A method and system for evaluating flow uniformity of partitioned fibrillation

Abstract

The present invention provides a method and system for evaluating the flow uniformity of partitioned fiber analysis, which involves the use of numerical simulation fluids and belongs to the technical field of electrical digital data processing. The present invention establishes a full-scale flow box pulp simulation model, uses a discrete phase model to numerically simulate the internal flow field of the entire flow box, divides the inlet position of the pulp distributor into regions, and explores the dispersion of streamlines of pulps in different partitions at the outlet. The present invention evenly divides the streamline results of the flow box outlet into a number of grids and performs a particle uniformity analysis, and calculates the uniformity of the outlet streamline distribution. The control variables are set to evaluate the flow uniformity at the flow box outlet at different inlet flow rates and turbulence, and the changing rules are analyzed. The present invention proposes a new method for evaluating the uniformity of fluid flow inside the flow box, which fills the deficiencies of the prior art in exploring the internal flow characteristics of the flow box and is low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of electric digital data processing, relates to the use of numerical simulation fluid, and specifically relates to a partitioned fibrillation flow uniformity evaluation method and system. Background Art

[0002] Aramid honeycomb paper is an important composite material used in military industry, aerospace, rail transportation and other fields. Compared with metal materials, aramid honeycomb paper is light in weight, high in strength, high in modulus, high in temperature resistance and corrosion resistance, which makes it widely used.

[0003] As an important equipment in the manufacturing technology of aramid honeycomb paper, the headbox needs to ensure that the incoming aramid fiber pulp can be effectively dispersed without fiber flocculation, so that the pulp is evenly distributed along the lateral direction of the equipment during the flow process. The pulp distributor is a device that stably delivers the pulp into the headbox. In order to solve the problem of uniform pulp distribution, it is necessary to set a reasonable inlet flow rate, inlet turbulence, etc. However, the flow of pulp inside the headbox is very complicated. The inlet position of the pulp distributor, the sudden contraction and expansion process that occurs during the flow, the flow process of the conveyor belt, etc., will greatly affect the uniformity of the pulp at the outlet.

[0004] Existing studies have mainly improved the structure and size parameters of the main and branch pipes of the pulp distributor through experimental analysis, and proposed new pulp distributors to improve the uniformity of pulp outlet, such as the non-reflow seam conical tube pulp distributor and the complementary pulp distributor. However, this method has high equipment cost and technical threshold, and it is difficult to fully evaluate the flow characteristics of pulp inside the headbox.

[0005] However, there are few studies on the numerical analysis methods of pulp flow characteristics inside the headbox, and the influencing factors of outlet flow uniformity are still unclear. Summary of the invention

[0006] The present invention is made to solve the above-mentioned problem, and aims to provide a method and system for evaluating flow uniformity of partitioned fibrillation.

[0007] The present invention provides a partitioned fibrillation flow uniformity evaluation method, which has the following characteristics and is used to evaluate the influence of the working conditions of the pulp input into the pulp distributor inlet of the headbox on the flow uniformity of the pulp at the headbox outlet, and comprises the following steps: S10, obtaining the size and structure of the headbox and establishing a corresponding geometric model; S20, using a discrete phase model to perform numerical simulation on the internal flow field in the geometric model; S30, in the numerically simulated internal flow field, releasing streamlines from different areas of the pulp distributor inlet to obtain the streamline distribution of the pulp at the headbox outlet; S40, using the Christiansen grid counting method to perform particle uniformity analysis on the distribution of streamlines released from different areas at the headbox outlet to obtain their uniformity; S50, controlling variables to change the working conditions, repeating steps S30-S40 to obtain different uniformity results, comparing the uniformity of streamlines at the headbox outlet under different working conditions, and realizing the uniformity evaluation of the pulp at the headbox outlet.

[0008] The method for evaluating flow uniformity of zoned fibrids provided by the present invention may also have the following characteristics: wherein the operating conditions include the flow rate and / or turbulence of the pulp.

[0009] The partitioned fibrillation flow uniformity assessment method provided by the present invention may also have the following features: wherein, in steps S10 to S20, the geometric model is a full-scale flow simulation model of the headbox, including a pulp distributor, a pulp distribution pipeline and a conveyor belt structure.

[0010] The partitioned fiber analysis flow uniformity evaluation method provided by the present invention may also have the following characteristics: wherein, the inlet of the pulp distributor is circular, and in step S30, the circular inlet of the pulp distributor is evenly divided into several sectors, and the streamlines flowing into different sector areas are calculated respectively to obtain the streamline distribution of the pulp at the outlet of the headbox.

[0011] The method for evaluating the flow uniformity of partitioned fibrillation provided by the present invention may also have the following feature: the circular inlet of the pulp distributor is evenly divided into 4 sector-shaped areas.

[0012] The partitioned fibrid flow uniformity assessment method provided by the present invention may also have the following features: wherein, in step S40, the headbox outlet is evenly divided into N grids, and the particle size in each grid is counted for quantitative calculation, and the calculation formula for uniformity is: , U is the uniformity, N is the total number of grids, p i For the i The number of particles in a grid, is the average number of particles in each grid, -100<U<+100, the larger the U, the more uniform it is, and the smaller the U, the more non-uniform it is.

[0013] The present invention also provides a partitioned fiber flow uniformity evaluation system, which has the following characteristics: it is used to evaluate the influence of the working conditions of the pulp input into the pulp distributor inlet of the headbox on the flow uniformity of the pulp at the headbox outlet, and includes: a data acquisition part, which is used to obtain the size and structure of the headbox and establish a corresponding geometric model; a numerical simulation part, which receives the geometric model and uses a discrete phase model to perform numerical simulation on the internal flow field in the geometric model; a flow field analysis part, which is used to release streamlines from different areas of the pulp distributor inlet according to the simulation results of the numerical simulation part to obtain the streamline distribution of the pulp at the headbox outlet; a uniformity calculation part, which uses the Christiansen grid counting method to perform particle uniformity analysis on the different streamline distributions obtained by the flow field analysis part to obtain uniformity; a control variable part, which is used to change the streamlines corresponding to different working conditions by controlling variables, and repeatedly input them into the flow field analysis part and the uniformity calculation part, so as to output and compare the uniformity results under different working conditions, so as to realize the uniformity evaluation of the pulp at the headbox outlet.

[0014] The beneficial effects of the present invention are:

[0015] (1) The present invention proposes a numerical analysis method to establish a full-scale headbox pulp flow simulation model, and uses a discrete phase model to numerically simulate the internal flow field of the headbox as a whole. The model divides the pulp distributor inlet position into regions and explores the dispersion of pulp streamlines at the outlet of different partitions. This method uses computer equipment and finite element software tools to analyze flow characteristics, and the cost and professional testing infrastructure required are superior to existing experimental analysis methods.

[0016] (2) The present invention evenly divides the streamline results at the headbox outlet into several grids and performs particle uniformity analysis to calculate the uniformity of the outlet streamline distribution. The control variable method is used to set different inlet flow rates and inlet turbulence to evaluate the flow uniformity at the headbox outlet, and its change law is analyzed. A new method for evaluating the uniformity of fluid flow inside the headbox is proposed, which fills the gap in the existing technology for exploring the flow characteristics inside the headbox. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flowchart of a method for evaluating flow uniformity of partitioned fibrillation according to an embodiment of the present invention.

[0018] Figure 2 It is a schematic diagram of the connection relationship of a partitioned fibrillation flow uniformity evaluation system according to an embodiment of the present invention.

[0019] Figure 3 It is a schematic diagram of the partitioning of the pulp distributor inlet area in the test example of the present invention.

[0020] Figure 4 It is the distribution condition and flow uniformity result at the headbox outlet in step S40 of the test example of the present invention. DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the following embodiments are combined with the accompanying drawings to specifically describe a partitioned fiber flow uniformity evaluation method and system of the present invention.

[0022] <Example>

[0023] Figure 1 It is a flowchart of a method for evaluating flow uniformity of partitioned fibrillation according to an embodiment of the present invention.

[0024] like Figure 1 As shown, this embodiment provides a method for evaluating flow uniformity of partitioned fibrillation, which is used to evaluate the influence of the working conditions of the pulp input into the pulp distributor inlet of the headbox on the flow uniformity of the pulp at the headbox outlet, and includes the following steps:

[0025] S10, obtaining the size and structure of the headbox, and establishing a corresponding geometric model (a full-size flow simulation model of the headbox, including the structure of a pulp distributor, a pulp distribution pipeline, and a conveyor belt).

[0026] S20, the discrete phase model is used to numerically simulate the internal flow field in the geometric model.

[0027] S30, in the internal flow field of the numerical simulation, streamlines are released from different areas of the inlet of the pulp distributor to obtain the streamline distribution of the pulp at the outlet of the headbox.

[0028] S40, the Christiansen grid counting method is used to analyze the particle uniformity of the distribution of streamlines released from different areas at the outlet of the headbox to obtain its uniformity.

[0029] Specifically, in this embodiment, the headbox outlet is divided into N grids, and the particle size in each grid is counted for quantitative calculation. The calculation formula for uniformity is:

[0030] .

[0031] Among them, U is the uniformity, N is the total number of grids, p i For the i The number of particles in a grid, is the average number of particles in each grid, -100<U<+100, the larger the U, the more uniform it is, and the smaller the U, the more non-uniform it is.

[0032] S50, controlling variables to change the flow rate and / or turbulence of the pulp, repeating steps S30-S40 to obtain different uniformity results, comparing the uniformity of streamlines at the headbox outlet under different working conditions, and realizing the uniformity evaluation of the pulp at the headbox outlet.

[0033] Figure 2 It is a schematic diagram of the connection relationship of a partitioned fibrillation flow uniformity evaluation system according to an embodiment of the present invention.

[0034] like Figure 2 As shown, the present embodiment further provides a partitioned fibrillation flow uniformity evaluation system 100, which uses the partitioned fibrillation flow uniformity evaluation method in the present embodiment. The partitioned fibrillation flow uniformity evaluation system 100 in the present embodiment includes a data acquisition unit 10, a numerical simulation unit 20, a flow field analysis unit 30, a uniformity calculation unit 40 and a control variable unit 50.

[0035] The data acquisition unit 10 is used to acquire the size and structure of the headbox and establish a corresponding geometric model.

[0036] The numerical simulation unit 20 receives the geometric model and performs numerical simulation on the internal flow field in the geometric model using a discrete phase model.

[0037] The flow field analysis unit 30 is used to release streamlines from different areas of the inlet of the pulp distributor according to the simulation results of the numerical simulation unit 20 to obtain the streamline distribution of the pulp at the outlet of the headbox.

[0038] The uniformity calculation unit 40 uses the Christiansen grid counting method to perform particle uniformity analysis on the different streamline distributions obtained by the flow field analysis unit 30 to obtain uniformity.

[0039] The control variable section 50 is used to change the streamlines corresponding to different working conditions (pulp flow rate and / or turbulence) by controlling variables, and repeatedly input them into the flow field analysis section 30 and the uniformity calculation section 40, so as to output and compare the uniformity results under different working conditions (pulp flow rate and / or turbulence), thereby realizing the uniformity evaluation of the pulp at the outlet of the headbox.

[0040] <Test example>

[0041] This test example uses a partitioned fibrillation flow uniformity assessment method and system in the embodiment to perform a simulation test.

[0042] The simulation test process is as follows:

[0043] S10, obtaining the size and structure of the headbox, and establishing a corresponding geometric model (a full-size flow simulation model of the headbox, including the structure of a pulp distributor, a pulp distribution pipeline, and a conveyor belt).

[0044] The inlet of the headbox is a circle with a diameter of 150 mm. The fluid will enter the pulp distributor through the inlet, flow through a total of 28 hoses with a radius of 28 mm, and after passing through the headbox, the end is a rectangular outlet with a size of 50 mm × 1300 mm.

[0045] S20, the discrete phase model is used to numerically simulate the internal flow field in the geometric model.

[0046] The turbulence equation is k - ω The model uses a discrete phase model to calculate the outlet streamlines, the inlet uses a mass flow inlet boundary condition, the outlet uses a pressure outlet boundary condition, and the internal flow is calculated based on a steady state pressure.

[0047] S30, in the internal flow field of the numerical simulation, streamlines are released from different areas of the inlet of the pulp distributor to obtain the streamline distribution of the pulp at the outlet of the headbox.

[0048] Specifically, in this test example, the circular entrance is divided into four sectors, which are numbered 1 to 4 in a clockwise direction. These four sectors are respectively recorded as entrance 1, entrance 2, entrance 3 and entrance 4. The partition positions are as follows: Figure 3 As shown, Figure 3 It is a schematic diagram of the partitioning of the pulp distributor inlet area in the test example of the present invention.

[0049] S40, the streamlines of inlet 1 to inlet 4 were counted using the Christiansen grid counting method (the initial operating condition was an inlet flow rate of 150 m 3 / h, turbulence 1%) at the headbox outlet, and the particle uniformity was analyzed to obtain its uniformity and evaluate the flow uniformity.

[0050] Specifically, in this test example, the headbox outlet is divided into N grids, and the particle size in each grid is counted for quantitative calculation. The calculation formula for uniformity is:

[0051] .

[0052] Among them, U is the uniformity, N is the total number of grids, p i For the i The number of particles in a grid, is the average number of particles in each grid, -100<U<+100, the larger the U, the more uniform it is, and the smaller the U, the more non-uniform it is.

[0053] Figure 4 It is the distribution condition and flow uniformity result at the headbox outlet in step S40 of the test example of the present invention.

[0054] like Figure 4 As shown, the uniformity U at the headbox outlet corresponding to inlets 1 to 4 of the pulp distributor in this test example are 3.47, 20.03, 1.56 and 11.23 respectively.

[0055] S50, based on the initial operating conditions in step S40, control variables to change the flow rate and / or turbulence of the pulp, repeat steps S30 to S40 to obtain different uniformity results, compare the uniformity of streamlines at the headbox outlet under different operating conditions (flow rate and / or turbulence), and implement uniformity evaluation of the pulp at the headbox outlet.

[0056] Specifically, in this test case, the control variables change the pulp inlet flow rate to 125 m 3 / h, 175 m 3 / h and 200 m 3 / h, and the calculation was performed by changing the pulp inlet turbulence to 5%, 10% and 15% respectively. The results of the headbox outlet uniformity corresponding to different fan-shaped areas (inlet 1 to inlet 4) of the pulp distributor inlet after controlling the variables are shown in Table 1.

[0057] Table 1 (The uniformity results of the headbox outlet under the initial working conditions of step S40 and the uniformity results of the headbox outlet corresponding to the control variables in step S50 changing the inlet flow rate and turbulence of the pulp respectively)

[0058]

[0059] As shown in Table 1, too high an inlet flow rate is not conducive to flow uniformity, while moderate inlet turbulence is conducive to improving flow uniformity.

[0060] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for evaluating flow uniformity of partitioned fibrillation, characterized in that: The method for evaluating the influence of the working condition of the pulp input into the pulp distributor inlet of the headbox on the flow uniformity of the pulp at the outlet of the headbox comprises the following steps: S10, obtaining the size and structure of the headbox and establishing a corresponding geometric model; S20, numerically simulating the internal flow field in the geometric model using a discrete phase model; S30, in the numerically simulated internal flow field, releasing streamlines from different areas of the inlet of the pulp distributor to obtain the streamline distribution of the pulp at the outlet of the headbox; S40, using the Christiansen grid counting method to perform particle uniformity analysis on the distribution of the streamlines released from different regions at the outlet of the headbox to obtain the uniformity thereof; S50, controlling variables to change the working condition, repeating steps S30 to S40 to obtain different uniformity results, comparing the uniformity of the streamlines at the headbox outlet under different working conditions, and implementing uniformity evaluation of the pulp at the headbox outlet. In step S30, the circular inlet of the pulp distributor is divided into a plurality of sectors, and the streamlines flowing into different sector areas are calculated respectively to obtain the streamline distribution of the pulp at the outlet of the headbox. In step S40, the headbox outlet is divided into N grids, and the particle size in each grid is counted for quantitative calculation. The calculation formula of the uniformity is: U is the uniformity, N is the total number of grids, p i is the number of particles in the i-th grid, is the average number of particles in each grid, -100<U<+100, the larger the U, the more uniform it is, and the smaller the U, the more uneven it is.

2. The method for evaluating flow uniformity of partitioned fibrillation according to claim 1, characterized in that: in, The operating conditions include the flow rate and / or turbulence of the pulp.

3. The method for evaluating flow uniformity of partitioned fibrillation according to claim 1, characterized in that: in, In steps S10 to S20, the geometric model is a full-scale flow simulation model of the headbox, including the structure of the stock distributor, the stock distribution pipeline and the conveyor belt.

4. The method for evaluating flow uniformity of partitioned fibrillation according to claim 1, characterized in that: in, The circular inlet of the pulp distributor is evenly divided into 4 sector-shaped areas.

5. A partitioned fibrillation flow uniformity evaluation system, characterized in that: The method for evaluating flow uniformity of partitioned fibrids according to any one of claims 1 to 4 is used to evaluate the influence of the working conditions of the pulp input into the pulp distributor inlet of the headbox on the flow uniformity of the pulp at the outlet of the headbox, comprising: A data acquisition unit, used to acquire the size and structure of the headbox and establish a corresponding geometric model; A numerical simulation unit receives the geometric model and uses a discrete phase model to perform numerical simulation on the internal flow field in the geometric model; A flow field analysis unit, for releasing streamlines from different inlet areas of the pulp distributor according to the simulation results of the numerical simulation unit, so as to obtain the streamline distribution of the pulp at the outlet of the headbox; A uniformity calculation unit, which uses a Christiansen grid counting method to perform particle uniformity analysis on different streamline distributions obtained by the flow field analysis unit to obtain uniformity; The control variable section is used to change the streamlines corresponding to the different working conditions by controlling variables, and repeatedly input the variables into the flow field analysis section and the uniformity calculation section, so as to output and compare the uniformity results under the different working conditions, so as to realize the uniformity evaluation of the pulp at the outlet of the headbox.

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