The steadystate measurements were conducted on a model francis turbine. Francis turbines may be designed for a wide range of heads and flows. Experimental investigation of a high head francis turbine. Frequency converter solutions and control methods for variable speed operation of pump storage plant. As a result of stresses induced by rotorstator interaction, a number of high head francis turbines have failed in the past 15 years. Introduction to francis turbine diagram, working principle the francis turbine is a mixed flow reaction turbine. Water enters the runner and flows towards the center of the wheel in the radial direction and leaves parallel to the axis of the turbine.
Please find below a list of our technical publications on francis and pelton turbines for water power plants. Highhead francis turbine for variable speed operation ntnu. Impulse turbines are suited for large h and a low q, e. Other deciding factors include how deep the turbine. In floody conditions turbines have to operate at overload conditions sometimes nondesigned conditions. Mixed flow turbine is also used in irrigation water pumping sets to pump water from ground for irrigation. High head francis turbine, high head francis turbine. Water with high head pressure enters the turbine through the spiral casing surrounding the guide vanes. Technical publications on francis and pelton turbines.
In general, impulse turbines are used for high head sites, and reaction turbines are used for low head sites. As a spiral casing is stranded, the runner is not simply available. The description of hydraulic and structural design of high head francis turbines and pelton turbines has been based mainly on the experience from. Transient cfdanalysis of a high head francis turbine ruben moritz and michel j. Gandhi 3 1 department of energy and process engineering, norwegian university of science and technology, trondheim no7491, norway. The francis turbine is also called a radial flow turbine, since water flows from the outer circumference towards the centre of runner. Resonance and pressure pulsations in high head francis runner. Dynamic stability of the high head francis turbines is one of the challenging problems. A water turbine is to be designed to produce 27 mw when running at 93. The kaplan turbine was an evolution of the francis turbine. The water looses a part of its pressure in the volute spiral casing to maintain its speed.
It is an inward flow reaction turbine that combines radial and axial flow concepts. Design, performance and maintenance of francis turbines. The francis99 test case consists of a highhead francis turbine model, whose geometry, together with meshing and. The type of hydropower turbine selected for a project is based on the height of standing waterreferred to as head and the flow, or volume of water, at the site. Investigations of compressible turbulent flow in a high. Medium and large hydro generators ge renewable energy. Pressure measurements on a highhead francis turbine. Francis, while working as head engineer of the locks and canals. Transient cfdanalysis of a high head francis turbine. The most common example is the pelton wheel turbine. This paper uses the methods described by seidel et al.
Flow field in a high head francis turbine draft tube. Since 1930, the company has installed over 190 units with heads above 300 m with a total output of more than 12000 mw. High speed machines used with francis and pelton turbines for high head hydro power. Assuming a model efficiency of 88%, estimate the volume flow rate through the. The francis turbine runners of the four ternary groups of grimsel 2 power plant in switzerland showed fatigue cracks at the runner blades much earlier than expected.
The fluid power is converted into kinetic energy in the nozzles. It is still the most widely used water turbine in the world today. A useful parameter for choosing the most suitable turbine. Pelton turbine or wheel is an impulsive turbine used mainly for high head hydroelectric schemes. Water exiting turbine will have significant velocity want to recover velocity head before exiting downstream to minimize losses draft tube slows water gradually draft tubes for nepalese francis turbine draft tube installation. Overall design and joint supply of turbines and generators for the worlds most powerful hydro plant to date at,300 mw.
Traditionally, francis turbine has been considered to be a simple and robust machine suitable for exploitation of water energy at a wide range of head, from 30 m up to 750 m. Under common conditions, stable runaway is only reached if after a load rejection, the control and protection mechanisms both fail and the guide vanes. Pdf as a result of stresses induced by rotorstator interaction, a number of high head francis turbines have failed in the past 15 years. This turbine is used for medium heads with medium discharge. Chirag trivedi transient pressure measurements on a high head. Refurbishment of high head francis turbines andritz. A wide variety of high head francis turbine options are available to. There are basically three types of hydraulic turbines. The main target of the investigations is the numerical. Francis 99 is a set of workshop aiming to determine the state of the art of high head model francis turbine simulations flow and structure under steady and transient operating conditions as well as to promote their development and knowledge dissemination openly. Investigation of a high head francis turbine at runaway.
The pelton wheel is among the most efficient types of water turbines. The simulation domain includes the spiral casing with stay and guide vanes, the runner and the draft tube. Francis99 test case is to provide an open platform to industrial and academic researchers to explore and develop the capabilities of cfd techniques within the. Numerical study of a high head francis turbine with. Cervantes abstractthe purpose of the present work has been to investigate the ability of the pro. Its invention allowed efficient power production in the low head application that was not possible with francis turbine. It is used when the head is between 80 to 500 metres. Hydraulic turbines pdf introduction, classification, impulse and reaction turbine, layout of hydroelectric power plant. Francis turbine working principle, main parts, diagram and. The francis turbine is a type of water turbine that was developed by james b.
Hydraulic turbineshydraulic turbines raven mechanical. With about 60% of the global hydropower capacity in the world, francis turbines are the most widely used type of hydro turbine. Francis turbine is characterized by a fixedblade francis runner that is hydraulically optimized for a narrow operating range. Instead of using water jets, reaction turbines fill a volute with swirling water that rotates the runner blades. Turbines that operate in this way are called impulse turbines. It is efficient over a wide range of water head and flow rate. Onboard measurements at a 100mw highhead francis turbine m. Sep 20, 2017 dynamic stability of the highhead francis turbines is one of the challenging problems. Compared to reaction turbines, impulse turbines require higher head, and work with a lower volume flow rate.
Losses in francis turbines draft tube output energy head m hydraulic efficiency % losses in francis turbines hydraulic efficiency % output energy output % friction losses between runner and covers. The following method was developed within a large research project to investigate a high head francis turbine with a specific speed of nq. Francis turbines with an operating head of 63 m and a runner diameter of 6. Francis turbine is the most widely used turbine in hydropower plants to generate electricity. A method to evaluate the lifetime of a high head francis runner. The francis turbine runners of the four ternary groups of grimsel 2 power plant in switzerland showed fatigue cracks at the runner blades much earlier. Hydraulic turbineshydraulic turbines session delivered by. Francis and kaplan turbines belong to this category.
It is for this reason that while the francis turbine is the most versatile, alternative designs are generally used for both very high and very low heads. All of our medium and large hydro generators 50 mva are engineered to reduce thermomechanical stress on the generator structure, which contributes to improved reliability and extended lifetime. The present work focuses on the pressure variations in a high head francis turbine during the transients. Kaplan turbines require high discharge rate along with low or medium head 270m. Experimental and numerical studies of a highhead francis.
Francis turbines are generally installed with their axis vertical. Onboard measurements at a 100mw highhead francis turbine. In the present paper numerical investigations of a complete high head francis turbine comprehensive of a spiral casing, stay and guide vanes and draft tube have been performed at three operating. Kaplan turbines with adjustable blade pitch are welladapted to wide ranges of flow or head conditions, since their peak efficiency can be achieved over a wide range of flow conditions.
Francis turbine its components, working and application. Francis turbines are the most common water turbine in use today. Challenging onboard measurements in a 100 mw highhead. Ge has successfully completed numerous installations of francis turbines with outputs up to 800 mw, including one of the largest francis turbines ever made each with a runner diameter of 10 meters and weighing over 450 tons. Pdf investigation of a high head francis turbine at runaway. The francis turbine runners of the four ternary groups of grimsel 2 power plant in switzerland showed fatigue cracks at. Consequently, the turbine runner accelerates to high speed, runaway speed, in seconds. Paper open access related content experimental investigation. On the performance of a high head francis turbine at. Those which used the kinetic energy of the water jet. Unsteady rotorstator interaction rsi develops dynamic stresses and leads to crack in the blades. In the presented work mangla power plants francis turbine is analyzed for high head operations as head variations are usual throught the year in this reservoir. Hydraulic turbines exhibit total load rejection during operation because of high fluctuations in the grid parameters. The best performance was achieved at height ratio of 2.
His analytical methods allowed design of highefficiency turbines to precisely match. An angular movement of the guide vanes gvs during transients such as load acceptance and rejection within short time raised significant concerns for increased wear and instabilities. Pdf on the performance of a high head francis turbine at. This versatility, along with their high efficiency, has made them the most widely used turbine in the world. Gandhithis content was downloaded from ip address 157. The full machine including spiral casing, stay vanes, guide vanes, runner and draft tube was simulated transient for three operating points defined by the francis. Turbines that operate in this way are called reaction turbines. Kaplan turbines are suited for low h and large q e. The water which is not durt free can cause extremely rapid wear in a high head francis turbine.
The type of hydropower turbine selected for a project is based on the height of standing waterreferred to as headand the flow, or volume of water, at the site. About 91% of these are alternative energy generators, 8% are electricity generation. Why is the pelton wheel suitable only for high heads. Vertical horizontal francis hydro turbine, high head water. Francis type units cover a head range from 40 to 600 m to 2,000 ft, and their connected generator output power varies from just a few kilowatts up to 800 mw. Recent citations numerical simulation and validation of a high head model francis turbine at part load. Selecting the appropriate type of turbine depends primarily on available head and less so on available flow rate. High velocity swirling flow during spinnoload snl induces unsteady pressure pulsations in the turbine, and these pulsations cause fatigue in the blades. Kaplan turbine is now widely used throughout the world for high flow, low head power production. High head francis turbine for variable speed operation. Pdf hydraulic turbines exhibit total load rejection during operation because of high fluctuations in the grid parameters.
Conversely, for low head applications the flow must be low or the turbine will become excessively large. If the machine transforms mechanical energy into hydraulic energy it. Technical publications on francis and pelton turbines andritz. Determination and measurements of the high stresses zones in the turbine.
Investigations of compressible turbulent flow in a highhead. Francis 99 turbine j nicolle and s cupillardnumerical simulation of flow in a high head francis turbine with prediction of efficiency, rotor stator interaction and vortex structures in the draft tube d jo t, a kerlavaj, m morgut et al. Design, performance and maintenance of francis turbines i. Turbine selection is based on the available water head, and less so on the available flow rate. In a high head turbine, vaneless space is small and the amplitudes of rsi frequencies are very high. Francis turbine development it is of interest to study the list of the most important high head francis turbines produced by kvaerner, and put in operation in norway after world war ii. Refurbishment of high head francis turbines christof gentner, manfred sallaberger, jurgen krenn abstract increasingly, operating utilities assess upgrading and refurbishment options of existing hydroelectric power plants in the view of the changed competitive environment of the electricity market. Hydraulic turbines are machines which convert hydraulic energy into mechanical energy. Participation in the supply of turbines, generators and electrical equipment for the worlds largest hydroelectric power plant with a total capacity of more than 18,000 mw. The turbine casing, with the runner fully immersed in water, must be strong enough to withstand the operating pressure. Then water passes through guide vanes where it is directed to strike the blades.
The primary objective is secure reliable operation and lifetime for high head francis turbines operating in the future energy market. Francis turbines are very able to sustain the high mechanical stress resulting from high heads. The calculations are used to partition the turbine operating regions and to clarify the unsteady flow behavior in the entire flow passage including the blade channel vortex in the runner. The francis turbine, named for him, is the first modern water turbine.
Vertical horizontal francis hydro turbine, high head water turbine. This chapter describes each turbine type, presented by decreasing head and increasing nominal flow. High head francis applications therefore require a large flow to be successful. To investigate the amplitude of unsteady pressure loading, transient pressure measurements were carried out in a model francis turbine during snl. Purpose the purpose of this paper is to describe how the hydraulic performance and pressure fluctuations in the entire flow passage of a francis turbine were predicted numerically for the highest head. Also, there are some disadvantages of francis turbine and those are listed below. Investigation of a high head francis turbine at runaway operating conditions article pdf available in energies 93. Jan 23, 2018 the ability of francis turbine to use both the kinetic and potential energy to produce power, shorts out a major problem of water head availability as it could be used efficiently for head as low as 50m to as high as 400m and also for a wide range of flow rates which could be as low as 10 metercube per second to as high as 700 metercube per. In a highhead turbine, vaneless space is small and the amplitudes of rsi frequencies are very high. Andritz hydro has long standing experience in design, model testing and manufacturing of high head francis turbines. Pdf investigation of a high head francis turbine at. Determine how water parameters such as vapor and gas content influences the pressure propagation speed and the damping of pressure oscillation in high head francis turbine components such as a guide vane cascade and in a.
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