Swirling flow evolution Part 1: Design and stereo PIV measurements at select planes

The next generation of aircraft will rely on airframe and propulsion integration, leading to the need to analyze the different effects that novel configurations will have on performance and operability of said systems. With the development of the StreamVane™ technology, the Virginia Tech Turbomachinery and Propulsion Laboratory has been able to push these investigations forward, while developing tools to analyze the fundamentals of the fluid dynamics involved in turbofan inlet distortions. A Lamb-Oseen vortex model was used to design a single vortex distortion device, generated with the aid of additive manufacturing. Two different designs, named StreamVane™ LoVort 2a and 2b, were tested for comparison and assessment of the device design. Stereoscopic particle image velocimetry was used to measure the development of the flow at six different measurement planes at a duct Reynolds number of 500,000. The results show that the interactions between the vortex and the wall cause it to migrate tangentially along the duct, as expected from this 2D vortex dynamics dominated flow. They also indicate that a StreamVane™ with less vanes, and therefore less blockage, was more effective in reproducing the design profile, with a maximum RMS difference to the design profile of 2.50 degrees in the tangential direction and 3.14 degrees in the radial direction at the measurement plane closest to the trailing edge of the distortion device. Further analysis of the generated profile is described in Part 2 of this paper.