Synergy of Advanced Measurement Techniques for Unsteady and High Reynolds Number Aerodynamic Investigations

The challenges addressed in the "ACARE Vision 2020" refer to the securing of the potential of technological innovation to build safer, greener and smarter aircraft. This is a key function within international competition and needs the support from scientific research establishments on national and European level. One essential goal of ACARE Vision 2020 is the reduction of noise- and exhaust- emissions during air traffic. This reduction can only be achieved by technical improvements, which need an extended knowledge about the basic physical processes e.g. in aircraft engine flows and in the aerodynamics of wings in high-lift-configuration. For the understanding of such flows with intrinsically unsteady behaviour (flow separation, transition, turbulence, vortex development and dynamics) with related flow-structure-interaction and flow induced noise sources and at high Reynolds numbers imaged based measurement methods are an indispensable tool for the determination of fluid mechanical significant measures in whole fields and on surfaces of (model-)parts in the flow. Nowadays, numerical methods are in a phase of rapid development enabling more and more the prediction of flows in the fields of unsteady and high Reynolds number aerodynamics by applying adapted turbulence- and transition- models or advanced simulation methods (Hybrid RANS-LES / DES). For being accepted as reliable tools for the design process of innovative aircraft concepts, which requires a coupling of these CFD codes with CSM and CAA methods for an integrated approach, extensive validation experiments by using image based measurement methods are necessary, because only they can deliver the needed spatially high resolved (unsteady) data in fields and volumes.

Uniquely in the world various and complementary non-intrusive and image based measurement techniques (PSP, TSP, IRT, PIV, BOS, IPCT, Acoustic  Array) for mobile use in wind tunnels and free flight experiments have been developed in the institutes of AS and AT. Common practice was the selective application of these measurement techniques for the characterisation of flow conditions around wind tunnel models or their acoustical respectively elastical effects. The combined application of optical and acoustical measurement techniques enables the quantification of different fluid mechanically, aero-acoustically and -elastically relevant measurement categories like pressure, velocity vectors, density, model deformation and noise sources in fields, on surfaces or even in whole volumes successively and parallel for a given wind tunnel model. By this as much as possible unsteady field data can be achieved, which cannot be determined otherwise. Such measurement data are of high importance for the development, validation and combination of complex simulation tools, like CFD (URANS, DES, LES, DNS), CSM or CAA. Furthermore, the combined application of these measurement techniques enables (partly for the first time) the investigation of physical interrelations (e.g. the noise source mechanisms of vortical flows or the elastic effects of (dynamical) forces and moments on model parts.)

 Application of image based measurement techniques at the high-lift- wing BNF ('community friendly aircraft ') at DNW-NWB
zum Bild Application of image based measurement techniques at the high-lift- wing BNF ("community friendly aircraft ") at DNW-NWB
For two central experimental fields of aerodynamic investigation: the high-lift-configuration wing, represented by the F16- and "community friendly aircraft (BNF)" model, and jet engine flows, represented by the UHBR and the ATRA-V2527 engine, combined image-based experimental measurement systems will be applied within SAMURAI in order to achieve a large field-dataset for the extension of the aero-dynamic, - elastic and -acoustic knowledge of these two complex flow regimes and for the validation of and combination with accompanying advanced numerical simulations. Therefore, within SAMURAI several core-competencies of the institutes of AS, AE, BK and AT will be connected in a way that their potential can be proven at concrete challenges and the analysis of complex flow systems.

Dr.rer.nat. Andreas Schröder
German Aerospace Center

Institute of Aerodynamics and Flow Technology
, Experimental Methods
Tel: +49 551 709-2190

Fax: +49 551 709-2830

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