Preliminary Development of a Single Camera Rotating Volumetric Velocimetry Technique

摘要

The technique of phase-locked flow field measurements has been employed in the past to investigate the flow over rotating wings. However, phase-locked measurements have several limitations including the inability to measure time-resolved flow fields and to comprehensively quantify cycle-to-cycle variations over the rotating wing. To overcome such limitations, this paper presents a novel single camera-based rotating frame of reference volumetric velocimetry technique to measure the flow over a rotating wing. Such high-fidelity measurements will allow for a comprehensive quantification of physical parameters, such as centripetal and Coriolis accelerations, that are unique to the flow over a rotating wing. By combining a mirror on the rotor hub with a plenoptic camera in the fixed frame of reference, this technique enabled the measurement of time-resolved 3D flow on a rotating surface over a large range of azimuthal angles. The feasibility of this methodology was demonstrated by implementing this technique on a rotating wing in a water tank. To overcome challenges in the visualization of the flow through a rotating mirror using a fixed frame of reference camera, a rotational volumetric calibration methodology was developed and implemented. The calibration was used to reconstruct volumes of particles. Preliminary particle image velocimetry (PIV) analysis was performed on these volumes to study the instantaneous and 3-D flow field over the rotating wing.