The self-excited rolling oscillations induced by fore-body vortices

Effects of Forebody Geometry on Side Forces on a Cylindrical Afterbody at High Angles of Attack

“…The asymmetry continues until x/d = 8.3, where, as the separations become turbulent on both sides, the larger values on the right hand side are balanced by equal values on the left. The present results agree well with the findings of Zhongyang, et al [32] for the blunted-nose forebody, which introduces a significant tip perturbation, interacting nonlinearly with the cross-flow boundary layer separation [42,43]. It is interesting to note that when the angle of attack, α, is increased to 50 degrees, immediately after the disappearance of the peak on the lee side, a much stronger asymmetry appears with a sharp gradient of the mean wall pressure from the left to the right.…”

Wing rock mode and its mechanism of a flying-wing aircraft

“…Among the wing rock motions of other aircraft, such as the slender delta wing (Arena & Nelson, 1994; Nelson & Pelletier, 2003), 85°/65° double delta wing (Yoshinaga, Otaka, & Tate, 2001), rectangular wing (Levin & Katz, 1992; Williams & Nelson, 1997), generic aircraft configuration (Brandon & Nguyen, 1988; Ma et al., 2015; Ma et al., 2017; Wang et al., 2011) and a kind of practical fighter aircraft (Chung et al., 2021), the tricyclic form of the – hysteresis loop is more common. The conceptual tricyclic – hysteresis loop of these aircraft is shown in figure 2( d ), although the actual – curve of the slender delta wing is thinner.…”

“…Its application background is mainly for micro air vehicles at low Reynolds numbers (Go & Maqsood, 2015;Gresham, Wang, & Gursul, 2010a;Hu, Cheng, Liu, Huang, & Akkermans, 2020;Levin & Katz, 1992;Williams & Nelson, 1997). The third type is the generic aircraft configuration (Brandon & Nguyen, 1988;Ericsson, Mendenhall, & Perkins, 1996;Ma, Deng, Rong, & Wang, 2015;Ma, Wang, & Deng, 2017;Shi, Deng, Wang, Li, & Tian, 2015), and a pair of forebody leeward vortices is the main feature of its flow field. Besides the above simplified models, many actual aircraft have also been reported to exhibit the wing rock phenomenon in wind tunnel experiments or flight tests, such as the HP 115 (Ross, 1972), F-4, F-5, F-14, Gnat, Harrier (Hsu & Lan, 1985), X-29, X-31 (Ericsson et al, 1996), AV-8B (Hall, Woodson, & Chambers, 2004), F/A-18E fighter (Owens, Bryant, & Barlow, 2006), F-35 fighter (Owens, McConnell, Brandon, & Hall, 2006), a canard-configuration aircraft (Wei, Shi, Geng, & Ang, 2017) and a generic fighter aircraft with a conical forebody (Chung, Cho, Kim, & Jang, 2021).…”

Vortex induced vibrations of wind turbine blades: Influence of the tip geometry

“…This phenomenon is characterized by a self-excited and large amplitude roll oscillation, and it has been observed for several fighter aircrafts at high angles of attack. The experiments of Ma et al (2015) studied the wing rock by means of static, forced, and free oscillation tests of an aircraft model. By imposing the same roll motion that was recorded in a previous free oscillation test, the authors identified the generation of motion-induced unsteady vortices for span regions that recorded stationary wakes in static conditions.…”

“…In the study of the concave cylinder included in Seyed-Aghazadeh et al (2015), the authors reported the reappearance of the vortex shedding when the elasticity of the system was enabled. Finally, Ma et al (2015) related the wing rock phenomenon to the reconfiguration of the stationary wake into an unsteady one. Assuming that the appearance of such motioninduced vortices is responsible for the lock-in condition identified in the present study, the necessary conditions for their generation remain the open question.…”