Investigation of Aerodynamic Interactions for a Distributed Flap System

This paper presents a computational investigation of aerodynamic interactions between trailing edge distributed flaps on a wind tunnel based on the Common Research Model (CRM) with an aspect ratio of 13.5. Trailing edge distributed flaps are being explored as a means for active control, particularly for real time drag optimization, maneuver load alleviation, gust load alleviation, and flutter suppression. In prior studies, control sensitives for lift and drag were determined by perturbing individual flaps in isolation. However, this approach neglects potential aerodynamic coupling effects between the neighboring flaps, which may affect the accuracy of drag prediction. To address this gap, a systematic study is conducted involving both isolated and simultaneous deflection of a series of pairs of flaps. The goal is to quantify and characterize the nonlinear aerodynamic interactions that arise when multiple control surfaces are actuated concurrently. An analytical interaction model is developed to estimate the incremental aerodynamic forces resulting from flap-to-flap coupling. The results demonstrate that aerodynamic interactions between flaps are non-negligible and can lead to measurable deviations in drag prediction when compared to linear superposition of single-flap effects.