Effect of aspect ratio variation on subsonic aerodynamics of cascade type grid fin at different gap-to-chord ratios

Abstract

ABSTRACTThis paper dwells upon investigating the effect of aspect ratio (AR) variation on the aerodynamic performance of unconventional control surfaces called grid fins by virtue of a series of subsonic experiments on a simplified grid fin variant called the cascade fin. Wind tunnel tests were performed for differentAR(variable span) grid fins. The same had been investigated for different gap-to-chord ratio (g/c) variants. Results demonstrated a tangible increase in the aerodynamic efficiency as well as stall angle reduction for higherAR. Moreover, higherARleads to increased pitching moment, which emphasizes elevated hinge moment requirements. The study ensued the presence of higher deviation between the lowARfins, that is$AR<2$compared to the pertinent deviations between the highARfins, that is$AR\geq2$. The effect associated with these variations was termed as span effect in this paper. It was established that, the deviations arising due to this phenomena were lesser for higherg/cand higherAR. The analysis ofARvariation for differentg/cpresented a limiting value ofARreduction for stall performance enhancement. Thus, optimised selection of theg/candARvalues can lead to enhanced aerodynamic efficiency alongside an improved stalling characteristic.