Investigation on the Influence of a Core Chevron Nozzle on the Performance of a Modern Bypass Engine

Abstract

In light of intensifying environmental concerns, the noise in aircraft gas turbine engines needs to be reduced significantly. Considerable work has been conducted to reduce jet noise produced by the mixing of high velocity gas streams with ambient air. Various nozzle designs such as lobed nozzles, serrated nozzles or chevron nozzles have been used and proposed to control and modify the velocity pattern of exhaust gas streams. This paper presents investigations on the influence of a core chevron nozzle on the performance of a modern bypass engine. The characteristic discharge, velocity and specific thrust coefficients of the chevron and non-chevron nozzles are determined by numerical calculations and are verified with experimental data. The nozzle coefficients form the basis for an engine performance comparison between the two hot nozzle configurations of the bypass engine. The effect of the nozzle configuration on overall engine performance and component working points has been investigated by applying an engine performance synthesis tool. The thrust loss and the corresponding SFC increase which has been observed by using the chevron nozzle have been related to engine internal rematching and changes in nozzle performance.