General Aviation Propeller Noise Reduction-Penalties and Potential

1981 ◽  
Author(s):  
Robert J. Klatte
Keyword(s):  
Noise Reduction ◽  
General Aviation ◽  
Propeller Noise

Some Measured and Calculated Effects of Forward Velocity on Propeller Noise

1977 ◽  
Author(s):  
R. J. Pegg ◽  
B. Magliozzi ◽  
F. Farassat
Keyword(s):  
Analytical Techniques ◽  
Operating Conditions ◽  
General Aviation ◽  
Noise Levels ◽  
Forward Flight ◽  
Low Frequencies ◽  
Blade Thickness ◽  
Propeller Noise ◽  
Field Noise ◽  
Static Conditions

The results of a program investigating the sources of noise in unshrouded propellers under forward flight conditions and a comparison with theory are reported. Tests were conducted using an instrumented three-bladed propeller installed on a turbine-powered, twin-engine, general aviation airplane. Measurements included far-field noise on the ground and on the aircraft wing tip, propeller blade surface pressures, atmospheric turbulence, and aircraft operating conditions. The primary result of the full-scale flight tests was to confirm that foward-flight propeller noise levels are lower than those experienced under static conditions and that the most significant reductions occur at the mid-frequencies which dominate perceived and A-weighted noise levels. Analytical techniques have been used to predict the observed experimental trends and to provide further insight into the noise generating mechanisms. Correlation with experimental data is shown to be good at low frequencies under static conditions and at all frequencies in forward flight. It is tentatively concluded that propeller noise generation in flight may result from steady loads (including blade thickness effects). Under static conditions, the principal noise source appears to be the intersection of the propeller with persistent turbulent eddies passing through the propeller disk.

The Effect of Active Noise Reduction Technology on Noise Induced Pilot Fatigue and Associated Cognitive Performance Decrements

1996 ◽  
Vol 40 (2) ◽  
pp. 67-71 ◽  
Author(s):  
John Jordan ◽  
Wayne C. Harris ◽  
Phillip N. Goernert ◽  
John Roberts
Keyword(s):  
Noise Reduction ◽  
Cognitive Performance ◽  
General Aviation ◽  
Flight Instruction ◽  
Active Noise ◽  
Subjective Fatigue ◽  
Flight Instructors ◽  
Active Noise Reduction ◽  
Pilot Fatigue

Fatigue in the general aviation cockpit is caused by a variety of factors including cockpit noise. Active Noise Reduction (ANR) headsets have been proposed as a method to decrease cockpit noise and thereby decrease fatigue and the cognitive performance decrements associated with fatigue. The present study contrasted the subjective fatigue and cognitive performance of Certified Flight Instructors (CFI) during a day of in-air flight instruction with ANR headsets versus conventional headsets. CFIs exhibited increased subjective fatigue and a pattern of more rapid but less accurate cognitive performance at the end of an instructional day. However, subjective fatigue and cognitive performance changes did not differ as a function of type of headset worn. The results suggest that subjective fatigue increases and cognitive performance changes occur during a day of flying but they provide no evidence that the use of ANR headsets modify these changes.

Experimental study on a compact lined circular duct for small-scale propeller noise reduction

2021 ◽  
Vol 179 ◽  
pp. 108062
Author(s):  
Jingwen Guo ◽  
Teng Zhou ◽  
Yi Fang ◽  
Xin Zhang
Keyword(s):  
Experimental Study ◽  
Noise Reduction ◽  
Small Scale ◽  
Circular Duct ◽  
Propeller Noise
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