Parametric Static Stability Study of Double-Delta Wings Using CFD

Sammanfattning

CFD simulations were performed on various double-delta wing planforms to study their stability characteristics. A double-delta wing is a type of wing with two sweep angles, giving it a very unique shape. It was initially developed by Saab in the 1950's for the Saab 35 Draken. Double-delta wings develop a unique flow field in flight, where two vortices form across their leading edges. These vortices interact and interfere with each other, and how they interact depend heavily on the two wing sweep angles and the location of the leading edge kink. To map out how these differences in geometry affect the stability of these wings, two different geometry sets were generated. One set had a constant root chord, while the other had its leading edge kink set to always be located 50% aft on the wing. The simulation data of the latter set showed that increasing the sweep angles allow these wings to maintain stability at higher angles of attack. However, the wings with a difference in sweep angles of 30° maintained their stability at the highest coefficients of lift. These characteristics also held for effective strake sweeps in sideslip greater than 75°. The data also showed that wings with a strake sweep of 75° behaved very differently from wings with sharper strakes. When both datasets were compared, it was found that shifting the kink aft generally increases roll stability. It also increased pitch stability, until some critical point between 50% and 65% aft, after which the pitch stability dropped sharply. These preliminary results invite further studies of a similar kind, to further map these characteristics out. Examples of possible further study include examining the strake sweep more closely to find a critical value, or generating more geometry sets of constant kink location to define this dependence for each planform.