ansys-cfx
در نشریات گروه مکانیک-
Modern pump and turbomachinery design merges innovative methodologies with computational tools for optimal efficiency and adaptability. This study delves into the intricate design of a parametric blade generator using Bézier curves, renowned for their precision in sculpting smooth, user-defined curves, and offering vast prospects in turbomachinery blade design. Leveraging this precision, our methodology employed eight pivotal anchor points to shape the Bézier surface blade: three at the base, three at the top, and two strategically placed midpoints. These midpoints enhance curvature control, ensuring the blade's form encapsulates the desired aerodynamic and fluid flow properties. Using these eight defined points and four bounding curves, the blade's holistic spatial profile was meticulously drafted. The CAD modeling system, with its advanced loft and guide curve functions, was instrumental in generating the blade surface, resulting in an aerodynamically adept profile optimized for maximum flow efficiency. Beyond the blade, the pump casing geometry was another pivotal focus. Adopting a parametric shape generation for the casing ensured system-wide design coherence, minimizing potential operational bottlenecks and inefficiencies. Classical optimization and iterative refinements were applied to the initial design, with each step analyzed to ensure the final model achieved high performance. Traditional blade design methodologies often offer limited flexibility, confining designers to specific templates and forms. However, this methodology provided greater design flexibility and set a new benchmark in performance optimization. As industries continually evolve and demand more from turbomachinery, the methodologies presented herein will be at the forefront, guiding us into an era of enhanced efficiency, adaptability, and innovation.Keywords: Type Your Computational Fluid Dynamics (CFD), Bézier Curve Parametrization, Pump Performance, ANSYS CFX, Dakota Optimization
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Pivot weirs are one of the most important structures for regulating the water level in rivers and canals. These weirs are constructed with one or more gates in a row in the waterways. Changing the angle of each gate is done individually with an independent system. Based on available information, the hydraulic performance of this type of weirs (especially in several gates and different angles) in different operational conditions has not been investigated. In present study, pivot weirs with two gates are simulated using Ansys CFX software with the angles of 27.8 to 90 degree and the discharges between 40 to 130 L/s. Further, the importance of the open space between the two adjacent weirs with different angles (lack of retail wall) and its hydraulic behavior have been studied. The model was calibrated based on valid laboratory data and using the K-ϵ turbulence model. Therefore, the weirs with equal angles were studied in the first step. In this case, the effective discharge angle coefficient was studied and its maximum value compared to the vertical angle was obtained 1.076 for the angle of 52°. Furthermore, relationships for discharge coefficient versus upstream water depth were developed. In the next step, the effective length of the crest was found to be increases by 30% under unequal angles operation and the discharge coefficient raised by 1.3 to 2.4 times. Also, it was recognized that, in case of two weirs with unequal angles, about 26% to 69% of the flow passes through the distance between the two weirs. Therefore, the performance of unequal angles operation seems to be more effective in controlling the water level and discharge in different conditions and especially in flood events.Keywords: Ansys CFX, Pivot Weir, k-ε turbulence model, Discharge coefficient, Free flow
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پمپ بازتولیدکننده، پمپ هایی با سرعت مخصوص بسیار پایین می باشند. مشخصه اصلی پمپ های بازتولیدکننده توانایی تولید هدهای بالا در دبی های پایین می باشد. باوجود مزایای بسیاری که پمپ های بازتولیدکننده دارند، این پمپ ها به طور ذاتی و ساختاری دارای یک نقطه ضعف هستند و آن داشتن بازده هیدرولیکی پایین می باشد. علت این پدیده الگوی پیچیده جریان سیال در این نوع از توربوماشین است. در این مقاله از روش های عددی و آزمایشگاهی جهت تحلیل و بهبود عملکرد پمپ های بازتولیدکننده و همچنین بررسی اثر جریان نشتی پیرامون پروانه استفاده شده است. از مدل اس اس تی (sst) برای مدل سازی آشفتگی استفاده گردیده است. به منظور اعتبار سنجی یک مدارتست آزمایشگاهی پمپ های بازتولیدکننده طراحی و ساخته شده است. مقایسه نتایج عددی و آزمایشگاهی از انطباق و تطابق بالایی برخوردار هستند که نشان دهنده صحت بالای شبیه سازی عددی می باشد. باتوجه به نتایج می توان بیان کرد افزایش ضخامت هندسی نشتی منجر به افزایش اختلاط سیال پرفشار نایحه خروجی و سیال کم فشار ناحیه ورودی گریده و نهایتا سبب کاهش مقدار هد تولیدی پمپ بازتولیدکننده می شود. پارامتر عملکردی بازده نیز با افزایش ضخامت هندسی نشتی به 4/0 میلیمتر کاهش چشمگیری نسبت به هندسه اصلی و اولیه با نشتی 26/0 میلیمتر خواهدداشت. از طرفی کاهش ضخامت نشتی به 2/0 میلیمتر منجر به بهبود پارامترهای عملکردی هد و بازده پمپ بازتولیدکننده خواهدگردید. همچنین هندسه ایده آل بدون نشتی جهت حد بیشینه و فرضی پارامترهای هد و بازده معرفی و محاسبه شده است.
کلید واژگان: پمپ بازتولیدکننده، نشتی پروانه، انسیس سی اف ایکس(Ansys CFX)، پروانه شعاعیRegenerative pumps are pumps with a very low specific speed. The main characteristic of regenerative pumps is the ability to produce high heads at low flow rates. In this article, numerical and experimental methods have been used to analyze and improve the performance of regenerative pumps and also to investigate the effect of leakage flow around the impeller. In order to validate, an experimental test circuit of regenerative pumps has been designed and built. The comparison of the numerical and experimental results have a good agreement, which indicates the high accuracy of the numerical simulation. Based on the results of the study, we conclude that increasing the geometric thickness of the leak leads to an increase in mixing the high-pressure fluid of the outlet nozzle with the low-pressure fluid of the inlet area, leading to a decrease in the generating head generated by the regenerative pump. The performance parameter of efficiency will also decrease significantly by increasing the geometric thickness of the leakage to 0.4 mm compared to the original geometry with a leakage of 0.26 mm. On the other hand, reducing the leakage thickness to 0.2 mm will lead to the improvement of the functional parameters of the head and the efficiency of the reproducing pump. Also, the ideal geometry without leakage has been introduced and calculated for the maximum and theoretical limit of head and efficiency parameters.
Keywords: Regenerative pump, Impeller leakage, Ansys CFX, Radial impeller -
In industry, the phenomenon of cavitation erosion can reduce the lifetime of the components of hydraulic machines. In this article, we present a new numerical approach to predict the mechanical impact resulting from the implosion of a cloud of bubbles, based on an energy approach. The objective of this approach is to determine the main damage mechanisms and to estimate the intensity of the impact pressure near the surface. The large eddy simulation (LES) approach is coupled with a homogeneous cavitation model to assess the risk of erosion around the hydrofoil NACA0009. Indeed, three functions, namely the Pressure Intensity Function (PIF), the steam intensity function and the Erosive Power Function (EPF), are applied to assess the spatial distribution of eroded areas. The calculations show that the functions based on the pressure term are in good agreement with the experiments, namely: the PIF and EPF functions. On the other hand, we assume that the implosion of the cloud of bubbles produces a pressure wave, which in turn causes the implosion of small bubbles near the wall. Then the erosion will be the result of these secondary implosions and not of the cloud of bubbles. Therefore, we vary the degree of proximity of these micro-bubbles near the wall to choose either the shock wave or the micro-jet to extrapolate the pressure field. We can compare these estimates with the existing erosion measurements and we can conclude that the calculations respond more to the probability of the presence of a micro-jet than to the presence of a shock wave.Keywords: Cavitation erosion, Shock wave, Micro-jet, 3D unsteady simulation, Ansys-CFX
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امروزه با پیشرفتهای چشمگیر در حوزه صنایع دریایی، طراحی بدنه و ملحقات اعم از پروانه، سکان و سیستم های کنترلی شناورها دستخوش تغییرات زیادی شده است. یکی از موضوعات مورد توجه در این روزها، شناورهای تندرو و افزایش سرعت پیشروی و قدرت مانور پذیری آنهاست. با پیشرفت تکنولوژی و طراحی های جدید در زمینه طراحی پروانه، امروزه پروانه هایی تحت عنوان پروانه های نیمه مغروق در شناورهای تندرو بسیار مورد استفاده قرار میگیرد. به علت اینکه شناورهای تندرو سطح تماس کمی با آب دارند، این پروانه ها در راندمان های بسیار خوب باعث رانش شناور در سرعت های بالا می شوند. یک نمونه از این پروانه ها، پروانه الافسون است که به عنوان یک نمونه تحقیقاتی در دسترس محققان قرار دارد. در این تحقیق نیز از مدل پروانه الافسون، جهت بررسی در فواصل مختلف سکان از پروانه، استفاده شده است. در این تحقیق به کمک نرم افزار ANSYS-CFX پروانه و سکان در سه فاصله مختلف از هم مورد آزمایش قرار گرفته و تراست و گشتاور تولیدی پروانه در یک دور کامل محاسبه می گردد. همچنین اثر نیرو و گشتاور تولیدی توسط پروانه بر سکان مورد بررسی قرار میگیرد. هدف از انجام این تحقیق، پیش زمینه ای برای تعیین موقعیت بهینه نصب سکان در شناورهای تندرو جهت افزایش بازدهی می باشد.کلید واژگان: پروانه نیمه مغروق، سکان، دینامیک سیالات محاسباتی، ANSYS-CFXToday, with significant advances in the maritime industry, body design and appendages, including Propellers, rudders, and surface control systems, have many changes. One of the topics of interest these days is high-speed vessels, which increase their speed and maneuverability. With the advancement of technology and new designs in the field of Propellers design, today Propellers called Surface piercing Propellers (SPP) are widely used in high-speed vessels. Because high-speed vessels have low levels of contact with water, these propellers cause very high efficiency at high speeds. One example of this butterfly is the Oloffson Propellers, which is available to researchers as a research sample. In this study, the Oloffson Propellers model was used to test the Propeller at different distance from the rudder. In this research, by using of ANSYS-CFX software, the interaction between Propeller and rudder at three different distances from each other were tested, and the thrust and torque produced by the Propeller are calculated in a complete cycle. Also, the effect of force and torque produced by the Propeller on the rudder is examined. The aim of this study is to provide a background for rudder installation optimum position on planing boats.Keywords: Surface piercing Propeller (SPP), rudder, Computational Fluid Dynamics (CFD), ANSYS-CFX
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یافتن الگوی صحیح جریان سیال در پمپ های دیافراگمی، توزیع نیروی حاصل از فشار اعمالی از سوی سیال بر دیافراگم و همچنین یافتن شرایط مناسب عملکرد برای طراحی به دور از حالت های ناپایداری چون کاویتاسیون، یکی از اهداف این مطالعه است. هدف این تحقیق یافتن روشی مناسب برای شبیه سازی عملکرد این نوع از پمپ ها در مقابل روش های پیچیده تحلیلی و هزینه بر آزمایشگاهی است. یک نمونه پمپ دیافراگمی متداول در ایستگاه تقلیل فشار گاز شهری مورد بررسی قرار گرفته، بر اساس اطلاعات فنی استخراج شده از این پمپ، مدلی برای شبیه سازی آن با نرم افزار انسیس سی اف ایکس پیشنهاد شده است. نرخ جریان سیال مرکاپتان با توجه به اطلاعات فنی پمپ در ایستگاه دریافت و نتایج مدل سازی با آن مقایسه شده است. برخی از نتایجی که در این مقاله به آن اشاره شده است عبارتند از میدان های سرعت و فشار برای سیال ورودی و خروجی، نرخ جریان سیال برحسب جابه جایی دیافراگم، حجم سیال ورودی و خروجی برحسب زمان و همچنین نرخ جریان سیال خروجی برحسب فرکانس حرکتی دیافراگم که نتایج موجود در بیشترین حالت دارای خطایی کمتر از 10 درصد می باشند.کلید واژگان: پمپ دیافراگمی، برهمکنش سازه و سیال، نرم افزار A N S Y S C F XDiaphragm pumps are positive displacement pumps which have many applications in the petrochemical, and gas industries. As an example, Infusion pumps can be mentioned which are highly regarded in the gas industry due to the good resistance against chemical fluids. Since the diaphragm pumps are composed of various mechanical parts, some of which, such as the diaphragm, are in direct contact with the fluid, many different causes of mechanical damage are reported from some consumer companies such as Gas Company for this purpose, finding a model similar to the actual model is very useful. One of these pump's design and manufacturing methods is using commercial codes for simulation rather sophisticated and expensive laboratory methods. Since the fluid in the pump is transmitted by a diaphragm motion, the concept called the fluid structure interaction is defined due to the problems related to simulations of fluid structure interaction, animated network simulation, and geometry of the pumps, limited deal of efforts has been done in the past for numerical analysis of these pumps. Today, with significant progress made in the development of computational systems and commercial codes, a good platform for the simulation of such problems is created. There are several methods for simulating fluid structure interaction problems; one-way method is selected for this simulation due to the small deformation of the diaphragm and flow fields in front of other aspects of the model pump. In order to reduce the size of the pump dimensional model calculations, this pump is simulated using ANSYS CFX commercial code. We have generated a model that could well show some parameters of this type of pump, and so, a more efficient model can be produced by reduced construction costs via future studies. One of the results of the presented method, is introducing one-way fluid structure interaction method as a suitable modeling method. The other results worthy of being mentioned are the study on the velocity and pressure fields, the effects of functional parameters such as engine speed and displacement diaphragm pump on stream, and other outcomes that are fully addressed in a season. In order to validate the model the boundary conditions of a real sample fluid injection pump, odorant in city gas company, is used; that after comparing the amount of output in terms of displacement diaphragm with the information contained in the pump catalog, in the worst case, error rate turns out to be 10%, and an average error is about 5%.Keywords: Diaphragm pump, fluid structure interaction, ansys CFX
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امروزه، با توجه به اهمیت انرژی و سرعت در سطح جهان و با در نظر گرفتن محدودیت انرژی جهان، در مباحث مربوط به بهینه‌سازی انرژی همواره باید بهترین حالت‌ها را برای طراحی در نظر گرفت. در بحث صنعت دریایی و با توجه به گستره‌ی مرزهای آبی کشور و در نظر گرفتن موقعیت استراتژی خاص منطقه همواره باید به دنبال راهی جهت کاهش مصرف انرژی و افزایش سرعت شناورهای تندرو بود. در این بررسی، طبیعت به عنوان راهنمایی جهت رسیدن به هدف مورد استفاده قرار گرفته است. با بررسی سطح پوست جانوران پرسرعت دریایی نظیر کوسه و دلفین، ایده‌ی استفاده از سطوح ریبلت‌دار به وجود آمد. جهت مطالعه اثرات ریبلت‌ها از نرم‌افزار انسیس CFX استفاده شده است. ریبلت‌ها بر روی یک ورق پروازی شبیه‌سازی شده و اثرات آنها مورد مطالعه قرار گرفته است. بر اساس نتایج آزمایشگاهی به دست آمده از آزمایش‌های عملی در حوضچه‌های کشش به اعتبارسنجی شبیه‌سازی‌های انجام شده پرداخته شده است. بر اساس نتایج حاصل از نرم‌افزار، ریبلت‌ها می‌توانند در حالت دوفازی تا شش درصد کاهش درگ برای ورق پروازی داشته باشند.
کلید واژگان: پارامترهای هیدرودینامیکی، ورق پروازی، کاهش درگ، ریبلت، اتسیس GFX، شبیه سازی دوفازیNumerical Simulation of the Effects of Micro Riblets on Hydrodynamics Parameters of Planning VesselsNowadays, considering the importance of the energy and speed in the world as well as the limited available energy, the optimum condition should be always considered in designing. In the field of marine industry, considering the length of the water constraints of our country and special strategic situation of the region, there should be an ongoing attempt to reduce energy consumption and increase speed of the high speed crafts. In this research, nature has been used as a guide to reach our target. Study of the skin of the fast marines faunas such as sharks and dolphins, has generated the idea of riblet covered surfaces. Various riblet surfaces made in the world and currently used has been studied and ANSYS-CFX has been used to study their performance. In this study riblets applied on planning plate and investigated the effects on hydrodynamics parameters. The results has been validated with the experimental results performed in the towing tank. Riblets can reduce the drag up to 6% in the two phase condition.
Keywords: Hydrodynamics Parameters, Planning plate, Riblet, ANSYS CFX, Drag Reduction -
The purpose of this study is to improve the aerodynamic performance of wind turbine blades, using the Ball-Spine inverse design method. The inverse design goal is to calculate a geometry corresponds to a given pressure distribution on its boundaries. By calculating the difference between the current and target pressure distributions, geometric boundaries are modified so that the pressure difference becomes negligible and the target geometry can be obtained. In this paper, The Ball-Spine inverse design algorithm as a shape modification algorithm is incorporated into CFX flow solver to optimize a wind turbine airfoil. First, the presented inverse design method is validated for a symmetric airfoil in viscous incompressible external flows. Then, the pressure distribution of the asymmetric airfoil of a horizontal wind turbine is modified in such a way that its loading coefficient increases. The lift coefficient and lift to drag ratio for the new modified airfoil get 5% and 3.8% larger than that of the original airfoil. The improved airfoil is substituted by the original airfoil, respectively. in the wind turbine. Finally, the aerodynamic performance of the new wind turbine is calculated by 3-D numerical simulation. The results show that the power factor of the new optimized wind turbine is about 3.2% larger than that of the original one.Keywords: ANSYS CFX, Improved Aerodynamics, Inverse Design, Wind Turbine Airfoil
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In recent years, ship transportation has been become in the interests, as well as land and air transportation. There has been an attempt so as to reduce the drag which exerts on vessels. Surely, if drag is considered to be on a downward trajectory it will be significant to have series of examinations. In this essay, nature is taken into consideration as a model in order to achieve the aforesaid purpose. By studying the high speed aquatic animals such as sharks and dolphins, and also their skin, the idea of utilizing riblet on the hull of vessels has ushered in maritime science. Among various methods of skin friction drag reduction, the use of riblet. For this reason there is an interest for construction and optimization of riblet as efficient and economical way. In this research, for first time the sharks skin was modeled on ANSYS CFX by using numerical simulation and Computational Fluid Dynamics, and then the effects of riblet on a submerged flat plate were analyzed. Different types of riblet based on height and space between micro channels were studied, and later on comparison between a ribletcovered plate and a smooth plate in various velocities were done. In the final, it is declared that by selecting the most appropriate type of riblet, 11% drag reduction is attained. Then, by comparing different types of riblets, selected the best choice for drag reduction. Furthermore, the obtained results were compared with the experimental ones.Keywords: Drag reduction, Shark, Flat plate, Riblet, CFD analysis, ANSYS CFX, Micro channels
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