Aeroelastic and Aeroacoustic Modeling of Active Twist Rotors

Students : Smith Thepvongs

Sponsor : Vertical Lift Rotorcraft Center of Excellence (VLRCOE)/U.S. Army


Helicopters in low-speed descent can produce intense noise caused by the interaction of tip vortices with passing rotor blades. This noise is often severe, restricting the operation of commercial helicopters near large cities and increasing detection in military operations. Active twist technology has the potential to reduce noise by altering the characteristics of the blade-vortex interactions.

This project uses numerical simulation to assess the impact of active twist on rotor noise and find the physical mechanisms responsible for the behavior. Currently, hub vibration penalties associated with reduced noise are being investigated.

Primary contributions:

  • Developed analysis code which couples the Non-linear Active Beam Solver (developed at A2SRL) with an aerodynamics code based on a panel method and free wake model (developed at the National Technical University of Athens).

  • Showed through experimental validation that the code can reproduce most noise trends

  • Analyzed vortex characteristics and identified several potential sources of noise reduction, including alterations of vortex strength, miss-distance, and interaction angles.

Framework of aeroelastic/aeroacoustic analysis


Comparison of numerical predictions against experimental data for BVI sound pressure level (dB) at 2.3m below a model BO-105 rotor in low-speed descent