The Effects of Blades Number, Blade Thickness, Blade Tip Angle, and Twist Angle on the Performance of the Rotor Wind Turbines

 تعتبر محركات الرياح واحدة من المصادر المهمة في توليد الطاقة الكهربائية. ذلك لان تعتبر من مصادر الطاقة المتجددة. كما انها في مقدمة المصادر الصديقة للبيئة.هذا البحث يتناول كيفية زيادة كفاءة هذه المحركات من خلال تسليط الضوء على العوامل الموثرة الرئيسية في في سلوك هذه المحركات. كما يتضمن البحث تقييم عن مدى اعتمادية معامل القدرة لهذه المحركات على معدل سرعة الرياح الخاص بامكان تنصيب هذه المحركات. يستخدم هذا البحث ايضا احد برامج المحاكات لدراسة سلوك المحركات مع تغيير عدد الريش وكذلك زوايها. The paper gives an experimental study on the performance on the wind turbine rotors with several numbers of blades as well as twist angle. The main goal of this study is to demonstrate the effect blades number, tip angles as well as the twist angle of the blades on the power coefficient (Cp) of the rotor. Moreover, this result represents a simple evaluation about the range of depending power coefficient on the average wind speed. Also, this paper studies the performance of wind turbines which are tested by carrying out 2-dimensional dynamic using ANSYS-Fluent

A study of micro structural, magnetic and electrical properties of La-Co-Sm nanoferrites (LCSF) synthesized by sol-gel method

A Lanthanum (La3+) doped Samarium-Cobalt nanoferrites (La_x,Co_0.2,Sm_0.2,Fe_(2-x) O_4, where x=0.0,0.5,1.0) have been synthesized by sol-gel method in citrate media. Obtained spinal ferrites micro structure properties have been investigated by XRD, FTIR, SEM-EDX, and TEM-SAED techniques. All the samples are nano in size with significant hysteresis. Micro structural analysis by XRD confirms the obtained samples showing the single phase cubic spinal structures with an average crystal size found from 12 nm to 25 nm, while the average particles sizes identified from TEM analysis are ranging from 21.5nm-26.8 nm (~23.4nm) and from 20.5 nm to 28(~26.4nm) nm for x=0.5,1.0. The lattice parameter found to be a= 8.402, 8.423, 8.467Å for the respective values of x= 0.0, 0.05, and 1.0. Electrical properties show increase in dc resistivity with increase in La3+ ion concentration. Finally, it was concluded that the doping of Lanthanum ion (La3+) in the ferrites structure is found to influencing the structural and electrical properties without scarifying the ferromagnetic character

Modeling, Simulation and Analysis of Doubly-Fed Induction Generator for Wind Turbines Under Grid Voltage Fluctuation

 لغرض ضمان أفضل حالة تشغيل لتوربينات الرياح في ظل الظروف الحرجة، من الضروري إجراء تحليل شامل لعناصر تحكم المحول في كل من جانبي الماكينة والشبكة. يلعب جانب الشبكة دورًا رئيسيًا، لذلك يجب تلبية متطلباته مثل التثبيت، وتجاوز الأخطاء، وتحسين جودة الطاقة، والمزامنة، والتحكم في الطاقة، والمتطلبات الأخرى. تهدف هذه الورقة إلى تحليل المولد الحثي ذو التغذية المزدوجة (DFIG). يجب أن يغطي التحليل الحالات التالية: تحت الشبكة المتوازنة، ترهل الجهد، تضخم الجهد، والتغيرات في الطلب على الطاقة التفاعلية وتحت التغيرات في تردد المصدر. هناك حاجة إلى نموذج لغرض تحليل والتحكم في لمولد الحثي ذو التغذية المزدوجة بأكمله في عمليات الحالة المستقرة والحالة العابرة. يتم استخدام محولات ظهر إلى ظهر في هذا النظام. يتم إنشاء نموذج لمحول الشبكة الذي يتحكم بشكل مستقل في الطاقة النشطة والمتفاعلة بما في ذلك جهد وصلة التيار المستمر. تم تصميم نموذج المحول الجانبي للآلة أيضًا بحيث يحافظ على عامل الطاقة الموحد ويتحكم في الطاقة التفاعلية بغض النظر عن الحالة العابرة للشبكة. تم استخدام    MATLAB / SIMULING لهذا التحليلTo ensure the best operations situation of the wind turbine under critical conditions, a thoroughly analysis of converter controls in both machine and grid sides is essential. The grid side is playing the major role therefore its codes as stabilization, fault ride through, quality of power improving, synchronizing, controlling power and other codes must be satisfied. This paper aims to analyze the Doubly-Fed Induction Generator (DFIG). Analysis shall cover the situations: under balanced grid, under voltage sag, under voltage swell, under changes in reactive power demand and under changes in supply frequency. The system model and controlling are needed to analyze the whole DFIG system in the steady-state and transient state operations. A back to back converters are used in this system. A model of the grid converter independently controlling the active and reactive power including dc-link voltage is constructed. Machine side converter model is also built such that it is maintaining the unity power-factor and controlling reactive power regardless the transient condition of the grid. MATLAB/SIMULING models are used for this analysis

Effect of Magnetic Water Treatment on Prevention of CaCO3 Scales

Permanent magnets of different intensities were used to investigate the effect of a magnetic field in the process of preventing deposits of calcium carbonate. The magnets were fixed on the water line from the tap outside. Then heating a sample of this water in flasks and measuring the amount of sediment in a manner weighted differences. These experiments comprise to the change of the velocity of water flow, which amounted to (0.5, 0.75, 1) m/sec through the magnetic fields that are of magnetic strength (2200, 6000, 9250, 11000) Gauss, and conduct measurements, tests and compare them with those obtained from the use of ordinary water.The results showed the effectiveness of magnetic treatment in reducing the rate of deposition of calcium carbonate where up to 60% after treatment, and this percentage is increasing with increasing magnetic field strength where up to 85% when the intensity of the magnetic field 9250 and 11000 Gauss at the velocity of the water flow of 0.75 m/sec. This percentage of reducing was investigated with increasing the velocity of flow of water through a magnetic field. Also the results showed an increase in total dissolved solids (TDS) as well as electrical conductivity and a decrease in the value of surface tension as a result of magnetic treatment.Observation with the photograph pictures of the distillation apparatus oriented in several laboratories, that the amount of sediment formed a thick layer in the device-free magnetic treatment, but it was not dense and in the few quantity in the apparatus treated with magnetic intensity (8000, 9250) Gauss