نوع مقاله : مقاله پژوهشی

نویسندگان

• حسین پرویزی ¹
• زهره رفیعی ²
• حدیث حاتمی ³
• علی مومن پور ⁴

¹ بخش آبیاری و فیزیک خاک، مرکز ملی تحقیقات شوری، سازمان تحقیقات، آموزش و ترویج کشاورزی، یزد، ایران.

² دانشجوی کارشناسی ارشد بخش مهندسی شیمی، دانشگاه شیراز، شیراز، ایران

³ بخش شیمی خاک و تغذیه گیاه، مرکز ملی تحقیقات شوری، سازمان تحقیقات، آموزش و ترویج کشاورزی، یزد، ایران

⁴ بخش تحقیقات زراعت و باغبانی، مرکز ملی تحقیقات شوری، سازمان تحقیقات، آموزش و ترویج کشاورزی، یزد، ایران

چکیده

دینامیک سیالات محاسباتی (CFD) ابزاری است مناسب به منظور مطالعۀ رفتار جریان در مجرای قطره‌چکان‌ها و می ­تواند شرایط مختلف مدیریتی و محیطی منجر به تغییر در عملکرد آن‌ها را با صرف هزینۀ پایین و در مدت زمان بسیار کوتاه شبیه سازی کند. در این پژوهش، رفتار جریان و میزان رسوب‌گذاری در قطره‌چکان‌های تنظیم‌کنندۀ فشار با مجراهای مارپیچ در شرایط مختلف از نظر شوری و فشار آب بررسی گردید. برای این منظور، از نرم‌افزار COMSOL برای شبیه ­سازی­ ها استفاده شد و نتایج حاصل با داده‌های آزمایشگاهی مقایسه گردید. بررسی تغییرات سرعت و فشار نشان داد که مجراهای مارپیچ به دلیل داشتن دندانه‌ها باعث افزایش سرعت جریان تا 2/8 متر بر ثانیه می­شوند و از رسوب‌گذاری ذرات جلوگیری می‌کنند. با این حال، در نواحی گردابی و گوشه‌ها، سرعت جریان به صفر نزدیک می­شود و خطر تجمع رسوبات افزایش می‌یابد. تحلیل استهلاک فشار نشان داد که دندانه‌های متعدد، فشار جریان را در قطره‌چکان‌های مختلف از 57 تا 87 درصد کاهش می‌دهند. مقایسۀ تغییرات رسوب شبیه‌سازی‌شده و آزمایشگاهی نیز تطابق بالایی (R²=0.98) را نشان داد. نتایج بررسی­ها حاکی است افزایش فشار آب ورودی تا حدود 2/5 بار و شوری آب تا 12 دسی زیمنس بر متر موجب افزایش میانگین حجمی رسوبات به­ترتیب به­میزان 50 و 114 درصد می­شود و قطره‌چکان‌هایی که دارای ناحیه ته‌نشینی اولیه پیش از مجرای مارپیچ هستند، عملکرد ضدگرفتگی بهتری دارند. همچنین افزایش تعداد خروجی‌های جریان منجر به کاهش زمان ماند ذرات درون مجرا و کاهش خطر گرفتگی می‌شود.  

کلیدواژه‌ها

• رسوب
• شوری
• فشار جریان
• مجرای مارپیچ
• COMSOL

موضوعات

• سامانه های نوین آبیاری

عنوان مقاله [English]

Study of Flow and Sediment in the labyrinth Channel of Pressure Compensating emitters Using Computational Fluid Dynamics (CFD)

نویسندگان [English]

• Hossein Parvizi ¹
• zohre Rafiei ²
• Hadis Hatami ³
• Ali Momenpour ⁴

¹ Department of Irrigation and Soil Physics, National Salinity Research Center, Agricultural Research, Education and Extension Organization, Yazd, Iran.

² M.Sc. Student, Department of Chemical Engineering, Shiraz University, Shiraz, Iran

³ Department of Soil Chemistry and Plant Nutrition, National Salinity Research Center, Agricultural Research, Education and Extension Organization, Yazd, Iran

⁴ Department of Agronomy and Horticulture Department, National Salinity Research Center, Agricultural Research, Education and Extension Organization, Yazd, Iran.

چکیده [English]

Extended Abstract
Introduction
Drip irrigation systems play a crucial role in water-efficient agricultural practices. However, clogging in emitters, particularly in labyrinth channels, significantly affects performance and longevity. The deposition of suspended particles within the flow path leads to reduced efficiency, necessitating precise analysis of flow behavior under different operating pressures and salinity conditions. While empirical studies provide valuable insights, computational fluid dynamics (CFD) has emerged as a powerful tool for simulating fluid flow and sedimentation in complex geometries, enabling cost-effective optimization of emitter designs.
Methodology
In this study, flow behavior and sediment deposition in pressure-compensating emitters with labyrinth channels were examined under various salinity and operating pressure conditions. Computational fluid dynamics (CFD) simulations were performed using COMSOL software, and the results were compared with experimental data. Moreover, in our study the pressure-compensating emitters of three different brands - Netafim (8 and 25 L/h), Eurodrip (8 and 24 L/h), and Peresi Zalvan (8 and 24 L/h)- were examined under three operating pressures (0.5, 1.5, and 2.5 bar) and two water salinity levels (5 and 12 dS/m). The COMSOL software was used for CFD simulations, focusing on flow velocity distribution, pressure dissipation, and sediment deposition within the labyrinth channels. Moreover, Experimental validation was conducted at the National Salinity Research Center in Yazd, Iran to compare simulated sediment deposition with actual results obtained from emitter degradation tests.
Results and Discussion
The analysis of velocity and pressure variations demonstrated that spiral channels, due to their serrated edges, increase flow velocity up to 2.8 m/s, effectively preventing particle deposition. However, in vortex regions and corners, the flow velocity approaches zero, increasing the risk of sediment accumulation. The pressure dissipation analysis revealed that multiple serrations reduce flow pressure in different emitters by 57% to 87%. Furthermore, the comparison between simulated and experimental sediment variations exhibited a high degree of correlation (R² = 0.98). The findings indicate that increasing the inlet water pressure to approximately 2.5 bar and the water salinity to 12 dS/m leads to a 50% and 114% increase in the average sediment volume, respectively. Emitters featuring a pre-settlement zone before the spiral channel demonstrate superior anti-clogging performance. Additionally, increasing the number of flow outlets reduces particle residence time within the channel, thereby lowering the risk of clogging. The findings demonstrated that increasing operating pressure up to 2.5 bar and water salinity resulted in higher sediment levels. In alignment with the simulated results, the laboratory study conducted by Parvizi et al. (2025) on the same emitters demonstrated that applying high pressures leads to an increased influx of particles into the labyrinth channels, thereby heightening the risk of clogging. Additionally, Li et al. (2024) stated that increasing the operating pressure within a specific range can improve the anti-clogging performance of a emitters with a star-shaped channel. However, this operating pressure should not exceed the typical working pressure for this type of emitter, which is approximately 1 bar. Among the tested models, Netafim 25 L/h demonstrated anti-clogging capabilities, attributed to its settling zone preceding the primary labyrinth channel. This structure allowed larger suspended particles to settle before entering finer flow paths, reducing clogging potential. Additionally, multi-exit flow designs, such as Netafim’s triple-channel configuration, can effectively minimized particle retention time, lowering obstruction risks. Increasing pressure up to 2.5 bar and salinity led to higher sediment accumulation, confirming that higher pressures exacerbate clogging risks. These findings align with prior research (Yang et al., 2024; Zhang et al., 2022), which demonstrated that modifying channel curvature and increasing exit pathways enhances clogging resistance. Studies have further confirmed that increasing flow velocity in labyrinth channels optimizes sediment transport mechanisms (Wei et al., 2008; Yu et al., 2018).
Conclusion
This research demonstrates that CFD simulation is a reliable tool for predicting and optimizing flow behavior and sediment deposition in pressure-compensating emitters. Overall, higher salinity and an increase in inlet flow pressure up to 2.5 bar led to greater sediment accumulation, which can raise the risk of clogging. The findings of this study demonstrated that the geometry of the spiral channel in drip emitters has a direct impact on flow patterns and clogging behavior. While the serrations in the spiral channel enhance flow velocity and reduce sediment accumulation, flow velocity decreases in vortex regions and corners, increasing the likelihood of particle deposition and clogging risks. Furthermore, it is recommended to reduce the risk of clogging by using emitters with modified curved edges instead of sharp ones. Manufacturers should also consider improving and refining sharp corner structures to enhance performance. Additionally, pressure dissipation is better achieved in emitters with multiple serrations, which likely improves their resistance to clogging. Moreover, this study suggests that CFD enables cost-effective and rapid assessment of pressure and salinity management strategies for pressurized irrigation systems.

کلیدواژه‌ها [English]

• labyrinth channel
• Operating pressure
• salinity
• sediment