Flight test data of helicopters indicate that vibratory levels in the fuselage exhibit a wide spectrum of frequencies including the dominant blade passage frequency and its integer multiples. The present work attempts to understand the reason for the existence of several frequencies in the response of the fuselage and possible cause for this observed phenomenon by formulating a computational aeroelastic model. In this theoretical study, a systematic approach has been undertaken to identify the effects of inflow modeling and sectional aerodynamic load evaluation, on helicopter trim, rotor blade response, and hub loads. Five different combinations of aerodynamic models of increasing complexity, representing rotor inflow and sectional aerodynamic loads, have been proposed. The differential equations of motion are solved in time domain in a sequential manner to obtain the response of all the blades in the rotor system, the inflow variables, and the sectional loads at every time step. The results of the present study show that the aerodynamic model incorporating dynamic wake and dynamic stall effects introduces a wide spectrum of harmonics in the hub loads including blade passage frequency and its integer multiples. The influence of aerodynamic modeling on the variation of trim parameters with forward speed has also been brought out. It is observed that the aerodynamic model incorporating dynamic wake and dynamic stall effects predicts the trim parameters whose variation with forward speed resemble qualitatively similar to those obtained in flight test. A comparison of the variation of blade sectional lift for various aerodynamic models indicates that in the advancing side of the rotor, a dynamic stall model introduces a shift in the azimuth angle at which the minimum lift occurs. The effect of structural flap-lag coupling due to blade pretwist on trim and rotor loads has been studied, and these results are compared with those pertaining to a straight blade configuration.


    Zugriff

    Zugriff über TIB

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Influence of dynamic stall and dynamic wake effects on helicopter trim and rotor loads


    Weitere Titelangaben:

    Einfluß von dynamischem Strömungsabriß und dynamischen Nachlaufeffekten auf Trimm- und Rotorlasten bei Hubschraubern


    Beteiligte:
    Laxman, V. (Autor:in) / Venkatesan, C. (Autor:in)

    Erschienen in:

    Journal of the American Helicopter Society ; 54 , 3 ; 032001/1-032001/18


    Erscheinungsdatum :

    2009


    Format / Umfang :

    18 Seiten, 20 Bilder, 2 Tabellen, 43 Quellen




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch




    Influence of Dynamic Stall and Dynamic Wake Effects on Helicopter Trim and Rotor Loads

    Laxman, V. / Venkatesan, C. / AHS international | British Library Conference Proceedings | 2008



    Wind Turbine Wake Vortex Influence on Helicopter Rotor Trim

    van der Wall, B. G. / Lehmann, P. H. | British Library Conference Proceedings | 2018


    Helicopter rotor wing dynamic stall control method and system

    SHI YONGJIE / LI CONGCONG / XU GUOHUA et al. | Europäisches Patentamt | 2020

    Freier Zugriff

    Investigation of Airfoil Dynamic Stall and Its Influence on Helicopter Control Loads

    F. O. Carta / G. L. Commerford / R. G. Carlson et al. | NTIS | 1972