Thursday, 8 March 2018

HYDRAULIC MACHINERY

HYDRAULIC MACHINERY


Hydraulic machining Turbine: - hydraulic energy -- Mechanical engineering. Pump: - mechanical engineering - hydraulic energy. Impact of jet V1, V2 = Absolute velocity of water with respect to ground at entry and exist. F plate = final momentum of water - Initial momentum of water M= mass flow rate of water which strikes the body Case 1= strike the stationary plate in normal direction. Note: - when jet strikes the flat plate it will exert force only in normal direction to plate (no tangential force) Case 2= Jet strikes stationary inclined plate. Case 3 = Jet strike vertical hanging plate. Case 4 = Jet strikes at the Centre of stationary curve point (blade / vane) Case 5= Jet strikes at the tip of stationary vane Case 6 = Jet strike moving plate U1, u2 = velocity of plate / blade at entry and exist Vr1, Vr2 = velocity of jet with respect to blade / plate at entry and exist Case 7= Jet strikes on inclined plate Case 8 = Jet strikes at the tip of moving vane.



Unsymmetrical vane a = nozzle angle, B=  angle between V2 and u2, Or angle at which water leaves the vane, Vw2,  vw1 = whirl velocity of water at exist and entry, Vf1 ,  Vf2 = flow velocity of water at entry and exist, Layout of hydro power plant Penstock :- large diameter pipes Used to carry water from the reservoir to Turbine. Surge tank: - It is a reservoir of water situation near to the Turbine and used to avoid water hammer in Pen-stock Turbine, Impulse, and Reaction. Tail race: - It is a passage of water used to carry the water from the Turbine to down stream of river 

Generator :- TYPES of head : 1) Gross head :- It is defined as the difference  between head race level and tail race level (or)  It is the head under which the plant is working 2)Net head :- It is the head available with the water at the inlet of Turbine (or)  It is the head at which Turbine is working .Power 1) water power / hydropower Wp/HP = mdh = PQgh 2) Runner power  RP = eQ (Vw1 u1 + Vw2 u2 )  3) Shaft power Sp = RP----- ( mechanical loss )  Efficiency :- 1) efficiency volume = discharge which strikes the runner / discharge which supplied by penstock Q= discharge supplied by pen-stock do = Leakage loss 

Impulse Turbine Principle: - water is supplied by penstock from reservoir to Turbine then water enters into the nozzle which convert the fluid energy into kinetic energy The water comes out from the nozzle in the form of jet, as the jet strikes over the vane it will exert a large magnitude force for a small fraction of the time called Impulse over the vane . This Impulse force will rotate the runner. Therefore these turbines are known as Impulse Turbine. Entry Kinematics energy P1= Patm = P2 V2 <<V1 Exit KE Smooth vane Vr1 = Vr2 Rough vane Vr2 < Vr1,    Vr2 = KvrK= coefficient of vane friction. Component used in Pelton wheel. 1) Casing No hydraulic fluid 
Used to avoid splashing of water over near by equipment 

Nozzle: - Spear: - To regulate the mass flow rate through nozzle a smooth Spear is provided which can move forward or backward with the help of Governor in order to increase or decrease flow area through nozzle. Runner :- It is a rotary unit over which a number of vanes are installed. braking jet or back nozzle :- It is used to bring runner at rest and also to avoid the critical speed of the Shaft Reaction Turbine / impulse reaction Turbine 

Principle: - water is supplied by penstock from reser it to Turbine . Then water enter into it casing which is the integral part of the Turbine. The casing is filled with water inside the casing a no of guide vanes are present which guide the water toward the runner at a particular as the water enters over the runner it has kinetic and pressure energy. As the water strikes over the vane of runner it will exert a high magnetic force tuje force for a small time called impulse same as in Pelton wheel As the water flows over the vanes it's pressure decrease due to aerodynamic shape of the vane. Due to decrease in pressure the water will exert a additional force over the vane called reaction force 

This impulse and reaction force will rotate the runner . Therefore these Turbine are known as impulse reaction Turbine Smooth vane  Vr2 > Vr1Rough vane Vr2 > Vr1 ,  Vr2= Vr1 ,  Vr2 < Vr1 Components used in reaction Turbine 1) casing = spiral /  volume /  scroll2) Guide vane / Fixed vane / wicket gates 3) runner Radial Axial Mixed4) Draft tube 1) casing :- It is an air tight passage ( leak proof )  of gradually decreasing area in forward direction The decrease area helps to maintain the velocity of water at inlet to runner . 2) Guide vane: - These vanes are permanently fixed their own with the casing but can rotate about pivot in order to decrease or increase discharge through Turbine by changing flow area Guide vanes are also used to guide the water toward the runner at a particular angle a= Guide vane angle They are also used to bring the runner at reaction (No breaking jet is required)  

Axial flow reaction Turbine / propeller /  Kaplan The water turn 90 degree in between guide vane and moving vane and for free vortex. Generally 3 to 6   vanes are used in Axial flow Turbine which is less compact to Francis Turbine ( 16 to 24 vanes )  therefore less frictional losses In propeller Turbine the blades are perpendicular fixed  with the hub Whereas in Kaplan Turbine blades are adjusted The blades are twisted that means thita and fya varies as diameter changes.


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