On the Estimation and Relevance of Internally Generated Turbine Broadband Noise

Abstract

The intention of this paper is quantifying the relevance of the internally generated broadband noise in the overall turbine signature. Results from five cold flow rigs of several low pressure turbines have been used to split the overall turbine noise in the two main sources: tonal and broadband. A comparison between both sources has allowed to determinate the relevance of the broadband noise and its dependence on the design style, operating conditions and turbine application. The methodology to get the broadband noise from a cold flow rig is also discussed and for one specific turbine, the broadband obtained from the rig is compared to engine results to demonstrate that rig noise measurements are enough representative of an engine. Finally, the broadband noise is evaluated at engine level and a turbine source breakdown EPNL is estimated for the three noise critical conditions of Approach, Cutback and Sideline. The main conclusion is that turbine broadband is a relevant source of noise at total aircraft level.