Mission Systems Identification Sub-Module of an Integrated Decision Support System for Mid-Life Upgrade of Maritime Helicopter

To reduce the troublesome second harmonic lagwise load in stiff in-plane rotor blades, tuned fluidlastic absorbers are proposed to be embedded in the blade cavity. The aeroelastic simulation of the coupled blade and fluidlastic absorber system is based on the generalized force formulation. The results indicate that placing an embedded fluidlastic absorber in the blade chordwise direction can reduce the second harmonic lagwise root bending moment by more than 85% at different steady flight states, which means fluidlastic absorbers are an effective means to control this load. The corresponding stroke of the absorber is limited within 2% blade chord length. Increasing tuning port area ratio is an effective means to reduce the stroke with relatively small influence on the performance of the absorber. The effects of the tuning frequency of the absorber, the damping, initial position, forward speed, and flight altitude on the performance of the absorber are also studied.

[1]  Edward C. Smith,et al.  Lagwise dynamic analysis of a variable speed rotor , 2013 .

[2]  Giovanni Bernardini,et al.  Tiltrotor Wing-Root Vibratory Loads Reduction Through Higher Harmonic Control Actuation , 2012 .

[3]  Farhan Gandhi,et al.  Rotor Vibration Reduction Using an Embedded Spanwise Absorber , 2012 .

[4]  Min,et al.  A Physics-Based Investigation of Gurney Flaps for Rotor Vibration Reduction , 2009 .

[5]  Edward C. Smith,et al.  Lagwise Loads Analysis of a Rotor Blade with an Embedded Chordwise Absorber , 2008 .

[6]  Edward C. Smith,et al.  Helicopter Blade Loads Control via Multiple Trailing-Edge Flaps , 2006 .

[7]  Lesieutre,et al.  Design and Model Testing of Helicopter Rotor Blade Lag Fluid Elastic Embedded Chordwise Inertial Dampers , 2005 .

[8]  Edward C. Smith,et al.  The Effects of Embedded Chordwise Absorbers on Blade Aeroelastic Stability , 2002 .

[9]  Carlos E. S. Cesnik,et al.  Vibratory loads reduction testing of the NASA/Army/MIT active twist rotor , 2001 .

[10]  M. R. Smith,et al.  The Model 427 Pylon Isolation System , 1999 .

[11]  Y.-M. Cheng,et al.  Aeroelastic response of a coupled rotor/fuselage system in hovering and forward flight , 1999 .

[12]  Brahmananda Panda,et al.  Application of passive dampers to modern helicopters , 1996 .

[13]  Dennis P. McGuire,et al.  Fluidlastic Dampers and Isolators for Vibration Control in Helicopters , 1994 .

[14]  J. G. Leishman,et al.  A Semi-Empirical Model for Dynamic Stall , 1989 .

[15]  Edward C. Smith,et al.  Experimental and Analytical Study of Blade Lag Damping Augmentation using Chordwise Absorbers , 2006 .

[16]  Wayne Johnson,et al.  Rotorcraft Dynamics Models for a Comprehensive Analysis , 1999 .

[17]  D. Owen,et al.  Finite elements in plasticity : theory and practice , 1980 .