Numerical Evaluation of Installation Effects in Semispan Model Wind-Tunnel Testing

Semispan aircraft models are commonly used in wind-tunnel testing to achieve higher Reynolds numbers. However, their stall characteristics can differ from those of the full-span models due to the aerodynamic effects of the peniche, which extends the symmetry plane of the model, and those of the floor boundary layer. Therefore, these installation effects are investigated through computational fluid dynamics simulations of the flow around the NASA high-lift common research model. To clarify the effects of the peniche and floor boundary layer, multiple configurations with different peniche geometry and tunnel floor boundary conditions are simulated numerically. The simulation results indicate that the floor boundary layer thickens the boundary layer over the fuselage and promotes the flow separation at the wing root. Also, the peniche increases the effective angles of attack at the inboard sections and makes the flow prone to separation. In contrast, the gap between the floor and the model decreases the effective angle of attack in the inboard region while reducing the adverse effects of the floor boundary layer. These results suggest that the combination of the gap and peniche is effective in reproducing the aerodynamics of the full-span configuration.