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Fm 1

  1. 1. Fluid Mechanics for Power Generation P M V Subbarao Associate Professor Mechanical Engineering Department IIT Delhi An Essential Science for All Thermal Processes !!!!!
  2. 2. <ul><li>As early as 400,000 BC, fire was kindled in the caves of Peking man. </li></ul>
  3. 3. The Aelopile : Generation of Mechanical Motion <ul><li>In 130BC. Hero, a Greek mathematician and scientist is credited with inventing the first practical application of steam power, the aelopile. </li></ul><ul><li>Simply a cauldron with a lid, the aelopile had two pipes that channeled steam into a hollow sphere. </li></ul><ul><li>The sphere, which pivoted on the steam pipes, had two nozzles situated on opposite sides of its axis. </li></ul><ul><li>Thus, the cauldron was fired, the water in it boiled, the steam was channeled into the sphere, and as the steam escaped through the nozzles, the sphere would spin. </li></ul><ul><li>It was a thought the device and a novelty. </li></ul>
  4. 4. Truths of Modern Life Using the steam/Gas to make the Electric Power ! Rotating the shaft(Rotor) is the ultimate goal of any power plant !!! How do you get mechanical power from Live-steam or Gas? “ How to get super energized (Live) steam/Gas ? “ How do u generate life in live-steam ? A science of Fluid Power is basis for all current and future power generation technologies. This Science of Fluid Power is called Fluid Mechanics.
  5. 5. Philosophy of Fluid Power <ul><li>Present and future power generation technologies are based on: </li></ul><ul><li>Conversion of any natural power into fluid power. </li></ul><ul><li>Transfer fluid power to shaft power. </li></ul><ul><li>Conversion of shaft power into Electric power. </li></ul><ul><li>Basic laws of Fluid power based power generation. </li></ul><ul><li>Impulse principle </li></ul><ul><li>Reaction principle </li></ul><ul><li>Impulse-reaction principle </li></ul><ul><li>Aerofoil theory. </li></ul><ul><li>Every Power Engineer should study FLUID MECHANICS. </li></ul>
  6. 6. Further Applications of Fluid Mechanics <ul><li>Transportation of Fuel. </li></ul><ul><li>Internal supply of fuel and air through the fuel handling equipment. </li></ul><ul><li>Internal circulation of flue gas and steam through steam generator & Condenser. </li></ul><ul><li>Operation of all journal bearings. </li></ul><ul><li>Operation of all the pumps, fans & compressors. </li></ul><ul><li>Operation of Many control systems. </li></ul>
  7. 7. Fluid Mechanics P M V SUBBARAO Associate Professor Mechanical Engineering Department IIT Delhi A Science, which devalued the importance of time !!!!
  8. 8. Time : A Pseudo Scientific Firm Concept <ul><li>A powerful pseudo concept. </li></ul><ul><li>Became an utmost important in engineering and science after Newton. </li></ul><ul><li>Changes with respect to time, in a body is the core of Engineering. </li></ul><ul><li>But Past and Present are more known than the future. </li></ul><ul><li>Past and future are not two distinct entities like Delhi and Mumbai. </li></ul><ul><li>………… .. </li></ul><ul><li>………… </li></ul><ul><li>Present day Engineering and Science is strongly centered around Time base. </li></ul><ul><li>Fluid Mechanics reduces the weight of time in Engineering. </li></ul>
  9. 10. Energy and Power <ul><li>The scalar product of force and displacement is Work. </li></ul><ul><li>Capability to execute a work is energy. </li></ul><ul><li>Rate of doing work or rate of change in energy is Power. </li></ul><ul><li>Finally Generation of Power is a temporal act. </li></ul>
  10. 15. V 1 V 2 V 1 V 1 V 2 V 2 Newton’s Second Law for Flow Device
  11. 16. Newton’s Second Law for Flow Device Newton’s Force: All quantities are invariant in time. Vary in spacial direction only…. Still it is possible to accomplish Power Generation…. More Advanced systems are more invariant with time….
  12. 17. Stage of A Turbine
  13. 18. Sequence of Energy Transactions Steam Thermal Power Steam kinetic Power Blade kinetic Power Nozzle Losses Moving Blade Losses Stage Losses Isentropic efficiency of Nozzle Blade Friction Factor
  14. 19. Fluid Dynamics of Coal Preparation & Supply BY P M V Subbarao Associate Professor Mechanical Engineering Department I I T Delhi Aerodynamics a means of Transportation ……
  15. 20. Major Components of Coal Fired Steam Generator
  16. 21. Schematic of typical coal pulverized system A Inlet Duct; B Bowl Orifice; C Grinding Mill; D Transfer Duct to Exhauster; E Fan Exit Duct.
  17. 22. Velocity through various regions of the mill during steady operation
  18. 23. Cyclone-type classifier. Axial and radial gas velocity components
  19. 24. Centrifugal Classifiers <ul><li>The same principles that govern the design of gas-solid separators, e.g. cyclones, apply to the design of classifiers. </li></ul><ul><li>Solid separator types have been used preferentially as classifiers in mill circuits: </li></ul><ul><li>centrifugal cyclone-type and gas path deflection, or </li></ul><ul><li>louver-type classifiers. </li></ul><ul><li>The distributions of the radial and axial gas velocity in an experimental cyclone precipitator are shown in Figures. </li></ul><ul><li>The flow pattern is further characterized by theoretical distributions of the tangential velocity and pressure, the paths of elements of fluid per unit time, and by the streamlines in the exit tube of the cyclone. </li></ul>
  20. 25. Particle Size Distribution--Pulverized-Coal Classifiers <ul><li>The pulverized-coal classifier has the task of making a clean cut in the pulverized-coal size distribution: </li></ul><ul><li>returning the oversize particles to the mill for further grinding </li></ul><ul><li>but allowing the &quot;ready to burn&quot; pulverized coal to be transported to the burner. </li></ul><ul><li>The mill's performance, its safety and also the efficiency of combustion depend on a sufficiently selective operation of the mill classifier. </li></ul>
  21. 26. Mill Pressure Drop <ul><li>The pressure loss coefficients for the pulverized-coal system elements are not well established. </li></ul><ul><li>The load performance is very sensitive to small variations in pressure loss coefficient. </li></ul>Correlation of pressure loss coefficient with Reynolds number through the mill section of an exhauster-type mill.
  22. 27. Fundamentals of Fluid Mechanics
  23. 28. Introduction <ul><li>Fluid mechanics is the science of fluids either at rest (fluid statics) or in motion (fluid dynamics) and their effects on boundaries such as solid surfaces or interfaces with other fluids. </li></ul><ul><li>Definition of a fluid: a substance that deforms continuously when subjected to a shear stress. </li></ul><ul><li>Consider a fluid between two parallel plates, which is subjected to a shear stress due to the impulsive motion of the upper plate </li></ul><ul><li>No slip condition: no relative motion between fluid and boundary, i.e., fluid in contact with lower plate is stationary, whereas fluid in contact with upper plate moves at speed U. </li></ul><ul><li>Fluid deforms, i.e., undergoes strain θ due to shear stress  </li></ul>