CFD/CSD-based flutter prediction method for experimental models in a transonic wind tunnel with porous wall

To predict the flutter dynamic pressure of a wind tunnel model before flutter test, an accurate Computational Fluid Dynamics/Computational Structural Dynamics (CFD/CSD)-based flutter prediction method is proposed under the conditions of a 2.4 m × 2.4 m transonic wind tunnel with porous wall. From the CFD simulations of the flows through an inclined hole of this wind tunnel, the Nambu’s linear porous wall model between the flow rate and the differential pressure is extended to the porous wall with inclined holes, so that the porous wall can be conveniently modeled as a boundary condition. According to the flutter testing approach for the current wind tunnel, the steady CFD calculation is conducted to achieve the required inlet Mach number. A time-domain CFD/CSD method is then employed to evaluate the structural response of the experimental model, and the critical flutter point is obtained by increasing the dynamic pressure step by step at a fixed Mach number. The present method is applied to the flutter calculations for a vertical tail model and an aircraft model tested in the current transonic wind tunnel. For both models, the computed flutter characteristics agree well with the experimental results.