By Fernando Monge, INTA, Madrid, Spain

The fluid dynamics area of INTA (Instituto Nacional de Tecnica Aeroespacial) has participated in a number of European aeronautical projects during the past several years, and has used FLUENT as a part of this work. Other CFD codes have been used in the projects as well, and a great deal of experimental data has been made available to scientists and engineers. Together, the project challenges, along with the wealth of information shared by the participants, have allowed INTA to realize FLUENT's potential for several important applications.

Wake vortices generated by a simplified aircraft in flight

The C-WAKE European project is one example. Coordinated by DaimlerChrysler Aerospace Airbus in Bremen, Germany, the goal of the project is to characterize and control vortex wakes generated by passenger aircraft. These wakes are of particular interest during take-off and landing maneuvers at busy airports when other aircraft are nearby, and during inflight periods on heavily traveled routes when the horizontal and vertical spacing limits between aircraft are in question. The timing between take-offs and landings has been established at commercial airports for maximum safety, but heavy air traffic has made increased demands on these guidelines. With this in mind, the C-WAKE project has focused on estimating the optimum separation between aircraft for inflight conditions and on airport runways. It has also focused on developing designs for new planes that generate reduced vortex wakes, so that reductions in aircraft separation can be considered. For this project, FLUENT has been used to calculate wakes from simplified airplane geometries. The CFD results will be compared with experimental data extracted from wind tunnel tests. INTA is also applying FLUENT to the development of second generation supersonic passenger carriers. These carriers are being investigated in response to increased demand for long distance flights with the desire to have shorter flight times. While these aircraft will undoubtedly meet the performance goals of longer distances in shorter times, they also must meet strict environmental guidelines and comply with stringent noise emission regulations. The European Project for Improvement of Supersonic Transport Low Speed Efficiency, or EPISTLE, is a group of European aircraft manufacturers and researchers who have joined forces to investigate the flight characteristics of these carriers in the low speed regime, in conditions typical of take-off and landing. One focus is on high lift devices near the leading edge of the wings that cause controlled flow separation, enhanced lift, but significant additional drag. The goal is to develop novel designs for these devices, test their operating characteristics when used with delta wing planes, and validate the findings against wind tunnel data. FLUENT simulations are currently being run to study high lift devices that allow an increase of 15 Ð 20% in the aerodynamic efficiency of supersonic aircraft flying at low speed.

INTA is involved in other projects as well:

• The aerodynamics of high lift systems for passenger aircraft of all kinds is the focus of the European High Lift Program, or EUROLIFT. To address the primary goal of reducing the development time and cost of these systems, INTA has tested the efficacy of 2D and 3D analyses to provide helpful design information in a timely manner.
• In its work with the Group for Aeronautical Research and Technology in Europe (GARTEUR), INTA has worked to adapt and validate CFD codes to study the adverse aerodynamic effects that result from icing. The results will subsequently be validated against wind tunnel data.

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