Bernd Stickan, Reik Thormann, Hans Bleecke

DOI Number: N/A

Conference number: IFASD-2019-015

Computation Fluid Dynamics (CFD) are used for the generation of unsteady aerodynamic models for dynamic computations like flutter and gust load analysis. For both application fields, the accurate prediction of control surface aerodynamics is of major importance. The presented study focusses on motion with relatively large amplitude to analyze unsteady nonlinear effects. To model this effect accurately, the Chimera/overlap grid technique is used. This CFD technique uses different mesh blocks with overlap areas. The overlap areas are used to interpolate the fluid quantities (e.g. density, pressure and velocity) between the blocks. For the here investigated control surface nonlinearities, the influence of the control surface gaps on the unsteady aerodynamic forces as a result of forced motion is analyzed. Starting point is the investigation of the gap-influence on steady results by comparing Chimera to a workaround solution, which applies mesh deformation including a blending area to allow large amplitude motion, rather than modeling the gap. The unsteady part starts with a first validation by comparing results with Chimera and with the workaround solution for very small amplitudes. Aerodynamic forces are analyzed thereafter for different motion amplitudes. Results are compared to the workaround solution. The influence of the unsteady control surface nonlinearities under large amplitudes is of particular importance for the simulation of gust load alleviation functions and limit cycle oscillations.

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In Categories: 1. IFASD 2019, Unsteady CFD
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