At the inlet of a francis runner a pressure shock in the water occurs each time a runner blade is passing through the wakes from a guide vane giving a pressure shock in the flow. Therefore this investigation studies the effect on the efficiency of the application of variable speed technology on a single francis turbine. Pdf hydroelectricity is one of the most suitable, efficient and nature friendly conventional source of energy. Pelton turbine design of gilgel gibe ii at a runner circumferential velocity of around half the jet velocity, the maximum efficiency in the energy conversion is reached because the energy of the discharging water is at its minimum. This has the advantage of centrifugal forces acting against the flow, thus reducing the tendency of the turbine to over speed.
Using the euler turbine equation, emevw1u1, where e is the energy transfer to the rotor per unit mass of the fluid. Generating electricity from the power of water represents large amounts of clean, renewable energy. Hence, these are the parameter changes that has to be incorporated in converting a francis turbine to kaplan turbine. Fluid machines in the reaction turbines, the fluid passes first through a ring of stationary guide vanes in which only part of the available total head is converted into kinetic energy. Francis turbines are the most common water turbine in use today.
How to draw a velocity triangle for various pumps or turbines. At the highhead range, the flow rate and the output must be large. This short note indicates how a preliminary design of an axail. What we have not done is the component of the reaction turbines, francis and kaplan, so i will spend some time to discuss the components, the velocity triangles. Hydraulic turbinesbasic principles and stateofthe art. The reason for this is the lower velocity in the guide vane wake compared to the average velocity from the guide vane system.
According to type of energy at inlet a impulse turbine pelton wheel requires high head and low rate of flow a reaction turbine fancis, kaplan requires low head and high rate of flow 2. H m is the mass flow rate in kgs and h is the pressure head difference over the turbine in. Meanline analysis of turbines with choked flow in the object. Parametrical and theoretical design of a francis turbine. Impulse turbine efficiency calculation methods with organic. That is, the blade pushes and turns the fluid in the direction of the blade motion, thereby doing work on the fluid. A francis type hydro turbine consists of five components which. Furthermore it evaluates if it is possible to quantify the benefits of variable speed technology with data provided by typical turbine model tests.
It is an inwardflow reaction turbine that combines radial and axial flow concepts. Improvements were made to the objectoriented turbomachinery analysis code otac to enable analysis of meanline turbine models with choked ow adds calculations for throat area and choked ow constraint modi es analysis case inputs to include exit static pressure revises the internal solver setup maps produced with new method exhibit characteristics. Water enters the runner of the turbine in the radial direction and leaves the runner in the axial direction. Operate in a water head from 10 to 650 meters 33 to 2,3 feet. Hydraulic turbines may be defined as prime movers that transform the.
Impulse turbine efficiency calculation methods with. The reaction turbine is further subdivided into the francis type, which is characterized by a radial. Dimensions of the outlet g a u b u g u b g c npsh a m r. Modern francis turbine is a mixed flow type turbine i. Design, performance and maintenance of francis turbines. Analytical study on flow through a pelton turbine bucket. Parametrical and theoretical design of a francis turbine runner with the help of computational fluid dynamics. Expressed in terms of pressure head the formula is w.
Evolution from francis turbine to kaplan turbine wikipedia. It was easy to convert high pressure heads to power easily but difficult to do so for low pressure heads. The 3d animation shows francis turbine 3d animation on vimeo. In the sections that follow, each type of hydraulic turbine will be studied separately in terms of the. Furthermore it evaluates if it is possible to quantify the benefits of variable speed technology with. In 1890 american engineer pelton developed impulse turbine, named pelton turbine. Abstract the aim for turbine design is to increase the efficiency and avoid cavitation and fractures during operation. With decades of continuous optimization based on the latest hydrodynamic research, well over half the turbines manufactured by voith hydro are of the francis type.
A brief discussion on a the design philosophy during the last 60 years with will be presented. The picture shows combined velocity triangle of steam turbine. Francis hydro turbine is the dominant turbine in the hydropower generation. The francis turbine, kaplan turbine and propeller turbines are reaction turbines. In this article, we see about the impulse turbine and reaction turbine principle, working and difference. In mixed flow water enters the blades radially and comes out axially, parallel to the turbine shaft. Dahlqvist approved 20121016 examiner damian vogt supervisor jens fridh commissioner contact person 1 abstract a turbine was investigated by various methods of calculating its efficiency. The vector nature of velocity is utilized in the triangles, and the most basic form of a velocity triangle consists of the tangential. Let us look at turbines first and there are two types of turbines a. At the outlet a draft tube with two piers is located.
Application of variable speed operation on francis turbines. The computational mesh of the turbine is shown in fig. Numerical simulation of a complete francis turbine. Velocity triangles for turbine and compressor design. In turbomachinery, a velocity triangle or a velocity diagram is a triangle representing the various components of velocities of the working fluid in a turbomachine. It adds swirl to the flow, converting internal energy into kinetic energy. Different arrangement of axial turbine in a power plant system 1 suitable for low head approx. According to the newtons second law of motion,the direction of force in the blades, work done in the direction of motion of the blades, mathematically, axial thrust on the wheel is the velocity difference between inlet and outlet steams flow.
The guide vane position has a direct effect on the inlet velocity. Set the brake at some level and measure the brake load using. This watertight bulb is submerged inside the water and bends at inlet to casing, draft tube etc. Francis turbine is a reaction type hydraulic turbine, used in dams and reservoirs of medium height to convert hydraulic energy into mechanical and electrical energy. Francis turbine is a radial inward flow reaction turbine. In axial flow turbine water flows parallel to the axis of the turbine shaft.
In the sections that follow, each type of hydraulic turbine will be studied separately in. Another purpose of the lab is to check turbine scaling laws. Experimental investigation on a high head model francis turbine during load rejection, iop conf. From the diagram pelton turbines are found to be cheaper than francis turbines for decreasing capacity. Efficiency will depend on turbine size or rotor diameter, blade geometries, speed, extreme condition of steam and other losses. Decision making on turbine types and capacities for runofriver hydroelectric power plants a case study on eglence1 hepp aim of this thesis is to overview a methodology for selecting the best fit turbine type which is one of the most important part of. Francis turbine blades are designed in such a way that one portion of the blade design creates the pressure difference between the opposite faces of the blade when water flows through it, and the remaining portions blade design use the impulse force of water hitting it and this combined action of pressure difference and impulse force generates enough power to get turbine moving at a required speed. Media in category velocity triangles for turbine and compressor design the following 43 files are in this category, out of 43 total.
Velocity triangles example velocity triangles example april 12, 2012 mechanical and aerospace engineering department 2. Impulse turbine and reaction turbineprinciple, working. Impulse turbine efficiency calculation methods with organic rankine cycle johan e. Impulse turbine and reaction turbineprinciple, working and. The computational model consists of spiral casing, 18 numbers of stay vanes and guide vanes, runner having numbers of blades and a draft tube. In 1870 professor fink introduced an important improvement in francis turbine byygg gp g making the guide vanes turning on a pivot in order to regulate the flow discharge. Our francis turbines, including the worlds largest and most powerful. Turbine speci c speed concepts the turbine speci c speed is a quantity derived from dimensional analysis. General differences between francis and kaplan turbines. Velocity triangles free download as powerpoint presentation.
The difference in the operating head can be extra simply controlled in francis turbine than in the pelton wheel turbine. Increase area of water exit, increase whirling action, suit for. The vortex e ect of francis turbine in electric power. The francis turbine is a type of water turbine that was developed by james b. Very simple kaplan turbine design durham university. A constant efficiency hill diagram was constructed to. Francis turbine converts energy at high pressure heads which are not easily available and hence a turbine was required to convert the energy at low pressure heads, given that the quantity of water was large enough. From the beginning, francis turbine development has always been synonymous with voith. Parametrical and theoretical design of a francis turbine runner with the help of computational fluid dynamics ayancik, fatma, celebioglu, kutay and aradag, selin author for correspondence department of mechanical engineering, tobb university of economics and technology, sogutozu avenue 43, sogutozu, ankara, 06560, turkey. Both use a fluid of gous nature at high temperature at high pressure to generate power. Steam turbine is the widely use as a prime mover in power plants, refineries, petrochemical plants, food processing plants, power plants etc.
Flow field in a high head francis turbine draft tube. Turbine selection the water turbine is the key to any hydro project and requires correct interfacing with the electrical, mechanical, hydraulic and civil aspects of the project. This is the fluid power supplied to the machine in the form of pressure and volume. The rated head and discharge for the turbine were 48 m and 7. Efficiency of kaplan turbine is higher than francis turbine. Therefore, an evolution took place that converted the francis turbine to. Increase area of water exit, increase whirling action, suit for helical flow. These are followed by 24 guide vanes and the runner with blades. Francis turbine working principle, main parts, diagram and. The inlet velocity triangle the outlet velocity triangle at the inlet there is no component of absolute velocity in the direction of rotation. In order to carry out a preliminary blade analysis consider a mean radius through the machine.
Velocity triangles may be drawn for both the inlet and outlet sections of any turbomachine. Francis in 1849 developed the radial turbine, named francis turbine. Steam consumption steam consumption of steam turbine is depending to required output power and efficiency of the turbine. This video explains the technical points of francis turbines, which are often integrated into pumpedstorage plants for power production. Fundamentals of fluid mechanics chapter 12 pumps and turbines. Francis turbines are probably used most extensively because of their wider range of suitable heads, characteristically from three to 600 metres. How to draw a velocity triangle for various pumps or. The investigated turbine is a francis turbine consisting of the spiral case with 23 stay vanes and a tip nose.
Hydraulic turbineshydraulic turbines raven mechanical. Investigation of a high head francis turbine at runaway. Characteristic curves of a turbine these are curves which are characteristic of a particular turbine which helps in studying the performance of the turbine under various conditions. Francis turbines are best suited for medium heads, say 40m. The main purpose of this lab is to measure the power output of a francis turbine and to compare this to the theoretical power output. Examples losses in francis turbines npsh main dimensions. All the turbine passage is completely full of water and atmospheric air has no access to them. Hefat2014 10th international conference on heat transfer, fluid mechanics and thermodynamics 14 16 july 2014 orlando, florida parametrical and theoretical design of a francis turbine runner with the help of computational fluid dynamics.
Fluid machines in the reaction turbines, the fluid passes first through a ring of stationary guide vanes in. The mechanical efficiency of the pelton wheel turbine decreases faster than the francis turbine. The francis turbine is an inward flow reaction turbine which was designed and developed by the american engineer james b. Ideal velocity triangle of francis turbine by anupamiit cc bysa 3. The runner of the pelton turbine consists of double hemispherical cups fitted on its periphery. Note that this analysis is approximate and is useful for a.
Francis turbine has been installed at most 60% of the hydropower in the world at present. In this article, we see about the impulse turbine and reaction turbineprinciple, working and difference. The francis turbine is a reaction turbine and it was developed by james b francis. In order to increase the amount of dissolved oxygen do level in hydroelectric plants, researchers have also used models where. In the same diagram the efficiency of the model turbine is included. Steam turbines are ideal wherever steam is available.
Pelton turbine design of gilgel gibe ii uchicago geosci. By influencing the rotor velocity the flow velocity triangle may be adapted to operate at different water heads with less efficiency losses. We can apply the same analysis techniques to a turbine, figure 12. Prepare a table to mention the values of all the parameters, such as head, flow rate, speed, diameter, specific speed, power. The cfd approach for prediction of efficiency of a 3 mw capacity horizontal axis francis turbine is presented.