Reliable Turbulence and Transition Modelling for Industrial Aerodynamics

Project background

RETTINA is a project dedicated to the improvement of the turbulence and transition (T&T) modelling in the hybrid unstructured Reynolds-averaged Navier-Stokes (RANS) code TAU of the Institute of Aerodynamics and Flow Technology (AS). The project, managed by AS in Göttingen, started in 2007. Its duration is four years.

RANS solvers could be established as standard design tools in industry besides wind tunnel testing and flight tests, for example, at Airbus, Eurocopter Deutschland (ECD) and EADS-M. For the design point of an aircraft a positive assessment of the numerical results could be achieved for many validation and application tests and the prediction capabilities could be positively evaluated. As a consequence, high confidence in numerical simulations could be achieved in industry and will finally allow more simulation and less physical testing.Currently, the integration of the TAU code into Airbus’ flow simulation system is underway, so that the TAU code becomes an element of the standard process chain at Airbus in Europe.RETTINA was set up in order to maintain and extend the high relevance and acceptance of theTAU code at Airbus and to guarantee the long-term importance of TAU at ECD, EADS-M, the DLR itself and in academia. RETTINA aims at strengthening the confidence in TAU from a modelling point of view by tackling operation areas of RANS solvers where prediction accuracycan be a problem.

There exist high demands on computational fluid dynamics (CFD) tools when they are applied to problems at the borders of the flight envelope or to configurations characterized by deflections and movements of control surfaces and by flow control mechanisms. Here, the prediction accuracy of CFD tools is still unsatisfactory. Typical flow features are: detached flow, unsteady flow phenomena, interaction with separation related flow phenomena, for example, shock-boundary layer interaction and laminar-turbulent transition and its interaction with separation. Therefore, it is necessary to improve the physical modelling capabilities of the TAU code significantly, for example, through the optimization and combination of models, by accounting for different scenarios and application spectra and by the provision of a Best Practice guide for the application of the different models and modelling approaches.

The aims of RETTINA are the following: provision of T&T modeling capabilities in the TAU code for flight envelope and off-design CFD applications (DLR vision Digital X-craft: virtual flight testing); grouping of T&T activities, exploitation of synergy effects, generation and distribution of comprehensive multi-project know how; avoidance of wrong decisions of the code user with respect to T&T modelling, with special emphasis on the borders of the flight envelope and off-design; provision of a T&T Best Practice guide; significant reduction of user induced prediction uncertainties.

RETTINA is a collaboration between AS (13.5 py) and the Institute of Aeroelasticity (AE, 3.5 py), has collaborative links to the DLR projects IMPULSE (AS), UCAV-2010 (AS), SIMCOS (AS), iGREEN (AE), APT (AS) and to one research area of the spacecraft branch and connections to the DLR project SHANEL (AS), the German research initiative MUNA and three national and international cooperations.

Dr.-Ing. Andreas Krumbein
German Aerospace Center

Institute of Aerodynamics and Flow Technology
, C²A²S²E Center for Computer Applications in AeroSpace Science and Engineering
Tel: +49 551 709-2557

Fax: +49 551 709-2416

E-Mail: Andreas.Krumbein@dlr.de
URL for this article