Technologies for Jet Noise Reduction in Turbofan Engines

Abstract

Turbofan engines are commonly used for commercial transport due to their advantages of higher performance and lower noise. Jet noise is one of the principal noise sources of turbofan aeroplane engines and remains an acute environmental problem that requires advanced solutions. The ever-increasing demand for quieter engines requires the exploration of alternative techniques that could be used by themselves or in conjunction with existing methods. Significant progress continues to be made with noise reduction for turbofan engines. Analytical and semiempirical models have been developed to investigate the influence of some design tools when they are employed in a multidisciplinary optimisation framework. This paper discusses the major components of jet noise in turbofan engines and presents a review of jet noise reduction technologies.

Supersonic Jet Noise: Main Sources and Reduction Methodologies

“…Additionally, takeoff noise reduction is a key challenge for developing future supersonic jetliners. After careful planning and testing, successful implementation of innovative jet noise reduction concepts in commercial turbofan engines and military aircraft engines may be achieved for reduction of jet noise at supersonic jet exhaust configurations [4].…”

Main Fan Noise Mitigation Technologies in Turbofan Engines

“…The discrete-frequency noise generated by unsteady blade row interactions between rotor and stator blades is of particular concern for the design of advanced turbofan engines, since jet noise is reduced considerably by the introduction of high bypass flows (Yamasaki, Tajima 1998;Gorji-Bandpy, Azimi 2012b). Many of the modern fan designs use a fan sweep near the tip to reduce aerodynamic losses associated with shocks and improve the stall margin.…”

Noise Reduction in Buildings Using Sound Absorbing Materials

“…Too much noise obviously impairs our physical and mental existence and therefore it is reasonable to pursue Technology Assessment concerning noisy technologies [1][2][3][4]. In other words, noise has turned into one of the most important among the environmental factors on which industry sets down a big part of its efforts and concerns.…”

“…Passive control involves reducing the radiated noise by energy absorption, while the active method involves reducing source strength or modifying acoustic field in the duct to obtain noise reduction. Active noise control is being used only at low frequencies [1]. At middle and high frequencies, active noise control is hard to implement because there are different phenomena of sound propagation.…”