scholarly journals Numerical aided design of Pelton nozzle jet deflector

2021 ◽  
Vol 5 (2) ◽  
pp. 149-156
Author(s):  
Andrej Lipej ◽  
Boro Popovski

Hydro energy still occupies an important place among renewable energy sources. In special operating conditions, Pelton turbines are irreplaceable and can be used for extremely small hydropower plants and also large hydro power plants. Pelton turbines can operate with high head and relatively small flow rates. In many cases, the height differences of the water are very large. Sometimes it is necessary to stop the operation of the turbine very quickly and the consequences of water hammer can be very severe. The responsible part to minimize the consequences of this phenomena is jet deflector, which can be in two different technical designs. The steps for 3-D geometry definition, pre-processing and post-processing, flow modelling and FEM analysis are presented. In the paper is presented the new optimized design of push-out jet deflector shape. Optimization consider 3-D CFD analysis of free surface flow and stress analysis. The main goal of the research was to minimize the influence of all force components on the torque of deflector servomotor. The final results present the geometry of the deflector, with a significant reduction in the stresses and deformations. These have been achieved with a crucial reduction in the hydrodynamic force and torque.

2021 ◽  
Vol 16 (1) ◽  
pp. 48
Author(s):  
Didit Setyo Pamuji ◽  
Harry Laksono Nugroho ◽  
Daru Sugati

<p><em>The interaction of turbine blades with vortex flow in micro-hydro power plants based on gravity vortex is still not clearly clarified, therefore numerical simulation is a tool to produce flow visualization that helps analyze the performance of experimental results. This study aims to compare the performance of a gravity vortex flow power generator using a conical basin with a </em><em>inclined</em><em> backward and </em><em>inclined </em><em>forward blade design using a numerical simulation approach. The simulation begins by validating the results of torque performance and visualizing the flow of experimental research conducted by previous researchers, then the simulation settings are used to compare the performance of the </em><em>inclined</em><em> backward and </em><em>inclined </em><em>forward blade turbine designs with variations in turbine rotation speed of 80, 120, 160 and 180 rpm. The simulation results show that the curved backward blade performance is better than the forward curved blade which is supported by visualizing the free surface flow and static pressure contours on the blade surface.</em><em></em></p>


2015 ◽  
Vol 21 (5) ◽  
pp. 756-772 ◽  
Author(s):  
Anant V KHANDEKAR ◽  
Jurgita ANTUCHEVIČIENĖ ◽  
Shankar CHAKRABORTY

There has been a rapid growth in construction activities during the last few decades owing to overall development in all facets of humanity. Due to technological advancements and ever increasing civilization, there is a persistent need of energy. Along with the conventional energy sources, the renewable energy sources have also significantly contributed to the rising energy needs. As a renewable source of energy, numerous small hydro-power plants (SHPPs) have been built up across the world in the recent past. Usually these SHPPs are being built and operated by the private developers complying with the government regulations. In order to assist a developer in selecting the most profitable and feasible SHPP for construction and subsequent operation, a method based on fuzzy axiomatic design principles is employed in this paper. The techno-commercial and socioeconomic criteria as considered for analyzing the feasibility of the candidate SHPPs are expressed qualitatively using trapezoidal fuzzy numbers. The performance of each SHPP is evaluated in terms of its total information content and the one with the least information content is selected to be the best venture for the required construction activity. The adopted methodology is found to have immense potential to the developers while selecting the most feasible project for construction.


Author(s):  
Hira Singh Sachdev ◽  
Ashok Kumar Akella

<p>Small hydro systems play a major role in meeting power requirements of remote, isolated, hilly areas in a decentralized manner by tapping water streams, rivulets and canals of small discharge. Small hydroelectric system captures the energy in flowing water and converts it to electricity.</p>Of all the non-conventional renewable energy sources, small hydro stands first as it is more resourceful, reduces system  losses, environment friendly, non-consumptive and source is renewable due to their enormous advantages over large hydro and other power plants, lot of small hydro-power plants have come up across the world to meet the ever increasing demand of electrical energy. Lowering the high initial cost of the small hydro-power plants and its popularization is today’s challenges. This paper describes basic techniques design of the small hydro-power development.


Author(s):  
Ф.О. Аракелян ◽  
И.П. Башилов ◽  
Ю.Н. Зубко ◽  
А.В. Николаев ◽  
Д.Г. Левченко

Рассмотрено состояние и перспективы развития атомной энергетики в связи с сейсмической и другими природнотехногенными опасностями. Анализирован опыт эксплуатации АЭС, статистика аварий на АЭС, их причины. В связи с авариями на ряде АЭС и глобальной сменой приоритетов энергетической политики в сторону возобновляемых источников энергии (ветра, солнца, гейзеров и т.п.) многие из технически развитых стран (США, Япония, Германия) заявляют о снижении роли атомной энергетики в собственных энергетических планах. Угроза опасности объединяет усилия таких стран как США, Франция, Россия, Япония, Южная Корея, Канада и Китай в сотрудничестве в области совершенствования технологий, усиления ядерной безопасности и развития ядерной инфраструктуры в странахновичках. Наиболее опасными признаны АЭС Азии, где отмечается повышенная сейсмичность. Благодаря усилиям по повышению безопасности АЭС, сделан вывод о снижении сейсмической опасности в связи с глубокой автоматизацией и передачей основных управляющих функций АЭС программному комплексу, совершенствованием алгоритмов принятия решений в случае землетрясения и других чрезвычайных ситуаций. Одна из главных целей глубоко эшелонированной защиты состоит в блокировании опасностей человеческих ошибок и сочетания отказов оборудования и ошибок операторов и распорядителей. Системы безопасности должны включаться автоматически и на некоторое время блокировать действия оператора АЭС. Эффективной защитой энергоблоков, построенных в последние десятилетия, являются герметичные оболочки (контейменты) и размещение над реактором емкости с большим количеством раствора бора, который выливается на реактор при аварии и нейтрализует радиоактивность в случае ее появления. Более детальный анализ сейсмотектонической ситуации площадок действующих АЭС мира привел к необходимости повышения ускорения безопасного останова в ряде АЭС. При проектировании АЭС недостаточно учитывать магнитуду и интенсивность предполагаемых землетрясений, для инженерных расчетов необходимо использовать конкретные параметры колебаний. Среди них важнейшее место занимает ускорение грунта, по которому можно с максимальной уверенностью судить о потенциальных нагрузках на сооружения и оборудование в зоне землетрясения. Приведена модернизированная система сейсмической защиты (ССЗ1М) энергоблоков отличающаяся надёжностью, отсутствием ложных срабатываний, стабильностью параметров во времени, защитой от внешних несанкционированных воздействий. The state and prospects of the development of nuclear energy in connection with seismic and other natural and technological hazards are considered in the article. The experience of operating nuclear power plants, statistics on accidents at nuclear power plants, and their causes are analyzed. Due to accidents at several nuclear power plants and a global change in energy policy priorities towards renewable energy sources (wind, solar, geysers, etc.), many of the technically developed countries (USA, Japan, Germany) declare a reduction in the role of nuclear energy in their energy plans. The threat of danger unites the efforts of countries such as the USA, France, Russia, Japan, South Korea, Canada and China in cooperation in the field of improving technologies, enhancing nuclear safety and developing nuclear infrastructure in newcomer countries. The most dangerous nuclear plants are located in Asia, where the increased seismicity is noted. As a result of the efforts to improve the safety of nuclear power plants, it is concluded that seismic hazard is reduced due to the deep automation and transfer of the main control functions of the nuclear power plant to the software package, improvement of decisionmaking algorithms in the event of an earthquake and other emergencies. One of the main goals of defense in depth is to block the dangers of human error and the combination of equipment failures and the errors of operators and managers. Safety systems should turn on automatically and block the actions of the NPP operator for a while. Sealed shells (containers) and placement of containers with a large amount of boron solution over the reactor, which is poured onto the reactor in the event of an accident and neutralizes radioactivity in case of its occurrence, are an effective protection for power units built in recent decades. A more detailed analysis of the seismotectonic situation of the sites of existing nuclear power plants in the world has led to the need to increase the acceleration of safe shutdown in several nuclear power plants. When designing a nuclear power plant, it is not enough to take into account the magnitude and intensity of the alleged earthquakes for engineering calculations, it is necessary to use specific vibration parameters. Among them, acceleration of the soil occupies the most important place, by which it is possible to judge with maximum confidence the potential loads on structures and equipment in the earthquake zone. The modernized seismic protection system (SSZ1M) of power units is characterized by reliability, the absence of false alarms, the stability of parameters in time, and protection against external unauthorized influences.


2017 ◽  
Author(s):  
Vittorio Verda ◽  
Elisa Guelpa

One of the main advantages of district heating system technology is the possibility of integrating multiple heat sources for domestic heating. In particular, it is often possible exploit low-exergy sources, such as waste heat recovered from industry or from renewable energy sources, that are often affected by time variation of the temperature. A very convenient and useful opportunity for predicting and analyzing district heating network behavior is modelling. Modelling allows to quantify opportunities related to changes in DH (district heating) network design or management, before real implementation. Therefore an important point is the creation of models able to simulate network, also very large and linked to many power plants, working at variable heat production conditions (i.e. variable mass flow rates and temperatures). The goal of this work is to propose a novel approach which combines exergy analysis with a DH network model for evaluating the best DH operating conditions. A thermo-fluid dynamic model based on conservation equation has been adapted for the discussed aims and applied to a network involving different low-exergy heat sources with variable temperatures. An evaluation of the implementation of these sources is provided for the Turin district heating network, which is the largest network in Italy.


2017 ◽  
Vol 35 (1) ◽  
pp. 113-119 ◽  
Author(s):  
Alina Kowalczyk-Juśko ◽  
Andrzej Mazur ◽  
Antoni Grzywna ◽  
Agnieszka Listosz ◽  
Roman Rybicki ◽  
...  

AbstractHydropower plants in Poland currently use only 19% of the river’s energy potential. Development of hydropower is limited by environmental regulations as well as by economic grounds. From the environmental point of view, it is desirable to build small hydropower plants integrated into the local landscape. This paper presents results of the research aimed at estimating the amount of energy that could be produced in the case of small hydroelectric power plants on weirs existing on the Tyśmienica River. There is also a legal framework that should be adapted at hydropower development. It was calculated that the technical capacity of the small hydropower plants that could be built on 4 existing weirs, is 0.131 MW. These power plants could produce 786 MWh of electricity per year. The economic efficiency of this production is currently difficult to assess, because a new support system for renewable energy sources is currently being implemented, which will be a decisive factor for entrepreneurs. It should be borne in mind that potential investments will be made in protected areas within the Natura 2000 network, which may limit their constructing or impose the obligation to assess their impact on selected environmental elements. Location within the protective area does not eliminate such investments, especially when solutions with the least possible environmental impact are used.


Volume 1 ◽  
2004 ◽  
Author(s):  
Mario Amelio ◽  
Silvio Barbarelli

Increasing interest in renewable energy sources makes attractive the exploitation of many small power hydraulic resources (micro-hydro – less than 100 kW). However, the high cost of hydraulic turbines hinders the actual realization of micro-hydro plants. An alternative cheaper solution could be to replace the turbine with a reverse-mode centrifugal pump, developing therefore a pump as turbine (PAT) system. Unfortunately, although a wide number of centrifugal pumps are commercially available for micro-hydro engineering plant, manufacturers do not provide information regarding the performance of centrifugal pumps in turbine mode. In this paper, a simple method based on a one-dimensional numerical code is presented for deriving the turbine efficiency of commercially available centrifugal pumps. The code estimates a sizing of the component using information such as impeller diameter, specific speed, head and flow rate at pump BEP, machine overall dimension which are provided in manufacturer catalogues, to deduce geometrical parameters of the machine, calculating the losses and thus determining PAT performances. The method was validated by a comparison of the predicted characteristic curves with some experimental measurements available on PATs working in a range of specific speed (Head in meters and flow rate in m3/s) from 9 to 65. The numerical code calculations effectively predicted the measured efficiency of PATs. At BEP, the efficiency was estimated with a relative error of ±10% which is a value much lower than one obtained by using the available in literature correlations. A prediction within this error range is generally accepted for this kind of application.


Author(s):  
Oleksiy Yakimov ◽  
Natalia Klimenko ◽  
Kateryna Kirkopulo ◽  
Andrey Pavlyshko ◽  
Sergyi Uminsky ◽  
...  

Development of modem power engineering follows the line of continuous increase in speed, coefficient of corrosive action and capacity of units. Gears and reducers are responsible parts of modem machinery and occupy an important place in the domestic power engineering construction. Durability and wear resistance of gears, apart from the design factors, also depends on the technological methods of treatment. The final stage of production of such wheels is the operation of gear grinding. In the process of gear grinding in a thin surface ball there are complex thermomechanical processes. As a result of short-time heating to high temperatures, structural transformations, burns, and in some cases even micro- and macro-thicknesses occur in such a surface bail. In addition, there are cases of making tooth wheels with adjacent defects grinding (for example, the appearance of the surface of the ball teeth of large tensioning forces), which reduces the life of the work, and in some cases causes a breakdown of the teeth in operating conditions. Development of effective measures to ensure the quality of the surface of the ball on the operation of grinding baggage in part depends on the possibility of predicting (or calculation) of temperatures and residual loads on the depth of the cemented teeth ball. The method of calculation of internal surplus Toads occurring during grinding of wheels with cemented steels is suggested. On the basis of the performed calculations and experiments the ways to improve the quality of production of working surfaces of gears, which are used in the wits of thermal and nuclear power plants are suggested and grounded.


2015 ◽  
Vol 19 (3) ◽  
pp. 771-780 ◽  
Author(s):  
Zihnija Hasovic ◽  
Boris Cosic ◽  
Adisa Omerbegovic-Arapovic ◽  
Neven Duic

This paper investigates current and planned investments in new power plants in Bosnia and Herzegovina and impact of these investments on the energy sector, CO2 emission and internationally committed targets for electricity from renewable sources up to year 2020. Bosnia and Herzegovina possesses strong renewable energy potential, in particular hydro and biomass. However, the majority of energy production is conducted in outdated power plants and based on fossil fuels, resulting in environment pollution. New major investments The Stanari Thermal plant (300 MW) and the investment in Block 7 (450 MW) at the Thermal Plant Tuzla are again focused on fossil fuels. The power sector is also highly dependent on the hydrology as 54% of current capacities are based on large hydro power. In order to investigate how the energy system of Bosnia and Herzegovina will be affected by these investments and hydrology, the EnergyPLAN model was used. Based on the foreseen demand for year 2020 several power plants construction and hydrology scenarios have been modelled to cover a range of possibilities that may occur. This includes export orientation of Stanari plant, impact of wet, dry and average year, delayed construction of Tuzla Block 7, constrained construction of hydro power plants, and retirement of thermal units. It can be concluded that energy system can be significantly affected by delayed investments but in order to comply with renewables targets Bosnia and Herzegovina will need to explore the power production from other renewable energy sources as well.


2021 ◽  
Author(s):  
Tommaso Diurno ◽  
Stella Grazia Tomasello ◽  
Tommaso Fondelli ◽  
Antonio Andreini ◽  
Bruno Facchini ◽  
...  

Abstract Nowadays, the ever-increasing world electricity generation by renewable energy sources has brought about changes in conventional power plants, especially in those ones where large steam turbines work, which were widely used to meet the world’s energy needs by operating mostly at fixed conditions. Now, instead, they have to be capable to operate with greater flexibility, including rapid load changes and quick starts as well, in order to make the most of the renewable resources while guaranteeing the coverage of any shortcomings of the latter with traditional fossil fuel systems. Such service conditions are particularly challenging for the exhaust hoods, which have a great influence on the overall turbine performance, especially at off-design conditions. In fact, the complex and high rotational 3D flow generated within the diffuser and the exhaust hood outer casing can cause an increase in aerodynamic losses along with the detriment of the hood recovery performance. For these reasons, an optimized design and adequate prediction of the exhaust hood performance under all the machine operating conditions is mandatory. Since it has been widely proven that the exhaust hood flow strongly interacts with the turbine rear stage, the necessity to model this as well into a CFD modeling becomes crucial, requiring a remarkable computational effort, especially for full transient simulations. Even if adopting simplified approaches to model the last stage and exhaust hood interfaces, such as the so-called Frozen Rotor and the Mixing Plane ones, helps to keep the computational cost low, it can be not for an exhaust hood optimization process, which requires a significant number of CFD simulations to identify the most performing geometry configuration. For these reasons, a simplified model of the exhaust hood must be adopted to analyse all the possible design variants within a feasible time. The purpose of this work is to present a strategy for the exhaust hood design based on the definition of a simplified CFD model. A parametric model has been developed as a function of key geometrical parameters of both the exhaust hood and the diffuser, taking into account the strong fluid-dynamic coupling between these components. A periodic approximation has been introduced to model the exhaust hood domain, thus allowing to augment the number of the geometrical parameters of the DOE, while keeping the computational effort low. A response surface has been achieved as a function of the key geometrical parameters, therefore an optimization method has allowed identifying the best performing configuration. A 3D model of the optimized periodic geometry has been then generated to assess the effectiveness of the procedure here presented. Finally, the presented procedure has been applied in several off-design operating conditions, in order to find out an optimal geometry for each operating point, evaluating how much they differ from that one got for the design point.


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