Sediment erosion can be found in all components however, the nature of erosion is different. He also conducted sophisticated tests and developed engineering methods for water turbine design. Turbines that operate in this way are called reaction turbines. This type of turbine is usually a deriaz or francis turbine in design. If the recommended turbine is not satisfactory, a second recommendation based on cost can be. The specific speed increases as flow rate increases and hydraulic head decreases. In many modern francis mixedflow hydroturbines, the flow exiting the turbine swirls in a direction opposite to that of the runner itself. This has the advantage of centrifugal forces acting against the flow, thus reducing the tendency of the turbine to over speed. From the beginning, francis turbine development has always been synonymous with voith. Modelling and analysis of a very low head kaplan turbine. Nowadays runner shape optimization methods based on genetic algorithm ga 1 are being developed widely in the world 29. It is an outward reaction turbine, resulting in a changed water pressure as the water moves through the turbine and gives up its energy.
The turbine connects to the pumped supply of the hydraulic bench. Turbines with more than one francis runner on a shaft were very common in the early days of hydroelectric development. This bearing is located closest to the turbine runner and radially supports the rotating runner and shaft assembly. The admission of a francis turbine is radial and the outlet is axial. Functional problems and maintenance operations of hydraulic. The speedup gear is referred to as a gear system in this manual in some. The francis turbine is an inward flow reaction turbine which was designed and developed by the american engineer james b. Our francis turbines, including the worlds largest and most powerful.
With new solutions dft in the last years became a very interesting selection for sites with specific operation. Therefore, turbines with high specific speed have also high values of stage reaction, because work exchanged between fluid and runner decreases if r increases. Earlier the present authors presented multiobjective optimization method for the design of francis turbine runner, based on 3d cfd analysis of the flow 5, 7. It is obvious from the equation of specific speed eq. The pumping load can also be varied with deriaztype units, which cannot be done with a francis runner. The paper deals with hydraulic and mechanical design features of a doubleflow francis turbine iec tr 664. In francis turbine water flow is radial into the turbine and exits the turbine axially. Turbine machines are pumps, fans, compressors, water turbines, gas turbines, steam turbines, wind turbines, aircraft and marine propellers, torque converters, hydrodynamic clutches etc.
Advanced cfd, fea technic is utilized in the designing process to ensure better technical solution. An example for such a singleregulated horizontal axis twin francis turbine is. Traditionally, francis turbine has been considered to be a simple and robust machine suitable for exploitation of water energy. Proportional or directional valves controlled by the governor operate cylinders that open and close wicket gates or needle valves to adjust the flow of water to the turbine in order to maintain a constant turbine speed.
It has fewer parts as compared to franciss turbine which has both fixed vanes and guided vanes. The roughness of the polished parts of the prototype. Possible turbine types for low head application axial axial type turbines heads approx. A further advantage of a deriaztype machine is that the runner blades can be closed read more. Sediment erosion in hydraulic turbines o global journals. It is an inwardflow reaction turbine that combines radial and axial flow concepts francis turbines are the most common water turbine in use today. It is used when the head is between 80 to 500 metres.
Introduction water from reservoir flows through penstock and then francis turbine consisting spiral casing, stay ring, distributor, runner and draft tube. Vertical horizontal francis turbine generator unit, high. There is no cavitation because water jet strikes only a specific portion of the runner. Generally, this kind of turbine has an axial flow runner that has three to six blades based on the water head that the turbine is designed to be utilized.
It was designed by american scientist james francis. The balances measure the turning force on the drum at the back of the turbine see figure 4. Rotational torque of the runner 9 is transmitted to a generator via the turbine main shaft 11 to generate electricity. Francis turbine is a kind of turbine suit to water head 20300meters and with certain suitable flow. Pelton wheel pelton turbine hydropower 3d animation. Cross section of a casted heavy francis turbine left and a modern high head turbine with welded runner and spiral casing right ii. Multiobjective shape optimization of runner blade for kaplan. This textbook is about principles of turbine machinery.
The advantage in the efficiency for kaplan turbines is obtained by the double. Besides the runner, the other major components are the scroll case, wicket gates, and draft tube. The head cover 3 is formed with an outerperiphery seal on the side of a runner crown 9a. The key double francis turbine components includes runner, distributor, main shaft, main shaft seal, turbine guide bearing, governor, among other. It could be divided into vertical and horizontal arrangement. In a francis turbine, the runner blades are divided into two parts. Dec 26, 2019 the crest of spillway is kept at full reservoir level. Francis improved the inward flow reaction turbine to over 90% efficiency. Energy systems hydraulic turbines and hydroelectric power plants 12. The pelton turbine is an impulse turbine that extracts energy from the impulse of moving water and is the preferred turbine for hydropower. Runner of francis turbine the shape of the blades of a francis runner is complex.
Outlet draft tube outlet runner inlet runner outlet guide vane inlet guide vane. The runner 9 is connected to the lower end portion of a turbine main shaft 11. They operate in a water head from 40 to 600 m to 2,000 ft and are used primarily for electrical power production. Design, performance and maintenance of francis turbines. The kaplan turbine runner was modelled in 3d model of runner of kaplan turbine in proe. Maximizing hydroelectric turbine performance and reliability. Turbines most material from fluid mechanics, cengel and cimbala, chapter 14 introduction and terminology. Multiobjective shape optimization of runner blade for. The technical scheme for solving the problem is as follows. Francis 1815 1892 an english born inventor who developed the turbine in the year 1849. This conventional method of design of francis excludes estimation of erosion in turbine blade in case of sediments in flow. Runner francis turbine propeller kaplan turbine generator generator 5. Optimizing runner blade profile of francis turbine to. Systems with medium head size are appropriate for francis turbine application.
It has fixed runner blades and adjustable guide vanes. The lower half is made in the shape of a small bucket so that it uses the impulse action of water to rotate the turbine. The turbine casing, with the runner fully immersed in water, must be strong enough to withstand the operating pressure. The francis turbine was invented in lowell, massachusetts in 1848 by james b. Losses in francis turbines npsh main dimensions francis turbines. It is an inwardflow reaction turbine that combines radial and axial flow concepts. Radial water flow to the runner and axial emerge as a result of the runner spinning. Francis turbines are generally arranged so that the axis is vertical although smaller turbines can have a horizontal axis. The turbine has a sturdy base which sits on the top of the hydraulic bench.
Wicket gates and a draft tube are two other main elements of the francis turbine. A francis turbine has a runner with fixed buckets vanes, usually nine or more. Francis turbines are the most common water turbine in use today. Dec 17, 2019 pelton wheel turbine is very easy to assemble. Two main kinds of reaction turbines are the propeller and the francis. Turbine governor the governor uses either mechanical or electronic feedback to sense the speed of the turbine. For the carrying out of certain efficiencies with high values throughout the entire guaranteed functionary domain, the turbine is provided with a double. Francis turbine have the advantage of high efficiency, small size and reliable structure. The performance of high head francis turbines in the same diagram the efficiency of the model turbine is included for comparison.
Francis and kaplan turbines belong to this category. Water is introduced just above the runner and all around it and then falls through, causing it to spin. Since the rotational speed of the new runner is significantly higher then the rotational speed of the original francis one, the direct coupling of the turbine to the generator can be applied. They have three to six runner blades and can be single or double regulated.
This governinf gives better performance since the force required for operation of francis turbine guide vanes is much more compared to pelton turbine. This is called reverse swirl, and is designed to extract the maximum possible momentum from the water, similar to how a pelton wheel turbine bucket turns the water nearly 180o around. Francis turbine is characterized by a fixedblade francis runner that is hydraulically optimized for a narrow operating range. Francis turbine is a radial inward flow reaction turbine. 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.
Water pressure decreases as it passes through the turbine imparting reaction on the turbine blades making the turbine rotate. For that reason, it takes about two weeks to perform the assembly. In high head pelton turbines, the absolute acceleration range normal to the surface could be 50,000 100,000 ms2. The turbine runner is usually directly coupled to the generator shaft and shall be above the downstream level. Introduction to turbine machinery university of ljubljana. The turbine manufacturer can only give the clearance. For liquids, we usually call them hydraulic turbines or hydroturbines. Feb 12, 2012 the pelton turbine is an impulse turbine that extracts energy from the impulse of moving water and is the preferred turbine for hydropower. Horizontal francis turbine unit, with horizontal shaft, could be 2 or three supports.
Pumped storage allow ready adjustment of the runnerblade angles to match the opposite requirements of pumping and power generation. The francis turbine is a type of water turbine that was developed by james b. Its runner shape was similar to that of a francis turbine. Aug 31, 2019 a water turbine is a rotary machine that converts kinetic energy and potential energy of water. A water turbine is a rotary machine that converts kinetic energy and potential energy of water.
Design of the runner of a kaplan turbine for small. The runner consists of the stainless steel runner blades mounted on the runner hub and the runner cap at the lower side of the hub, enhancing the optimized hydraulic shape. 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. Water enters the turbine through spiral casing, and starts entering the runner blades, passing through stay vanes and guide vanes, as it moves along the length of casing the decreasing crosssection area of the spiral casing makes sure that the pressure energy of water would remain uniform along its length, as a portion of water is also entering the runner blades. Turbine is a general term for any device that extracts mechanical energy from a fluid generally converting it to rotating energy of a turbine wheel. Further a manual separated operation of each guide vane servomotor will be. The invention discloses a doublerunner ultralow specific speed axial flow hydraulic turbine for driving a cooling tower fan, which can effectively solve the problems of high specific speed, large size and low efficiency of a hydraulic turbine. Mavels kaplan turbines are optimal for runofriver projects with low heads from 1. Francis turbine working principle, main parts, diagram and. Twin francis turbines bryan leyland consulting engineer. Vertical horizontal francis turbine generator unit. Pelton turbine runner peltion turbine runner consists of splitter, bucket tip and bucket surface. In this turbine, the free jet from the nozzle strikes doublecupped buckets, which are coupled with.
Francis turbines are best suited for medium heads, say 40m. The kaplan turbine runner was modelled in 3d model of runner of kaplan turbine in proe engineer software and after calculating the blade. Hydraulic turbinesbasic principles and stateofthe art. Design, performance and maintenance of francis turbines i. Torque t this is the torque measured by the two spring balances. Application of reaction turbines is in sites with lower heads and higher flow rates. Turbine types turbines are classified into two types according to. This requires that the runner should admit a comparatively large quantity of water for a given power output and. They operate in a water head from 40 to 600 m to 2,000 ft and are used. What is the difference between runner and shaft in hydraulic. The francis turbine is a laboratoryscale reaction turbine for use with tecquipments digital hydraulic bench h1f, available separately. Turbine power this is the power absorbed by the turbine wheel, taken from water, 2 60 or. Selecting hydraulic reaction turbines bureau of reclamation. The francis turbine, named for him, is the first modern water turbine.
Cn101915196b doublerunner ultralow specific speed axial. Pdf the paper deals with hydraulic and mechanical design features of a doubleflow francis turbine iec tr 664. While shaft is connecting medium between the blades and the generator which rotates when th. In the proposed methodology the following two terms are defined as the indicator and the means of estimating of relative erosion in the francis turbine runner. The paper deals with hydraulic and mechanical design features of a double flow francis turbine iec tr 664. In hydraulic turbines, the blades are also called as runners which rotates when the fluid flows in the casing and comes in contact with it. Francis turbine is the first hydraulic turbine with radial inflow. The crest of spillway is kept at full reservoir level. 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.
1353 944 1406 411 953 1270 193 779 775 1084 1637 852 343 1191 237 1479 1462 1410 616 1437 1296 1338 1022 1024 1275 696 1074 312 890 44 1248 514 199 1217 195 625 828 1462 293