Small-sized direct current blowdown sand wind tunnel for field use

Abstract

The utility model relates to a kind of field use small direct-current blowing formula sand wind tunnel, its structure includes air inlet round pipe, fan, square round deformation pipe, honeycomb rectifier, square mouth contraction pipe and several experimental wind channel, square round deformation pipe, honeycomb rectifier and square mouth contraction pipe are sequentially connected;The air inlet round pipe includes straight pipe section and elbow section, elbow section forms the air inlet of bending and upwarping, the air inlet round pipe is provided with the flange baffle of height higher than the upper edge of air inlet outside air inlet, soft connecting pipe is provided between air inlet round pipe and square round deformation pipe.The utility model is easy to install, tough and durable, data stable, wind speed measurement accuracy is high, frequency is big, and experimental data can be automatically stored by data acquisition box, overcome the existing wind tunnel generally existing cannot conveniently, quickly, accurately, high-frequency measurement near-surface wind speed profile difficult problem, suitable for soil wind erosion and dust release characteristics and the identification research work of main dust source.

Description

Technical Field

[0001] This utility model relates to a wind tunnel device, specifically a small-scale DC blowing sand wind tunnel for outdoor use. Background Technology

[0002] Many arid and semi-arid regions face severe soil erosion problems. Long-term wind erosion coarsens the soil, deteriorates its structure, reduces soil fertility, and lowers land productivity. The concentrated emission of dust during wind erosion events is also a major cause of sandstorms. To understand the hazards of wind erosion, various instruments and research methods for measuring and studying soil wind erosion have been developed, primarily including field observations and indoor wind tunnel experiments. Field observations are the fundamental method for measuring and studying soil wind erosion, offering the advantages of objectivity and accuracy. However, due to the complex and variable nature of the wind and sand environment in the field, and its lack of human control, conducting systematic wind erosion research in the field is quite difficult. Indoor wind tunnel experiments, through the artificial control of wind speed and soil surface properties, are a good supplement to field observation methods; however, they cannot replicate the original surface conditions in the field, and the experimental results cannot be directly applied to practical situations.

[0003] Existing wind tunnel equipment capable of conducting field experiments generally suffers from limitations in conveniently, quickly, accurately, and frequently measuring near-surface wind speed profiles. Furthermore, the rigid connections of the wind tunnel's components mean that vibrations generated during wind turbine operation significantly impact the experimental duct, reducing the accuracy of experimental data. Therefore, current instruments cannot conveniently, quickly, and autonomously simulate real-world wind erosion processes or accurately measure near-surface wind field parameters. Summary of the Invention

[0004] The purpose of this invention is to provide a small-scale DC blowing sand wind tunnel for field use, in order to solve the problem that existing instruments and equipment cannot conveniently, quickly, autonomously, and controllably simulate the real surface wind erosion process and accurately measure near-surface wind field parameters.

[0005] The purpose of this utility model is achieved as follows:

[0006] A small-scale DC blowing sand tunnel for field use includes an air inlet pipe, a fan, a square-round deformable pipe, a honeycomb rectifier, a square-mouth contraction pipe, and several experimental air ducts. The square-round deformable pipe, the honeycomb rectifier, and the square-mouth contraction pipe are connected in sequence. The air inlet pipe includes a straight pipe section and an elbow section. The bending angle of the elbow section is 30° to 40°, forming an upward-curved air inlet. A folded edge wind baffle plate with a height higher than the upper edge of the air inlet is provided outside the air inlet of the air inlet pipe. A flexible connecting pipe is provided between the air inlet pipe and the square-round deformable pipe.

[0007] Furthermore, the flexible connecting pipe is a canvas sleeve, and its two ends are fixed to the connection ports of adjacent components using steel rings with clamps, thereby forming a connection structure that is easy to assemble and disassemble, and reducing the impact of vibration during the operation of the fan.

[0008] Furthermore, the folded edge wind deflector includes a middle plate and two side guard plates connected by hinges. Angle steel is fixed to the lower edge of the middle plate and the guard plates. The angle steel has insertion holes for inserting steel rods so as to fix it to the ground in front of the air inlet pipe.

[0009] Furthermore, the experimental air duct is a door-shaped cover made of stainless steel plate. Rectangular windows are opened on the side and top of the experimental air duct, and detachable transparent plexiglass plates are installed on the windows to facilitate observation and operation inside the experimental air duct.

[0010] Furthermore, an array of three Pitot tubes arranged side by side is inserted into one of the experimental air ducts. The three Pitot tubes are fixed to the top surface of the experimental air duct by buckles. A horizontal bending section is provided at the lower end of the Pitot tubes. The end of the bending section is the air inlet. The air inlets of the three Pitot tubes face the windward side of the experimental air duct and are on a vertical line.

[0011] Furthermore, the bending sections of the three Pitot tubes are set at different heights, corresponding to the upper, middle, and lower parts of the experimental air duct, to measure the wind speed at different heights within the experimental air duct.

[0012] This invention uses a flexible connecting pipe to connect the inlet circular pipe and the square-round deformable pipe, thereby avoiding the adverse effects of vibrations generated during fan operation on the experimental air duct and experimental data. A detachable acrylic plate is installed on the experimental air duct, which not only facilitates observation of the experiments inside the wind tunnel, but also allows for the removal of any acrylic plate to conduct experiments without disassembling the wind tunnel, thus maximizing the authenticity of the surface conditions. A folded-edge windbreak plate is installed to create a relatively calm wind environment at the air inlet of the wind tunnel, preventing the interference of external wind turbulence on the wind tunnel speed and ensuring the stability of the wind tunnel speed.

[0013] This invention is easy to install, robust and durable, provides stable data, and has high accuracy and frequency in wind speed measurement. It can also automatically store experimental data through a data acquisition box, thus overcoming the common problem in existing wind tunnels that cannot conveniently, quickly, accurately, and frequently measure near-surface wind speed profiles. It is suitable for research on soil wind erosion and dust release characteristics as well as the identification of major dust sources. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] Figure 2 This is a schematic diagram of a Pitot tube array.

[0016] In the diagram, 1. Inlet duct, 2. Fan, 3. Flexible connector, 4. Square-round deformable tube, 5. Honeycomb rectifier, 6. Square-mouth shrink tube, 7. Experimental air duct one, 8. Experimental air duct two, 9. Experimental air duct three, 10. Experimental air duct four, 11. Electrical control cabinet, 12. Folded edge wind deflector, 13. Pitot tube matrix, 14. Data acquisition box, 15. Gasoline generator. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0018] like Figure 1 As shown, this utility model includes a wind baffle 12, an air inlet circular pipe 1, a fan 2, a flexible connecting pipe 3, a square-round deformable pipe 4, a honeycomb rectifier 5, a square-mouth contraction pipe 6, and four experimental air ducts (divided into experimental air duct one 7, experimental air duct two 8, experimental air duct three 9, and experimental air duct four 10). Except for the flexible connecting pipe and the fan, all other parts are connected by flanges and bolts. This connection structure is not only simple in structure but also convenient for assembly and disassembly. The flanges are sealed with soft sealing gaskets, ensuring the airtightness of the sand tunnel and preventing airflow leakage.

[0019] The air inlet duct 1 consists of a straight section and an elbow section. The elbow section has a bending angle of 30° to 40°, forming an upward-curving air inlet. The purpose of the upward-curving elbow section is twofold: first, to prevent strong winds from blowing directly into the air inlet duct; and second, to prevent soil and dust from entering with the wind. A 10-mesh filter screen is attached to the air inlet of the air inlet duct 1 to prevent debris from falling in. The diameter of the straight section of the air inlet duct 1 is 600mm. The fan 2 is installed inside the straight section of the air inlet duct 1, with the centerline of the fan 2 coinciding with the centerline of the straight section of the air inlet duct. The fan 2 can be a POG type axial flow fan with a motor power of 3.0KW and a power frequency speed of 2900rpm. The fan speed is controlled by a variable frequency drive (0~50.0 Hz), achieving a speed range of 0~22.0m·s. -1 Linear adjustment of experimental wind speed within the range.

[0020] A folded-edge windbreak plate 12 is installed at the front of the air inlet pipe 1. The folded-edge windbreak plate 12 consists of a middle plate and two side guard plates connected by hinges. The middle plate is 1000mm high and 1000mm wide, while the side guard plates are 1000mm high, 400mm wide, and 8mm thick, weighing approximately 10kg. Angle steel with insertion holes is fixed to the lower edge of the middle plate and the guard plates for securing with steel spikes. The side guard plates of the folded-edge windbreak plate 12 are arranged in a V-shape and positioned approximately 500mm in front of the air inlet of the air inlet pipe, directly facing the wind direction, to prevent the turbulent fluctuations of the incoming air from interfering with the wind speed in the wind tunnel.

[0021] A square-round deformable tube 4 is installed at the rear of the air inlet pipe 1, and a flexible connecting tube 3 is connected between the air inlet pipe 1 and the square-round deformable tube 4. The flexible connecting tube 3 is a canvas sleeve structure, and its two ends are fixedly connected to the adjacent ends of the air inlet pipe 1 and the square-round deformable tube 4 by using steel rings with clamps. The free length of the flexible connecting tube 3 after connecting the components at both ends is not less than 50mm, so as to effectively isolate the transmission of mechanical vibration to the rear of the sand and wind tunnel.

[0022] The square-round deformable tube 4 is a deformable tube that changes from round to square, meaning one end of the tube has a circular opening, the other end has a square opening, and the middle is a deformable transition section. The diameter and side length of the square-round deformable tube 4 are both 600mm. The square opening at the rear end of the square-round deformable tube 4 is connected to the honeycomb rectifier 5.

[0023] The honeycomb rectifier 5 consists of a honeycomb mesh sealed within a rectangular shell. The shell is 100mm thick and has a cross-sectional dimension of 600×600mm. The honeycomb mesh has hexagonal openings with opposite sides of 15mm. The honeycomb rectifier 5 rectifies the turbulent airflow generated by the deformation of the square-round deformable tube 4, ensuring that the airflow blown in by the fan enters the experimental air duct smoothly. A square-mouth contraction tube 6 connects to the rear of the honeycomb rectifier 5. The square-mouth contraction tube 6 is 440mm long, with an inlet dimension of 600×600mm and an outlet dimension of 350×350mm, exhibiting a contraction ratio close to 3:1 to increase the gas velocity entering the experimental air duct. Four sections of the experimental air duct connect to the rear of the square-mouth contraction tube 6.

[0024] These four experimental air ducts are Experimental Air Duct 1 (7), Experimental Air Duct 2 (8), Experimental Air Duct 3 (9), and Experimental Air Duct 4 (10). Each duct is a folded stainless steel cover, 1000mm long, with an internal cross-section of 350×350mm, weighing approximately 20kg. The cross-section is door-shaped, designed to cover the experimental surface. Rectangular windows are located on the sides and top of the ducts, each fitted with a removable transparent acrylic panel to create viewing windows for easy observation of the internal experimental process. The viewing windows have a visible area of ​​200×400mm, with their inner walls flush with the stainless steel surface of the ductwork. The acrylic panels are designed for easy removal and repositioning, allowing items to enter and exit the ducts during experiments.

[0025] like Figure 1 , Figure 2As shown, a Pitot tube array 13, consisting of three side-by-side Pitot tubes, is inserted into the top of experimental air duct 3 (9). The Pitot tube array 13 is an array composed of three custom-made Pitot tubes 13-1, 13-2, and 13-3 arranged vertically. The three Pitot tubes are fixed to the top surface of experimental air duct 3 (9) by clips 13-4 and 13-5, and are positioned on the same vertical plane. At the lower ends of the three Pitot tubes 13-1, 13-2, and 13-3, there are transverse bending sections. The spacing between the three bending sections can be set and adjusted according to experimental needs. A differential pressure sensor for measuring wind speed is connected to each bending section. The bending sections of the three Pitot tubes are set at different heights, corresponding to the upper, middle, and lower parts of the experimental air duct, to measure the wind speed at different heights within the duct. The ends of the bending sections of the three Pitot tubes are air inlets, facing the windward side of the experimental air duct. The air inlets of the three Pitot tubes are on a vertical line. The static pressure connector 13-6 and differential pressure connector 13-7 on each Pitot tube are connected to the high-precision differential pressure sensor in the data acquisition box 14 via rubber tubing, and the wind speed detection data in the experimental air duct is obtained through the differential pressure sensor.

[0026] The external configuration of this utility model includes a data acquisition box 14, an electrical control cabinet 11, and a gasoline generator 15. The data acquisition box 14 houses a wind speed measurement and control module developed using a microcontroller. This module acquires wind speed data from a differential pressure sensor within the experimental duct via a data cable. Simultaneously, it connects to the electrical control cabinet 11 via a cable, enabling communication with the frequency converter within the cabinet to adjust the fan speed and airflow in real time.

[0027] The Pitot tube array 13 and the data acquisition box 14 together form a wind speed profile measurement and control system. The electrical control cabinet 11 is electrically connected to both the wind turbine 2 and the wind speed profile measurement and control system. The frequency converter in the electrical control cabinet 11 adjusts the speed of the wind turbine 2 via a frequency conversion of 0~50.0 Hz. The gasoline generator 15 provides power to both the sand tunnel and the wind speed profile measurement and control system.

[0028] During operation, all components are installed, connected, leveled, and calibrated according to specifications at the experimental test points. The Pitot tube array 13 of the wind speed profile measurement and control system is installed on the experimental air duct 39. After the fan 2 is started, the generated airflow is directly circulated through the honeycomb rectifier 5. The airflow can be controlled from 0 to 22 m / s via the electrical control cabinet 15. -1 The wind speed inside the sand tunnel can be adjusted arbitrarily within a certain range, and the wind speed profile measurement and control system can be used to accurately measure the wind speed at different ground heights within the experimental wind tunnel, thereby achieving accurate measurement of the surface wind speed profile, aerodynamic roughness, and frictional wind speed. Combined with equipment such as sand collectors and dust collectors, it is also possible to achieve comprehensive, systematic, and accurate measurement of surface wind erosion characteristics.

Claims

1. A small-scale DC blowing sand tunnel for field use, comprising an air inlet circular pipe, a fan, a square-round deformable pipe, a honeycomb rectifier, a square-mouth contraction pipe, and several experimental air ducts, wherein the square-round deformable pipe, the honeycomb rectifier, and the square-mouth contraction pipe are connected sequentially; characterized in that, The air inlet pipe includes a straight section and an elbow section. The elbow section has a bending angle of 30° to 40°, forming an upward-curving air inlet. A folded baffle plate with a height higher than the upper edge of the air inlet is provided outside the air inlet of the air inlet pipe. A flexible connecting pipe is provided between the air inlet pipe and the square-round deformed pipe.

2. The small-scale DC blowing sand tunnel for field use according to claim 1, characterized in that, The flexible connecting tube is a canvas sleeve, and its two ends are fixed to the connection ports of adjacent components using steel rings with clamps.

3. The small-scale DC blowing sand tunnel for field use according to claim 1, characterized in that, The folded windbreak plate includes a middle plate and two side guard plates, which are connected by hinges. Angle steel is fixed to the lower edge of the middle plate and the guard plates, and the angle steel has insertion holes for inserting steel rods.

4. The small-scale DC blowing sand tunnel for field use according to claim 1, characterized in that, The experimental air duct is a door-shaped cover made of stainless steel plate. Rectangular windows are opened on the side and top of the experimental air duct, and transparent plexiglass plates are installed on the windows.

5. The small DC blowing sand tunnel for field use according to claim 4 is characterized in that a Pitot tube array consisting of three Pitot tubes placed side by side is inserted into one of the experimental air ducts. The three Pitot tubes are fixed to the top surface of the experimental air duct by buckles. A transverse bending section is provided at the lower end of the Pitot tubes. The end of the bending section is an air inlet. The air inlets of the three Pitot tubes face the windward side of the experimental air duct and are on a vertical line.

6. The small-scale DC blowing sand tunnel for field use according to claim 5, characterized in that, The three Pitot tubes have different bend heights, corresponding to the upper, middle, and lower parts of the experimental air duct.

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