Optical characterization of the transient behaviour in laminar separation bubbles

普惠加拿大公司（P&WC）是一家领先的商用喷气式飞机涡轮风扇发动机制造商。这些发动机的高效率依赖于高涵道比风扇叶片的使用，对于高涵道比风扇叶片，叶片要求翼型轮廓是细长的。通常在操作期间，这些风扇叶片上的流动导致层流分离泡（LSB）的形成，并且边界层流变得过渡。在高海拔和低雷诺数（Re）下，过渡点的运动可能会产生不稳定载荷，这可能会导致叶片的严重振动，称为颤振。本项目的目标是研究LSB的形成及其运动对颤振的影响。一个SD 7003翼型剖面将被拖在皇后大学新建的光学拖曳水池中，以模拟风扇叶片上的气流。翼型上的速度场将使用时间分辨平面粒子图像测速仪（PIV）进行采样。翼型上的升力和阻力将通过六分量ATI Gamma力/扭矩天平测量。力的历史将与从PIV数据获得的流动结构相关联，这可能提供关于层流分离颤振的重要信息。

Pratt and Whitney Canada (P&WC) is a leading manufacturer of turbofan engines used in business jets. The high efficiency of these engines relies on the use of high-bypass ratio fan blades, for which the blades require the airfoil profile to be slender. Often during operation, the flow over these fan blades leads to the formation of a laminar separation bubble (LSB), and the boundary layer flow becomes transitional. At high altitudes and at low Reynolds numbers (Re), movement of the transition point may create unsteady loadings, which can potentially lead to severe vibration of the blade, known as flutter. The goal of this project is to investigate how the formation of the LSB and its movement can contribute to flutter. A SD7003 airfoil profile will be towed in the newly built optical towing tank at Queen's University to simulate flow over fan blades. The velocity field over the airfoil will be sampled using time-resolved planar Particle Image Velocimetry (PIV). The lift and drag force on the airfoil will be measured by a six-component ATI Gamma force/torque balance. The force histories will be correlated to the flow structures obtained from PIV data, which may provide important information about laminar separation flutter.