Particle generator with adjustable particle size

Abstract

The invention discloses a particle-size-adjustable particle generator, which belongs to the technical field of flow field display, and comprises a particle tank and a particle conveying cavity arranged below the particle tank, the two sides of the particle conveying cavity are fixedly communicated with a to-be-detected gas inlet pipe and a to-be-detected gas outlet pipe respectively; the particle tank and the particle conveying cavity are fixedly communicated through a transfer particle storage barrel, a screw conveying mechanism is arranged in the middle of the top of the particle tank, and the screw conveying mechanism is used for uniformly conveying particles in the transfer particle storage barrel into the particle conveying cavity. Through cooperative use of the particle storage and recovery mechanism and the negative pressure pumping mechanism, particles remaining in the particle tank, the transfer particle storage cylinder and the particle conveying cavity can be raised through flowing of air flow and flow into the particle storage tank along with the air flow air cylinder for particle recovery, and the situation that when a next particle with different particle sizes is subjected to an experimental test in the follow-up process, the particle recovery efficiency is greatly improved is avoided. And mixing of particles with two or more particle sizes occurs, so that the accuracy of a subsequent test result is influenced.

Description

Technical Field

[0001] The invention relates to the technical field of flow field display, in particular to a particle generator with adjustable particle size. Background Art

[0002] Non-contact flow field optical diagnostic technology enables non-contact, instantaneous flow field velocity measurement. During measurement, particles are generally spread in the flow field. By capturing the scattered light from the particles, the particle motion state is determined, thereby obtaining the flow state of the flow field. Existing flow field measurement methods have high requirements for particles. Particles with larger particle sizes will directly destroy the flow field structure, affecting measurement accuracy and, consequently, image acquisition results. Existing particle generators use particles of varying sizes in different experimental processes. When experiments require the use of particles of different particle sizes, the existing particles in the particle tank must be recovered and the tank walls cleaned. Then, an appropriate amount of particles of the desired experimental size are added to the tank to complete the particle size change.

[0003] For example, the Chinese invention patent with the authorization announcement number CN114042393B discloses a particle generator, which includes: a particle tank having a particle feed port for accommodating tracer particles; a particle conveying cavity protruding from the bottom of the particle tank and connected to the interior of the particle tank, the inner cavity cross-section of the particle conveying cavity being smaller than the inner cavity cross-section of the particle tank; a gas inlet pipe to be measured, connected to the particle conveying cavity, for introducing the gas to be measured into the particle conveying cavity; a gas outlet pipe to be measured, connected to the particle conveying cavity, for discharging the mixture of the gas to be measured and the tracer particles to the test flow field; and a conveying screw, which is used to uniformly convey the tracer particles in the particle tank to the particle conveying cavity. The particles in the particle tank are more uniformly conveyed vertically downward to the particle conveying cavity at the bottom of the particle tank by the conveying screw. During the particle conveying process, the particle flow rate is kept stable, which facilitates more accurate control of the number of tracer particles entering the flow field.

[0004] In actual application of the above patent, when it is necessary to replace particles of different particle sizes for testing, it is not possible to conveniently recover the excess particles in the particle tank and replace them with particles of another particle size for testing, and there is a lack of cleaning and recovery of particles adsorbed on the inner wall of the particle tank and the particle conveying cavity. If the particles remaining in the particle tank and the particle conveying cavity are not cleaned, and the optical speed measurement experiment of the next particle size is directly carried out, the final test results may be affected by the mixing of particles of different particle sizes.

[0005] Therefore, it is necessary to provide a particle generator with adjustable particle size to solve the above technical problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a particle generator with adjustable particle size to solve the problems in the prior art of being unable to conveniently recover excess particles in a particle tank and replace them with particles of another particle size for testing, as well as the lack of cleaning and recovery of particles adsorbed on the inner wall of the particle tank and the particle transport cavity.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: a particle generator with adjustable particle size, including a particle tank and a particle conveying cavity arranged below the particle tank, the two sides of the particle conveying cavity are respectively fixedly connected with an air inlet pipe for a gas to be measured and an air outlet pipe for a gas to be measured, the air inlet pipe for a gas to be measured is connected to an external air source through an electromagnetic valve, and is used to introduce the gas to be measured into the particle conveying cavity, the gas to be measured refers to the target gas for forming a flow field that ultimately needs to be subjected to particle image velocity measurement, the air outlet pipe for a gas to be measured is used to output a mixture of the gas to be measured entering from the air inlet pipe for measuring and the particles conveyed to the particle conveying cavity by the screw conveying mechanism to the particle generator, so as to discharge the gas to be measured carrying particles to the part to be measured, and form a flow field to be measured in the part to be measured; it can be understood that the outlet end of the air outlet pipe for a gas to be measured is connected to the part to be measured, and the part to be measured refers to the carrier of the flow field to be measured, such as a transparent tube body The particle tank and the particle conveying cavity are fixedly connected through the intermediate dump particle barrel, and a screw conveying mechanism is provided at the middle position of the top of the particle tank, and the screw conveying mechanism is used to uniformly convey the particles in the intermediate dump particle barrel into the particle conveying cavity, and a dust-proof cylinder is fixedly installed at the middle position of the top of the inner wall of the particle tank, and an up and down reciprocating driving mechanism is provided inside the dust-proof cylinder, and a compacting and blocking block is provided at the bottom end of the up and down reciprocating driving mechanism, which is used to compact the particles in the particle tank into the intermediate dump particle barrel, reducing the gaps between the particles inside the intermediate dump particle barrel, thereby facilitating the subsequent screw conveying mechanism to uniformly convey the particles, and a plurality of particle storage and recovery mechanisms distributed in a circular array are provided on the top of the particle tank and around the screw conveying mechanism, and a negative pressure pumping mechanism is provided between the plurality of particle storage and recovery mechanisms; The upper and lower ends of the compacting and blocking block are both conical, so that when it moves up and down, it can smoothly pass through the particles accumulated in the particle tank, so that it can smoothly compact the particles accumulated in the particle tank into the intermediate dump particle cylinder or escape from the particle pile in the intermediate dump particle cylinder and the particle tank; By cooperating with the particle storage and recovery mechanism and the negative pressure extraction mechanism, the flow of air can be used to lift the particles retained in the particle tank, the intermediate storage cylinder and the particle conveying cavity, and flow them into the particle storage tank along with the air flow cylinder for particle recovery, thereby avoiding the mixing of two or more particle sizes when conducting subsequent experimental tests on particles of a different particle size, which affects the accuracy of subsequent test results.

[0008] As a further description of the above technical solution: the screw conveying mechanism includes a drive motor with adjustable speed, which is fixedly installed at the middle position of the top of the particle tank through a U-shaped frame. The output end of the drive motor is coaxially fixedly connected to a transmission rod through a coupling. The bottom end of the transmission rod extends to the interior of the particle conveying cavity and is fixedly sleeved with a spiral conveying blade, and the compaction sealing block is movably sleeved on the outer surface of the transmission rod.

[0009] As a further description of the above technical solution: the up and down reciprocating drive mechanism includes a reciprocating screw, the reciprocating screw fixed sleeve is arranged on the outer surface of the rotating rod, and is located inside the dustproof cylinder near the upper end, the outer surface of the reciprocating screw is threadedly connected with a screw sleeve, both sides of the screw sleeve are fixedly connected with sliders, the sliders are slidingly connected to the inner wall of the dustproof cylinder, the bottom of the screw sleeve is fixedly connected with a plurality of elastic telescopic parts distributed in a circular array, the bottom end of the elastic telescopic part is fixedly connected with a connecting plate, the bottom of the connecting plate is fixedly connected with a connecting rod, and the bottom end of the connecting rod is fixedly connected to the top of the compaction sealing block.

[0010] As a further description of the above technical solution: the elastic telescopic part includes a telescopic rod and a spring, the top ends of the telescopic rod and the spring are fixedly installed on the bottom of the screw sleeve, and the bottom ends of the telescopic rod and the spring are fixedly connected to the top of the connecting plate.

[0011] As a further description of the above technical solution: the compaction and blocking block is adapted to the intermediate grain dump cylinder, that is, the diameter of the compaction and blocking block is the same as the inner diameter of the intermediate grain dump cylinder.

[0012] As a further description of the above technical solution: the particle storage and recovery mechanism includes a particle storage tank fixedly installed on the top of the particle tank, the bottom end of the particle storage tank is fixedly connected to a particle discharge pipe, the top of the particle storage tank is fixedly connected to an exhaust pipe, a filter plate is fixedly installed on the inner wall of the particle storage tank near the bottom end, a particle recovery pipe is fixedly connected to one side of the particle tank and below the filter plate, the other end of the particle recovery pipe is connected to the top of the particle tank, and a particle filling port is fixedly connected to one side of the particle storage tank and below the filter plate.

[0013] As a further description of the above technical solution: a solenoid valve 1 is fixedly installed on the particle discharge pipe, a solenoid valve 2 is fixedly installed on the air extraction pipe, and a solenoid valve 3 is fixedly installed on the particle recovery pipe.

[0014] As a further description of the above technical solution: a small vibrator is provided at the bottom of the filter plate, and the small vibrator is used to drive the filter plate to vibrate with a small amplitude and high frequency, so as to shake off the particles adsorbed on the bottom of the filter plate, prevent the filter plate from being blocked, and improve the filtering effect and efficiency of the filter plate on particles.

[0015] As a further description of the above technical solution: the negative pressure extraction mechanism includes a fixed frame fixedly installed between several particle storage tanks, the top of the fixed frame is fixedly installed on the exhaust fan, the end of the exhaust pipe away from the particle storage tank is fixedly connected to the exhaust end of the exhaust fan, and the exhaust end of the exhaust fan is connected to the atmosphere.

[0016] As a further description of the above technical solution: a control panel is fixedly installed on the front of the particle tank, and a support frame is fixedly installed on the bottom of the particle tank.

[0017] The present invention has the following beneficial effects: The present invention cooperates with the particle storage and recovery mechanism and the negative pressure extraction mechanism to utilize the flow of airflow to lift the particles retained in the particle tank, the intermediate storage cylinder and the particle conveying cavity, and flows them into the particle storage tank along with the airflow cylinder for particle recovery, thereby avoiding the mixing of two or more particle sizes when the next experimental test is carried out on the next particle of a different particle size, which affects the accuracy of the subsequent test results.

[0018] The present invention uses a screw conveying mechanism and an up and down reciprocating driving mechanism in conjunction with each other, which can drive the compaction sealing block to move up and down. During the downward movement, the particles in the particle tank can be compacted into the intermediate dump particle barrel, reducing the gap between adjacent particles. Therefore, when the spiral conveying blade rotates to convey the particles in the intermediate dump particle barrel downward, the particles can fill the material storage space between the adjacent pitches of the spiral conveying blade, avoiding the situation that the spiral conveying cavity on the spiral conveying blade cannot be evenly filled due to the possibility of cavities when the particles fall, which leads to uneven particle flow during subsequent spiral conveying. By conveying particles into the particle conveying cavity in a uniform manner, the accuracy of subsequent optical speed measurement experimental data is improved.

[0019] The present invention cooperates with the particle storage and recovery mechanism to recover and clean the particles retained in the particle tank, the intermediate dump particle cylinder and the particle conveying cavity. The intermediate dump particle cylinder is intermittently sealed by the compacting and blocking block. After the compacting and blocking block is moved into the intermediate dump particle cylinder to seal it, it is difficult for the gas to flow from the bottom to the top of the intermediate dump particle cylinder. At this time, the negative pressure pumping mechanism can extract the gas inside the particle tank to the outside, making its interior a negative pressure state. Subsequently, after the compacting and blocking block exits the intermediate dump particle cylinder, the intermediate dump particle cylinder and the particle tank are restored to communication. At this time, since the internal pressure of the particle tank is relatively small, a large amount of external gas quickly flows into the particle conveying cavity, the intermediate dump particle cylinder and the particle tank, thereby achieving the impact force of the fast-flowing airflow on the inner wall to blow away and clean the particles adsorbed on the inner wall, thereby reducing the residual particles on the inner wall as much as possible, effectively preventing the mixing of residues of particles of various particle sizes during the experiment, and facilitating improving the accuracy of the optical speed measurement experiment data. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the overall structure of a particle generator with adjustable particle size proposed by the present invention; Figure 2 This is a schematic diagram of the structure of a particle tank and a particle storage tank of a particle generator with adjustable particle size proposed by the present invention; Figure 3 This is a schematic diagram of the structure of a particle tank and an air inlet pipe for the gas to be measured of a particle generator with adjustable particle size proposed by the present invention; Figure 4 A schematic diagram of the internal structure of a particle tank of a particle generator with adjustable particle size proposed by the present invention; Figure 5 A schematic diagram of a screw conveying mechanism and an up-and-down reciprocating drive mechanism of a particle generator with adjustable particle size proposed by the present invention; Figure 6 This is a schematic diagram of the particle storage and recovery mechanism and negative pressure extraction mechanism of a particle size adjustable particle generator proposed by the present invention; Figure 7 This is a schematic diagram of the particle storage and recovery mechanism and exhaust fan structure of a particle size adjustable particle generator proposed by the present invention; Figure 8 This is a schematic diagram of the internal structure of a particle storage tank of a particle generator with adjustable particle size proposed by the present invention; Figure 9 This is a schematic diagram of the structure of a fixed frame and a particle storage tank of a particle generator with adjustable particle size proposed by the present invention; Figure 10 This is a structural schematic diagram of the elastic expansion parts and connecting plates of a particle generator with adjustable particle size proposed by the present invention.

[0021] In the figure: 1. Particle tank; 2. Particle delivery chamber; 3. Inlet pipe for the gas to be tested; 4. Outlet pipe for the gas to be tested; 5. Transfer and storage cylinder for particles; 6. Screw conveying mechanism; 601. Drive motor; 602. Coupling; 603. Transmission rod; 604. Screw conveying blade; 605. U-shaped frame; 7. Dustproof cylinder; 8. Up and down reciprocating drive mechanism; 801. Reciprocating screw; 802. Screw sleeve; 803. Slider; 804. Elastic telescopic member; 8041. Telescopic rod; 8042. Spring; 805. Connecting plate; 806. Connecting rod; 9. Compact the blocking blocks; 10. Particle storage and recovery mechanism; 1001. Particle storage tank; 1002. Particle discharge pipe; 1003. Air extraction pipe; 1004. Filter plate; 1005. Particle recovery pipe; 1006. Particle filling port; 1007. Small vibrator; 1008. Solenoid valve 1; 1009. Solenoid valve 2; 10010. Solenoid valve 3; 11. Negative pressure extraction mechanism; 1101. Fixed frame; 1102. Exhaust fan; 13. Control panel; 14. Support frame; 15. Solenoid valve 4. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] As attached Figure 1 To the attached Figure 10 As shown: Embodiment 1: The present invention provides a particle generator with adjustable particle size, comprising a particle tank 1 and a particle conveying cavity 2 arranged below the particle tank 1, wherein the two sides of the particle conveying cavity 2 are respectively fixedly connected with an air inlet pipe 3 for a gas to be measured and an air outlet pipe 4 for a gas to be measured, an electromagnetic valve 4 15 is fixedly installed on the air inlet pipe 3 for a gas to be measured, and an electromagnetic valve 4 15 is fixedly installed on the air inlet pipe 3 for a gas to be measured, and the air inlet pipe 3 for a gas to be measured is connected to an external gas source through the electromagnetic valve, and is used to introduce the gas to be measured into the particle conveying cavity, and the gas to be measured is the most The target gas for forming the flow field that needs to be measured by particle image velocity is finally obtained. The gas outlet pipe 4 to be measured is used to output the mixture of the gas to be measured entering from the gas inlet pipe 3 to be measured and the particles transported to the particle transport cavity 2 by the screw transport mechanism 6 to the particle generator, so as to discharge the gas flow to be measured carrying particles to the object to be measured, and form the flow field to be measured in the object to be measured; it can be understood that the outlet end of the gas outlet pipe 4 to be measured is connected to the object to be measured, and the object to be measured refers to the carrier of the flow field to be measured, such as a transparent tube body, the particle tank 1 and the particle inlet The delivery cavity 2 is fixedly connected through the intermediate dump particle cylinder 5. A screw conveying mechanism 6 is provided at the middle position of the top of the particle tank 1. The screw conveying mechanism 6 is used to uniformly convey the particles in the intermediate dump particle cylinder 5 to the particle delivery cavity 2. A dustproof cylinder 7 is fixedly installed at the middle position of the top of the inner wall of the particle tank 1. The interior of the dustproof cylinder 7 is provided with an up and down reciprocating drive mechanism 8. The bottom end of the up and down reciprocating drive mechanism 8 is provided with a compacting and blocking block 9. The compacting and blocking block 9 is adapted to the intermediate dump particle cylinder 5, that is, the compacting and sealing The diameter of the blocking block 9 is the same as the inner diameter of the intermediate dump particle cylinder 5. The compacting blocking block 9 is used to compact the particles in the particle tank 1 into the intermediate dump particle cylinder 5, reducing the gaps between the particles inside the intermediate dump particle cylinder 5, thereby facilitating the subsequent screw conveying mechanism 6 to uniformly convey the particles. A plurality of particle storage and recovery mechanisms 10 distributed in a circular array are provided at the top of the particle tank 1 and around the screw conveying mechanism 6. A negative pressure pumping mechanism 11 is provided between the plurality of particle storage and recovery mechanisms 10. By cooperating with the screw conveying mechanism 6 and the up and down reciprocating drive mechanism 8, the compaction sealing block 9 can be driven to move up and down. During the downward movement, the particles in the particle tank 1 can be compacted into the intermediate dump particle barrel 5, reducing the gap between adjacent particles. Therefore, when the spiral conveying blade 604 rotates to convey the particles in the intermediate dump particle barrel 5 downward, the particles can fill the material storage space between the adjacent pitches of the spiral conveying blade 604, avoiding the situation that the spiral conveying cavity on the spiral conveying blade 604 cannot be evenly filled due to the possible formation of cavities when the particles fall, resulting in uneven particle flow during subsequent spiral conveying. By conveying particles into the particle conveying cavity 2 in a uniform manner, it is beneficial to improve the accuracy of subsequent optical speed measurement experimental data.

[0024] The screw conveying mechanism 6 includes a drive motor 601 with adjustable speed, which is fixedly installed at the middle position on the top of the particle tank 1 through a U-shaped frame 605. The output end of the drive motor 601 is coaxially fixedly connected to a transmission rod 603 through a coupling 602. The bottom end of the transmission rod 603 extends to the interior of the particle conveying cavity 2 and is fixedly sleeved with a spiral conveying blade 604.

[0025] The upper and lower reciprocating drive mechanism 8 includes a reciprocating screw 801, which is fixedly sleeved on the outer surface of the rotating rod and is located near the upper end of the dust-proof cylinder 7. The outer surface of the reciprocating screw 801 is threadedly connected with a screw sleeve 802, and both sides of the screw sleeve 802 are fixedly connected with sliders 803. The sliders 803 are slidably connected to the inner wall of the dust-proof cylinder 7. The bottom of the screw sleeve 802 is fixedly connected with a plurality of elastic telescopic members 804 distributed in a circular array. The bottom end of the elastic telescopic member 804 is fixedly connected with a connecting plate 805. The bottom of the connecting plate 805 is fixedly connected with a connecting rod 806. The bottom end of the connecting rod 806 is fixedly connected to the top of the compacting and blocking block 9. In the process of recycling and cleaning the particles stored in the particle tank 1, the intermediate storage particle barrel 5 and the particle conveying cavity 2, the particle storage and recovery mechanism 10 and the negative pressure pumping mechanism 11 are used in conjunction with each other. The screw conveying mechanism 6 and the up and down reciprocating drive mechanism 8 are used in conjunction with each other to drive the compaction and blocking block 9 to intermittently block the intermediate storage particle barrel 5. After the compaction and blocking block 9 is moved into the intermediate storage particle barrel 5 to block it, it is difficult for the gas to flow from the intermediate storage particle barrel 5 from bottom to top. At this time, the operation of the negative pressure pumping mechanism 11 can extract the gas inside the particle tank 1 to the outside, so that the gas inside the particle tank 1 can be discharged. The interior of the particle tank 1 is in a negative pressure state, and then after the compacted sealing block 9 exits the intermediate dump particle cylinder 5, the intermediate dump particle cylinder 5 and the particle tank 1 are restored to communication. At this time, due to the relatively low pressure inside the particle tank 1, a large amount of external gas quickly flows into the particle conveying cavity 2, the intermediate dump particle cylinder 5 and the particle tank 1, thereby achieving the impact force of the fast-flowing airflow on the inner wall to blow away and clean the particles adsorbed on the inner wall, minimize the residual particles on the inner wall, and effectively prevent the mixing of residues of particles of various particle sizes during the experiment, which is beneficial to improving the accuracy of the optical speed measurement experiment data.

[0026] The elastic telescopic member 804 includes a telescopic rod 8041 and a spring 8042. The top ends of the telescopic rod 8041 and the spring 8042 are fixedly mounted on the bottom of the screw sleeve 802, and the bottom ends of the telescopic rod 8041 and the spring 8042 are fixedly connected to the top of the connecting plate 805. Through the setting of the elastic telescopic part 804, during the downward movement of the compaction sealing block 9, if there are too many compacted particles inside the intermediate storage barrel 5, causing the compaction sealing block 9 to be unable to continue to move downward, the elastic telescopic part 804 can adaptively shrink, thereby ensuring that the screw sleeve 802 can move normally with the rotation of the reciprocating screw 801, avoiding jamming.

[0027] The particle storage and recovery mechanism 10 includes a particle storage tank 1001 fixedly installed on the top of the particle tank 1, the bottom end of the particle storage tank 1001 is fixedly connected to a particle discharge pipe 1002, the top of the particle storage tank 1001 is fixedly connected to an exhaust pipe 1003, a filter plate 1004 is fixedly installed on the inner wall of the particle tank 1001 near the bottom end, a particle recovery pipe 1005 is fixedly connected to one side of the particle tank 1 and below the filter plate 1004, the other end of the particle recovery pipe 1005 is connected to the top of the particle tank 1, a particle filling port 1006 is fixedly connected to one side of the particle tank 1001 and below the filter plate 1004, an electromagnetic valve 1 1008 is fixedly installed on the particle discharge pipe 1002, an electromagnetic valve 2 1009 is fixedly installed on the exhaust pipe 1003, and an electromagnetic valve 3 10010 is fixedly installed on the particle recovery pipe 1005.

[0028] A control panel 13 is fixedly installed on the front of the particle tank 1. The electrical components in this application are electrically connected to the external power supply through the control panel 13. The control panel 13 is used to control the opening or closing of the electrical components, and a support frame 14 is fixedly installed on the bottom of the particle tank 1.

[0029] It can be understood that the particle generator with adjustable particle size disclosed in the embodiment of the present application can be used in a particle image testing system. The particle image testing system generally includes: a particle generator, a flow field to be tested, a light source system and an image acquisition and processing system, wherein the tracer particle generator generates certain solid particles according to the measurement requirements, so that they follow the air flow into the flow field to be tested and move along the flow field to be tested, that is, the particle generator provides solid particles for the flow field to be tested. The light source system may include a laser source and a sheet light generator. The laser is used to emit multiple beams of cylindrical laser beams. The sheet light source generator is used to modulate the laser beam into a thin sheet of laser light. The laser sheet light illuminates the area of ​​the flow field to be tested that needs to be measured. In the direction perpendicular to the laser sheet light, the image acquisition component is used to collect the position changes of the tracer particles in the flow field on the two images at a sampling interval, thereby calculating the instantaneous velocity of the fluid particles at the tracer particles inside the flow field at the sampling moment.

[0030] Working principle: Step 1: The staff first adds a proper amount of particles of different particle sizes into the multiple particle storage tanks 1001 through the particle filling port 1006 for storage. Then the test gas inlet pipe 3 is connected to the external gas source to introduce the test gas into the particle conveying cavity. The test gas refers to the target gas that will eventually need to perform particle image velocimetry to form a flow field. Subsequently, the outlet pipe of the test gas outlet pipe 4 is connected to the test piece. The mixture of the test gas entering from the test gas inlet pipe 3 and the particles conveyed to the particle conveying cavity 2 by the screw conveying mechanism 6 is output to the particle generator to discharge the test gas flow carrying particles to the test piece, forming a test flow field in the test piece. The test piece refers to the carrier of the test flow field. The preparation work is completed. Step 2: When the experiment is needed, the solenoid valve 1008 corresponding to the particle storage tank 1001 storing particles of the required particle size is opened through the control panel 13, so that the particles stored in the particle storage tank 1001 are discharged into the particle tank 1 through the particle discharge pipe 1002. After an appropriate amount of particles fall into the particle tank 1, the solenoid valve 1008 is closed, and then the solenoid valve 15 is opened through the control panel 13, so that the external air source is blown into the particle conveying cavity 2 through the test air inlet pipe 3. At the same time, the drive motor 601 is turned on through the control panel 13, and the output end of the drive motor 601 rotates and drives the transmission rod 603 to rotate through the coupling 602, thereby driving the threaded conveying blade to rotate. At the same time, the rotation of the rotating rod also drives the reciprocating screw 801 to rotate synchronously. Since the slider 803 is slidably installed on the inner wall of the dustproof cylinder 7, it limits the screw sleeve 802, so that the reciprocating screw 801 rotates. The movable screw sleeve 802 moves back and forth along the axial direction of the transmission rod 603, and then drives the compaction blocking block 9 to move back and forth up and down through the elastic telescopic member 804 and the connecting rod 806. During this process, the compaction blocking block 9 intermittently presses down into the intermediate dump particle cylinder 5, thereby pressing the particles inside the particle tank 1 down into the intermediate dump particle cylinder 5, and can compact the particles in the intermediate dump particle cylinder 5, reducing the gap between adjacent particles, so that when the spiral conveying blade 604 rotates to convey the particles in the intermediate dump particle cylinder 5 downward, the particles can fill the material storage space between the adjacent pitches of the spiral conveying blade 604, avoiding the situation that cavities may appear when the particles fall, and the spiral conveying cavity on the spiral conveying blade 604 cannot be evenly filled, resulting in uneven particle flow during subsequent spiral conveying. By conveying particles into the particle conveying cavity 2 in a uniform manner, it is beneficial to improve the accuracy of subsequent optical speed measurement experimental data. Step 3: When the test of one particle size is completed and it is necessary to switch to another particle size for the experiment, the electromagnetic valve 4 15 is closed, and the negative pressure pumping mechanism 11 and the electromagnetic valve 2 1009 and the electromagnetic valve 3 10010 on the particle storage and recovery mechanism 10 with the same particle size as the particle tank 1 are opened. At this time, the negative pressure pumping mechanism 11 extracts the gas in the particle storage tank 1001 outwards through the exhaust pipe 1003, and the particle storage tank 1001, the particle recovery pipe 1005, the particle tank 1, the intermediate transfer particle storage cylinder 5, the particle conveying cavity 2 and the gas outlet pipe 4 to be measured are interconnected, so that the external gas passes through the gas outlet pipe 4 to be measured, the particle conveying cavity 2, the intermediate transfer particle storage cylinder 5, the particle recovery pipe 1005, the particle tank 1, the intermediate transfer particle storage cylinder 5, the particle conveying cavity 2 and the gas outlet pipe 4 to be measured in sequence. Sub-tank 1, particle recovery pipe 1005, particle storage tank 1001, exhaust pipe 1003, and then discharged from the negative pressure extraction mechanism 11. During the gas circulation process, the particles can be lifted and driven to flow into the particle storage tank 1001. Through the setting of the filter plate 1004 inside the particle storage tank 1001, the particles in the particle storage tank 1001 can be filtered and intercepted to prevent the particles from being discharged from the exhaust pipe 1003, thereby realizing the recovery of the particles retained in the particle tank 1, the intermediate storage cylinder 5 and the particle conveying cavity 2, and avoiding the mixing of two or more particle sizes when the next experimental test is carried out on the next particle of different particle size, which affects the accuracy of the subsequent test results. Step 4: During the operation of step 3, the screw conveying mechanism 6 and the up and down reciprocating driving mechanism 8 are used in conjunction to drive the compacting and blocking block 9 to move up and down, that is, the compacting and blocking block 9 intermittently enters the middle transfer grain barrel 5. After the compacting and blocking block 9 moves down and enters the middle transfer grain barrel 5, it can block the middle transfer grain barrel 5, making it difficult for gas to flow from the middle transfer grain barrel 5 from bottom to top. At this time, the negative pressure pumping mechanism 11 can be operated to pump out the gas inside the particle tank 1, making its interior into a negative pressure state, and then After the compacted blocking block 9 exits the intermediate dump particle cylinder 5, the intermediate dump particle cylinder 5 and the particle tank 1 are restored to communication. At this time, due to the low pressure inside the particle tank 1, a large amount of external gas quickly flows into the particle delivery cavity 2, the intermediate dump particle cylinder 5 and the particle tank 1, thereby achieving the impact force of the fast-flowing airflow on the inner wall to blow away and clean the particles adsorbed on the inner wall, reducing the residual particles on the inner wall as much as possible, and effectively preventing the mixture of residues of particles of various particle sizes during the experiment, which is beneficial to improving the accuracy of the optical speed measurement experiment data; Step 5: After the particles remaining in the particle conveying cavity 2, the intermediate dump particle cylinder 5 and the particle tank 1 are cleaned and recovered, the operation of step 2 is repeated to add particles of the required particle size into the particle tank 1 again, thereby replacing particles of different particle sizes and realizing the adjustable particle size of the optical speed measurement experiment, so that particles of different particle sizes can be used for optical speed measurement experiments according to needs.

[0031] Example 2: This example is basically the same as the previous example, except that a small vibrator 1007 is provided at the bottom of the filter plate 1004. The small vibrator 1007 is used to drive the filter plate 1004 to vibrate with a small amplitude and high frequency to shake off the particles adsorbed on the bottom of the filter plate 1004.

[0032] When recovering the particles remaining in the particle conveying cavity 2, the intermediate dump particle cylinder 5 and the particle tank 1, the small vibrator 1007 is turned on through the control panel 13 to drive the filter plate 1004 to vibrate with a small amplitude and high frequency, so that the particles adsorbed and accumulated on the bottom of the filter plate 1004 are separated by vibration, thereby effectively preventing the filter plate 1004 from being blocked and improving the filtering effect and efficiency of the filter plate 1004 on the particles.

[0033] Example 3: This example is basically the same as the previous example, except that the negative pressure extraction mechanism 11 includes a fixing frame 1101 fixedly installed between several particle storage tanks 1001, the top of the fixing frame 1101 is fixedly installed on the exhaust fan 1102, the end of the exhaust pipe 1003 away from the particle storage tank 1001 is fixedly connected to the exhaust end of the exhaust fan 1102, and the exhaust end of the exhaust fan 1102 is connected to the atmosphere.

[0034] When it is necessary to recover the particles remaining in the particle conveying cavity 2, the intermediate storage particle cylinder 5 and the particle tank 1, the exhaust fan 1102 is turned on through the control panel 13, the exhaust end of the exhaust fan 1102 generates suction, and the air in the particle storage tank is extracted outwards through the exhaust pipe 1003, so that the interior is in a negative pressure state, and the particle storage tank is connected to the particle tank 1 through the particle recovery pipe 1005, and then by exhausting air, the flow of air flow is used to drive the particles to be lifted up and transferred to the particle storage tank with the flow of air flow, thereby realizing the recovery of the remaining particles in the particle tank 1.

[0035] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A particle generator with adjustable particle size, comprising a particle tank (1) and a particle transport cavity (2) arranged below the particle tank (1), wherein both sides of the particle transport cavity (2) are fixedly connected to an inlet pipe (3) of a gas to be measured and an outlet pipe (4) of a gas to be measured, respectively, and characterized in that: The particle tank (1) and the particle conveying cavity (2) are fixedly connected through the intermediate transfer particle barrel (5); a screw conveying mechanism (6) is provided at the middle position of the top of the particle tank (1); the screw conveying mechanism (6) is used to uniformly convey the particles in the intermediate transfer particle barrel (5) to the particle conveying cavity (2); a dustproof cylinder (7) is fixedly installed at the middle position of the top of the inner wall of the particle tank (1); an upper and lower reciprocating driving mechanism (8) is provided inside the dustproof cylinder (7); a compacting and blocking block (9) is provided at the bottom end of the upper and lower reciprocating driving mechanism (8); the compacting and blocking block (9) is used to compact the particles in the particle tank (1) to the intermediate transfer particle barrel (5); a plurality of particle storage and recovery mechanisms (10) distributed in a circular array are provided at the top of the particle tank (1) and around the screw conveying mechanism (6); a negative pressure extraction mechanism (11) is provided between the plurality of particle storage and recovery mechanisms (10).

2. The particle generator with adjustable particle size according to claim 1, characterized in that: The screw conveying mechanism (6) comprises a drive motor (601) with adjustable speed, the drive motor (601) being fixedly mounted at the middle position of the top of the particle tank (1) via a U-shaped frame (605), the output end of the drive motor (601) being coaxially fixedly connected to a transmission rod (603) via a coupling (602), the bottom end of the transmission rod (603) extending into the interior of the particle conveying cavity (2) and being fixedly sleeved with a spiral conveying blade (604).

3. The particle generator with adjustable particle size according to claim 1, characterized in that: The up-and-down reciprocating drive mechanism (8) comprises a reciprocating screw (801), the reciprocating screw (801) being fixedly sleeved on the outer surface of the rotating rod and located inside the dustproof cylinder (7) near the upper end, the outer surface of the reciprocating screw (801) being threadedly connected to a screw sleeve (802), both sides of the screw sleeve (802) being fixedly connected to sliders (803), the sliders (803) being slidably connected to the inner wall of the dustproof cylinder (7), the bottom of the screw sleeve (802) being fixedly connected to a plurality of elastic telescopic members (804) distributed in a circumferential array, the bottom end of the elastic telescopic member (804) being fixedly connected to a connecting plate (805), the bottom of the connecting plate (805) being fixedly connected to a connecting rod (806), the bottom end of the connecting rod (806) being fixedly connected to the top of the compacting and blocking block (9).

4. The particle generator with adjustable particle size according to claim 3, characterized in that: The elastic telescopic member (804) comprises a telescopic rod (8041) and a spring (8042), the top ends of the telescopic rod (8041) and the spring (8042) being fixedly mounted on the bottom of the lead screw sleeve (802), and the bottom ends of the telescopic rod (8041) and the spring (8042) being fixedly connected to the top of the connecting plate (805).

5. The particle generator with adjustable particle size according to claim 1, characterized in that: The compacting and blocking block (9) is adapted to the intermediate grain dump cylinder (5), that is, the diameter of the compacting and blocking block (9) is the same as the inner diameter of the intermediate grain dump cylinder (5).

6. The particle generator with adjustable particle size according to claim 1, characterized in that: The particle storage and recovery mechanism (10) comprises a particle storage tank (1001) fixedly mounted on the top of the particle tank (1), the bottom end of the particle storage tank (1001) is fixedly connected to a particle discharge pipe (1002), the top end of the particle storage tank (1001) is fixedly connected to an air extraction pipe (1003), a filter plate (1004) is fixedly mounted on the inner wall of the particle storage tank (1001) near the bottom end, a particle recovery pipe (1005) is fixedly connected to one side of the particle tank (1) and below the filter plate (1004), the other end of the particle recovery pipe (1005) is connected to the top of the particle tank (1), and a particle filling port (1006) is fixedly connected to one side of the particle storage tank (1001) and below the filter plate (1004).

7. The particle generator with adjustable particle size according to claim 6, characterized in that: The particle discharge pipe (1002) is fixedly mounted with a solenoid valve 1 (1008), the air extraction pipe (1003) is fixedly mounted with a solenoid valve 2 (1009), and the particle recovery pipe (1005) is fixedly mounted with a solenoid valve 3 (10010).

8. The particle generator with adjustable particle size according to claim 6, characterized in that: A small vibrator (1007) is provided at the bottom of the filter plate (1004), and the small vibrator (1007) is used to drive the filter plate (1004) to vibrate with a small amplitude and high frequency.

9. The particle generator with adjustable particle size according to claim 6, characterized in that: The negative pressure extraction mechanism (11) comprises a fixing frame (1101) fixedly mounted between a plurality of particle storage tanks (1001), the top of the fixing frame (1101) being fixedly mounted on an exhaust fan (1102), and one end of the exhaust pipe (1003) away from the particle storage tank (1001) being fixedly connected to an exhaust end of the exhaust fan (1102).

10. The particle generator with adjustable particle size according to claim 1, characterized in that: A control panel (13) is fixedly mounted on the front of the particle tank (1), and a support frame (14) is fixedly mounted on the bottom of the particle tank (1).

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