D. Szelag, Z. Lorenc, L. Fornasier, P. Posadzy

A new experimental test up featuring a variable stiffness, real time computer- controlled spring system has been developed for allowing wind tunnel analysis of the nonlinear flutter phenomena and generation of a linear and non linear validation database for numerical simulation methods. The two-dimensional flutter model with NACA 0012 airfoil was built and tested in the low speed, low turbulence wind tunnel of the Warsaw Institute of Aviation. The experiments have proved the effectiveness of the new system with digitally controlled stiffness characteristics of the heave and rotation degrees of freedom. By the application of the electro-dynamic exciters as stiffness generators the concept delivers a surprisingly wide range of obtainable characteristics both with hardening and softening non-linear rule. The exciters were activated by the control system in order to maintain the prescribed force-displacement relation in real time. Using this concept any numerically programmable relations between any transducer output and the exciter force can be easily obtained. The cubic stiffness for both degrees of freedom of the model has been extensively tested. The CPU based on 486 processor was able to drive two interfering nonlinearities without significant characteristic shift in the frequency range up to 50 Hz. The stability of the control circuit generally has not been a problem, however it has not been yet systematically analysed. The numerical simulation of the dynamic response of the model during the tunnel tests has been performed to prove the value of the presented technique as an acceptable tool in validation testing. The EADS M Aero Elastic Coupling Library developed in the framework of the European Project TAURUS has been utilized for the task. Both the linear and the nonlinear cases have been studied. Preliminary results obtained using an unstructured Euler flow solver show calculations being very close to the experimental data.

International Forum on Aeroelasticity and Structural Dynamics, 2005, München

Conference Paper

englisch

21,0 x 29,7 cm, 12 Seiten

DGLR-Bericht, 2005, 2005-04, International Forum on Aeroelasticity and Structural Dynamics 2005; S.1-12; 2005; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

in getr. Zählung;

aeroelasticity, wind tunnel tests, flutter

Bibliothek

2005