Assessment of a 2D Synthetic Turbulence Method for Predicting the ACAT1 Fan's Broadband Noise

Kurzfassung

Fan broadband noise, particularly rotor-stator-interaction noise, is an important noise mechanism in modern aircraft engines. However, its prediction is not trivial. Applied approaches range from fast but simplified analytical approaches to computationally demanding scale-resolving simulations. RANS-informed synthetic turbulence methods present a promising compromise between accuracy and cost. Two-dimensional simulations on a single streamline are especially attractive as they can be easily computed on conventional computers. While a good agreement with NASA SDT experimental data could be shown in the past, it can be questioned how representative a 2D simulation at an arbitrarily chosen streamline position can truly be since the flow and turbulence in the interstage region is highly dependent on the fan geometry and its operating conditions. In this paper, the authors propose a new, 3D-equivalent approach for setting up a 2D synthetic turbulence simulation. The results are compared to approaches that were applied for past investigations. In addition, a detailed comparison to the comprehensive, acoustic test data for the AneCom AeroTest Rotor 1 (ACAT1) transonic fan is shown. The good agreement between numerical and experimental data proves that a fast, two-dimensional synthetic turbulence method is indeed capable of accurate fan broadband noise predictions.