David E. Fogarty, Ph.D.
Resident at: Aeroelasticity Branch, MS 340
U.S. Army Vehicle Technology Directorate
NASA Langley Research Center
Hampton, VA 23681-2199
Tel: (757) 864-1063
Fax: (757) 864-8678
Email: david.fogarty@nianet.org
Research Interests
- Rotorcraft vibration and acoustics
- Blade-vortex interaction (BVI) noise
- Computational fluid dynamics (CFD)
- Aerodynamic and aeroelastic modeling
- Wind tunnel testing
Current Research
- Helicopter noise is a topic of research which has been investigated widely over the years. Quieting programs are researching and developing designs and techniques which offer noise reduction for both commercial and military applications. One of the most important challenges facing rotorcraft designers today is the public acceptance of helicopters. One type of noise that can hamper public acceptance of helicopters is blade-vortex interaction (BVI) noise. This type of noise occurs primarily during low-speed descent and maneuvering flight conditions. BVI noise is an impulsive type noise and is a result of the interaction of a blade with the shed tip vortices from preceding blades. These interactions produce pressure fluctuations on the rotor blade generating impulsive noise which radiates away from the helicopter. Current research efforts are investigating approaches, methods, and technologies, primarily, active-twist control, which will suppress or minimize BVI noise.
- Current prediction methods utilize several state-of-the-art computational codes to calculate helicopter noise. Aeroelastic behavior of helicopter blades is modeled using the Comprehensive Analytical Model for Rotorcraft Aerodynamics and Dynamics (CAMRAD II) code. Helicopter noise is modeled using the acoustic code PSU-WOPWOP3. The computational fluid dynamics (CFD) code OVERFLOW is also being used to predict rotorcraft behavior for various flight conditions.
- Comparisons between predicted noise data and experimental noise data from wind tunnel testing have shown the accuracy of the acoustic analysis in predicting helicopter noise, in particular BVI noise.
- Read NIA Flier article “Doing The Twist” - NIA Explorer Newsletter, Volume V, Issue 1, Fall 2008.
Publications
- Fogarty, D. E., Wilbur, M. L., and Sekula, M. K., “The Effect of Non-Harmonic Active Twist Actuation on BVI Noise”, Presented at the American Helicopter Society 67th Annual Forum, Virginia Beach, VA, May 3-5, 2011.
- Fogarty, D. E., Wilbur, M. L., and Sekula, M. K., “A Computational Study of BVI Noise Reduction Using Active Twist Control”, Presented at the American Helicopter Society 66th Annual Forum, Phoenix, AZ, May 11-13, 2010.
- Niven, A.J. and Fogarty, D.E., 2003, "Turbine Blade Design for the Minimization of Viscous Entropy Generation per Unit Work Output", CEAS Aerospace Aerodynamics Research Conference, R.Ae.S Headquarters, London, June 10-12, 2003