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Published byLaurel White Modified over 9 years ago
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Design & Aerodynamics of Inlets & Nozzles P M V Subbarao Professor Mechanical Engineering Department Understanding of Real Flow Through Passive Devices…….
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Frictional Flow through A Variable CS Area Mass flow rate through any cross section of area A
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Design Steps for Inlet Supersonic flights: Decide and optimize number of oblique shocks and final downstream conditions of normal shock. Compute all properties at the just upstream of inlet. Subsonic flight: Outer cone affected Ambient air properties and flight Mach number are upstream conditions for inlet. Define upstream inlet conditions as: p i,T i,V i …… Cycle calculations demand a mass flow rate.
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Step by Step Design of Intakes or Nozzles Select appropriate value of dx. Assume that all properties remain unchanged over the length dx and same as inlet condition. Therefore,
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Total Pressure Recovery Pressure Recovery after dx: Continue till the exit of the intake.
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Exit Conditions for Inlets Limiting the exit dimensions. Limiting the exit Mach Number. Limiting the length of the inlet.
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Extra Input Data !!!! Variation of diameter of Intake.(dD h /dx) Variation of Area of Intake (dA/dx). Variation of Mach Number (dM/dx) Final Design is A compromise between size and performance.
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An Ideal Intake Duct Geometry
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Real Subsonic Intakes
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Aerodynamic Performance of Subsonic Intakes Subsonic intakes exhibit four different flow regimes or stall characteristics. Non dimensional axial length (length/inlet area) and the total divergence angle of the diffuser are chosen as the primary variables to identify the flow regimes. Fully attached exit flow with steady internal flow Fully attached exit flow with internal unsteady flow Fully developed stall flow Jet Flow Pressure Recovery Factor
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Flow Regimes in Subsonic Intake
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Characteristics of Flow Regimens in Subsonic Intake Axial Length/Entrance Area
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Pressure Recovery Factor for Planar Intakes Area Ratio
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Pressure Recovery Factor for Conical Intakes Area Ratio
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Pressure Recovery Factor for Annular Intakes Area Ratio
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Typical External flow at Subsonice Cruising Conditions
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External Flow Patterns
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External Stream Tube
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Factors Limiting the Intake Performance
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