Designing The JT9D Engine to Meet Low Noise Requirements for Future Transports

This paper discusses the design of the JT9D-1 engine from the viewpoint of the noise reduction features which have been incorporated. Fan noise is predominant from high bypass ratio turbofans. The various sources of fan noise are discussed and the research work of the past several years on methods of noise reduction are reviewed. The paper discusses the application of the results of this work to the JT9D-1 design.