بررسی تاثیر صفحه تنظیم‌کننده جریان خروجی بر عملکرد سیکلون آرد: مطالعات تجربی و شبیه‌سازی عددی

سیکلون‌ها با توجه به هزینه‌های ساخت و نگهداری نسبتاً پایین و سادگی آن‌ها همواره در صنعت و کشاورزی مورد توجه بوده‌اند. دینامیک سیالات محاسباتی (cfd) یکی از ابزارهای توانمند برای پیش‌بینی رفتار در شرایط مختلف است که با حل عددی معادلات ناویر استوکس درک بهتری از حل عددی در شرایط آشفتگی جریان سیال می‌دهد. در این مطالعه تاثیر صفحه تنظیم جریان مکشی در یک سیکلون مورد استفاده در صنعت آرد، بر روی جریان‌های داخلی در داخل سیکلون مورد بررسی قرار گرفته است. از نرم‌افزار گمبیت و نرم‌افزار انسیس فلوئنت نسخه‌ی 15 به‌ترتیب برای رسم هندسه مسئله، ایجاد شبکه، اعمال شرایط مرزی و هم‌چنین برای حل معادلات بقا بهره گرفته شد. از مدل آشفتگی تنش‌های رینولدز rsm برای شبیه‌سازی آشفتگی جریان داخل سیکلون استفاده گردید. لازم به ذکر است که با توجه به رقیق بودن جریان آرد در داخل جریان هوای حامل از مدل فاز گسسته (dpm) برای ردیابی ذرات از طریق میدان جریان استفاده گردیده است. در زوایای صفحه صفر، 15، 30، 45، 60 و 75 درجه، پارامترهای اندازه سرعت، سرعت محوری، بازده جمع‌آوری، افت فشار، ضریب اصطکاک سطح و هم‌چنین شدت آشفتگی با جزئیات استخراج گردیده و در قالب کانتورهای هم‌ارز شده با شاخص یکسان، با یکدیگر مقایسه شدند. علاوه بر این برای درک هرچه بیش‌تر رفتار جریان، کانتورهای مربوط به مسیر حرکت برای سیکلون استخراج گردیدند. نتایج نشان داد که با در نظر گرفتن تمامی شرایط، زاویه صفحه تنظیم‌کننده 30 درجه با افت فشار 134.2 پاسکال و بازده جمع‌آوری 95.3 درصد دارای بهترین شرایط در بین حالت‌های مورد بررسی می‌باشد.

Investigating the Effect of Output Flow Regulator Plate on the Performance of Flour Cyclone: Experimental Studies and Numerical Simulations

IntroductionCyclone separators use the centrifugal force generated by the gas flow stream to separate the particles from their carrier gas. Simple design, low capital, and easy maintenance make them ideal for use as a valuable prerefining or sedimentation device. The cause of the particles moving towards the wall and separating from the fluid phase is the centrifugal force created by the rotational flow in a cyclone.Computational fluid dynamics (CFD) is one of the most wellknown and widely used advanced modeling methods used for a variety of applications, including separation processes, thermal processes such as dryers, as well as a wide range of engineering and agricultural applications. The numerical solution of NavierStokes equations is the basis of all CFD techniques, which is the result of the rapid progress of computers and a deep understanding of the numerical solution of turbulence phenomena.Materials and MethodsThe measurement system of experimental data includes a cyclone separator, feeder, piping, and fan. Measurements of velocity and pressure were carried out using a hot wire air flow rate, (Model 8465TSI with a resolution of 0.07 m.s1 and a working range of 0.125 to 150 m.s1), as well as a differential pressure gauge (CPE310s KIMO, with an accuracy of 0.1 Pa), respectively. To investigate the effect of the output flow regulator plate on the cyclone performance, five different positions in addition to the base position (zero degree angle or fully open) including angles of 15, 30, 45, 60, and 75 degrees were evaluated.The conservation laws governing the various flows and geometries in the CFD include the conservation law of mass, conservation law of momentum, and conservation law of energy.According to the Mach number value, the pressure base solver was selected. Also, the Reynolds stress model (RSM) was applied to model the flow turbulence. In the discrete phase model (DPM), the fluid phase is solved continuously by solving averaged time equations, while the dispersed phase is calculated by tracing a large number of particles through the flow field.The boundary conditions used in this study include the inlet velocity boundary condition at the inlet of the cyclone, the outlet pressure boundary condition in the upper and lower outlet sections, and the nonslip wall boundary condition for other surfaces. The particle collision to the wall was also defined as reflective. In the mesh section of the cyclone simulation, five mesh levels were used to check the mesh independence test. The numbers of mesh cells in the five levels were 196810, 283120, 427890, 634940, and 1045290. The selected mesh was 427890 level regarding time consideration.Results and DiscussionIn the first section, the validation of simulation results with experimental results is discussed. The value of the velocity magnitude decreased with increasing the angle of the plate, which is probably due to the reduction of the inlet level as well as the reduction of the exhaust airflow in the cyclone air outlet.The maximum value of velocity magnitude occurred according to the direction of the air inlet in the cyclone inlet, which is gradually reduced due to the rotational motion inside the cyclone.The collection efficiency in the cyclone at different levels of regulating plate has values of 85.1% to 95.3%, with maximum collection efficiency at 30° which was 95.3%. The turbulent intensity contours show that turbulence intensity decreases to an angle of 30 °, and then reaches an almost constant value for the 30, 45, and 60 ° angles.ConclusionAs the angle of the output current regulator plate increased, the magnitude of velocity decreased significantly.The separation efficiency showed an increasingdecreasing trend for different values of the regulator plate such that up to a 30° angle of the plate had a positive effect on the separation efficiency.In general, considering the compromise between separation efficiency and pressure drop as two key parameters affecting the performance of the cyclone, an angle of 30 degrees was selected as the best angle among the studied angles for application.