Brush-type seal microflow display and pressure loss measurement system and method

Abstract

This invention relates to a microflow display and pressure loss measurement system for brush-type sealed brush filaments, comprising: a gas supply system for supplying gas; a visible ion generation and capture system; and an experimental section connected to the gas supply system. The experimental section includes a radially arranged optical fiber; one end of the optical fiber is equipped with a blue cold light source, and the other end is blackened. A front pressure sensor is located at the point where the flue gas flows through the optical fiber, and a rear pressure sensor is located at the point where it flows through the optical fiber. The visible ion generation and capture system includes a visible ion generation and capture controller, an oil pump, a capillary tube, a high-speed high-definition camera, and an oil tank. The oil pump is connected to the capillary tube and the oil tank, and supplies oil to the capillary tube, with the oil seeping out through small holes in the capillary tube. The visible ion generation and capture controller is connected to the capillary tube, and by applying current, it causes the oil evenly distributed on the capillary tube to generate smoke. The smoke trail flows with the micro-airflow through the optical fiber, and the high-speed high-definition camera captures the trajectory of the smoke trail.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, specifically to a system and method for displaying microflow and measuring pressure loss between brush filaments in a brush seal. Background Technology

[0002] Advanced sealing technology is indispensable for improving the performance of aero-engines; good sealing technology can increase engine thrust by about 1.5%. With the development of aero-engines, sealing technology has evolved from comb-type seals to advanced technologies such as brush seals and graphite seals. Therefore, research on sealing technology has deepened to seek optimal structural parameters to adapt to more complex engine operating conditions. Currently, research on the microflow between the brush filaments in brush seals has also been carried out with the advancement of PIV technology, especially the development of Micro-PIV technology. The application of laser display technology with microscopic capabilities has made experimental research on the microflow of airflow between the brush filaments possible. This technology incorporates tracer ions into the airflow and uses lasers to capture the trajectory of these tracer ions. Additionally, computer simulation software can be used to simulate and calculate the flow between the brush filaments.

[0003] The current Micro-PIV technology used for microflow display between brush filaments in aero-engine brush seals is too expensive. A single Micro-PIV device typically costs around 4 million yuan. With the addition of other supporting facilities, this experimental research cannot be carried out in a comprehensive manner, which limits the development of microflow research on brush filaments.

[0004] Currently, the fluorescent tracer ions used in PIV (Pilot Air Injection) are generally harmful to the body and are usually directly released into the air, posing an inhalation hazard to laboratory personnel. The concentration of tracer ions incorporated into the air also needs to be adjusted according to the air flow rate. Therefore, for experiments with varying pressure and flow rates, the concentration of tracer ions needs to be pre-calibrated, making the experiment cumbersome, difficult to operate and master, and requiring experienced researchers to find the optimal ion concentration through several trials. Furthermore, verifying in advance whether the added tracer ions achieve the same or similar physical motion characteristics as the air medium is also quite troublesome, as it can easily alter the flow state of the air medium.

[0005] PIV (Polyimation Image Processing) is a motion display technology that requires post-processing of the captured flow field. Post-processing is a demanding task that is not easy to master and requires highly specialized personnel to operate.

[0006] Computer simulation-based flow display technology is rather idealistic, simplifying many nonlinear problems in flow, resulting in a significant gap from reality and being overly idealistic.

[0007] Current smoke generation devices rely on manual oiling or free dripping from an oil container, resulting in uneven oil distribution on the tobacco shreds and uneven smoke thread thickness. Furthermore, the smoke threads are prone to being intermittent, making the flow trajectory of captured smoke ions unclear or discontinuous, which makes it difficult to analyze the flow mechanism.

[0008] In view of this, the present invention is hereby proposed. Summary of the Invention

[0009] This invention proposes a microflow display and pressure loss measurement system and method between brush-type sealing brush filaments to solve the aforementioned technical problems.

[0010] The above-mentioned technical objective of the present invention is achieved through the following technical solution: One aspect of this disclosure discloses a microflow display and pressure loss measurement system between brush-type sealing brush filaments, comprising: Gas supply system, used for supplying gas; A visible ion generation and capture system is used to generate and capture visible smoke trails that flow with micro-airflow. The experimental section is connected to the gas supply system. The experimental section is equipped with a radially arranged optical fiber; The optical fiber is equipped with a blue cold light source at one end and is painted black at the other end; The experimental section has a front pressure sensor at the front section where the flue gas flows through the optical fiber, and a rear pressure sensor at the rear section where the flue gas flows through the optical fiber. The visible ion generation and capture system includes a visible ion generation and capture controller, an oil pump, a capillary tube, a high-speed high-definition camera, and an oil tank. The oil pump is connected to the capillary tube and the oil tank, and supplies oil to the capillary tube, with the oil seeping out through the small holes in the capillary tube; The visible ion generation and capture controller is connected to the capillary tube, and the oil evenly distributed on the capillary tube generates smoke by applying current. The smoke trail flows through the optical fiber with the micro-airflow, and the high-speed high-definition camera is used to capture the trajectory of the smoke trail.

[0011] Furthermore, the gas supply system includes an air compressor unit, an air storage tank, and a pressure regulating valve; The air compressor unit pressurizes and inflates the air storage tank; The pressure regulating valve can adjust the outlet pressure of the gas storage tank.

[0012] Furthermore, a pipeline, a transfer section, and a diffuser section are provided between the experimental section and the gas storage tank.

[0013] Furthermore, the experimental section is equipped with a pressure balancing mesh and a straight airflow honeycomb structure; The airflow first passes through the pressure balance mesh and the airflow straight honeycomb, and then through the capillary.

[0014] Furthermore, an oil inlet hose is provided between the oil pump and the capillary tube.

[0015] Furthermore, the oil inlet hose is also connected to an oil return hose, the other end of which extends into the oil tank.

[0016] Furthermore, the top plate of the experimental section is made of optical glass.

[0017] In another aspect of this disclosure, a method for displaying microflow and measuring pressure loss between brush filaments in a brush-type sealing system is disclosed, comprising the following steps: Step 1: Assemble and manufacture the components and devices, and debug the subsystems according to the experimental requirements; Step two: Perform overall connection debugging; Step 3: Begin formal experiment preparation, including developing an experiment outline, experimental plan, and technical requirements; Step 4: Begin the experiment. According to the experimental outline, install the experimental section with a bristle density of 100. The bristle density refers to the number of bristles per square centimeter. Set the pressure in front of the bristles to P1. After the pressure stabilizes, turn on the visible ion generation and capture controller to conduct the experiment. Measure and record the actual static pressure before and after the bristles. Step 5: Change the pressure before brush bristles to P2, P3, P4, and P5, and repeat step 4 to complete the data measurement of at least five pressures. Step 6: Change to experimental sections with different bristle densities and repeat steps 4 and 5 to complete the experimental measurement of all bristle densities. Step 7: Process the data and define the pressure loss coefficient as follows. : In the formula Static pressure before brush bristle application. The static pressure behind the bristles allows us to obtain the functional relationship between the loss coefficient and the pressure before the bristles under the same bristle density, and the functional relationship between the loss coefficient and the bristle density and pressure under the same bristle pressure for different bristle densities. We can also obtain the microflow mechanism between the bristles under the corresponding working conditions, thereby achieving qualitative and quantitative multidimensional analysis and obtaining a bristle sealing structure with better performance.

[0018] Furthermore, in step one, subsystem debugging includes: Air supply system: including air compressor unit, air tank, pressure regulating valve; pressurize and fill the air tank to the design pressure and maintain the pressure in the air tank for more than 30 minutes without dropping; Brush filament simulation and debugging: In actual applications, metal brush filaments are used. To ensure clear flow visualization and capture of the flow state, glass optical fibers are used as a substitute in the experiment. The diameter is the same as the actual brush filaments, and the brush filament density is defined. The number of brush filaments per square centimeter is defined as the brush filament density, denoted as n / cm². 2 The fiber optic filament simulation device is manufactured as a single unit, with six replaceable experimental sections of filaments at filament densities of 100, 120, 140, 160, 180, and 200. One end of each fiber optic filament is connected to a blue cold light source, and the other end is sealed with black opaque paint. The brightness of the blue cold light source is adjustable. When the blue cold light source is turned on, it is ensured that the blue light propagates along each fiber optic filament. Debugging of the visible ion generation, release, and capture system: This system is an automated device that controls the generation, release, and capture of visible ions; individual debugging of each component, oil circuit system: turn on the oil pump, observe whether oil droplets are generated on the surface of the capillary metal porous tube, and record the time T from turning on the oil pump to the generation of oil droplets. 油 Turn on the capillary heating and adjust the heating current, recording the time T for smoke to be generated on the capillary at each current. 烟 Adjust the capture device to obtain clear photos of the experimental brush filaments. Pressure measurement and calibration: Initial reading is correct; positive and negative pressure is applied, and the reading pattern is correct.

[0019] The beneficial effects of this invention include: The present invention's visual tobacco filament generating device adopts automatic control and eliminates the shortcomings of uneven manual oiling of hot tobacco filaments, achieving automatic oiling and uniform oil production, thus unifying the thickness and concentration of tobacco filaments. This facilitates the analysis of the flow field mechanism and the summarization of patterns.

[0020] The brush filaments of this invention are simulated using optical fibers, so that each brush filament can be illuminated, and the light intensity of this cold light source can be adjusted, making it easier to capture clearer and more visual flow trajectories.

[0021] The experimental techniques of the experimental apparatus of this invention are easy to master, allowing even non-professionals to use the device and achieve high-quality visualized flow capture. This reduces both the difficulty and cost of the experiment, enabling wider application and research of flow visualization between brush filaments.

[0022] The experimental apparatus of this invention produces smoke of extremely low concentration and fine tobacco shreds, and the oil can be vegetable oil, which is environmentally friendly, harmless to the human body, and more beneficial to the health of experimental personnel.

[0023] The experimental method of this invention can simulate the microflow between brush bristles in brush-type sealing structures with different bristle shapes and arrangements, and can also conduct non-flow display experiments, such as studies on the sealing characteristics of brush bristles and the influence of different bristle shapes and layouts on sealing performance. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the measurement system of the present invention; Figure 2 This is a schematic diagram of a partial structure of the experimental section; Figure 3 This is a schematic diagram of the local structure of another state of the experimental section.

[0025] Figure 4 This is a schematic diagram of the capillary structure; Figure 5 This is a partial structural diagram of the bristle section.

[0026] In the diagram: 1. Air compressor unit; 2. Air tank; 3. Pressure regulating valve; 4. Pipeline; 5. Transfer section; 6. Experimental section; 7. Pressure balance network; 8. Straight airflow honeycomb; 9. Visual ion generation and capture controller; 10. Front pressure sensor; 11. High-speed high-definition camera; 12. Rear pressure sensor; 13. Optical glass; 14. Diffusion section; 15. Blue cold light source; 16. Optical fiber; 17. Capillary tube; 18. Oil inlet hose; 19. Oil pump; 20. Oil tank; 21. Terminal; 22. Oil return pipe. Detailed Implementation

[0027] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0030] like Figure 1-5 As shown, the entire experimental system is divided into three parts: the gas supply system, the visible ion generation and capture system, and the brush filament simulation experimental section. The gas supply system uses an air compressor unit 1 to pressurize and fill the gas storage tank 2. The gas storage tank 2 has pressure monitoring, and the host computer sets the inflation pressure of the gas storage tank 2. When the set pressure is reached, the air compressor unit 1 automatically stops. The pressure regulating valve 3 can adjust the outlet pressure of the gas storage tank 2 to meet the experimental requirements. The visible ion generation and capture system mainly generates and captures smoke ions. This part uses a visible ion generation and capture controller 9 to automatically control the oil pump 19, the capillary tube 17 heating, and the high-speed high-definition camera 11. Its control logic is as follows: when the airflow pressure is adjusted by the pressure regulating valve 3 in experimental section 6, and then rectified by the pressure balance network 7 and the airflow straight honeycomb 8, the uniformity of the airflow is greatly improved, which plays an important role in generating visible smoke ions. At this time, the visible ion generation and capture controller 9 issues a command, and the oil pump 19 turns on, starting to supply oil to the capillary tube 17. Because the capillary tube 17 has small holes, oil droplets will seep out evenly on the capillary tube 17. Excess oil returns to the oil tank 20 through the return oil pipe 22. The oil pump 3 is turned on, and the oil pump 19 is turned off after 3 seconds. The visible ion generation and capture controller 9 begins to apply current to the capillary tube 17. Since the oil pump 19 and the capillary tube 17 are connected by the oil inlet hose 18, they are not conductive. The capillary tube 17 heats up instantly, causing the oil evenly distributed on the capillary tube 17 to generate smoke. The smoke moves with the micro-airflow, producing a visible smoke line. At this time, the visible ion generation and capture controller 9 controls the high-speed high-definition camera to take pictures and capture the smoke line trajectory, completing the capture of the airflow trace. The capture time can be set to stop the heating of the capillary tube 17. The experimental section for simulating brush filaments is a single, integrated design. The brush filaments are replaced by optical fibers 16 with the same diameter as real brush filaments. These fibers 16 are fabricated at the bottom of the experimental section according to the brush filament density and fixed to the base plate. The top plate of experimental section 6 is made of optical glass 13, facilitating the capture of the smoke trail by the high-speed, high-definition camera 11. One end of the optical fiber 16 is connected to a blue cold light source 15, while the other end is blackened to prevent light transmission. When the blue cold light source 15 is turned on, the optical fiber transmits blue light, illuminating the brush filaments formed by the fiber. The pressure before and after the brush filaments is measured by a front pressure sensor 10 and a rear pressure sensor 12.

[0031] like Figure 2As shown, the optical fiber 16 has linearly arranged bristles. A capillary tube 17 is installed in front of the bristles. The capillary tube 17 has terminals 21 at both ends for connection to other parts. One end of the capillary tube 17 is closed, and the other end is connected to the oil inlet tube 18. Figure 3 As shown, the capillary tube 17 is pressurized by the oil pump 19, which generates uniform oil droplets on its surface. These oil droplets, when heated, produce smoke, which, carried by the airflow, forms tobacco shreds. The tobacco shreds flow around the brush fibers. Figure 4 As shown, the capillary tube 17 has a teardrop-shaped streamlined cross-section, which minimizes its impact on airflow and facilitates the generation of a continuous and uniform smoke stream. Several small holes are formed at the tail of the capillary tube 17; these holes are oil seepage holes, thus generating uniform oil droplets at the tail of the capillary tube. Figure 5 As shown, the actual angle of the brush filaments in operation is 45 degrees. Therefore, the angle between the brush filaments simulated by the optical fiber 16 and the horizontal plane in the experimental system is 45 degrees. The top of the brush filaments is not fixedly connected to the optical glass 13 and can move freely along the optical glass 13 under air pressure. The bottom of the brush filaments is fixedly connected to the wall of the experimental section 6, simulating the fixed end of the brush filaments. The angle of the cross-sectional wall plate of the experimental section 6 is the same as the angle of the brush filaments to reduce flow interference.

[0032] The present invention is specifically implemented on a sealed test bench. Taking the test process under one working condition as an example: A 0.05mm diameter optical fiber was used to replace the brush filaments (hereinafter referred to as brush filaments) to create an experimental simulation section with a brush filament density of 100, i.e., 100 brush filaments per square centimeter. The brush filament angle was 45 degrees, and the experimental section was installed.

[0033] Debug the visual ion generation and capture controller. Ordinary soybean oil was selected as the oil solution. The oil pump was turned on, and the capillary droplet generation time was recorded as T. 油 =3 seconds, heat the capillary tube, adjust the current, and record the time for smoke to be produced by the capillary tube at different currents, as shown in Table 1:

[0034] Table 1 The pressure before the bristles was set to 0.05 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, and 0.25 MPa. Measurements were taken of the pressure before and after the bristles under different pressures, and the calibration data are recorded as shown in Table 2.

[0035] Table 2 When the bristle density is 100, calculate the loss factor: As shown in Table 3:

[0036] Table 3 It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A microflow display and pressure loss measurement system between brush-type sealing brush filaments, characterized in that, include: Gas supply system, used for supplying gas; A visible ion generation and capture system is used to generate and capture visible smoke trails that flow with micro-airflow. The experimental section is connected to the gas supply system. The experimental section is equipped with a radially arranged optical fiber; The optical fiber is equipped with a blue cold light source at one end and is painted black at the other end; The experimental section has a front pressure sensor at the front section where the flue gas flows through the optical fiber, and a rear pressure sensor at the rear section where the flue gas flows through the optical fiber. The visible ion generation and capture system includes a visible ion generation and capture controller, an oil pump, a capillary tube, a high-speed high-definition camera, and an oil tank. The oil pump is connected to the capillary tube and the oil tank, and supplies oil to the capillary tube, with the oil seeping out through the small holes in the capillary tube; The visible ion generation and capture controller is connected to the capillary tube, and the oil evenly distributed on the capillary tube generates smoke by applying current. The smoke trail flows through the optical fiber with the micro-airflow, and the high-speed high-definition camera is used to capture the trajectory of the smoke trail.

2. The microflow display and pressure loss measurement system between brush-type sealing brush filaments according to claim 1, characterized in that: The air supply system includes an air compressor unit, an air tank, and a pressure regulating valve; The air compressor unit pressurizes and inflates the air storage tank; The pressure regulating valve can adjust the outlet pressure of the gas storage tank.

3. The microflow display and pressure loss measurement system between brush-type sealing brush filaments according to claim 2, characterized in that: The experimental section and the gas storage tank are connected by a pipeline, a transfer section and a diffuser section.

4. The microflow display and pressure loss measurement system between brush-type sealing brush filaments according to claim 1, characterized in that: The experimental section is equipped with a pressure balance net and a straight airflow honeycomb structure. The airflow first passes through the pressure balance mesh and the airflow straight honeycomb, and then through the capillary.

5. The microflow display and pressure loss measurement system between brush-type sealing brush filaments according to claim 1, characterized in that: An oil inlet hose is provided between the oil pump and the capillary tube.

6. The microflow display and pressure loss measurement system between brush filaments of a brush seal according to claim 5, characterized in that: The oil inlet hose is also connected to an oil return hose, the other end of which extends into the oil tank.

7. The microflow display and pressure loss measurement system between brush-type sealing brush filaments according to claim 1, characterized in that: The top plate of the experimental section is made of optical glass.

8. A method for displaying microflow and measuring pressure loss between brush-type sealing brush filaments, using the measurement system as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Assemble and manufacture the components and devices, and debug the subsystems according to the experimental requirements; Step two: Perform overall connection debugging; Step 3: Begin formal experiment preparation, including developing an experiment outline, experimental plan, and technical requirements; Step 4: Begin the experiment. According to the experimental outline, install the experimental section with a bristle density of 100. The bristle density refers to the number of bristles per square centimeter. Set the pressure in front of the bristles to P1. After the pressure stabilizes, turn on the visible ion generation and capture controller to conduct the experiment. Measure and record the actual static pressure before and after the bristles. Step 5: Change the pressure before brush bristles to P2, P3, P4, and P5, and repeat step 4 to complete the data measurement of at least five pressures. Step 6: Change to experimental sections with different bristle densities and repeat steps 4 and 5 to complete the experimental measurement of all bristle densities. Step 7: Process the data and define the pressure loss coefficient as follows. : In the formula Static pressure before brush bristle application. The static pressure behind the bristles allows us to obtain the functional relationship between the loss coefficient and the pressure before the bristles under the same bristle density, and the functional relationship between the loss coefficient and the bristle density and pressure under the same bristle pressure for different bristle densities. We can also obtain the microflow mechanism between the bristles under the corresponding working conditions, thereby achieving qualitative and quantitative multidimensional analysis and obtaining a bristle sealing structure with better performance.

9. The method for displaying microflow and measuring pressure loss between brush bristles in a brush-type seal according to claim 8, characterized in that: Step one, subsystem debugging includes: Air supply system: including air compressor unit, air tank, pressure regulating valve; pressurize and fill the air tank to the design pressure and maintain the pressure in the air tank for more than 30 minutes without dropping; Brush filament simulation and debugging: In actual applications, metal brush filaments are used. To ensure clear flow visualization and capture of the flow state, glass optical fibers are used as a substitute in the experiment. The diameter is the same as the actual brush filaments, and the brush filament density is defined. The number of brush filaments per square centimeter is defined as the brush filament density, denoted as n / cm². 2 The fiber optic filament simulation device is manufactured as a single unit, with six replaceable experimental sections of filaments at filament densities of 100, 120, 140, 160, 180, and 200. One end of each fiber optic filament is connected to a blue cold light source, and the other end is sealed with black opaque paint. The brightness of the blue cold light source is adjustable. When the blue cold light source is turned on, it is ensured that the blue light propagates along each fiber optic filament. Debugging of the visible ion generation, release, and capture system: This system is an automated device that controls the generation, release, and capture of visible ions; individual debugging of each component, oil circuit system: turn on the oil pump, observe whether oil droplets are generated on the surface of the capillary metal porous tube, and record the time T from turning on the oil pump to the generation of oil droplets. 油 Turn on the capillary heating and adjust the heating current, recording the time T for smoke to be generated on the capillary at each current. 烟 Adjust the capture device to obtain clear photos of the experimental brush filaments. Pressure measurement and calibration: Initial reading is correct; positive and negative pressure is applied, and the reading pattern is correct.

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