Method for measuring flow field in leather and fur processing process
By using tracer particles with the same density and marked obvious markings during leather and fur processing, recording their motion trajectories and analyzing the velocity vector, the problem of difficult measurement of complex flow fields is solved, and the rapid and low-cost visualization of the flow field and detailed data acquisition are achieved.
Patent Information
- Application Number
- CN202311806408.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-26
- Publication Date
- 2025-06-27
AI Technical Summary
Current technical means cannot quickly and at low cost to visualize and measure the complex bath fluid flow fields during leather and fur processing, especially in drums or squeaks. The complexity and non-transparency of the flow field make it difficult to apply traditional flow field visualization technology.
By adding tracer particles with the same density as the bath solution and having a distinctly marked mark to the flow field, the motion trajectory of the tracer particles is recorded with a digital camera, and the velocity vector of the tracer particles is obtained using the particle velocity measurement software, and the flow lines are drawn to visualize the flow field.
It realizes rapid and low-cost visualization of the flow field of the leather and fur processing process, and can obtain streamline and multi-point rate data of the flow field at the same time, providing information such as vortex and spin of the fluid.
Smart Images
Figure CN120213392A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of leather and fur processing and manufacturing, and specifically relates to a method for the flow field during the processing of leather and fur. Background Art
[0002] The leather industry converts raw hides, which are waste products of the meat processing industry and the dairy industry, into high-value-added and durable leather products. Most of the leather and fur processing process is carried out in a drum or a trough. Complex physical and chemical reactions occur between the animal hides and the bath solution (including water and chemicals) in the drum or trough, so as to obtain high-performance and high-quality leather and fur products. In-depth study of the flow field in the drum or trough is of great significance for clarifying the fluid-solid coupling effect between leather / fur and the bath solution and realizing the improvement of quality and efficiency in the leather and fur processing process.
[0003] Flow field measurement technology is an important means to display the dynamic change process of the flow field and explore the change law of the flow field. It can intuitively display the velocity vector of the flow field, so as to effectively improve the intuitiveness and comprehensiveness of the expression of flow field information. With the development of science and technology, a series of flow field visualization technologies have emerged successively, such as the Pitot tube velocity measurement method, the hot wire / film anemometry method, the laser Doppler velocimetry method, and the particle image velocimetry method.
[0004] The flow field in the rotating drum or trough during the leather and fur processing process is extremely complex. It not only involves the complex physical field of liquid-solid two-phase flow, but also the bath solution itself is not an ideal transparent liquid. Therefore, the above-mentioned means cannot effectively obtain the real bath solution flow field. At the same time, as a flexible porous medium, leather / fur moves continuously in the drum or trough, and the shape and area of leather / fur change at all times, which makes the flow characteristics of the bath solution in contact with it also change. The physical and chemical properties of leather / fur and the bath solution will also change significantly as the processing process progresses. These complex phenomena further increase the difficulty of obtaining the flow field. To sum up, the current technical means cannot perform rapid and low-cost visualization measurement on this complex flow field.
[0005] In view of this, this patent proposes an observation method for the bath solution flow field and a tracer particle structure during the leather and fur processing process. Summary of the Invention
[0006] The purpose of the present invention is to establish a method for flow field visualization that is fast, low-cost and applicable to the leather and fur processing process.
[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for measuring the flow field in leather and fur processing, adding tracer particles with obvious identification into the flow field of the leather or fur processing to be measured, recording the movement trajectories of each tracer particle with a digital camera, identifying and distinguishing each tracer particle in the movement trajectories with particle velocity measurement software, and obtaining the velocity vectors of each tracer particle at different times, and drawing streamlines according to the velocity vectors to obtain the flow field; wherein, the leather or fur processing process refers to stirring animal skins and bath solutions in a sealed device; the density of the tracer particles is the same as that of the bath solution.
[0008] Preferably, the bath solution can be a processing solution of water and one or more chemicals, or a processing solution containing only water.
[0009] Preferably, the sealed device is selected from one or more of a drum and a paddle vat, and at least one side is transparent, and the material of the transparent surface is selected from any one or more of quartz glass and transparent plastics.
[0010] Preferably, the leather and fur processing process is selected from any one or more of soaking, liming, depilation, degreasing, softening, pickling, tanning, rewetting, neutralizing, retanning, dyeing, fatliquoring, and filling.
[0011] Preferably, the chemicals are selected from any one or more of enzyme preparations, tanning agents, retanning agents, dyes, fatliquoring agents, and leather and fur processing aids.
[0012] Preferably, the diameter of the tracer particles is 1.0 mm to 5.0 cm.
[0013] Preferably, the tracer particle material is selected from any one or more of polyolefins, polyamides, polyesters, polyaldehydes, polyurethanes, stone powder, and wood powder.
[0014] Preferably, the identification of the tracer particles is selected from any one or more of color, pattern, number, shape, and pattern.
[0015] Preferably, the number of the tracer particles is 10 to 300.
[0016] Preferably, record the movement trajectories of the tracer particles for 1 min to 5 h.
[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The flow field measurement method for leather and fur processing provided by the present invention puts tracer particles with the same density as the bath solution and obvious identification into the flow field. The tracer particles have little disturbance to the flow field. Later, the velocity vectors of each tracer particle can be obtained by using self-programmed particle velocity measurement software, and a simple flow field can be quickly drawn to realize the visualization of the flow field in leather and fur processing.
[0018] 2. The method for measuring the flow field in leather and fur processing provided by the present invention uses tracer particles that are simple and easy to obtain. The shooting process can use a conventional digital camera without irradiating the flow field with a laser (sheet light source). The flow field data can be processed using self-programmed particle velocity measurement software, so the cost is low.
[0019] 3. Compared with the smoke method that can only obtain streamlines and the pressure test method that can only obtain the single-point rate in the flow field, the flow field measurement method in leather processing provided by the present invention can simultaneously obtain simple flow field streamlines and the rates at multiple points in the flow field, and can also obtain data such as the vorticity and curl of the fluid around the tracer particles. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a schematic diagram of the experimental method of the present invention. In the figure, 1 is a sealing device, 2 is a tracer particle, and 3 is a digital camera; Figure 2 Different spherical tracer particles are exemplified; Figure 3 Flow field diagrams drawn for Examples 1-3. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention. For those not specified in the embodiments, they are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.
[0022] Reference Figure 1 , the embodiment provided by the present invention is: a method for measuring the flow field in leather and fur processing, adding tracer particles with obvious marks into the flow field of the leather or fur processing to be measured, using a digital camera to record the movement trajectories of the tracer particles, using particle velocity measurement software to identify and distinguish each tracer particle in the movement trajectories, and obtaining the velocity vectors of each tracer particle at different times, and drawing streamlines according to the velocity vectors to obtain the flow field; wherein, the processing process of the leather or fur refers to stirring animal skins and bath solutions in a sealing device; the density of the tracer particles is the same as the density of the bath solution.
[0023] The key point of the embodiment of the present invention is that the density of the tracer particles is the same as the density of the bath solution, so the disturbance of the tracer particles to the flow field is small.
[0024] In some preferred embodiments, the tracer particles should have distinct markings so that they can be accurately identified directly using a digital camera and software, and the velocity vectors of each particle can be calculated accordingly.
[0025] As some preferred embodiments, the particle markings include one or more of color, shape, identification symbols (such as numbers, patterns, patterns, etc.), such as Figure 2 shown.
[0026] There are no special limitations on the number and diameter of the tracer particles. Those skilled in the art can determine them according to the volume of the sealing device used to obtain a more accurate flow field. For example, when the volume of the sealing device is larger, the diameter of the particles is larger and the number is more. In some preferred embodiments, the number of tracer particles is 10 to 300, and the diameter is 1 mm to 5 cm.
[0027] The sealing device is selected from any one or more of a rotary drum and a grooved drum. At least one side of the sealing device is transparent to facilitate recording the movement of the tracer particles. The material used for the transparent surface of the sealing device is a common transparent material, such as quartz glass, transparent plastic, etc.
[0028] As some preferred embodiments, the material of the particles is selected from any one or more of polyolefins, polyamides, polyesters, polyacetals, polyurethanes, stone powder, and wood powder.
[0029] In some specific embodiments, the method for measuring the flow field specifically includes: loading leather / fur into a sealing device with at least one transparent side. Adding the bath solution required for leather / fur processing, adjusting the light source until the light evenly and sufficiently irradiates the shooting surface, and then adding 10 to 300 tracer particles with a diameter of 1 mm to 5 cm that have the same density as the bath solution. Starting the sealing device, waiting for the flow field to stabilize, and using a high-frame-rate digital camera to shoot a video of the particle movement trajectory for 1 min to 5 h. Importing the video into particle velocity measurement software, identifying and distinguishing each tracer particle, analyzing the position change of each particle between two adjacent frames of the video, obtaining the velocity vectors of each particle at different times, and thus drawing streamlines to obtain the flow field.
[0030] To further elaborate on the technical solution of the present invention, the following will use multiple embodiments to detail the method for measuring the process during leather and fur processing and the measurement effect.
[0031] Example 1 The following material dosages are all in terms of the mass percentage (wt%) of leather.
[0032] Put pigskin into a drum with a length of 40 cm and a diameter of 30 cm. The front of the drum is made of quartz glass. Add 100 wt% of water and 0.5 wt% of leather softening enzyme. Adjust the light source until the light evenly and sufficiently irradiates the shooting surface. Then add 10 tracer particles. The materials of the particles are polyamide, wood powder, and pigments. The pigments are red, green, and blue. The particle diameter is 1 mm, and the density is the same as that of the bath solution. Start the drum. After the flow field is stable, use a high-speed digital camera to shoot a 1-minute video. Import the video into self-programmed particle velocity measurement software, identify and distinguish the particles, calculate the position change of each particle between two adjacent frames of the video, obtain the velocity vectors of each particle at different times, and thus draw streamlines to obtain the flow field, as Figure 3 shown.
[0033] Example 2 The following material dosages are all in terms of the mass percentage (wt%) of leather.
[0034] Put sheepskin into a drum with a length of 60 cm and a diameter of 120 cm. The front of the drum is made of transparent plastic. Add 80 wt% of water and 6 wt% of tanning agent. Adjust the light source until the light evenly and sufficiently irradiates the shooting surface. Then add 60 tracer particles. The materials of the particles are polyethylene and stone powder, and the surface is marked with different numbers (1 - 20). The particle diameter is 7 mm, and the density is the same as that of the bath solution. Start the drum. After the flow field is stable, use a high-speed digital camera to shoot a 10-minute video. Import the video into commercial particle velocity measurement software, identify and distinguish the particles, calculate the position change of each particle between two adjacent frames of the video, obtain the velocity vectors of each particle at different times, and thus draw streamlines to obtain the flow field, as Figure 3 shown.
[0035] Example 3 Put rabbit skin into a grooved drum with a width of 40 cm and a diameter of 30 cm. The front of the grooved drum is made of transparent plastic. Add 14 L of water, 420 g of sodium chloride, 560 g of anhydrous sodium sulfate, 7 g of degreasing agent, 7 g of surfactant, and 70 mL of formic acid. Adjust the light source until the light evenly and sufficiently irradiates the shooting surface. Then add 20 tracer particles. The materials of the particles are polytetrafluoroethylene and polyethylene, and the surface is marked with different letters (A - V). The particle diameter is 1 cm, and the density is the same as that of the bath solution. Start the drum. After the flow field is stable, use a high-speed digital camera to shoot a 30-minute video. Import the video into self-programmed particle velocity measurement software, identify and distinguish the particles, calculate the position change of each particle between two adjacent frames of the video, obtain the velocity vectors of each particle at different times, and thus draw streamlines to obtain the flow field, as Figure 3 shown.
[0036] Example 4 The following material dosages are all based on the mass percentage (wt%) of the leather.
[0037] Load the cowhide into a drum with a length of 250 cm and a diameter of 350 cm. The front of the drum is made of transparent plastic. Adjust the light source until the light evenly and sufficiently irradiates the shooting surface, and then add 300 tracer particles. The materials of the particles are polyethylene terephthalate and polypropylene, and the surface is marked with different patterns (triangles, pentagrams, etc.). The particle diameter is 5 cm, and the density is the same as that of the bath solution. Then add 100 wt% of water and 9 wt% of retanning agent, and rotate for 90 min; then add 1.5 wt% of dye and rotate for 90 min; finally add 12 wt% of fatliquor and rotate for 60 min; then add 1.2 wt% of formic acid and rotate for 60 min. Use a high-frame-rate digital camera to shoot a video with a total duration of 5 h. Import the video into self-programmed particle measurement software, identify and distinguish the particles, calculate the position change of each particle between two adjacent frames of the video, obtain the velocity vectors of each particle at different times, and thus draw streamlines to obtain the flow field.
[0038] Example 5 Load the mink skin into a trough with a width of 85 cm and a diameter of 60 cm. The front of the trough is made of transparent plastic. Add 100 L of water, and add 4000 g of salt, 2000 g of ammonium alum, 200 g of aluminum tanning agent, 400 g of auxiliary tanning agent, and 200 g of baking soda. Adjust the light source until the light evenly and sufficiently irradiates the shooting surface, and then add 80 tracer particles. The materials of the particles are polyvinyl chloride and polyoxymethylene, and the surface is marked with different patterns (triangles, squares, pentagrams, etc.). The particle diameter is 2 cm, and the density is the same as that of the bath solution. Start the drum, and wait until the flow field is stable. Use a high-frame-rate digital camera to shoot a video with a duration of 1 h. Import the video into self-programmed particle velocity measurement software, identify and distinguish the particles, calculate the position change of each particle between two adjacent frames of the video, obtain the velocity vectors of each particle at different times, and thus draw streamlines to obtain the flow field.
[0039] Example 6 Load the fox skin into a trough with a width of 400 cm and a diameter of 300 cm. The front of the trough is made of quartz glass. Add 140 L of water, and add 70 g of soaking aid, 168 g of degreasing agent, and 14 g of fungicide. Adjust the light source until the light evenly and sufficiently irradiates the shooting surface, and then add 200 tracer particles. The materials of the particles are polyurethane, polyamide, and pigments. The pigments are orange, green, blue, and black. The particle diameter is 4 cm, and the density is the same as that of the bath solution. Start the drum, and wait until the flow field is stable. Use a high-frame-rate digital camera to shoot a video with a duration of 2 h. Import the video into self-programmed particle velocity measurement software, identify and distinguish the particles, calculate the position change of each particle between two adjacent frames of the video, obtain the velocity vectors of each particle at different times, and thus draw streamlines to obtain the flow field.
[0040] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A method for measuring the flow field during leather and fur processing, characterized in that Add tracer particles with obvious identification into the flow field of the leather or fur processing process to be measured, record the movement trajectories of each tracer particle with a digital camera, identify and distinguish each tracer particle in the movement trajectories with particle velocity measurement software, obtain the velocity vectors of each tracer particle at different times, and draw streamlines according to the velocity vectors to obtain the flow field; Among them, the leather or fur processing process refers to stirring animal skins and bath solutions in a sealed device; The density of the tracer particles is the same as that of the bath solution.
2. The method for measuring the flow field during leather and fur processing according to claim 1, characterized in that, The bath solution can be a processing solution of water and at least one chemical, or a processing solution containing only water.
3. The method for measuring the flow field during leather and fur processing according to claim 1, characterized in that At least one side of the sealed device is transparent.
4. The method for measuring the flow field in the leather and fur processing process according to claim 1, wherein The leather and fur processing process includes any one of soaking, liming, dehairing, degreasing, softening, pickling, tanning, rewetting, neutralizing, retanning, dyeing, fatliquoring, and filling.
5. The method for measuring the flow field during leather and fur processing according to claim 2, characterized in that, The chemicals are selected from any one or more of enzyme preparations, tanning agents, retanning agents, dyes, fatliquoring agents, and leather and fur processing aids.
6. The method for measuring the flow field during the processing of leather and fur according to claim 1, characterized in that, The diameter of the tracer particles is 1.0 mm to 5.0 cm.
7. A method for measuring the flow field during leather and fur processing according to claim 1 or 6, characterized in that, The tracer particle material is selected from any one or more of polyolefins, polyamides, polyesters, polyaldehydes, polyurethanes, stone powder, and wood powder.
8. A method for measuring the flow field during the processing of leather and fur, as claimed in claim 1 or 6, characterized in that The identification of the tracer particles is selected from any one or more of colors, patterns, numbers, shapes, and patterns.
9. The method for measuring the flow field during leather and fur processing according to claim 1, wherein, The number of the tracer particles is 10 to 300.
10. A method for measuring the flow field during the processing of leather and fur, as described in claim 1, characterized in that, Record the movement trajectories of the tracer particles for 1 min to 5 h.