiency, enhance process control and monitoring equipment safety and reliability, etc. Common velocity measurement methods for gas vortex flow include visual measurement, non-invasive measurement and invasive measurement. Visual measurement generally places tracer particles such as powder, smoke or droplet spray in the gas vortex for observation to indirectly reflect the velocity and flow structure. Non-invasive measurement usually uses laser Doppler velocimeter, particle image velocimeter, phase Doppler particle analyzer and other equipment to measure the gas vortex flow velocity. Invasive measurement usually uses equipment such as Pitot tube to measure the gas vortex flow velocity.

[0004] Compared with these three methods, the visualization measurement method can only roughly reflect the speed size and direction without obtaining the specific speed value, so it can only be used as a qualitative observation in the preliminary research; the non-invasive measurement equipment is very expensive, and such equipment also needs to place tracer particles in the flow field to measure the speed. Due to the strong centrifugal effect of the gas vortex flow, this measurement method is also difficult to obtain very accurate velocity distribution results; the invasive measurement test cost is low and can obtain accurate velocity values, but if the global result of the velocity needs to be measured, it is often necessary to arrange multiple measuring points, which will cause a large disturbance to the flow field. In addition, the significant pressure and temperature gradients of the gas vortex flow will cause the density of the airflow to change from the center to the periphery. The conventional pitot tube measurement method often uses a fixed gas density under standard conditions to calculate the velocity, which will also affect the velocity measurement accuracy of the pitot tube.

[0005] The present invention proposes a more accurate gas vortex flow velocity measurement device and a method of using the same based on the Seebeck effect and the Bernoulli principle. Compared with conventional gas vortex flow velocity measurement methods, the present invention can simultaneously obtain total pressure, static pressure, temperature, velocity magnitude and direction data at the measuring point position, effectively improving the measurement accuracy. The measuring point is continuously and accurately moved by a measuring point position control mechanism to obtain velocity distribution information of different measuring points, thus avoiding interference of multiple measuring points on the flow field. The present invention has broad application prospects in the scientific research of gas vortex flow. Summary of the invention

[0006] A velocity measuring device for gas vortex flow, comprising a pitot tube, a measuring point position control mechanism, a vortex tube and an equipment support, wherein the pitot tube is clamped at the bottom of the measuring point position control mechanism and inserted into the vortex tube, the measuring point position control mechanism is located above the vortex tube and fixed at the top of the equipment support, and the vortex tube is located below the pitot tube and fixed at the bottom of the equipment support; the pitot tube comprises a first pressure-inducing tube, a second pressure-inducing tube and an insulating shell; the first pressure-inducing tube and the second pressure-inducing tube are two inverted L-shaped hollow metal tubes and are arranged in a back-to-back manner, the first pressure-inducing tube is made of pure iron or pure copper material, and the second pressure-inducing tube is made of copper-nickel alloy; the bottom ends of the first pressure-inducing tube and the second pressure-inducing tube are fixed into an integrated velocity measuring head through a welding seam, the bottom of the velocity measuring head is hemispherical, and the outer surfaces of the first pressure-inducing tube and the second pressure-inducing tube except for the welding seam do not contact each other. A first pressure inlet and a second pressure inlet are respectively arranged on both sides of the welding seam in the speed measuring head, and the first pressure inlet and the second pressure inlet are distributed in opposite directions on the same horizontal line; the top ends of the first pressure tube and the second pressure tube are respectively the first pressure outlet and the second pressure outlet; the first pressure inlet and the first pressure outlet are interconnected through a first hollow channel inside the first pressure tube; the second pressure inlet and the second pressure outlet are interconnected through a second hollow channel inside the second pressure tube; a first bolt terminal is provided on the top horizontal rod of the first pressure tube, and a second bolt terminal is provided on the top horizontal rod of the second pressure tube; the insulating shell fixes and wraps the outer surfaces of the first pressure tube and the second pressure tube except the first bolt terminal, the second bolt terminal and the speed measuring head.

[0007] The measuring point position control mechanism is composed of an X direction control mechanism, a θ direction control mechanism, and an R direction control mechanism connected in sequence;

[0008] The X-direction control mechanism is composed of a first stepper motor, an X-direction lead screw, an X-direction slider, a first crossbeam and a lead screw frame; the first stepper motor is connected to the X-direction lead screw and controls it to rotate, the X-direction lead screw and the X-direction slider are rotatably connected through a threaded through hole, the X-direction slider is slidably connected to the trapezoidal guide rail at the bottom of the first crossbeam through a trapezoidal groove at the top thereof, the first stepper motor and the lead screw frame are respectively fixedly mounted at both ends of the first crossbeam, and the lead screw frame is rotatably connected to the X-direction lead screw through a first bearing at the center thereof;

[0009] The θ direction control mechanism is composed of a second stepper motor, an upper connecting frame, and a lower connecting frame; the second stepper motor and the upper connecting frame are both fixed to the bottom of the X direction slider, the upper connecting frame is rotatably connected to the rotating shaft of the second stepper motor through the second bearing at the center of its bottom, and the rotating shaft is matched with the groove at the top of the lower connecting frame and fixed by a cylindrical pin;

[0010] The R direction control mechanism is composed of a third stepper motor, a guide rail frame, an R direction lead screw, a slider frame, and a Pitot tube cover; the third stepper motor is fixed on the middle platform of the guide rail frame, the third stepper motor is connected to the R direction lead screw and controls its rotation, the R direction lead screw and the slider frame are rotationally connected through a threaded blind hole, the slider frame is slidingly connected to the trapezoidal double guide rails on the inner side of the guide rail frame through the trapezoidal double grooves on its outer side, there are T-shaped grooves on the bottom of the slider frame and the surface of the Pitot tube cover, and the Pitot tube is pressed into the T-shaped groove by screws.

[0011] The vortex tube is composed of an inlet pipe section, a vortex generating tube, a hot end tube, a control valve, a cold orifice plate, and a cold end tube; the inlet pipe section includes an air inlet pipe and a vortex chamber sleeve, and the inlet pipe section and the hot end tube are connected by flanges to press the vortex generating tube into the vortex chamber sleeve; a number of air inlet channels tangential to the inner wall are evenly distributed in the tube wall of the vortex generating tube, and both sides of the vortex generating tube are provided with limit sealing grooves, and O-rings are placed in the limit sealing grooves; the side walls of the vortex chamber sleeve and the hot end tube are provided with limit annular bosses, and after the vortex chamber sleeve and the hot end tube are connected by flanges, the limit annular bosses will sink into the limit sealing grooves and press the O-rings, thereby fixing the vortex generating tube between the inlet pipe section and the hot end tube; a number of sealing structures are evenly distributed vertically along the X direction of the hot end tube, and the sealing structure consists of a hollow stud, a hollow rubber column, a nut, and a pin, wherein the inner wall surface of the hollow stud and the outer wall surface of the hollow rubber column are both frustums The surfaces are of equal taper; no pin is installed at the position where the speed is measured, and the hollow rubber column is squeezed downward by tightening the nut so that the hollow rubber column presses the inner wall of the truncated cone of the hollow stud, and the hollow stud applies an inward reaction pressure to the hollow rubber column so that the cylindrical contact surface between the hollow rubber column and the pitot tube is compressed, thereby realizing the sliding seal of the pitot tube, and the position where the speed is not measured locks the pin by tightening the nut to close the hollow channel; the hot end pipe is flange-connected to the control valve, and the control valve consists of a valve housing, a hollow valve core and a valve core, the valve housing is threadedly connected to the hollow valve core, the hollow valve core is threadedly connected to the valve core, and grooves are provided at the ends of the hollow valve core and the valve core; there is a cold air flow discharge hole in the center of the cold orifice plate, and the cold orifice plate is installed between the inlet pipe section and the cold end pipe and is pressed by a flange connection; the control valve can adjust the overall opening of the hollow valve core and the valve core or remove the valve core, and the cold orifice plate can be replaced with a blind plate.

[0012] The equipment bracket consists of a first rectangular frame, a second rectangular frame, a second crossbeam, two pipe clamping seats and two limit sliders; the first rectangular frame and the second rectangular frame are fixedly connected by the first crossbeam and the second crossbeam, the second crossbeam is arranged in parallel and directly below the first crossbeam, and a second trapezoidal guide rail is arranged on the surface of the second crossbeam; the two pipe clamping seats and the two limit sliders are slidably connected to the second trapezoidal guide rail, the two pipe clamping seats are composed of a base, a pipe clamp and a fixing screw, and the distance between the two bases can be adjusted by sliding to adapt to the installation of vortex tubes of different lengths; the vortex tube is wrapped by the base and the pipe clamp and is tightened by the fixing screws; the two limit sliders are located between the two pipe clamping seats and are respectively close to the sides of the two pipe clamping seats; limit screws are arranged on the two limit sliders, and the two limit sliders are fixed to the second trapezoidal guide rail after the limit screws are tightened.

[0013] The present invention also provides a method for using a velocity measurement device for gas vortex flow, comprising the steps of:

[0014] S1. Adjust the installation mode of the control valve and cold orifice plate of the vortex tube according to the desired countercurrent, cocurrent, single-flow or double-circuit gas vortex flow;

[0015] S2. Select a pipe clamping seat of appropriate size according to the hot end pipe diameter of the vortex tube, adjust the distance between the pipe clamping seats to an appropriate length, use the pipe clamping seat to clamp the hot end pipe of the vortex tube, and lock the limit slider onto the second crossbeam;

[0016] S3. Connect the two pressure outlets of the pitot tube to the two pressure transmitters through two silicone tubes, and connect the two bolt terminals of the pitot tube to the temperature inspection instrument through wires;

[0017] S4. Install the measuring point position control mechanism on the top of the equipment bracket, install the Pitot tube on the bottom of the measuring point position control mechanism, and use the X-direction control mechanism to adjust the position of the Pitot tube to the first measuring hole in the X direction;

[0018] S5. Unscrew the sealing structure at the measuring position and remove the pin, and use the R direction control mechanism to insert the velocity measuring head of the pitot tube downward to the central axis of the hot end tube of the vortex tube, and then slide and seal the pitot tube by locking the sealing structure;

[0019] S6, supplying a fixed flow of compressed gas to the air inlet pipe of the vortex tube through the compressor to generate a vortex flow in the vortex tube;

[0020] S7. After the indication of the temperature inspection instrument is stable, the temperature T at the position of the velocity measuring head is collected, and the velocity measuring head of the pitot tube is rotated 360 degrees using the θ direction control mechanism, and the pressure data of the two pressure transmitters are collected as the angle θ changes;

[0021] S8, according to the maximum pressure difference P between the two pressure transmitters during the 360° rotation of the speed measuring head θ -P θ+180º The corresponding Pitot tube θ orientation can reflect the velocity direction of the gas vortex flow. The velocity direction is the axis direction of the two pressure inlets when the pressure difference is the maximum. The corresponding pressure value when the pressure difference between the two pressure transmitters is zero is the static pressure P at the velocity head position. θ+90º ;

[0022] S9, according to the temperature T and static pressure P at the speed measuring head position θ+90º The gas density ρ=P can be calculated θ+90º / R g T, where R g Represents the gas constant, which is the total pressure P corresponding to the maximum pressure difference between the two pressure transmitters. θ and the static pressure P corresponding to zero pressure difference θ+90º The dynamic pressure P can be obtained θ -P θ+90º , the velocity magnitude at the velocity head is obtained from the dynamic pressure and gas density at the velocity head: {V}_{\theta}=\sqrt {\left [ {2\left ( {{P}_{\theta}-{P}_{\theta +{90}^{\circ}}} \right ) / \rho} \right ]} ;

[0023] S10, using the R direction control mechanism to move the Pitot tube upward by a certain distance ΔR, and then repeating steps S7 to S9, thereby obtaining the velocity direction and magnitude of the gas vortex flow at different radial positions R;

[0024] S11, turn off the compressor to stop air supply, unscrew the sealing structure and move out the pitot tube through the R direction control mechanism, and close the sealing structure at the speed measurement position by locking the pin;

[0025] S12, using the X-direction control mechanism to move the Pitot tube to another speed measuring axial position X, and repeating steps S5 to S11, thereby obtaining the speed direction and magnitude at different X positions and R positions.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] There is a temperature and pressure gradient from the center to the periphery of the gas vortex flow, which will cause a significant change in gas density and thus bring errors to the velocity measurement of the gas vortex flow. The present invention adopts a Pitot tube that integrates the Seebeck effect and the Bernoulli principle, and simultaneously obtains the temperature, static pressure and total pressure at the measuring point to calculate the gas density and thus measure the velocity data, which improves the accuracy of the cyclone velocity measurement;

[0028] The pitot tube speed measurement needs to be aligned with the incoming flow direction, and the manual alignment error is large. The present invention adopts a displacement mechanism controlled by a stepping motor to enable the pitot tube to continuously collect pressure and pressure difference information during the rotation process, thereby directly obtaining the speed direction, which avoids the cumbersome correction process of the pitot tube speed measurement direction;

[0029] The traditional pitot tube measurement method often uses a multi-measurement point arrangement to measure the spatial velocity distribution. The present invention uses a pitot tube that can accurately move the measurement point position to measure the distributed information of the velocity, which avoids the flow field interference problem caused by the multi-measurement point arrangement.

[0030] In addition, the vortex tube of the gas vortex generating device in the present invention can realize different forms of gas vortex flow structures without the need to manufacture different vortex generating devices separately, which effectively reduces the testing cost. Therefore, the present invention has broad application prospects in engineering and scientific research of gas vortex flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of a velocity measurement device for gas vortex flow;

[0032] Figure 2 This is a schematic diagram of the structure of the Pitot tube;

[0033] Figure 3 is a cross-sectional schematic diagram of a Pitot tube;

[0034] Figure 4 It is the front view of the Pitot tube;

[0035] Figure 5 This is the AA position section view of the front view of the Pitot tube;

[0036] Figure 6 It is the BB position section view of the front view of the pitot tube;

[0037] Figure 7 This is the cross-sectional view of the CC position of the front view of the pitot tube;

[0038] Figure 8 It is a structural diagram of the measuring point position control mechanism;

[0039] Fig. 9 It is a structural schematic diagram of the X-direction control mechanism;

[0040] Fig.10 It is a structural schematic diagram of the θ direction control mechanism;

[0041] Fig.11 It is a structural schematic diagram of the R direction control mechanism;

[0042] Fig.12 is a schematic diagram of the structure of the vortex tube;

[0043] Fig.13 is a cross-sectional schematic diagram of a vortex tube;

[0044] Fig.14 It is the front view of the vortex generating tube;

[0045] Fig.15 It is the cross-sectional view at the DD position of the front view of the vortex generating tube;

[0046] Fig.16 It is the EE position cross-sectional view of the front view of the vortex generating tube;

[0047] Fig.17 The figure is a schematic diagram of the installation of the vortex generating pipe, the inlet pipe section and the hot end pipe;

[0048] Fig.18 It is a schematic diagram of the composition of the sealing structure;

[0049] Fig.19 It is a schematic diagram of the sliding seal pitot tube of the sealing structure;

[0050] Fig. 20 A schematic diagram of a locking pin of a sealing structure;

[0051] Fig.21 Schematic diagram of four installation modes of vortex tube;

[0052] Fig. 22 It is a structural schematic diagram of the equipment bracket;

[0053] Fig.23 This is a typical three-dimensional streamline structure diagram of gas vortex flow;

[0054] Fig.24 This is a top view of typical streamlines of gas vortex flow;

[0055] Fig.25 This is a schematic diagram of the process of pressure changes in the two pressure tubes as the rotation angle changes during the rotation of the Pitot tube.

[0056] Labels in the figure: 1- Pitot tube; 2- measuring point position control mechanism; 3- vortex tube; 4- equipment bracket; 11- first pressure-inducing tube; 12- second pressure-inducing tube; 13- insulating shell; 14- welding seam; 15- velocity head; 21- X direction control mechanism; 22- θ direction control mechanism; 23- R direction control mechanism; 31- inlet pipe section; 32- vortex generating tube; 33- hot end tube; 34- control valve; 35- cold hole plate; 36- cold end tube; 41- first rectangular frame; 42- second rectangular frame; 43- second Second crossbeam; 44-pipe clamping seat; 45-limiting slider; 111-first pressure inlet; 112-first pressure outlet; 113-first hollow channel; 114-first bolt terminal; 121-second pressure inlet; 122-second pressure outlet; 123-second hollow channel; 124-second bolt terminal; 211-first stepper motor; 212-X direction screw rod; 213-X direction slider; 214-first crossbeam; 215-screw rod frame; 221-second stepper motor; 222-upper connecting frame; 223-lower connecting frame; 231-third stepping motor; 232-guide rail frame; 233-R direction screw rod; 234-slider frame; 235-Pitot tube cover plate; 236-T-shaped groove; 311-inlet pipe; 312-vortex chamber sleeve; 321-inlet channel; 322-limiting sealing groove; 323-limiting annular boss; 331-sealing structure; 341-valve housing; 342-hollow valve core; 343-valve core; 351-cold air flow discharge hole; 431-second trapezoidal guide rail; 441-base; 44 2-pipe clamp; 443-fixing screw; 451-limiting screw; 2131-threaded through hole; 2132-trapezoidal groove; 2141-trapezoidal guide rail; 2151-first bearing; 2211-rotating shaft; 2221-second bearing; 2231-groove; 2232-cylindrical pin; 2321-middle platform; 2322-trapezoidal double guide rail; 2341-threaded blind hole; 2342-trapezoidal double groove; 3311-hollow stud; 3312-hollow rubber column; 3313-nut; 3314-pin; Fig.21 (a) is a counter-flow vortex tube, (b) is a co-flow vortex tube, (c) is a single-flow vortex tube, and (d) is a double-circuit vortex tube. The solid arrows represent the supply of compressed gas, the hollow arrows represent the exhaust of hot gas, and the dotted arrows represent the exhaust of cold gas. Fig.23 and Fig.24 V θ 、V T and V X They represent the total velocity, tangential velocity component and axial velocity component of the gas vortex flow at the measuring point respectively. DETAILED DESCRIPTION

[0057] The present invention provides a velocity measurement device for gas vortex flow and a method for using the same. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0058] See also Figure 1 , a velocity measuring device for gas vortex flow, composed of a pitot tube 1, a measuring point position control mechanism 2, a vortex tube 3 and an equipment support 4. The pitot tube 1 is clamped at the bottom of the measuring point position control mechanism 2 and inserted into the vortex tube 3, and its function is to obtain the velocity magnitude and direction of the gas vortex flow by measuring the temperature, pressure and pressure difference at different positions in the vortex tube 3. The measuring point position control mechanism 2 is located above the vortex tube 3 and fixed on the top of the equipment support 4, and its function is to clamp and move the pitot tube 1 to different measuring positions. The vortex tube 3 is located below the pitot tube 1 and fixed at the bottom of the equipment support 4, and its function is to generate gas vortex flows with different characteristics.

[0059] See also Figure 1-7 The Pitot tube 1 is composed of a first pressure-introducing tube 11, a second pressure-introducing tube 12 and an insulating shell 13. The first pressure-introducing tube 11 and the second pressure-introducing tube 12 are two inverted L-shaped hollow metal tubes and are arranged back-to-back. The first pressure-introducing tube 11 is made of pure iron or pure copper, and the second pressure-introducing tube 12 is made of copper-nickel alloy. The bottom ends of the first pressure-introducing tube 11 and the second pressure-introducing tube 12 are fixed into an integrated speed measuring head 15 through a welding seam 14. The bottom of the speed measuring head 15 is hemispherical, and the other outer surfaces of the first pressure-introducing tube 11 and the second pressure-introducing tube 12 except the welding seam 14 do not contact each other. The first pressure-introducing inlet 111 and the second pressure-introducing inlet 121 are respectively arranged on both sides of the welding seam 14 in the speed measuring head 15. The first pressure-introducing inlet 111 and the second pressure-introducing inlet 121 are arranged in the opposite direction on the same horizontal straight line. The top ends of the first pressure-introducing tube 11 and the second pressure-introducing tube 12 are respectively the first pressure-introducing outlet 112 and the second pressure-introducing outlet 122. The first pressure inlet 111 and the first pressure outlet 112 are connected to each other through the first hollow channel 113 inside the first pressure tube 11. Similarly, the second pressure inlet 121 and the second pressure outlet 122 are connected to each other through the second hollow channel 123 inside the second pressure tube 12. A first bolt terminal 114 is provided on the top horizontal rod of the first pressure tube 11, and a second bolt terminal 124 is provided on the top horizontal rod of the second pressure tube 12. The insulating shell 13 fixes and wraps the outer surfaces of the first pressure tube 11 and the second pressure tube 12 except the first bolt terminal 114, the second bolt terminal 124 and the speed measuring head 15.

[0060] See also Figure 1 and Figure 8-11The measuring point position control mechanism 2 is composed of an X direction control mechanism 21, a θ direction control mechanism 22, and an R direction control mechanism 23 connected in sequence.

[0061] The X-direction control mechanism 21 is composed of a first stepper motor 211, an X-direction screw rod 212, an X-direction slider 213, a first crossbeam 214 and a screw rod frame 215. The first stepper motor 211 is connected to the X-direction screw rod 212 and controls it to rotate. The X-direction screw rod 212 and the X-direction slider 213 are connected in rotation through a threaded through hole 2131. The X-direction slider 213 is connected in sliding with the first trapezoidal guide rail 2141 at the bottom of the first crossbeam 214 through the trapezoidal groove 2132 at the top thereof. The first stepper motor 211 and the screw rod frame 215 are respectively fixedly mounted at both ends of the first crossbeam 214, and the screw rod frame 215 is connected in rotation with the X-direction screw rod 212 through the first bearing 2151 at the center thereof. When it is necessary to measure the gas vortex flow velocity at different X directions in the vortex tube 3, the X-direction screw rod 212 is driven to rotate by the first stepper motor 211, thereby controlling the X-direction slider 213 to move linearly in the X direction along the first crossbeam 214.

[0062] The θ direction control mechanism 22 is composed of a second stepper motor 221, an upper connecting frame 222, and a lower connecting frame 223. The second stepper motor 221 and the upper connecting frame 222 are both fixed to the bottom of the X-direction slider 213. The upper connecting frame 222 is rotatably connected to the rotating shaft 2211 of the second stepper motor 221 through the second bearing 2221 at the bottom center thereof. The rotating shaft 2211 is matched with the groove 2231 at the top of the lower connecting frame 223 and fixed by a cylindrical pin 2232. When it is necessary to measure the gas vortex flow velocity at different θ angles in the vortex tube 3, the rotating shaft 2211 is controlled to rotate by the second stepper motor 221, so that the lower connecting frame 223 is driven to rotate to different θ angles.

[0063] The R direction control mechanism 23 is composed of a third stepper motor 231, a guide rail frame 232, an R direction lead screw 233, a slider frame 234, and a pitot tube cover plate 235. The third stepper motor 231 is fixed on the middle platform 2321 of the guide rail frame 232. The third stepper motor 231 is connected to the R direction lead screw 233 and controls it to rotate. The R direction lead screw 233 and the slider frame 234 are rotatably connected through a threaded blind hole 2341. The slider frame 234 is slidably connected to the trapezoidal double guide rails 2322 on the inner side of the guide rail frame 232 through the trapezoidal double grooves 2342 on its outer side. There are T-shaped grooves 236 on the bottom of the slider frame 234 and the surface of the pitot tube cover plate 235. The pitot tube 1 can be pressed into the T-shaped groove 236 by screws. When it is necessary to measure the gas vortex flow speed at different R directions in the vortex tube 3 , the third stepping motor 231 drives the R direction lead screw 233 to rotate, thereby controlling the slider frame 234 to move linearly in the R direction along the guide rail frame 232 .

[0064] See also Figure 12-20 The vortex tube 3 is composed of an inlet pipe section 31, a vortex generating pipe 32, a hot end pipe 33, a control valve 34, a cold orifice plate 35, and a cold end pipe 36. The inlet pipe section 31 includes an air inlet pipe 311 and a vortex chamber sleeve 312. The air inlet pipe 311 is used to introduce compressed gas. A plurality of air inlet channels 321 are evenly distributed in the wall of the vortex generating pipe 32 along the inner wall tangentially. Both sides of the vortex generating pipe 32 are provided with a limit sealing groove 322, and an O-ring is placed in the limit sealing groove 322. The side walls of the vortex chamber sleeve 312 and the hot end tube 33 are both provided with a limiting annular boss 323. After the vortex chamber sleeve 312 and the hot end tube 33 are connected by flanges, the limiting annular boss 323 will sink into the limiting sealing groove 322 and press the O-ring, thereby fixing the vortex generating tube 32 between the inlet pipe section 31 and the hot end tube 33, and preventing the vortex generating tube 32 from leaking the two side walls in contact with the vortex chamber sleeve 312 and the hot end tube 33, which would affect the generation effect of the gas vortex at the air inlet channel 321. The hot end tube 33 has a plurality of sealing structures 331 evenly distributed vertically along the X direction, and its function is to slide and seal the Pitot tube 1 inserted into the vortex tube 3 to prevent air leakage and affect the velocity measurement result. The sealing structure 331 is composed of a hollow stud 3311, a hollow rubber column 3312, a nut 3313 and a pin 3314, wherein the inner wall surface of the hollow stud 3311 and the outer wall surface of the hollow rubber column 3312 are both frustum surfaces and have the same taper. The pin 3314 is not installed at the position for measuring speed. The hollow rubber column 3312 is squeezed downward by tightening the nut 3313 so that the hollow rubber column 3312 presses against the inner wall surface of the frustum of the hollow stud 3311. The hollow stud 3311 applies an inward reaction pressure to the hollow rubber column 3312 so that the cylindrical contact surface between the hollow rubber column 3312 and the Pitot tube 1 is compressed, thereby realizing a sliding seal for the Pitot tube 1. At the position where the speed is not measured, the pin 3314 is locked by tightening the nut 3313 to close the hollow channel to prevent air leakage. The hot end pipe 33 is flange-connected to the control valve 34. The control valve 34 consists of a valve housing 341, a hollow valve core 342 and a valve core 343. The valve housing 341 is threadedly connected to the hollow valve core 342. The hollow valve core 342 is threadedly connected to the valve core 343. The ends of the hollow valve core 342 and the valve core 343 are both provided with grooves for easy rotation to control the valve opening. There is a cold air flow discharge hole 351 in the center of the cold orifice plate 35. The cold orifice plate 35 is installed between the inlet pipe section 31 and the cold end pipe 36 and is tightened by a flange connection. The control valve 34 can adjust the overall opening of the hollow valve core 342 and the valve core 343 or remove the valve core 343. The cold orifice plate 35 can be replaced with a blind plate, which is used to form a Fig.21 The four types of vortex tubes shown, namely counter-flow, co-flow, single-flow and double-loop, are used to provide gas vortex flows with different characteristics, thereby reducing the test cost.

[0065] See also Figure 1 , Figure 8 , Fig. 22 The equipment support 4 is composed of a first rectangular frame 41, a second rectangular frame 42, a second crossbeam 43, two pipe clamping seats 44 and two limit sliders 45. The first rectangular frame 41 and the second rectangular frame 42 are fixedly connected by the first crossbeam 214 and the second crossbeam 43. The second crossbeam 43 is arranged in parallel directly below the first crossbeam 214, and a second trapezoidal guide rail 431 is provided on the surface of the second crossbeam 43. The two pipe clamping seats 44 and the two limit sliders 45 are slidably connected to the second trapezoidal guide rail 431. The two pipe clamping seats 44 are composed of a base 441, a pipe clamp 442, and a fixing screw 443. The distance between the two bases 441 can be adjusted by sliding to adapt to the installation of vortex tubes 3 of different lengths. The vortex tube 3 is wrapped by the base 441 and the pipe clamp 442, and is pressed by the fixing screw 443. The two limit sliders 45 are located between the two pipe clamping seats 44, and are respectively close to the sides of the two pipe clamping seats 44. The two limit sliders 45 are provided with limit screws 451 , which are tightened to fix the two limit sliders 45 to the second trapezoidal guide rail 431 , so as to prevent the two pipe clamping seats 44 that clamp and fix the vortex tube 3 from sliding along the second trapezoidal guide rail 431 .

[0066] The above-mentioned velocity measuring device is used to measure the gas vortex flow, and the specific method of using it is as follows:

[0067] S1. Adjust the installation mode of the control valve and cold orifice plate of the vortex tube according to the desired countercurrent, cocurrent, single-flow or double-circuit gas vortex flow;

[0068] S2. Select a pipe clamping seat of appropriate size according to the hot end pipe diameter of the vortex tube, adjust the distance between the pipe clamping seats to an appropriate length, use the pipe clamping seat to clamp the hot end pipe of the vortex tube, and lock the limit slider onto the second crossbeam;

[0069] S3. Connect the two pressure outlets of the pitot tube to the two pressure transmitters through two silicone tubes, and connect the two bolt terminals of the pitot tube to the temperature inspection instrument through wires;

[0070] S4. Install the measuring point position control mechanism on the top of the equipment bracket, install the Pitot tube on the bottom of the measuring point position control mechanism, and use the X-direction control mechanism to adjust the position of the Pitot tube to the first measuring hole in the X direction;

[0071] S5. Unscrew the sealing structure at the measuring position and remove the pin, and use the R direction control mechanism to insert the velocity measuring head of the pitot tube downward to the central axis of the hot end tube of the vortex tube, and then slide and seal the pitot tube by locking the sealing structure;

[0072] S6, supplying a certain flow rate of compressed gas to the air inlet pipe of the vortex tube through the compressor to generate a vortex flow in the vortex tube;

[0073] S7. After the indication of the temperature inspection instrument is stable, the temperature T at the position of the velocity measuring head is collected, and the velocity measuring head of the pitot tube is rotated 360 degrees using the θ direction control mechanism, and the pressure data of the two pressure transmitters are collected as the angle θ changes;

[0074] S8, according to the maximum pressure difference P between the two pressure transmitters during the 360° rotation of the speed measuring head θ -P θ+180º The corresponding Pitot tube θ orientation can reflect the velocity direction of the gas vortex flow. The velocity direction is the axis direction of the two pressure inlets when the pressure difference is the maximum. The corresponding pressure value when the pressure difference between the two pressure transmitters is zero is the static pressure P at the velocity head position. θ+90º ;

[0075] S9, according to the temperature T and static pressure P at the speed measuring head position θ+90º The gas density ρ=P can be calculated θ+90º / R g T, where R g Represents the gas constant, which is the total pressure P corresponding to the maximum pressure difference between the two pressure transmitters. θ and the static pressure P corresponding to zero pressure difference θ+90º The dynamic pressure P can be obtained θ -P θ+90º , the velocity magnitude at the velocity head is obtained from the dynamic pressure and gas density at the velocity head: {V}_{\theta}=\sqrt {\left [ {2\left ( {{P}_{\theta}-{P}_{\theta +{90}^{\circ}}} \right ) / \rho} \right ]} ;

[0076] S10, using the R direction control mechanism to move the Pitot tube upward by a certain distance ΔR, and then repeating steps S7 to S9, thereby obtaining the velocity direction and magnitude of the gas vortex flow at different radial positions R;

[0077] S11, turn off the compressor to stop air supply, unscrew the sealing structure and move out the pitot tube through the R direction control mechanism, and close the sealing structure at the speed measurement position by locking the pin;

[0078] S12, using the X-direction control mechanism to move the Pitot tube to another speed measuring axial position X, and repeating steps S5 to S11, thereby obtaining the speed direction and magnitude at different X positions and R positions.

[0079] The measuring principle of the present invention is as follows: the pitot tube in the present invention is a hollow tube made of two different metal materials. One end is welded to form a velocity measuring head. The other outer surface is insulated and the bolt terminal is connected to the temperature inspection instrument. Based on the Seebeck effect, the temperature T at the position of the velocity measuring head can be measured. The comprehensive static pressure P θ+90º The gas density ρ=P can be obtained by the ideal gas state equation after the measurement results are obtained. θ+90º / R g T, where R g represents the gas constant. See Figure 23-25 The typical streamlines of gas vortex flow are spiral lines. At each fixed X and R position, the total velocity of the gas vortex is V θ The tangential velocity component V T and the axial velocity component V X Composition, and the total speed V θ and the axial velocity component V X The angle between the two pressure pipes is θ. The second stepper motor of the θ direction control mechanism controls the angle between the straight line where the pressure inlet of the Pitot tube is located and the axis to increase continuously from 0. When the pressure difference collected by the pressure transmitter connected to the two pressure pipes is the largest, that is, the total pressure P collected by the first pressure pipe is θ The second pressure pipe collects the leeward pressure P θ+180º At this time, the angle θ between the corresponding pressure inlet line and the axis is the gas vortex flow velocity V θ When the pressure collected by the first pressure-inlet pipe and the second pressure-inlet pipe is equal, that is, the straight line where the two pressure-inlet inlets are located is perpendicular to the direction of the gas vortex flow velocity, the first pressure-inlet pipe and the second pressure-inlet pipe both collect static pressure P θ+90º . Based on Bernoulli's principle, we can get the magnitude of the gas vortex flow velocity: {V}_{\theta}=\sqrt {\left [ {2\left ( {{P}_{\theta}-{P}_{\theta +{90}^{\circ}}} \right ) / \rho} \right ]} , combined with the velocity direction θ, the tangential and axial velocity components can also be obtained.

[0080] Compared with the traditional gas vortex flow velocity measurement technology, the present invention takes into account the density change problem in the gas vortex, and simultaneously measures the temperature and pressure data at the measuring point position to calculate the gas density to obtain more accurate velocity information. The pitot tube velocity measurement needs to be aligned with the incoming flow direction, and the error of manual alignment is large. The displacement mechanism controlled by the stepper motor in the present invention can accurately arrange the position and direction of the pitot tube, and continuously collects pressure and pressure difference information during the rotation of the pitot tube to obtain the velocity direction, which avoids the cumbersome correction process of the pitot tube velocity measurement direction. The movable pitot tube can measure the distributed information of the velocity, avoiding the flow field interference problem caused by the arrangement of multiple measuring points. In addition, the vortex tube, a gas vortex generating device, can realize four different forms of gas vortex flow structures, and there is no need to manufacture different vortex generating devices separately, which effectively reduces the testing cost. Therefore, the present invention has broad application prospects in engineering and scientific research on gas vortex flow.

[0081] It should be noted that some parts not described in the present invention can be implemented by adopting or drawing on existing technologies.

[0082] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A velocity measuring device for gas vortex flow, characterized in that: The device comprises a pitot tube (1), a measuring point position control mechanism (2), an eddy current tube (3) and an equipment bracket (4); the pitot tube (1) comprises a first pressure-inducing tube (11), a second pressure-inducing tube (12) and an insulating shell (13); the first pressure-inducing tube (11) and the second pressure-inducing tube (12) are two inverted L-shaped hollow metal tubes and are arranged back-to-back; the first pressure-inducing tube (11) is made of pure iron or pure copper, and the second pressure-inducing tube (12) is made of a copper-nickel alloy; the first pressure-inducing tube (1 1) and the bottom ends of the second pressure-introducing tube (12) are fixed to form an integrated speed measuring head (15) through a welding seam (14); the bottom of the speed measuring head (15) is hemispherical; the first pressure-introducing tube (11) and the second pressure-introducing tube (12) have no contact with each other except for the welding seam (14); a first pressure-introducing inlet (111) and a second pressure-introducing inlet (121) are respectively provided on both sides of the welding seam (14) in the speed measuring head (15); the first pressure-introducing inlet (111) The first pressure-introducing tube (11) and the second pressure-introducing tube (12) are arranged in the same horizontal straight line in opposite directions; the top ends of the first pressure-introducing tube (11) and the second pressure-introducing tube (12) are respectively the first pressure-introducing outlet (112) and the second pressure-introducing outlet (122); the first pressure-introducing tube (111) and the first pressure-introducing outlet (112) are interconnected through a first hollow channel (113) inside the first pressure-introducing tube (11); the second pressure-introducing tube (121) and the second pressure-introducing outlet (122) are interconnected through a second hollow channel (123) inside the second pressure-introducing tube (12); a first bolt terminal (114) is provided on the top horizontal rod of the first pressure-introducing tube (11), and a second bolt terminal (124) is provided on the top horizontal rod of the second pressure-introducing tube (12); the insulating shell (13) fixes and wraps the outer surfaces of the first pressure-introducing tube (11) and the second pressure-introducing tube (12) except for the first bolt terminal (114), the second bolt terminal (124) and the speed measuring head (15); The measuring point position control mechanism (2) is composed of an X-direction control mechanism (21), a θ-direction control mechanism (22), and an R-direction control mechanism (23) which are connected in sequence; The θ direction control mechanism (22) is composed of a second stepper motor (221), an upper connecting frame (222), and a lower connecting frame (223); the second stepper motor (221) and the upper connecting frame (222) are both fixed to the bottom of the X-direction slider (213); the upper connecting frame (222) is rotatably connected to the rotating shaft (2211) of the second stepper motor (221) via a second bearing (2221) at the center of its bottom; the rotating shaft (2211) is matched with a groove (2231) at the top of the lower connecting frame (223) and fixed via a cylindrical pin (2232); The R direction control mechanism (23) is composed of a third stepper motor (231), a guide rail frame (232), an R direction lead screw (233), a slider frame (234), and a pitot tube cover plate (235); the third stepper motor (231) is fixed on a middle platform (2321) of the guide rail frame (232); the third stepper motor (231) is connected to the R direction lead screw (233) and controls the lead screw to rotate; the R direction lead screw (233) and the slider frame (234) are rotatably connected via a threaded blind hole (2341); the slider frame (234) is slidably connected to the trapezoidal double guide rails (2322) on the inner side of the guide rail frame (232) via a trapezoidal double groove (2342) on its outer side; a T-shaped groove (236) is present on the bottom of the slider frame (234) and the surface of the pitot tube cover plate (235); the pitot tube (1) is pressed into the T-shaped groove (236) by a screw.

2. The device for measuring the velocity of gas vortex flow according to claim 1, characterized in that: The X-direction control mechanism (21) is composed of a first stepper motor (211), an X-direction lead screw (212), an X-direction slider (213), a first crossbeam (214), and a lead screw rack (215); the first stepper motor (211) is connected to the X-direction lead screw (212) and controls the lead screw to rotate; the X-direction lead screw (212) and the X-direction slider (213) are rotationally connected via a threaded through hole (2131); the X-direction slider (213) is slidably connected to a trapezoidal guide rail (2141) at the bottom of the first crossbeam (214) via a trapezoidal groove (2132) at the top; the first stepper motor (211) and the lead screw rack (215) are respectively fixedly mounted at two ends of the first crossbeam (214); and the lead screw rack (215) is rotationally connected to the X-direction lead screw (212) via a first bearing (2151) at the center thereof.

3. The device for measuring the velocity of gas vortex flow according to claim 1, characterized in that: The vortex tube (3) is composed of an inlet pipe section (31), a vortex generating tube (32), a hot end tube (33), a control valve (34), a cold hole plate (35), and a cold end tube (36); the inlet pipe section (31) includes an air inlet pipe (311) and a vortex chamber sleeve (312); a plurality of air inlet channels (321) are evenly distributed in the tube wall of the vortex generating tube (32) along the inner wall tangent direction; both sides of the vortex generating tube (32) are provided with a limiting sealing groove (322), and an O-ring is placed in the limiting sealing groove (322); the side wall surfaces of the vortex chamber sleeve (312) and the hot end tube (33) are provided with a limiting annular boss (323); ... ) and the hot end pipe (33) are connected by flanges, the limiting annular boss (323) will sink into the limiting sealing groove (322) and press the O-ring, thereby fixing the vortex generating pipe (32) between the inlet pipe section (31) and the hot end pipe (33); the hot end pipe (33) is evenly and vertically distributed with a plurality of sealing structures (331) along the X direction, and the sealing structure (331) is composed of a hollow stud (3311), a hollow rubber column (3312), a nut (3313) and a pin (3314), wherein the inner wall surface of the hollow stud (3311) and the outer wall surface of the hollow rubber column (3312) are both conical cone surfaces and have the same taper; the position where the speed is measured is not stable The pin (3314) is installed, and the hollow rubber column (3312) is pressed downward by tightening the nut (3313) so that the hollow rubber column (3312) presses against the inner wall surface of the truncated cone of the hollow stud (3311). The hollow stud (3311) exerts an inward reaction pressure on the hollow rubber column (3312) so that the cylindrical contact surface between the hollow rubber column (3312) and the pitot tube (1) is pressed, thereby achieving a sliding seal on the pitot tube (1). The position where the speed is not measured is closed by tightening the nut (3313) and locking the pin (3314); the hot end pipe (33) is flange-connected to the control valve (34), and the control valve (34) is The cold orifice plate (35) is composed of a valve housing (341), a hollow valve core (342) and a valve core (343); the valve housing (341) is threadedly connected to the hollow valve core (342); the hollow valve core (342) is threadedly connected to the valve core (343); the ends of the hollow valve core (342) and the valve core (343) are both provided with grooves; a cold air flow discharge hole (351) is provided in the center of the cold orifice plate (35); the cold orifice plate (35) is installed between the inlet pipe section (31) and the cold end pipe (36) and is tightened by a flange connection; the control valve (34) can adjust the overall opening of the hollow valve core (342) and the valve core (343) or remove the valve core (343); the cold orifice plate (35) can be replaced with a blind plate.

4. The device for measuring the velocity of gas vortex flow according to claim 1, characterized in that: The equipment support (4) is composed of a first rectangular frame (41), a second rectangular frame (42), a second crossbeam (43), two pipe clamping seats (44) and two limit slide blocks (45); the first rectangular frame (41) and the second rectangular frame (42) are fixedly connected by a first crossbeam (214) and a second crossbeam (43); the second crossbeam (43) is arranged parallel to and directly below the first crossbeam (214); a second trapezoidal guide rail (431) is provided on the surface of the second crossbeam (43); the two pipe clamping seats (44) and the two limit slide blocks (45) are slidably connected to the second trapezoidal guide rail (431); the two pipe clamping seats (44) and the two limit slide blocks (45) are fixedly connected to the first crossbeam (214) and the second crossbeam (43); (44) is composed of a base (441), a pipe clamp (442), and a fixing screw (443); the distance between the two bases (441) can be adjusted by sliding to adapt to the installation of vortex tubes (3) of different lengths; the vortex tube (3) is wrapped by the base (441) and the pipe clamp (442), and is pressed by the fixing screw (443); the two limit sliders (45) are located between the two pipe clamping seats (44) and are respectively close to the sides of the two pipe clamping seats (44); the two limit sliders (45) are provided with limit screws (451), and after the limit screws (451) are tightened, the two limit sliders (45) are fixed to the second trapezoidal guide rail (431).

5. The method for using the device for measuring the velocity of gas vortex flow according to claim 1, characterized in that: The method of use comprises the steps of: S1. Adjust the installation mode of the control valve and cold orifice plate of the vortex tube according to the desired countercurrent, cocurrent, single-flow or double-circuit gas vortex flow; S2. Select a pipe clamping seat of appropriate size according to the hot end pipe diameter of the vortex tube, adjust the distance between the pipe clamping seats to an appropriate length, use the pipe clamping seat to clamp the hot end pipe of the vortex tube, and lock the limit slider onto the second crossbeam; S3. Connect the two pressure outlets of the pitot tube to the two pressure transmitters through two silicone tubes, and connect the two bolt terminals of the pitot tube to the temperature inspection instrument through wires; S4. Install the measuring point position control mechanism on the top of the equipment bracket, install the Pitot tube on the bottom of the measuring point position control mechanism, and use the X-direction control mechanism to adjust the position of the Pitot tube to the first measuring hole in the X direction; S5. Unscrew the sealing structure at the measuring position and remove the pin, and use the R direction control mechanism to insert the velocity measuring head of the pitot tube downward to the central axis of the hot end tube of the vortex tube, and then slide and seal the pitot tube by locking the sealing structure; S6, supplying a fixed flow of compressed gas to the air inlet pipe of the vortex tube through the compressor to generate a vortex flow in the vortex tube; S7. After the indication of the temperature inspection instrument is stable, the temperature T at the position of the velocity measuring head is collected, and the velocity measuring head of the pitot tube is rotated 360 degrees using the θ direction control mechanism, and the pressure data of the two pressure transmitters are collected as the angle θ changes; S8, according to the maximum pressure difference P between the two pressure transmitters during the 360° rotation of the speed measuring head θ -P θ+180º The corresponding Pitot tube θ orientation can reflect the velocity direction of the gas vortex flow. The velocity direction is the axis direction of the two pressure inlets when the pressure difference is the maximum. The corresponding pressure value when the pressure difference between the two pressure transmitters is zero is the static pressure P at the velocity head position. θ+90º ; S9, according to the temperature T and static pressure P at the speed measuring head position θ+90º The gas density ρ=P can be calculated θ+90º / R g T, where R g Represents the gas constant, which is the total pressure P corresponding to the maximum pressure difference between the two pressure transmitters. θ and the static pressure P corresponding to zero pressure difference θ+90º The dynamic pressure P can be obtained θ -P θ+90º , the velocity at the velocity head is obtained from the dynamic pressure and gas density at the velocity head ; S10, using the R direction control mechanism to move the Pitot tube upward by a certain distance ΔR, and then repeating steps S7 to S9, thereby obtaining the velocity direction and magnitude of the gas vortex flow at different radial positions R; S11, turn off the compressor to stop air supply, unscrew the sealing structure and move out the pitot tube through the R direction control mechanism, and close the sealing structure at the speed measurement position by locking the pin; S12, using the X-direction control mechanism to move the Pitot tube to another speed measuring axial position X, and repeating steps S5 to S11, thereby obtaining the speed direction and magnitude at different X positions and R positions.

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