Initial basic design of all the components of francis turbine is completed based on basic fluid dynamics turbo machinery. Evolution from francis turbine to kaplan turbine wikipedia. The video gives you the basic concepts of francis turbine along with its vector diagram. Velocity triangle for moving blade of an impulse turbine 1. In a vertical francis turbine, the runner speed is 380 r. The nps institutional archive reports and technical reports all technical reports collection 196404 radialinflow turbines vavra, m. A francis turbine is a type of turbine used most frequently in medium or largescale hydroelectric plants. These turbines can be used for heads as low as 2 meters and as high as 300 meters.
What purpose do velocity triangles serve in cases of. Francis turbine is a reaction turbine in which the working fluid comes to the turbine under immense pressure and the energy is extracted by the turbine blades from the working fluid. The turbine rotor then extracts work from the flow by removing the kinetic energy associated with the swirl velocity. Velocity triangle for moving blade of an impulse turbine. The steam expands first in the stationary or fixed blades where it gains some velocity as it drops in pressure.
Francis turbine converts energy at high pressure heads which are not easily available and. It helps to calculate flow and whirl velocities at both end of impeller or turbine blade. But for smooth flowing of the steam while existing, it creates an angle of moving blades. The blades for a reaction turbine are always so shaped that the tangential or whirling component of velocity at the outlet becomes zero 0 2 v w. A wicket gate around the outside of the turbines rotating runner controls the rate of water flow through the. Introduction to francis turbine diagram, working principle the francis turbine is a mixed flow reaction turbine. They operate in a water head from 40 to 600 m to 2,000 ft and are used primarily for electrical power production.
The francis turbine was developed by an american engineer james bichens francis around 1855. Pelton turbine and its velocity triangles unacademy. In this video, i explained velocity triangle and work done of francis turbine with animation and following topic. Francis turbine runner to analyze the static stress characteristics in the francis turbine runner at various operating points. Francis turbine is the most common type of turbine in practice, which presents a sidebyside design of generator. Now let the jet glides over the inside surface and leaves the blade at d, as shown in fig. Now a days francis turbine is the most commonly used turbine because of its working conditions. Svartisen p 350 mw h 543 m q 371,5 m s d 0 4,86 m d 1 4,31m d 2 2,35 m b 0 0,28 m n 333 rpm. The vector nature of velocity is utilized in the triangles, and the most basic form of a velocity triangle consists of the tangential. The appropriate velocity triangles are shown in figure 12. To define the twist of the blade, the velocity triangles at six different radii of the blade are.
The draft tube is an expanding tube which is used to discharge the water through the runner and next to the tailrace. The adopted procedure for the runner analysis is as follows. This video includes how to draw velocity triangle of old francis turbine and modern francis turbine in fluid power engineering. The velocitycompounded impulse turbine was first proposed by c. Good morning, i welcome you all for todays discussion on hydraulic turbines. This relationship is illustrated in the velocity parallelogram of a liquid particle. This turbine is used for medium heads with medium discharge. Consider a steam jet entering a curved blade after leaving the nozzle at c. His design is extremely flexible and can be tailored to different head heights and flow rates. It is explained in easiest terms so that every one can understand the concept. With about 60% of the global hydropower capacity in the world, francis turbines are the most widely used type of hydro turbine.
How to draw a velocity triangle for various pumps or. Water enters the runner and flows towards the center of the wheel in the radial direction and. The main function of the draft tube is to reduce the water velocity at the time of discharge its crosssection area increases along its length, as the water coming out of runner blades, is at considerably low pressure, so its expanding crosssection area helps it. Gas with an absolute velocity c 1 making an angle a 1, angle measured from the axial direction enters the nozzle in impulse turbine or stator blades in reaction turbine. To get more accurate result we should put more operating points during analysis. Total 11 points, which including the highest head 79m, and the lowest head 51 m.
Francis turbine works on medium head and medium discharge i. See alsoedit francis turbine kaplan turbine velocity triangle turbine threedimensional losses and correlation in turbomachinery. How to draw velocity triangle of francis turbine old. High head francis turbine design ns80 to 90 is very complex in nature. It is an inwardflow reaction turbine that combines radial and axial flow concepts francis turbines are the most common water turbine in use today. A fatigue analysis of a hydraulic francis turbine runner. Usually the flow velocity velocity perpendicular to the tangential direction remains constant throughout, i. Velocity triangles example velocity triangles example april 12, 2012 mechanical and aerospace engineering department 2.
A part of the fluid energy is converted to mechanical energy because of pressure changes occurring in the blades of the turbine, determined by the expression of degree of reaction. The francis turbine is a type of water turbine that was developed by james b. Using the euler turbine equation, where e is the energy transfer to the rotor per unit mass of the fluid. This video includes how to draw velocity triangle of kaplan turbine in fluid power engineering. It is moving tangentially at velocity u and over the surface at velocity the absolute velocity of the water is the vector sum of these two and is denoted v. Impulse turbine and reaction turbineprinciple, working. Francis turbinevelocity triangleanimation,work done.
The fluid pressure is atmospheric throughout and the velocity is constant except for a slight reduction due to friction. Jet ratio 12 in most casescalculate, d nozzle diameter. Draw the absolute velocity vector velocity triangles at b. Mean diameter of the rotor is 690 mm, it rotates at 4500 revolutions per minute. The casing of this turbine should be air tight because pressure varies. A turbine was investigated by various methods of calculating its efficiency. Velocity triangles for both impulse and reaction turbines and the force on the blades references for impulse and reaction turbines with worked examples.
Impulse turbine efficiency calculation methods with. Additionally, these turbines are beneficial as they work equally well when positioned horizontally as they do when they are oriented vertically. Losses in francis turbines npsh main dimensions francis turbines. Various methods of loss calculation were explored in the search for a. Find efficiency of turbine compared to available wind power varies with not well known ratio upstream, turbine areas maximum c. Example 3 a pelton wheel buckets are square to jet when they are ahead of the normal position a. A reaction turbine has rows of fixed blades alternating with rows of moving blades. The water on the blade has two velocity components. How to draw velocity triangle of kaplan turbine fluid power.
The dashed line shows the initial value of flow, and the solid line represents the velocity triangle for a increased flow. The curtis stage turbine, as it came to be called, is composed of one stage of nozzles as the singlestage. For more video on engineering mathematics click on below link. Start by drawing the axial velocity to some scale 10 units here velocity triangles at b. The velocity triangle is the vectorial representation of kinematic movement. For such type of machine for any value of flow rates, the head remains constant as shown in. 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. Velocity triangles may be drawn for both the inlet and outlet sections of any turbomachine. Pdf erosive wear of turbine components has been a major technical. Then enters the moving blades where its direction of flow is changed thus producing an impulse force on the moving blades.
The principal feature of a reaction turbine that distinguishes it from an impulse turbine is that only a part of the total head available at the inlet to the turbine is converted to velocity head, before the runner is reached. Velocity triangles free download as powerpoint presentation. Computeraided analysis of hydraulic reaction turbines american. The moving blades are running at horizontal direction with a tangential velocity v and v 2 the absolute velocity of steam leaving of moving blades create an angle. To carry out design of a typical low power pelton turbine, a.
Examples losses in francis turbines npsh main dimensions. In this study, a francis turbine with specific speed of mkw was designed on the basis. Pdf development of francis turbine using computational. From inlet velocity triangle, vw1 v1 assuming no shock and ignoring frictional losses through the vane, we have vr1 vr2 v1 u1 in case of pelton wheel, the inlet and outlet are located at the same radial distance from the centre of runner and hence u1 u2 u from outlet velocity triangle, we have vw2 vr2 cos u2 v1 ucos u. Curtis to solve the problems of a singlestage impulse turbine for use with high pressure and temperature steam. This is made to keep the kinetic energy at outlet a minimum. Main parts of francis turbines francis turbine reaction turbine. The project was based on an existing impulse turbine, a onestage turbine set in an organic rankine cycle with the working fluid being r245fa. Thus the steam velocity through the turbine will be less than 1150 fps for a reaction turbine and less than 2300 fps for an impulse turbine, or about 1570 mph, more than twice the speed of sound. Lecture on francis turbine indian institute of technology. Velocity triangles may be drawn for both the inlet and outlet sections of any turb. Velocity triangle for reaction turbine,part6,unit2. Velocity triangle for reaction turbine,part6,unit2,dynamic of machine 4b engineers. This v r2 can be obtain by subtracting the v and v 2 and it create some angle f 1.
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