Some Applications of Hartmann-Type Sources in Aircraft Noise Research.
Abstract
A description is given of a Hartmann-type air-jet noise generator which has been developed at RAE to aid in the assessment of airframe shielding effects. In this application, in-flight shielding experiments were performed with a slender-delta research aircraft, the Handley-Page 115, fitted with needle-stabilized generators having 19mm diameter driving jets operated from the HP turbine of the aircraft engine. The acoustic power output of the device was about 1 kW and consisted of a strong fundamental 2.8kHz tone and a few higher harmonics which were easily discernible above engine noise. Comparative wind-tunnel experiments employed quarter-scale versions built to match the tunnel model and these operated at about 11 kHz, the output level being well above tunnel background noise. Calibration in an anechoic room showed the output to be steady and nearly omni-directional. These devices are rugged, efficient, and relatively simple to construct and operate; they provide a compact, well-defined and powerful sound source of reasonable size which can be easily scaled acoustically and physically. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1980
- Accession Number
- ADA102869
Entities
People
- R. W. Jeffery
- T. A. Holbeche
Organizations
- Royal Aircraft Establishment