Dynamic Aeroelastic Instabilities of an Aircraft Wing with Underwing Store in Transonic Regime

The research used the transonic small disturbance theory to better understand the dynamic aeroelastic phenomena and factors that affect the onset of flutter and store induced limit-cycle oscillations (LCO) in the transonic regime. Several parametric studies of the flutter and LCO of an aircraft wing with underwing store in the transonic regime were conducted, as well as an investigation of the effect of inclusion of store aerodynamics on the onset of flutter. The flutter sensitivity was analyzed for the following store parameters: (1) location of underwing store center of gravity with respect to aerodynamic root chord; (2) location of underwing store along the span of the wing; and (3) underwing clearance (pylon length). The parametric studies indicated that as the store center of gravity is moved fore of the elastic axis, the flutter velocity of the wing increased. Also, as the store is moved towards the aerodynamic tip chord, the flutter velocity of the wing decreased. The research work also concluded that as the underwing clearance is increased, the flutter velocity of the wing decreased. In addition to these results, it also helped in understanding that addition of store aerodynamics had no significant influence on the flutter velocity of the wing. Also, studies were conducted to identify the onset of LCO for different configurations of underwing store and flight regimes (unmatched analysis), thereby identifying the parameters that induce LCO. The sensitive parameters that affect flutter and LCO are identified.