Characterization of Convecting-Rotating Cylinder (CRC) as a Surrogate Vortex for Vortex-Surface Interactions

A novel experimental approach is proposed using a Convecting Rotating Cylinder (CRC) system to emulate the pressure perturbations imposed on a wall by an advecting vortex in a controlled and repeatable manner. The CRC system is constructed and characterized using Particle Image Velocimetry (PIV) and pressure measurements to understand the spatio-temporal characteristics of the imposed pressure. Stationary experiments were conducted to inform and finalize the design of the CRC. Designs with larger fins induced pressure perturbations with greater magnitudes and spread but the flow field deviated significantly from an ideal Rankine vortex. The final design uses a bare cylinder with a smooth surface for this reason. Translating experiments have been conducted with pressure and PIV measurements. The magnitude of the pressure perturbation measured at the wall is 42.5% that predicted by theory. An ensemble averaged PIV field around the translating cylinder illustrates a flow field resembling an ideal Rankine vortex. This work demonstrates the CRC’s ability to impose a translating pressure perturbation on the wall by producing a Rankine vortex in a controllable and repeatable manner. Future work will entail fully characterizing the CRC temporally, and investigating the effects of pressure perturbations on the dynamics of turbulent boundary layers.