Earlier velocity triangles were drawn for pumps in a very similar manner. Very simple kaplan turbine design grant ingram 30th january 2007 nomenclature b blade height g gravitational acceleration h head k loss coe. Velocity triangles may be drawn for both the inlet and outlet sections of any turbomachine. The compressor operates with an axial inlet flow velocity of 250 ms at 3000 rpm. Vu1, vu2 tangential component of absolute velocities at inlet and outlet. Velocity triangle for moving blade of an impulse turbine. Variation in nozzle blade heightrotor inlet diameter corresponding to. Velocity triangle for reaction turbine,part6,unit2. Velocity triangles example velocity triangles example april 12, 2012 mechanical and aerospace engineering department 2. Aerodynamics rotational theory and velocity triangle at. Initially i did the simulation of both nozzle and turbine and gave the inlet velocity condition based on nozzle angle.
An inward flow reaction turbine has an external diameter of 1m and its breadth at inlet is 250mm. Velocity triangles turbine dynamics mechanics free. An axial turbine has similar construction as an axial compressor, but it operates in the reverse. In this turbine, the work is broken down into various stages. Figure 3 velocity triangle v1, v2 absolute velocities at inlet and outlet. How to draw a velocity triangle for various pumps or. In figure 12 velocity triangles for a typical turbine stage have.
Very simple kaplan turbine design durham university. Example 3 a pelton wheel buckets are square to jet when they are ahead of the normal position a. The jet of fluid that strikes the turbine blades, has its two components. Various methods of loss calculation were explored in the search for a. Velocity triangle for reaction turbine,part6,unit2,dynamic of machine 4b engineers. Since the geometry of the blades is very complex only the. Francis turbine is a mixed hydraulic turbine the inlet velocity has radial and tangential. Selfprepared notes assignment 1 5 tb1 4174 principle of similarity in. The pico propeller turbine uses a closed scroll casing that directs water onto the propeller. The inlet velocity triangle the outlet velocity triangle at the inlet there is no component of absolute velocity in the direction of rotation. The water which is not durt free can cause extremely rapid wear in a high head francis turbine. It is the component which is responsible for actual work done across blades.
Steam turbine 1 content chapter description page i purpose 2 ii steam turbine types 2 2. Impulse turbine efficiency calculation methods with. Influence of reaction on totaltostatic efficiency with fixed values of. Performance improvement through velocity triangle optimization. Another impulse turbine is the pressure compound or ratteau turbine. Velocity triangles can be used to calculate the basic performance of a turbine stage. Velocity triangle change expected after the optimization process73 figure 4.
As the fluid flows over the blade of the turbine, the blades having such design that the velocity of fluid flowing above and below the turbine blades are different and hence creating a pressure difference between above and below the blade and so exerting a net force and giving a. It was discovered in 188 0 by an american engineer lestera. Draw the velocity triangle for the first stage rotor exit and hence estimate the specific work output. Structural and conceptual design analysis of an axial. Such a turbine would be an imaginary one and is called specific turbine. Evolution from francis turbine to kaplan turbine wikipedia. The inlet pipe is axial, and fluid enters the eye, that is the center of the impeller with little, if any, whirl component of velocity. The appropriate velocity triangles are shown in figure 12. Velocity triangles are used to illustrate the flow in the bladings of. Turbine speci c speed concepts the turbine speci c speed is a quantity derived from dimensional analysis. Mean diameter of the rotor is 690 mm, it rotates at 4500 revolutions per minute. What is the difference in velocity triangles of impulse. At exit from the runner, the flow is shown leaving the runner without a whirl velocity, i. Note that the velocity diagram of the turbine differs from that of the compressor, in that the change in tangential velocity in the rotor, dc w, is in the direction opposite to the blade speed u.
Turbines are sometimes differentiated on the basis of the type of inlet flow, whether the inlet velocity is in axial direction, radial direction or a combination of both. A turbine was investigated by various methods of calculating its efficiency. For analysis purposes, it will be assumed that the plate is fixed and the jet is moving with a velocity of vv ms. Velocity triangles in turbomachinery linkedin slideshare. 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. Hydraulic turbines may be defined as prime movers that transform the kinetic energy of the falling. Pelton turbine among different types of impulse turbines, pelton wheel is the only turbine beingused at present. Theory of turbo machinery turbomaskinernas teori chapter 4. The turbine rotor then extracts work from the flow by removing the kinetic energy associated with the swirl velocity. Reaction turbine 2 iii steam turbine operating range 2 3.
Assume 10% of the area of the flow is blocked by blade thickness. Each stage consists of a nozzle and blade row where the kinetic energy of the jet is absorbed into the turbine rotor as useful work. Fundamentals of fluid mechanics chapter 12 pumps and turbines. Simulation of radial gas turbine, inlet velocity components. Whereas the flow in the turbine in inwards, the flow in the pumps is outwards. Velocity triangle for francis turbine guide vane exit velocity triangle at 2. An axial turbine is a turbine in which the flow of the working fluid is parallel to the shaft, as opposed to radial turbines, where the fluid runs around a shaft, as in a watermill. Velocity triangles are used to illustrate flow conditions. Chaplin encyclopedia of life support systems eolss conditions in turbine blades can be conveniently visualized and analyzed by drawing vector diagrams of the fluid velocities. The documents for the gunt fluid machin ery provide details on the.
The fluid pressure is atmospheric throughout and the velocity is constant except for a slight reduction due to friction. Aerodynamic design of a gas turbine rotor blade lund university. Velocity triangle for reaction turbine,part6,unit2,dynamic of machine. Also, there are some disadvantages of francis turbine and those are listed below. Gas exits the stationary turbine nozzle guide vanes at absolute velocity va1. The rotor relative exit angle is set at 34 degrees at a mean radius of 0. Let, v velocity of the plate, as a result of the impact of jet a little conversation will show that the relative velocity of the jet with respect to the plate equal to vv ms. The compressors in most gas turbine applications, especially units over 5mw, use axial. Please read the document introduction to quiz, which contains all the. This was done by manual modification of the throat area in the meanline code input file until the same relative mach number at the blade outlet was reached. Steam turbine convert a part of the energy of the steam evidenced by high. Introduction to turbine machinery univerza v ljubljani. Velocity triangles free download as powerpoint presentation. Velocity triangles turbine physical sciences free 30.
Computeraided analysis of hydraulic reaction turbines american. Fundamentals of fluid mechanics chapter 12 pumps and. The project was based on an existing impulse turbine, a onestage turbine set in an organic rankine cycle with the working fluid being r245fa. Now let the jet glides over the inside surface and. That is, the blade pushes and turns the fluid in the direction of the blade motion, thereby doing work on the fluid. Consider a steam jet entering a curved blade after leaving the nozzle at c. That is, the blade pushes and turns the fluid in the direction of the blade motion, thereby doing. The first option is a filehandling utility that allows saving, opening, printing. Based on the velocity triangles at the entrance or exit. A big radial expansion of the section between inlet and outlet of a pure mean mass flow axial turbine in otherwise action turbine gibe you a typical reaction triangle. Specific speed of a water turbine in the speed at which a geometrically similar turbine would run if producing unit power 1 kw and working under a net head of 1 m. Velocity triangle for moving blade of an impulse turbine 1. The air that leaves the moving blades enters the next set of nozzles where the enthalpy decreases further, and the velocity is. Extract energy from the fluid the fluid does work on them.
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