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Fan & Systems

Fan & Systems. Chris Carr PE H. Clay Moore & Associates Rod Furniss Howden North America Key Account Manager - Nuclear. Aerodynamics. 3. • Pressure & Flow Definitions and Measurement • Development of Fan Curves • Performance of Various Blade Shapes • Fan Controls System Effects.

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Fan & Systems

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  1. Fan & Systems Chris Carr PE H. Clay Moore & Associates Rod Furniss Howden North America Key Account Manager - Nuclear

  2. Aerodynamics 3 • • Pressure & Flow Definitions and Measurement • • Development of Fan Curves • • Performance of Various Blade Shapes • • Fan Controls • System Effects

  3. HNA Profile

  4. Aerodynamics What is a Fan? • Any device for producing a current of air by the movement of a broad surface or a number of such surfaces.

  5. Aerodynamics Pressure & Flow Definitions and Measurement Fan Flow Rate • Often called inlet volume • Measured at the fan inlet, by convention • Measured in cubic feet per minute (cfm) • May be converted to scfm (standard cubic feet per minute), or mass flow (lb/hr) • Fan manufacturers commonly use acfm (actual cubic feet per minute)

  6. Aerodynamics Pressure & Flow Definitions and Measurement Pressure • Force per Unit Area • Commonly measured in psi or inwg Absolute Pressure • Pressure when the datum is absolute zero • iiAlways positive • Barometric Pressure • Absolute pressure exerted by the atmosphere • Always positive • Gauge Pressure • Pressure when the datum is barometric pressure • May be positive or negative

  7. Aerodynamics Pressure & Flow Definitions and Measurement Static Pressure • Pressure due to degree of compression and density only • May be positive or negative Velocity Pressure • Pressure due to rate of motion and density only • Always positive • Total Pressure • Algebraic sum of static and velocity pressures at a point • May be positive or negative

  8. Aerodynamics Pressure & Flow Definitions and Measurement Fan Total Pressure • Difference in Total Pressure between the fan outlet and fan inlet • FTP = TPo - TPi Fan Velocity Pressure • Pressure corresponding to the average velocity at the fan outlet • FVP = VPo • Fan Static Pressure • Fan Total Pressure minus Fan Velocity Pressure • FSP = SPo – TPi • Static Pressure Rise • Difference in Static Pressure between the fan outlet and fan inlet • SPR = SPo - SPi

  9. Aerodynamics Pressure & Flow Definitions and Measurement Fan Pressure Terms • For a Given Fan, SPR is iiiAlways Greater Than FSP • If the Specified Pressure is iiiAssumed to Be FSP, the Fan iiiSelected Will Be Smaller Image area

  10. Aerodynamics Pressure & Flow Definitions and Measurement Pitot – Static Tube Image area

  11. Aerodynamics Pressure & Flow Definitions and Measurement Fan Laboratory Test Setup Image area

  12. Aerodynamics Development of Fan Curves Fan Curve Image area

  13. Aerodynamics Development of Fan Curves System Curve Image area

  14. Aerodynamics Development of Fan Curves P-V and Peak Fan Pressure Image area

  15. Aerodynamics Development of Fan Curves Selection Range Image area

  16. Aerodynamics Performance of Various Blade Shapes Common Blade Shapes • Airfoil • Backward Curved / Backward Inclined • Radial / Radial Tip • Forward Curved • Axial

  17. Aerodynamics Performance of Various Blade Shapes Airfoil • Highest Efficiency Centrifugal DDesign • Limit Load HP Characteristic • Low Noise • Usually for Clean Applications • Largest Diameter Centrifugal • Highest Cost Centrifugal Image area

  18. Aerodynamics Performance of Various Blade Shapes Backward Curved / Backward Inclined • Essentially a Single TThickness Airfoil • Efficiency slightly less than AAirfoil • Limit Load HP Characteristic • Low Noise • For Clean or Dirty AApplications • Lower Cost than Airfoil Image area

  19. Aerodynamics Performance of Various Blade Shapes Radial / Radial Tip • Lower Efficiency • Continuously Rising HP .. CCharacteristic • Higher Noise Levels • May have Predominant BFP TTone • Smaller Diameter • Easily Armored for Erosive SService • Lower Cost Image area

  20. Aerodynamics Performance of Various Blade Shapes Forward Curved (SiroccoTM) • Lower Efficiency • Continuously Rising HP CCharacteristic • Smallest Diameter Centrifugal • Suited for High Volume/Low PPressure • Distinctive Dip in P-V Curve • Seldom Used Today Image area

  21. Aerodynamics Performance of Various Blade Shapes Axial • Airflow Parallel to Axis of RRotation • High Efficiency • Limit Load HP Characteristic • Low Noise • Suited for High Volume/Low PPressure • Adjustable or Controllable Pitch • Distinctive Dip in P-V Curve • Controllable Pitch has HigherCCost Image area

  22. Aerodynamics Fan Controls Fan Control • Reasons for Providing Fan Control • Methods of Control • Efficiency Comparison • Mechanical Arrangements • Control Criteria

  23. Aerodynamics Fan Controls Reasons for Providing Fan Control • Uncertainty in System Calculations • Safety Factor or Margin • Expected Changes in the System with Time • Normal Process Variations • Provisions for Extraordinary Events

  24. Aerodynamics Fan Controls System Pressure Loss and Fan Design Pressure Image area

  25. Aerodynamics Fan Controls Moving the Operating Point Image area

  26. Aerodynamics Fan Controls System Duty Cycle Image area

  27. Aerodynamics Fan Controls Methods of Control • None • Outlet / System Damper • Inlet Box Dampers • Variable Inlet Vanes (VIV) • Variable Speed • Blade Pitch Control • Combinations of the Above

  28. Aerodynamics Fan Controls Outlet Damper / System Damper Image area

  29. Aerodynamics Discharge Damper

  30. Aerodynamics Fan Controls Inlet Box Dampers Image area

  31. Aerodynamics Fan Controls Inlet Box Dampers Image area

  32. Aerodynamics Fan Controls Inlet Box Dampers Image area

  33. IBD Discharge

  34. IBD Discharge

  35. Aerodynamics Fan Controls Variable Inlet Vanes Image area

  36. Aerodynamics Fan Controls Physical Arrangement of Cantilevered VIV Image area

  37. Aerodynamics Fan Controls Physical Arrangement of Radial Vane Control Image area

  38. Aerodynamics Fan Controls VIV Fabrication Image area

  39. Aerodynamics Fan Controls Variable Inlet Vanes Image area

  40. Aerodynamics Fan Controls Variable Speed Image area

  41. Aerodynamics Fan Controls Variable Speed- VFD and Gỳrol Fluid Drive Rotating Stall

  42. Aerodynamics Fan Controls Blade Pitch Control Image area

  43. Aerodynamics Fan Controls Efficiency Comparison Image area

  44. Aerodynamics Fan Controls Physical Arrangement of Various Control Devices Image area

  45. Aerodynamics Fan Controls Physical Arrangement of Axial Blade Pitch Control Image area

  46. Aerodynamics Fan Controls Control Criteria • Turndown / Leakage • Sensitivity to Change / Stability / Transients • Accuracy Required • Repeatability • Expected Efficiency • Acoustic Considerations • Structural Considerations

  47. System Effects – Poor Flow

  48. System Effects – Poor Flow

  49. System Effects – Poor Flow

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