Numerical simulation of jet mixing noise associated with engine exhausts

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This project is concerned with the numerical prediction of engine exhaust noise. This topic is of particular interest because it involves many different flow features, mixing of cold and hot jet turbulent flows, free shear layers and wall bounded flows. Therefore, special numerical developments will have to be achieved in the CFD codes in order to obtain accurate estimates of the acoustic sources and their near field in subsonic jets. Several numerical approaches will be investigated and validated with other CFD partners of the project. In parallel the difficult question about the physical relevance of unsteady wall flow computations and their applicability to acoustic far field estimates will be addressed. For that purpose, an experimental benchmark from the French partner will be used. This benchmark combines a turbulent jet flow with the quasi periodic disturbance of a circular cylinder impinging on a downstream located airfoil. Thus, the problem of a wall bounded flow in the vicinity of a turbulent jet flow is addressed experimentally. Most results of this experiment are already available, but a few additional measurements will be carried out. Comparisons will be made both on the unsteady flow field and on the acoustic far field. Far field computations will be achieved by integrating the instantaneous sources terms into an advanced time formulation of the Ffwocs-Williams-Hawkings analogy.