Aeroacoustics Noise Prediction of Low Mach Number Flow using Hybrid Wave Equation Model

Noise source and noise propagation from bluff bodies has been studied extensively by several researchers using both experimental and numerical techniques. The results of these studies have provided useful information and guidance on the design and behavior of components subjected to external airflow in a variety of different applications. One area where these studies are of great significance is in the prediction of airframe and aircraft component noise. Several simple test cases have been developed to help identify the possible characteristics of more complicated structures; one of the most cited and used examples is the flow over tandem cylinders. This arrangement - where one cylindrical bluff body is exposed to the wake of another - occurs in several real-world applications, for example, overhead power lines and aircraft landing gear. In this paper, solutions from an Acoustic Wave Equation (AWE) model implemented in the general purpose CFD code ANSYS Fluent [1] are compared with experimental data for a tandem cylinder case provided as part of the AIAA Workshop on Benchmark Problems for Airframe Noise Computations (BANC-I, [2]). The AWE model in ANSYS Fluent is derived from the APE2 model developed by Ewert and Schroeder [3], for incompressible flow; sound sources are predicted using high-fidelity, incompressible, scale-resolving turbulence models, and wave propagations are modelled using the acoustic perturbation wave equation. In addition, a Kirchhoff integral surface model, newly implemented in ANSYS Fluent, is used to calculate perceived sound signals at remote microphone locations.