In this study, extensive instantaneous velocity measurements were conducted within a flow area by stereo particle image velocimetry (SPIV) to investigate the influence of the yaw angle, β, on the vortical flow structure formed on a slender delta wing. This sideslip angle, β, in the yaw plane was varied from 4^° up to 20^° with an interval of 4^° at two critical angles of attack, α = 25° and 35°, respectively. In order to reveal the influence of the yaw angle, β over the flow structure of the delta wing, time-averaged flow statistics, and instantaneous flow data obtained by the SPIV technique in the plan-view plane close to the suction surface of the delta wing were presented. It was observed that even a low yaw angle, for instance β = 8°, becomes to be effective on the flow characteristics of the delta wing, and this effect was augmented with increasing β. The influence of β is quite high on the vortical flow structure at α= 35° compared to the angle of attack of α = 25°. The flow structure that is symmetrical with respect to the centerline of the wing in the case of no yaw has disrupted with the existence β. Furthermore, the extent of the asymmetry enlarges with increasing β. The leading-edge vortex (LEV) on the windward side broken earlier and dominated the flow on the wing surface. It is concluded that this asymmetric flow structure can deteriorate the aerodynamic performance and cause other adverse effects such as unsteady loading.

在这项研究中，通过立体粒子图像测速仪（SPIV）在流动区域内进行了广泛的瞬时速度测量，以研究偏航角β对细长三角翼上形成的涡流结构的影响。在两个临界攻角α = 25°和35°时，偏航平面中的侧滑角β在4 ^°到20 ^°之间以4 ^°的间隔变化。为了揭示偏航角的影响，β在三角翼的流动结构上，给出了在靠近三角翼吸入面的平面图中通过SPIV技术获得的时间平均流动统计数据和瞬时流量数据。观察到，即使偏航角很小，例如β = 8°，也对三角翼的流动特性变得有效，并且随着β的增加，这种影响会增强。与α = 25°的迎角相比，在α = 35°时，β对旋涡流动结构的影响很大。在不存在偏航的情况下，相对于机翼中心线对称的流动结构因存在β而中断。此外，不对称程度随β的增加而增大。迎风侧的前缘涡旋（LEV）较早破裂并控制了机翼表面的气流。结论是，这种不对称的流动结构会恶化空气动力学性能并引起其他不利影响，例如不稳定载荷。