Industry perspective on jet noise—Prediction and reduction requirements

Abstract

Spectacular growth of airline passenger traffic, nearly tenfold since 1970, has been fueled by a steady trend toward lower cost airfares made possible by technological achievements in airframe and aircraft engine design. Of all the advancements in aircraft design, none has been more important than that of the high bypass ratio (HBPR) turbofan engine, first introduced in 1969 on the Boeing 747. Since then, HBPR turbomachinery noise technology has kept pace with other engine refinements, allowing newer aircraft to meet increasingly stringent community noise requirements. Even more advanced turbomachinery and nacelle noise technology is now at hand as a result of government/industry efforts in both Europe and the United States. Engines with substantially lower fan noise will be introduced. Jet noise will remain the major obstacle to further noise reduction. Since the majority of new commercial aircraft over the next 20 years will be powered by HBPR engines, research in jet noise must be a major priority. This paper examines the needs for jet noise reduction across the range of commercial aircraft types, and suggests technology development efforts including CFD tools for jet characterization, active flow control, installation effects, and novel suppression devices. This paper also discusses challenges in jet noise technology for supersonic airliners.