Analysis of Compressors

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Analysis of Compressors

• P M V Subbarao
• Professor
• Mechanical Engineering Department

Active Devices for Infusion of Life into Fluid.
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Classification of Compressors
Rotodynamic Compressors
Positive Displacement
of Compressors
Centrifugal Compressors
Axial Compressors
Reciprocating Compressors
Rotory Compressors
Mixed Compressors
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Centrifugal Vs Axial Flow Area
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Centrifugal Vs Axial Level of interaction
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In search of Time scale in Requirement

• Primary characteristics of a requirement.
• The effect Dp
• The Capacity Flow Rate Q (m3/s).
• Density of fluid r(kg/m3).

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Machine-Fluid Matching Parameter
For compressible fluid machines
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(No Transcript)
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Take j -3/2
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Take i 1/2 j -3/4
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Time Scale of a Machine to Resource
Speed N (rpm) or n (rps)
This is named as Specific Speed, Ns
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Mixed
Centrifugal
Axial
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Role of specific Speed on Design of A Compressor
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Centrifugal Compressors

• The centrifugal compressor consists essentially
  of a stationary casing containing a rotating
  impeller which imparts a high velocity to the
  air, and
• A number of diverging passages (Diffuser) in
  which the air is decelerated with a consequent
  rise in static pressure.
• Air is sucked into the impeller eye and whirled
  round at high speed by the vanes on the impeller
  disc.
• Centripetal acceleration leads to increase in
  rise of some amount of static pressure.
• The remaining increase in rise of pressure occurs
  in diffuser.

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Multi Stage Compressors
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ImpellerDiffuser Rotor-Stator
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Anatomy of A Centrifugal Compressors
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Gas Dynamics of A Perfect Impeller
Va2
Vf2 Vr2
Vw2 Utip
Ueye
b1
Vr1
Vw10
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Va2
Reality of Fluid Mechanics
Vr2
b2
Vw2
Va2
Vf2
Vr2
Vw2
b1
Vf1Va1
Vr1