A new dynamic, unstructured-mesh methodology was developed to simulate unsteady flows about single or multiple objects in relative motion and to compute the trajectory of their motion as determined by the aerodynamic loads. For this purpose, the method coupled the governing equations of the fluid dynamics and rigid body dynamics. The grid adaptation was performed within windows put around the moving boundaries to improve the computational efficiency. However, for very large amplitude motions, the window adaptation would require highly dense meshes for the major portion of the domain, otherwise a partial remeshing procedure would be necessary. This idea is currently under investigation. Using the experimentally determined force and moment fields, the present trajectory code was used to compute the 6-DOF (degrees of freedom) trajectory of a store separating from a wing. The results compared well with the trajectory used in the wind-tunnel tests. The flow past a sinusoidally oscillatory airfoil was computed and compared with the experimental data. The minor discrepancies were attributed to the viscous effects. Then, the same NACA 0012 airfoil was given a 3-DOF motion and immersed in a transonic freestream flow. This case demonstrated the robustness of the adaptive window procedure for large displacements as well as the ability of the flow solver to capture strong moving shock waves. Finally, the overall methodology was demonstrated through a two-dimensional example: the carriage, separation, and the free-fall of a store from a wing section (airfoil). The motion and its trajectory were entirely determined by the instantaneous aerodynamic loads provided by the unsteady flowfield computations and the force of gravity. Unlike the quasisteady approaches, the present approach also captured the boundary-induced flow component, and the time-dependent, dynamic interference between a stationary body and a moving body. Thus, this study suggests that the present dynamic, unstructured-mesh method is a viable alternative to the dynamic, overlapped structured-grids approaches.
Dynamic unstructured method for flows past multiple objects in relative motion
Dynamisch unstrukturiertes Verfahren zur Simulation von Strömungen entlang mehrerer Objekte, die sich relativ zueinander bewegen
AIAA Journal ; 33 , 4 ; 641-649
1995
9 Seiten, 11 Bilder, 19 Quellen
Article (Journal)
English
numerisches Verfahren , Simulationsmodell , instationäre Strömung , Tragflügelumströmung , Strömungsvorgang , Aerodynamik , Randbedingung , Relativströmung , NACA-Profil , kompressible Strömung , Euler-Gleichung , reibungsfreie Strömung , Maschennetz , Vergleichsmessung , Algorithmus , Vektor , Anpassungsfähigkeit , Druckverteilung , Anströmwinkel , Freiheitsgrad , Nachlauf
Dynamic Unstructured Method for Flows Past Multiple Objects in Relative Motion
Online Contents | 1995
|Dynamic Unstructured Method for Flows Past Multiple Objects in Relative Motion
British Library Conference Proceedings | 1994
|Dynamic Unstructured Method for Flows Past Multiple Objects in Relative Motion
British Library Conference Proceedings | 1994
|