Numerical and experimental investigation of the interaction of wing-tip vortices and engine jets in the near field

Abstract

The near wake of a rectangular wing/engine con- figuration is investigated using numerical simulations and PIV measurements. The analysis is focused on the interaction of the engine jet and the wing-tip vortex in the near wake. The essential details of the solution technique such as turbulence modeling, boundary conditions, and the experimental setup are presented first. The engine jet is experimentally gen- erated by a jet apparatus and simulated numerically using artificial boundaries within the engine. The paper concentrates on the influence of the engine jet on the development of the wing-tip vortex at varying thrust and engine positions. Finally, physical aspects of the flow in the near field behind the wing are discussed and compared with experimental data. and detrainment of the engine exhaust into the vortex cores, which is of importance in the study of aircraft emissions in the atmosphere. Recent measurements3 and numerical studies of the isolated turbulent wing-tip vortex4 were successfully carried out for a rectangular wing with small aspect ratio. It was shown in the numerical investigations that good agreement with experimental results could be only achieved with appropriate grid resolution, turbulence models, and boundary conditions. Other authors5'7'8 investigated the dynamics of engine jets and vortices in the far field using simplified models to predict the inflow conditions from the near wake. These investigations included a wide range of parameters that influence the wake, such as stratification, wind shear, buoyancy, and geometrical parameters. Since the dynamics of vortices is largely dependent on the axial and circumferential velocity distribution, a detailed prediction of the velocity field would require the simulation of the wake flow field including all vortices and also the engine jets. The intricacy of the structure and long-term behavior of aircraft vortices was shown in numerous experiments3'4'6. The numerical simulation of the wake including the far field has many challenges that were observed in previous works10'11. The length scale of the vortex core is one or two magnitudes smaller than that of the generating wing. The necessary requirement of a sufficient resolution of the vortex cores and the shear layer of the wing wake increases considerably the amount of the grid points for numerical simulations. Therefore a numerical method was proposed for the accurate and sufficient calculation of the wake flow of the wing12, that can be combined with regular numerical schemes for the calculation of the wing flow or that can be used to extend experimental measurements, which are usually limited to the near field, into the far field.