Techsburg and Virginia Tech to present paper at 2024 ASME IGTI Turbo Expo June 24-28 in London, UK entitled "Flutter Parameter Study on a Complex Inlet Swirl Distortion Generator"

ABSTRACT: StreamVane devices consist of a custom designed complex vane pack that is used to produce inlet swirl distortion for fan tests, compressor tests, and ground testing of jet engines. Due to being placed upstream of these expensive test rigs, their structural integrity is very important. Since very little research has been conducted on flutter of complex vane packs like StreamVanes, this work focused on examining flutter of one of these models in more detail as well as studying the effects of various parameters on the critical flutter speed and frequency of these devices. For this study, a quad swirl StreamVane that was previously experimentally found to flutter was further analyzed using unsteady CFD with periodic mesh deformation based off the mode shape. This showed the flow in the passage between the fluttering vanes switching between a choked state and a subsonic state as the vanes moved together and apart from each other. This initial quad swirl model was then used as the basis for a series of small-scale flutter tests. These tests examined multiple parameters including chord length, vane thickness, blockage effects, and turning angle variation. To further analyze any potential causes of the excitation, oil flow visualization was conducted and found to show some leading-edge separation and minor corner separation but no pattern to indicate these flow features are responsible for the unsteady loading driving flutter. The results in this paper provide insight into the flutter behavior of these complex vane packs.