Development of an improved core noise prediction method for long-cowl engines

This paper describes the process of developing an improved method to predict the core noise radiated by long-cowl engines under static and flight conditions. The proposed method follows the same approach as the industry standard SAE ARP 876 method in terms of structure and source model, but uses: (1) a new, analytical frequency-dependent directivity accounting for radiation, convection and refraction effects through the jet and (2) a new empirical source spectrum determined using a source breakdown code applied to external phased array data acquired on a Rolls-Royce BR700-type engine.</p