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Lehigh University logo

Leo Massimino and Mary Thorsen

Experimental Investigation of Tip Leakage Vortex Breakdown and High-Speed 3D Scanning Stereoscopic PIV in a Water Channel

Department: Mechanical Engineering
Advisor: Dr. Tobias Rossmann and Dr. Daniel Sabatino

Abstract:
Lafayette College’s 1000 gallon water channel is used to observe flow at low speed for many different applications. The advantage of using a water channel to conduct fluid dynamics research is mainly the large scale of the structures observed in the flow. There are currently two experiments happening simultaneously in the water channel: An experimental investigation into the tip leakage vortex breakdown, and an implementation of a high-speed 3D scanning stereoscopic PIV system.

In gas turbine engines, tip leakage vortex breakdown is a phenomenon caused by the existence of a small gap between the blades and the engine casing known as the tip gap. Fluid from the pressure side of a blade is prone to leak over the tip gap to the suction side and roll up into a vortex. This vortex continues downstream where it can rapidly expand or “break down” due to the presence of an adverse pressure gradient. These broken down vortices cause flow blockages which lead to irreversible energy losses. This project aims to experimentally model tip leakage vortex breakdown in a water channel and then validate a computational fluid dynamic (CFD) model of the experiment using the experimental data as a baseline. Validating allows engine manufacturers to make more design decisions based on CFD results. This is important due to the relative cost of engine tests.

Stereoscopic particle image velocimetry uses two cameras at different angles to view the interrogation window to establish the 3D velocity vector field in a single plane. When a scanning mirror is introduced, it sweeps the laser sheet across multiple planes so the cameras can capture the flow field throughout a volume. Fully turbulent areas are too complex to examine, but both turbulent spots and fully turbulent areas are comprised of hairpin vortices. Therefore, by examining the hairpin vortex structure with PIV, fully turbulent areas can be better investigated. High-speed 3D scanning stereo PIV data will be taken looking at hairpin vortices with a 250 Hz scanning mirror, a 10 kHz camera frame rate, and a 40 kHz pulsing laser. The results will then be compared to previous tomo PIV data on hairpin vortices.

About Leo Massimino:
Leo Massimino is a senior mechanical engineering major at Lafayette College. His main academic areas of interest are fluid dynamics, heat transfer, and thermodynamics. His research focuses on low speed fluid dynamics for gas turbine engine flow applications. He plans on entering the engineering industry after college.

About Mary Thorsen:
Mary Thorsen is a senior mechanical engineering student with a minor in mathematics at Lafayette College. She is from Lancaster Pennsylvania. Mary is researching techniques in particle image velocimetry and implementing a 3D scanning stereo PIV system to examine hairpin vortices. Her research is being conducted at the Lafayette College water channel lab under the supervision of Dr. Daniel Sabatino and Dr. Tobias Rossmann. In addition to her involvement in research, she is also a member of the Lafayette club field hockey team and club softball team.