CFD Wind Tunnel Assessment on the case study of the MOTHIF Blown Flap

Abstract

The increasing interest in Small Air Transportation (SAT), to enhance global connectivity, is highlighting the need for reducing take-off distance: lift coefficient has to be increased without penalizing the configuration drag, weight and complexity. Within the EU Clean Sky 2 projects, a blown flap configuration has been developed to allow STOL capabilities of a future affordable and green commuter belonging to EASA CS 23. The blowing system design choice is aimed at keeping the inevitable associated increase in pitching moment very low, and not penalizing performance when blowing fails. In collaboration between Piaggio Aerospace and the MOTHIF consortium, a wing model was designed, built and tested in the VKI’s large subsonic L1-A wind tunnel, reproducing bi-dimensional preliminary results obtained during the design phase. In order to reduce and predict three dimensional and blockage effects, CFD has been used extensively to obtain a proper test chamber configuration and to reproduce some wind tunnel test results, so that both the accuracy of wind tunnel and design methodology can be assessed. This work presents the comparison between experimental data and CFD simulations to demonstrate the usefulness of simulations to reduce both the risk for erroneous results in experimental activities and their related cost.