Accession Number:

ADP011125

Title:

Helicopter Noise Reduction by Individual Blade Control (IBC) -Selected Flight Test and Simulation Results-

Descriptive Note:

Corporate Author:

DEUTSCHES ZENTRUM FUR LUFT-UND RAUMFAHRT (DRL) BRAUNACHWEIG (GERMANY)

Personal Author(s):

• Splettstoesser, W. R.
• Schultz, K. J.
• van der Wall, B.
• Buchholz, H.
• Gembler, W.

Report Date:

2001-06-01

Pagination or Media Count:

16.0

Abstract:

A collaborative flight test programme was conducted to study among other objectives the potential of open- loop Individual Blade Pitch Control IBC to reduce the external noise of a helicopter in partial power descent, a flight regime known to generate the highly annoying Blade-Vortex Interaction BVI impulsive noise. The blade root control system employing actuators in the rotating frame, was installed on a BO 105 helicopter, which was flown over an extended linear microphone array. The acoustic measurements on the ground were synchronised to the flight track and rotor performance measurements supplemented by limited simultaneously acquired on-board acoustic and blade surface pressure data. Selected test results quantifying the noise reduction potential of the IBC technique, are presented and compared to numerical rotor simulation results calculated by the aeromechanic S4 code and the acoustic AKUROT code of the DLR. A significant noise reduction benefit exceeding 5 dB of the maximum A-weighted BVI noise level was obtained for the 2rev IBC mode further, over a wide range of IBC phase angles simultaneous noise and vibration reductions were observed. The complete data base acquired will contribute to the development and validation of a fast control algorithm for closed-loop IBC applications.

Descriptors:

• *ROTOR BLADES(ROTARY WINGS)
• *HELICOPTERS
• *NOISE REDUCTION
• *IMPULSE NOISE
• *FLIGHT SIMULATION
• *AIRCRAFT NOISE
• TEST AND EVALUATION
• DATA BASES
• ALGORITHMS
• FLIGHT TESTING
• VIBRATION
• PITCH(INCLINATION)
• NUMERICAL ANALYSIS
• VORTICES
• ACOUSTIC MEASUREMENT
• LEVEL(QUANTITY)
• GERMANY
• ACTUATORS
• FRAMES
• SYNCHRONISM
• FLIGHT ENVELOPE
• LINEAR ARRAYS
• RANGE(EXTREMES)
• GERMAN LANGUAGE
• MICROPHONES

Subject Categories:

• Helicopters
• Astronautics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE