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Though long of concern to neighbors of major airports, aircraft noise first became a major problem with the introduction of turbojet-powered commercial aircraft (Tupolev 104, Boeing 707, Dehavilland Comet) in the late 1950s. It was recognized at the time that the noise levels produced by turbojet powered aircraft would be unacceptable to persons living under the take-off pattern of major airports. Accordingly, much effort was devoted to developing jet noise suppressors, with some modest success.
The Noise Problem
Effects of Noise
Hearing Loss
Noise Interference
Sleep Disturbance
Noise Influence on Health
Noise Sources
Jet Noise
Turbomachinery Noise
Noise Measurement and Rules
Noise Effectiveness Forecast (NEF)
Effective Perceived Noise Level (EPNL)
Noise Certification
Noise limits
Calculations
Tupolev 154M Description
Noise calculations
Take-off Noise Calculation
Landing Approach Noise Claculation
Noise Suppression
Jet Noise Suppression
Duct Linings
Duct Lining Calculation
Using experimental data, we determine lining and cell geometry:
For the first harmonic, parameters will be:
For the second harmonic, parameters will be the following:
Figure 7.4 shows the placement of the lining in engine nacelle.
Figure 7.4 Lining placement in the nacelle.