Francis 1815 1892 an english born inventor who developed the turbine in the year 1849. 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. Recent citations numerical simulation and validation of a high head model francis turbine at part load. Those which used the kinetic energy of the water jet. A method to evaluate the lifetime of a high head francis runner. Hydraulic turbines pdf introduction, classification, impulse and reaction turbine, layout of hydroelectric power plant. Francis turbine is characterized by a fixedblade francis runner that is hydraulically optimized for a narrow operating range. Hydraulic turbines are machines which convert hydraulic energy into mechanical energy. Flow field in a high head francis turbine draft tube. 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.
Andritz hydro has long standing experience in design, model testing and manufacturing of high head francis turbines. The francis turbine is also called a radial flow turbine, since water flows from the outer circumference towards the centre of runner. 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. A useful parameter for choosing the most suitable turbine. Hydraulic turbineshydraulic turbines session delivered by. There are basically three types of hydraulic turbines. Francis turbines are generally installed with their axis vertical. High velocity swirling flow during spinnoload snl induces unsteady pressure pulsations in the turbine, and these pulsations cause fatigue in the blades.
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. Mixed flow turbine is also used in irrigation water pumping sets to pump water from ground for irrigation. Vertical horizontal francis hydro turbine, high head water turbine. High speed machines used with francis and pelton turbines for high head hydro power. Turbines that operate in this way are called impulse turbines. Francis, while working as head engineer of the locks and canals. 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. Kaplan turbines are suited for low h and large q e. 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.
High head francis applications therefore require a large flow to be successful. 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. The francis turbine runners of the four ternary groups of grimsel 2 power plant in switzerland showed fatigue cracks at. The francis99 test case consists of a highhead francis turbine model, whose geometry, together with meshing and. Under common conditions, stable runaway is only reached if after a load rejection, the control and protection mechanisms both fail and the guide vanes. 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. Pdf as a result of stresses induced by rotorstator interaction, a number of high head francis turbines have failed in the past 15 years. Turbine selection is based on the available water head, and less so on the available flow rate.
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. Francis turbines are very able to sustain the high mechanical stress resulting from high heads. The turbine casing, with the runner fully immersed in water, must be strong enough to withstand the operating pressure. The pelton wheel is among the most efficient types of water turbines.
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. Hydraulic turbines exhibit total load rejection during operation because of high fluctuations in the grid parameters. Technical publications on francis and pelton turbines andritz. Impulse turbines are suited for large h and a low q, e. It is used when the head is between 80 to 500 metres. Dynamic stability of the high head francis turbines is one of the challenging problems. 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. To investigate the amplitude of unsteady pressure loading, transient pressure measurements were carried out in a model francis turbine during snl. The kaplan turbine was an evolution of the francis turbine. Investigation of a high head francis turbine at runaway operating conditions article pdf available in energies 93. High head francis turbine, high head francis turbine.
Also, there are some disadvantages of francis turbine and those are listed below. The present work focuses on the pressure variations in a high head francis turbine during the transients. It is efficient over a wide range of water head and flow rate. Experimental investigation of a high head francis turbine. 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. Francis turbine is the most widely used turbine in hydropower plants to generate electricity. The description of hydraulic and structural design of high head francis turbines and pelton turbines has been based mainly on the experience from. Paper open access related content experimental investigation.
The primary objective is secure reliable operation and lifetime for high head francis turbines operating in the future energy market. Francis turbines with an operating head of 63 m and a runner diameter of 6. Its invention allowed efficient power production in the low head application that was not possible with francis turbine. The fluid power is converted into kinetic energy in the nozzles.
Design, performance and maintenance of francis turbines i. This chapter describes each turbine type, presented by decreasing head and increasing nominal flow. Refurbishment of high head francis turbines andritz. It is an inward flow reaction turbine that combines radial and axial flow concepts. Pressure measurements on a highhead francis turbine. 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 the runner blades much earlier. 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. Why is the pelton wheel suitable only for high heads. The most common example is the pelton wheel turbine. Francis turbines may be designed for a wide range of heads and flows.
Pdf investigation of a high head francis turbine at. 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. Conversely, for low head applications the flow must be low or the turbine will become excessively large. Please find below a list of our technical publications on francis and pelton turbines for water power plants. Resonance and pressure pulsations in high head francis runner. Water with high head pressure enters the turbine through the spiral casing surrounding the guide vanes. In general, impulse turbines are used for high head sites, and reaction turbines are used for low head sites. Pdf hydraulic turbines exhibit total load rejection during operation because of high fluctuations in the grid parameters. Onboard measurements at a 100mw highhead francis turbine m. Kaplan turbine is now widely used throughout the world for high flow, low head power production. 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. 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. 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.
Investigations of compressible turbulent flow in a highhead. Hydraulic turbineshydraulic turbines raven mechanical. Medium and large hydro generators ge renewable energy. Turbines that operate in this way are called reaction turbines. In floody conditions turbines have to operate at overload conditions sometimes nondesigned conditions. This turbine is used for medium heads with medium discharge. The steadystate measurements were conducted on a model francis turbine. Francis and kaplan turbines belong to this category. It is still the most widely used water turbine in the world today. The water which is not durt free can cause extremely rapid wear in a high head francis turbine. Then water passes through guide vanes where it is directed to strike the blades. On the performance of a high head francis turbine at.
Overall design and joint supply of turbines and generators for the worlds most powerful hydro plant to date at,300 mw. If the machine transforms mechanical energy into hydraulic energy it. High head francis turbine for variable speed operation. Francis turbines are the most common water turbine in use today.
Pdf on the performance of a high head francis turbine at. The francis turbine is a type of water turbine that was developed by james b. Challenging onboard measurements in a 100 mw highhead. Experimental and numerical studies of a highhead francis. A wide variety of high head francis turbine options are available to. The water looses a part of its pressure in the volute spiral casing to maintain its speed. Onboard measurements at a 100mw highhead francis turbine. 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. 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. 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.
Turbine type of energy head discharge direction of flow specific name type speed pelton wheel impulse kinetic high head 250m to m low tangential to runner low high velocity swirling flow during spinnoload snl induces unsteady pressure pulsations in the turbine, and these pulsations cause fatigue in the blades. 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. His analytical methods allowed design of highefficiency turbines to precisely match. The simulation domain includes the spiral casing with stay and guide vanes, the runner and the draft tube. Consequently, the turbine runner accelerates to high speed, runaway speed, in seconds. Other deciding factors include how deep the turbine. The following method was developed within a large research project to investigate a high head francis turbine with a specific speed of nq. Sep 20, 2017 dynamic stability of the highhead francis turbines is one of the challenging problems. Investigations of compressible turbulent flow in a high. Compared to reaction turbines, impulse turbines require higher head, and work with a lower volume flow rate. This versatility, along with their high efficiency, has made them the most widely used turbine in the world. Instead of using water jets, reaction turbines fill a volute with swirling water that rotates the runner blades. 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.
Introduction to francis turbine diagram, working principle the francis turbine is a mixed flow reaction turbine. Selecting the appropriate type of turbine depends primarily on available head and less so on available flow rate. The best performance was achieved at height ratio of 2. Cervantes abstractthe purpose of the present work has been to investigate the ability of the pro. The francis turbine, named for him, is the first modern water turbine. Frequency converter solutions and control methods for variable speed operation of pump storage plant. Since 1930, the company has installed over 190 units with heads above 300 m with a total output of more than 12000 mw. Unsteady rotorstator interaction rsi develops dynamic stresses and leads to crack in the blades. Gandhi 3 1 department of energy and process engineering, norwegian university of science and technology, trondheim no7491, norway. Francis turbine working principle, main parts, diagram and.
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. Gandhithis content was downloaded from ip address 157. 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. As a spiral casing is stranded, the runner is not simply available. Vertical horizontal francis hydro turbine, high head water. Technical publications on francis and pelton turbines.
Francis turbine its components, working and application. With about 60% of the global hydropower capacity in the world, francis turbines are the most widely used type of hydro turbine. In a high head turbine, vaneless space is small and the amplitudes of rsi frequencies are very high. Chirag trivedi transient pressure measurements on a high head. Numerical study of a high head francis turbine with. Transient cfdanalysis of a high head francis turbine ruben moritz and michel j. As a result of stresses induced by rotorstator interaction, a number of high head francis turbines have failed in the past 15 years. A water turbine is to be designed to produce 27 mw when running at 93. In a highhead turbine, vaneless space is small and the amplitudes of rsi frequencies are very high. Pelton turbine or wheel is an impulsive turbine used mainly for high head hydroelectric schemes. The main target of the investigations is the numerical. Assuming a model efficiency of 88%, estimate the volume flow rate through the. Design, performance and maintenance of francis turbines. Highhead francis turbine for variable speed operation ntnu.
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