| In the traditional water treatment field,it mainly includes two parts of mixing and flocculation.The degree of mixing result is directly related to the subsequent flocculation process and sedimentation process,and has a direct correlation with the quality of the treated water.With the rapid development of computer technology,the hydrodynamics research of SK static mixer by numerical simulation has been recognized by more and more scholars.The results of most studies show that the internal fluid motion of SK static mixer is mixed with originals.The number and the special structure of the original mixer are determined by factors such as the structure.For some specific flow fields,because the coupling exists between different physical fields,it is impossible to simulate different physical fields at the same time by using common models.Therefore,many models will calculate specific flow scenarios.The result of distortion.This paper is study the mixing stage in the flocculation system.The purpose is to test the SK static mixer by a more efficient and simple test method,and compare the experimental results with the numerical calculation results,and then analyze the different models.The calculation accuracy of low Reynolds number mixing provides theoretical basis and technical support for the research of coagulation system.In this paper,the numerical simulation of different models is used to calculate the internal flow field of the SK static mixer,and the parameters such as mixing degree,density distribution,velocity field and pressure drop are obtained and the calculation results are analyzed.At the same time,the high-density mixture is used to simulate flocculation.The mixing test was carried out to explore the mixing state of the first-stage and third-stage mixers under different Reynolds numbers,and the test results were compared with the numerical simulation to analyze the calculation accuracy of different models.The specific contents are as follows:(1)Based on the research background and significance of the subject,the development and research status and numerical simulation of static mixers at home and abroad are briefly described from various aspects,and the research contents and methods are proposed according to the research objectives.(2)The main flow state inside the mixer is obtained through the study of the mixing mechanism.The low Reynolds number is mainly composed of laminar flow mixing.It also points out the effect of the mixing elements of the mixer on the internal flow field.Under the influence of the specific shape of the mixing element,the fluid is subjected to successive left and right rotation changes inside the mixer,and at the junction of the mixing elements,the fluid is continuously cut and merged,so that the mixing effect in the radial direction is continuously increased.(3)Analyze the mixing stage in the flocculation system and design a test plan.Use a high concentration mixture instead of the flocculant in the flocculation system,and use the flow meter and adjust the height difference between the outlet and the inlet to control the flow rate inside the mixer.The adjustable sampling tool is used to sample the specific section of the mixing unit outlet to obtain a density distribution,and the U-tube is used to measure the pressure drop in real time.The mixing performance of the mixer was investigated by measuring the pressure drop of the primary and tertiary mixers in the low Reynolds number range,the degree of mixing and the density distribution of the mixer outlet section.(4)Perform numerical simulation on the SK static mixer,select a variety of different calculation models,and compare and analyze the important parameters such as the mixing degree,velocity field distribution,density distribution and pressure drop of the calculation results and the test results.On the other hand,the ranking of the matching results of all the models is obtained,and the model which is more suitable for calculating the mixing of static mixers with low Reynolds numbers is obtained. |
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