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Obermeier F.,TU Bergakademie Freiberg | Konstantinov M.,Institute For Aerodynamik Und Stromungstechnik | Shishkin A.,Institute For Aerodynamik Und Stromungstechnik | Wagner C.,Institute For Aerodynamik Und Stromungstechnik
Notes on Numerical Fluid Mechanics and Multidisciplinary Design | Year: 2014

Aerodynamic noise generated by low Mach number flow through a pipe with two differently sized diaphragm orifices is investigated both theoretically as well as numerically. Such a flow may be considered as a simple model of an aircraft climate control system. The theory is based on an acoustic analogy introduced by Möhring and Obermeier in the seventies. They identified by means of the so-called Green’s vector function acoustic sources in unsteady flows as the unsteady motion of vorticity “vortices are the voice of flows”. In addition, the unsteady flow through the pipe, the aerodynamic sources, and the spectra of sound are evaluated numerically. Here effects of different numerical algorithms (PISO—PIMPLE) and of different numerical boundary conditions at the outlet of the pipe (advective, convective— wave transmissive) are identified and discussed. © Springer International Publishing Switzerland 2014. Source

Hubner A.-R.,Institute For Aerodynamik Und Stromungstechnik
DLR Deutsches Zentrum fur Luft- und Raumfahrt e.V. - Forschungsberichte | Year: 2010

The investigations presented in this report are concerned with the application and assessment of wind tunnel measurements and analytical and numerical methods for the determination of the steady and in particular unsteady behavior of a generic transport aircraft configuration with a high aspect ratio wing in the subsonic speed range For the experimental determination of the dynamic data a new combined motion test capability was developed at the DNW-NWB, using a unique six degree-of-freedom test rig called MPM (Model Positioning Mechanism) With that device a modern generic transport aircraft configuration (DLR-F12) was tested in three rotary modes (roll, pitch and yaw) and two translatory modes (heave and lateral oscillation) The light-weight model was built in CFRP sandwich construction and permits the measurement of steady and unsteady forces, moments and pressure distributions Numerical solutions under steady-state conditions for longitudinal as well as for lateral motions are calculated using the panel method VSAERO Also, quasi-steady motions around all body-fixed axes are simulated Finally, the unsteady Euler-/Navier-Stokes equations are solved for steady conditions, for quasi-steady and unsteady motions using the DLR-TAU code Additionally, handbook methods are used for the calculation of the dynamic derivatives. Source

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