On the role of the radiation directivity in noise reduction for STOL aircraft.The radiation characteristics of distributed randomly fluctuating acoustic sources when shielded by finite surfaces are discussed briefly. A number of model tests using loudspeakers as artificial noise sources with a given broadband power density spectrum are used to demonstrate the effectiveness of reducing the radiated noise intensity in certain directions due to shielding. In the lateral direction of the source array noise reductions of 12 dB are observed with relatively small shields. The same shields reduce the backward radiation by approximately 20 dB. With the results obtained in these acoustic model tests the potentials of jet noise reduction of jet flap propulsion systems applicable in future STOL aircraft are discussed. The jet flap configuration as a complex aerodynamic noise source is described briefly.
Document ID
19730052475
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Gruschka, H. D. (Tennessee, University Tullahoma, Tenn., United States)
Date Acquired
August 7, 2013
Publication Date
January 1, 1972
Subject Category
Aircraft
Meeting Information
Meeting: Inter-noise 72; International Conference on Noise Control Engineering