The Forward Mounted Spoiler as a Source of Buffet Excitation,
BRISTOL UNIV (UNITED KINGDOM) DEPT OF AEROSPACE ENGINEERING
Pagination or Media Count:
Tests have been made with fixed transition at low Reynolds Numbers usually 0.56 million, based on chord on a wing with a spoiler of length 8 chord hinged at 13 chord. Different classes of flow leading to differing spoiler performance have been identified. However signal analysis has shown that the non-dimensional frequency n sub 1 fl sub bv where f is the frequency, l sub b teh length f separated flow from the spoiler free edge lying over the wing in the case of a closed bubble, l sub b is the bubble length and V the freestream velocity. Since n sub l depends on l sub b, a good idea of the nature of buffet excitation can be formed from an observation of the scale of separated flow lying over the wing. With one class of flow, there was no change in steady state lift following spoiler deployment, but the formation of a separation bubble over much of the wing upper surface led to a high level of buffet excitation. This underlines the difficulty of trying to deduce the fluctuating component of lift from a steady mean.