A 4-Dof Whirl Flutter Analysis Of Tractor And Pusher (Saras) Type Propeller Nacelle System Of Aircraft

Mukherjee, Somenath and Deepak , K.N (2005) A 4-Dof Whirl Flutter Analysis Of Tractor And Pusher (Saras) Type Propeller Nacelle System Of Aircraft. Technical Report. NAL, Bangalore.

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    Abstract

    A Four-Degree Of Freedom Model (Pitch, Yaw And Two Off The Propeller Plane Deformations From Blade Flexibility) Has Been Used For Flutter Analysis Of The Propeller-Nacelle Assembly . The Formulation, Originally Based On A Tractor Configuration, Has Been Modified To Include The Pusher Configuration Of The SARAS . Explicit Mathematical Expressions Have Been Derived . An In-House Computer Code In MATLAB Has Been Prepared And Benchmarked With Re-Tilts Of The 2 DOF Model For The Tractor Configuration Of The Report NASA TN D-659 In Which Blade Flexibility Has Been Eliminated . Results Have Been Generated For Different Altitudes Of Flight For Each Altitude, The Advance Ratio Values (J=V/2nr) Have Been Specified. At Neutral Stability, The Forward And Backward Whirl Frequencies And The Corresponding Necessary Damping Go For Stability Boundary Conditions At The Speed V Are Generated. The Present Model Predicts That The Configuration Of The SARAS Propeller Assembly With Rigid Blades Is Quite Stable In Whirling Motion . Results Have Been Generated For Various Attitudes Of Flight With Variable Hypothetical Blade Flexibility And Support Stiffness Values. From Thess parametric Studies, It Has Been Observed That Reduction In Structural Stiffness Leads To An Increase In The Critical Damping In Backward Whirl At The Stability Boundary. Stability Is Ensured When Experimentally Determined Damping Exceeds Critical Damping . Critical Condition In Terms Of Lower Bound Of Stiffness Of The Rotor-Propeller Assembly Has Been Estimated.

    Item Type: Proj.Doc/Technical Report (Technical Report)
    Uncontrolled Keywords: Ractor; Pusher; Yaw And Pitch Degrees Of Freedom; Blade Flexibility; Advance Ratio; Backward And Forward Whirls; Neutral Stability Conditions.
    Subjects: ASTRONAUTICS > Astronautics (General)
    Division/Department: Structural Integrity Division, Structural Integrity Division
    Depositing User: M/S ICAST NAL
    Date Deposited: 07 Aug 2012 13:19
    Last Modified: 07 Aug 2012 13:19
    URI: http://nal-ir.nal.res.in/id/eprint/10687

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