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Blade is a sensitive and important part of turbines, and a few companies can produce it. Airfoil of blade has three-dimensional surfaces; therefore, it is necessary to have specific equipment for dimensional control of it. The purpose of this project is to design and manufacture a mechanical system for dimensional control of the airfoil. The foregoing device can produce two-dimensional contours of airfoil on the screen of the profile projector using fine pins. In the mentioned system, the blade is located on the table of device and two sets of pins approach it. In this situation pins are moved forward along their axis until their tips touch the surface of the blade, therefore the tips of pins, shape the contour of the airfoil. Then two sets of pins get away from each other and are moved to the focal area of lens of profile projector via a precision linear system. Then two sets of pins approach each other and reshape the previous contour again. In this situation, tips of pins are projected and contour of airfoil is made on the screen of the profile projector with a predefined scale. Produced contours can be compared with reference ones that have been printed on transparent sheets.

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Blade is a sensitive and important part of turbines, and a few companies can produce it. Airfoil of blade has three-dimensional surfaces; therefore, it is necessary to have specific equipment for dimensional control of it. The purpose of this project is to design and manufacture a mechanical system for dimensional control of the airfoil. The foregoing device can produce two-dimensional contours of airfoil on the screen of the profile projector using fine pins. In the mentioned system, the blade is located on the table of device and two sets of pins approach it. In this situation pins are moved forward along their axis until their tips touch the surface of the blade, therefore the tips of pins, shape the contour of the airfoil. Then two sets of pins get away from each other and are moved to the focal area of lens of profile projector via a precision linear system. Then two sets of pins approach each other and reshape the previous contour again. In this situation, tips of pins are projected and contour of airfoil is made on the screen of the profile projector with a predefined scale. Produced contours can be compared with reference ones that have been printed on transparent sheets.

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Repowering means addition of gas turbine unit(s) to a steam power plant in order to make use of the exhaust gas heat and to increase efficiency of the new combined cycle. There are two groups of repowering methods: partial repowering and full repowering. Full repowering is more common and is used in power plants with nearly ended useful lifetime. In this case the capital investment is considerably reduced compared with the case of making a similar combined cycle. Objective functions are per kWh electricity cost and exergy efficiency. These functions are based on important independent variables of heat recovery boiler, steam turbines, gas turbine. Finally, considering the introduced objective functions, it is tried to achieve the most optimized techno-economic characteristics for Be'sat power plant repowering cycle, using genetic algorithm optimization method with two scenarios of single and multiobjective.

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Thermal power plants consume near to 50 billion cubic meters of natural gas each year. So, optimization of power plants in terms of fuel consumption has become an important issue because of economic values and environmental effects. More than 50 percent of electricity is produced by CCGT and SCGT. In addition, CCGT efficiency is much higher than that of SCGT. So, in this paper these technologies are compared. The outcomes show benefits over costs ratio is affected by fuel price and utilization time. In subsidy prices (before energy price reform), B/C ratio of this substitution is less than one. If fuel price increases more than 500 Rials per cubic meter, using CCGT is more economical than SCGT for mid load power plants. If fuel prices are more than 1300 Rials per cubic meter, B/C ratio will be greater than one in any utilization time.  But this ratio is not greater than one for all cases. If all SCCTs are substituted with CCGTs, yearly natural gas consumption will reduce near to 3.5 billion cubic meters. These are 7% and 2.5% of yearly fuel consumption in power plants and total yearly natural gas consumption respectively. 

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In this research, the aerodynamic design of a radial inflow turbine impeller is carried out using a direct design Method.This new method consists of 2 steps; one dimensional design and three dimensional design. In this design, the blade 3D geometry is obtained with new method. Moreover flow properties in various blade points can be investigated. The advantages this method in comparison with previous other method is less time & cost consuming and more accuracy. At the first step of the aerodynamic design, 1D design is done. This program’s inputs consists of; stagnation temperature, stagnation pressure, mass flow rate and pressure ratio. The goal of 1-d design is to obtain according to optimum experimental data. This procedure based on impeller efficiency convergence. At the second part of this research, by developing a novel design method, the 3D profiles of blade and impellers will be obtained. To validate of one dimensional design results, experimental results and for three dimensional designs, Computational fluid dynamic (CFD) analysis is used. In all this steps, good agreement is observed.

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This paper has proposed‎ ‎a gain-scheduled controller‎ with stability proof and guaranteed cost for a turboshaft driving a variable pitch propeller‎‎. ‎In order to overcome the complexity of the nonlinear model‎, a linear parameter varying (LPV) model is proposed for the first time which is in affine form.‎ Proposed model is established based on a family of local linear models and is suitable for LPV gain scheduling methods‎. Thus a gain scheduled design procedure is proposed which considers parameter dependent Lyapunov matrices to ensure stability and a quadratic cost function for guaranteed performance of the closed loop system‎‎. Proposed procedure also has the advantage of considering an upper bound for change rate of the scheduling signal which decreases conservativeness. ‎Controller design problem and calculating its gain matrices is formulated in a set of Linear Matrix Inequalities‎ which easily can be solved using LMILAB toolbox. Simulation results showed the effectiveness and practicality of the proposed procedure.    

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One of the methods of blade production is forging. But according to the complexities of the blades, they cannot be produced in one stage and it's necessary for them to consider preform. In this research, a basic geometry with elliptical cross section for airfoil of blade, was considered and response surface method was used to optimize this preform. Optimization purposes were considered completely die filling and reduction of flash volume, forging load and strain variance. At the end, optimized preform was compared with the model of mass distribution method. Results show response surface method give better results than mass distribution method. Also physical modeling was used for verification of simulation results. Results show simulation results have a good corresponding with experimental results.

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The performance of turbine section of a gas turbine deteriorates over operation because of working in high temperature conditions and characteristics of the entry gas. On the other hand, due to complexity of the flow field within the turbine, three-dimensional analysis is required. This paper presents a numerical study of roughness effects on turbine flow field and performance. In this paper, effects of blade surface roughness caused by operation conditions on turbine performance were numerically calculated. Numerical calculations were carried out for the fourth stage of an axial turbine which was experimentally tested in the technical university of Hannover, using ANSYS software. Calculated results were verified with the measured data and showed a good agreement. To find out the effects of blade surface roughness on turbine stage performance and flow field, Two equivalent sand-grain roughness heights of 106㎛ (transitionally rough regime) and 400㎛ (fully rough regime) in four different mass flow rates were considered. Results showed that summation of efficiency reductions of the rough stator and rough rotor approximately equals to that of the totally rough stage for each roughness height and effect of stator roughness on efficiency reduction is same as the effect of rotor roughness on stage efficiency.

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High temperatures and different properties of entering gas into the turbine of a gas turbine cycle can decrease its performance. Considering the complexity of the flow distribution inside the turbine, three-dimensional analysis to find out the flow and temperature field in the turbine stages is very important. As time passing the increasing of the roughness of blades is unavoidable. The aim of this paper is investigation of the blades roughness effects on flow field and efficiency of gas turbine with numerical calculations. In this research, a two-stage turbine is modeled in the form of three-dimensional and the results are validated with experimental data. Then the effects of blades roughness on flow field and performance of turbine in five pressure ratios is investigated. Also, in order to determine the role of stators and rotors in decreasing the turbine efficiency, in a special roughness, the first and second stators and then corresponding rotors have separately been examined and then this phenomenon affected on blades simultaneously. Results showed that the efficiency drop by applying all together on the turbine stage is approximately equal to summation of efficiency drops by applying separately.

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In this paper the effect of pressure ratios on the performance characteristics of a radial twin entry turbine is investigated using computer aided design (CAD) and computational fluid dynamics (CFD). First, geometric models of the turbine flow passages are constructed by simultaneous use of measuring tools and computer aided design software. Because of geometrical complexity of flow passages, tetrahedral cells are used to generate unstructured grid in the computational domain. Three dimensional flow of steady, viscous, and compressible nature is solved by Multiple Reference Frame (MRF) technique. Characteristic curves of the turbine are obtained by post processing flow simulation results. Mass flow parameter, delivered torque parameter and total to static turbine efficiency are plotted against different pressure ratios. Results show that at constant rotational speed, increasing pressure ratio leads to increase in mass flow parameter until choke limit while the total to static efficiency decreases and delivered torque increases.

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In this study, the radial flow turbine of a cooling turbine is investigated numerically and then compared with the experimental results at some operation conditions. Performance characteristics of the compressor are obtained experimentally by measurements of rotor speed and flow parameters. In this investigation, the turbine performance curve is obtained and three dimensional flow field in the turbine is analyzed. The rotor and casting geometry are modeled in BLADE GEN and CATIA softwares respectively. The TURBO GRID software is used for grid generation of rotor while the ANSYS MESH software is applied for grid generation of casting. Finally, 3D numerical solution of fluid flow in the turbine is solved by CFX flow solver. In this approach, compressible flow equations are solved according to the pressure based method with SST turbulence model. To ensure the numerical results, the grid independency is studied. Finally, the performance characteristics of the turbine are obtained numerically which are then compared to the experimental results. The comparison shows good agreement between numerical and experimental results.

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Due to growth of energy consumption and depletion of fossil fuels sources, power generation of renewable energy sources such as wind energy has become one of the main interests of researchers. Among different types of wind turbines used for extracting electric power from wind flow, vertical axis wind turbines can be implemented in urban areas and in proximity of energy consumers because of their independence of wind direction, low sensitivity to wind turbulence and lower noise production. In this paper a straight-bladed vertical axis wind turbine has been simulated 3 dimensionally by use of a commercial CFD code. The numerical results have been validated against available experimental data. To improve the performance of the turbine, the effects of blade mount point offset and preset pitch have been investigated. The results show that appropriate blade offset and preset pitch for this case study leads to a 60 and 65 percent increase in the maximum performance coefficient respectively.

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In the present paper a micro-pelton turbine with very small dimension has been studied. This micro turbine was designed for 15 kW output power and was utilized in KhorasanRazavi. To analyze and evaluate the efficiency and effectiveness of physical and geometrical parameters, the turbine flow was simulated using the commercial software Ansys CFX 13 and the simulation results of the performance point were compared and evaluated with experimental results. Because of complexity of simulation and heavy computation, instead of entire turbine, just a part of it containing several buckets was simulated. A 3D transient flow simulation was applied using the SST turbulent model. In order to model two-phase flow, the standard homogeneous free surface model was employed. In the results the effect of rotating speed on the efficiency was investigated. Moreover, the effect of physical parameters: flow rate and head and geometric parameters: the distance from nozzle to the axis of buckets, the number of buckets in constant pitch circle diameter and constant bucket size, the number of buckets in constant pitch circle diameter and variable bucket size and the number of buckets in variable pitch circle diameter and constant bucket size on the performance of a micro-turbine was investigated.

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In this paper, three-dimensional boundary layer flows on wind turbine blades as well as separation event have been studied. At first, boundary layer and three-dimensional momentum integral equations were obtained for incompressible flow considering rotation effects. Next, the effects of pitch angle and the angle between the flow direction and rotation vector on the Coriolis terms were applied using geometry factor definition and Blade Element Momentum (BEM) theory. Then, the integral parameters and effective geometry factors on separation positions and stall structure were investigated for a rotating blade. The obtained results show that rotational ratio, aspect ratio and radial position are three basic parameters for separation occurrence and separation and stall can be delayed via controlling them. Moreover, the results show that the area near the root is strongly influenced by rotational effects. In addition, it is concluded that the centrifugal pumping due to rotation decreases the boundary layer thickness and delays separation especially in the near root region and increases the blade aerodynamic coefficients.

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With the advancements of numerical upstream and central difference methods in modeling the subsonic and supersonic flows in different paths including the flow inside turbine blades, employing the numerical CUSP technique in the Jameson’s finite volume method can simultaneously benefit from the positive features of both mentioned methods. The novelty of this paper is first, improving Jameson’s finite volume method in modeling a 2D supersonic flow between the blades of a steam turbine using the CUSP method, and second, defining the most optimum control function mode using the Marquardt-Levenberg inverse method and by accounting for the mass conservation equation. By considering the importance of the shock regions in the blade’s surface suction side, the focus of the mentioned method is on this part which results in the significant improvement of the pressure ratio in Jameson’s finite volume method. The results of the first combined method (Jameson and CUSP) at the shock region of the blade’s suction surface desirably agree with the experimental data, and a decrease of numerical errors at this region is resulted. Furthermore, the results of the second combined method (Jameson, CUSP and inverse method) shows that in comparison with original Jameson’s method and the first combined method, by average, the conservation of mass condition is improved 15% at the shock region of the blade’s suction surface.

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Single shaft gas turbine and the cycles based on it are sensitive to frequency drops and sudden change loads or large frequency dips might affect their stability. This phenomenon is related to reduction of air mass flow rate through the gas turbine during frequency dips, which might lead to interaction between the governor and temperature control loop. This interaction will prevent the gas turbine from being loaded further and might affect its stability. In this paper, the performance of the two well-known power generation cycles based on the gas turbine -combined cycle and steam injected gas turbine (STIG cycle)- are investigated during frequency dips and transient maneuvers. For this purpose, two similar units are developed based on these cycles and their performance are studied and compared in different scenarios. The simulation results show that the steam injected gas turbine has a better performance during frequency drops and it can handle larger step change loads. This superior performance of the steam injected gas turbine unit is almost twice as good as the similar combined cycle unit in some of the operating conditions.

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Nowadays, using renewable energies, specifically ocean wave energy, is of importance in the world. One of the methods by which this energy can be harnessed is through using axial turbines with low head. In this study, performance of an axial turbine ocean wave of Wells type installed on the floating oscillating platform has been numerically studied. The length of the oscillating bed is equal to the wave length of the ocean upon its center the Wells turbine has been installed. This design causes the inlet flow rate to be doubled, which will in turn increase the power. In this way, the governing equations include continuity and momentum equations have been solved considering SST turbulence model. Furthermore, the acquired results have been verified through mesh independency analysis and have been validated by comparison with the available experimental data. The results show that with decreasing the clearance and setting it to 2% of the chord length value, the maximum efficiency, which is approximately 35%, will be gained. Moreover, by varying the angles from 0 to 12° with respect to its tip, achieve higher efficiency in different velocity ratios. On the other hand, employing a blade with variable profile will lead to postponing stall phenomena. Moreover, employing multistage turbines with guide vanes at the mid stage can improve efficiency by 9 percent.

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Intense pressure pulsations, which are caused by the vortex rope in the runner cone and the draft tube of pump-turbines, result in vibrations and noise under partial load conditions in turbine mode and also reduce the machine’s efficiency. The most common method for reducing these fluctuations is injecting air through the shaft. This method has some disadvantages such as, negative influence on efficiency, high cost, and technical difficulties. In the present paper, the concept of locating grooves on the conic surface of runner has been investigated. In this regard, the runner and the draft tube geometry has been designed according to the specifications and the accessible information of Siah-Bishe project. Afterwards, the 3-dimensional flow field has been solved numerically, using Ansys CFX package. The numerical results have been verified by investigating their independency from grid size and comparing the results with experimental ones. Maximum difference between the proposed and the existing design’s performance has been less than 2 percent. The results indicate that locating grooves on the conic surface of the runner results in an increase in the flow velocity beneath the runner cone. Moreover, pressure pulsations have been decreased and the low-pressure area at the beginning of the draft tube shrank. The maximum amount of decrease in pressure pulsations has been recorded in two opening positions of the guide vanes (lower than 60% and more than 90% of design point). In addition, maximum efficiency drop in the revised design has been less than 0.3 percent.

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With respect to special conditions apply to the gas turbine, its blades are affected by many different factors such as, hot corrosion, oxidation, wear, impact of external particles, and etc. and are destroyed. Due to the reduction of their working life time, the turbine efficiency reduces and ultimately the heavy costs of periodic repairs are needed, and also new replacements of their blades are unavoidable. The aim of this study is investigation of the effects of corrosion and blade damage on flow field and gas turbine performance, by numerical simulation. In this research, a two stage turbine is modeled in the form of three dimensional and the results are validated with experimental data. To analyze of the behavior of entire flow, conservation of mass, momentum, and energy equations are solved. The numerical simulation of the turbine is done with ANSYS CFX software. Then the increased rotors tip clearance effects with decreasing thickness due to corrosion in both nozzles and blade leading edge and trailing edge were separately studied on turbine flow field and its performance in five actual different pressure ratios. The results showed that the most important factor in reducing the efficiency of gas turbine is due to rotor tip clearance increasing. Also corrosion of the blade edge respect to the trailing edge damage is a little more affected on reducing efficiency and increasing loss coefficients.

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The ratio of lift to drag coefficient in wind turbine blades is within the most important parameters affecting the power coefficient of wind turbines. Due to the performance of Magnus wind turbines in low speed air flow; such turbines are attractive for research centers. In the present work, a new geometry for the blades of Magnus wind turbines is defined. The defined geometry is based on the geometry of a Treadmill with a difference that the diameter of its leading circle is greater than that of its trailing one. In the present work, the body is supposed to a low speed air flow while a tangential velocity is applied to the airfoil surfaces and then, its effect on the lift and drag coefficient is studied by numerical method. The effect of generated tangential velocity on the surfaces is investigated for different air flow speed and attack angles and then, its results are compared with that for stationary surfaces. The results show that generating tangential velocity along the surfaces caucuses the lift and drag coefficients and, their ratio to be varied, greatly. By the tangential movement of the surfaces, the maximum ratio of lift to drag coefficient occurs in zero attack angle which is equal to 109. Moreover, maximum magnitude of lift to drag coefficient for attack angles 5, 10, and 15 degrees are 81, 64, and 57; respectively.