Noise from a Turbofan Engine Without a Fan from the Engine Validation of Noise and Emission Reduction Technology (EVNERT) Program

Abstract

ar-field noise levels of a turbofan engine are composed of many noise sources including the fan inlet, fan discharge, compressor stages, combustor, turbine stages, air valves, and external jet. A turbofan engine was run with and without the fan in order to quantitatively determine the fan’s contribution to both forward- and aft-radiated noise. The shaft load from the fan was replaced by a water brake when running without the fan. Instrumentation internal to the combustor was added to determine its modal structure and help identify any combustor tones in the far-field data. The data was then compared to predictions using industry-standard routines.