M. Bross & W. Straka - The Pennsylvania State University, Applied Research Laboratory

Описание: “The Pennsylvania State University Applied Research Lab:
Experimental Fluid Mechanics at the Garfield Thomas Water
Tunnel”

Abstract: The Garfield Thomas Water Tunnel (GTWT) is a collection of research facilities, including the 48 inch-diameter test section water tunnel, used in support of the Pennsylvania State University Applied Research Lab’s (Penn State ARL) fundamental and applied research in hydrodynamics and hydro-acoustics. The GTWT was dedicated in 1949 and has supported research within the broad-scope of Navy interests for underwater vehicles and fundamental fluid mechanics. In 1996, the GTWT was designated as National Historic Mechanical Engineering Landmark by the American Society of Mechanical Engineers (ASME) and celebrated it’s 75th anniversary in 2024. In the first part of this talk, an overview of Penn State ARL and GTWT’s research facilities and capabilities with an emphasis on cavitation testing will be given.

In the second half of the talk, different approaches for measuring skin friction drag and wall-shear-stress (WSS) at high Reynolds numbers flows will be discussed. Skin friction drag can contribute to more than 50% of the total drag for cruising aircraft and marine vehicles. Therefore, accurately determining skin friction drag is of interest to the drag reduction community and important for scaling wall-bounded turbulence and validating numerical models. As the range of turbulent scales grow with increasing Reynolds number, accurately measuring the strong velocity gradients near the wall, which is required for estimating WSS, is challenging. However, with novel optical measurement approaches, accessing these small scales is possible. For rough wall or other engineered surface applications, optical access may be limited. In that case, direct measurement of the skin friction drag force is needed. In this presentation, novel optical based wall-shear-stress measurements on a zero-pressure gradient turbulent boundary layer up to friction Reynolds numbers up to Reτ = 9000 will be discussed. In addition, direct measurements of the integrated skin friction on a flat plate and body-of-revolution (BOR) over the Reynolds number ranges ReX = 0.5 × 106 − 1.5 × 107 and Reτ = 1000− 6000 will be shown.

Bio: Dr. Matthew Bross joined Penn State ARL as an assistant research professor in 2022 and was recently promoted to associate research professor in 2025. Prior to his current position, he worked as a research scientist and group leader for turbulence research at the Institute of Aerodynamics and Fluid Mechanics at the Universit¨at der Bundeswehr M¨unchen (UniBw) from 2015 to 2022. He graduated with a PhD in Mechanical Engineering and Mechanics from Lehigh University in 2015 with a dissertation titled ”Flow Structure on Unsteady Maneuvering Wings”. He also holds a M.E. in Mechanical Engineering (2013) from Lehigh University
and a B.S. in Physics (2010) from Moravian College. In the last 10 years, he has focused his professional expertise on the structural topology and scaling of high-Reynolds number turbulent wall-bounded flows, skin friction drag determination and the development of state-of-the-art 2D and 3D digital particle image and tracking velocimetry (PIV/PTV) techniques. Due to his focus on experimental fluid mechanics, he has managed, designed, implemented, and evaluated data for dozens of wind/water tunnel experiments. His research has led to more than 40 high-quality journal publications, refereed proceedings and technical memorandums, with a focus on turbulence research and the development of novel PIV and PTV methods applied to high-speed incompressible and compressible flows.

Mr. William Straka is the Head of the Research Facilities Division within the Fluid Dynamics and Acoustics Office (FDAO) at Penn State ARL. In this role, he is responsible for the management and operations of the hydrodynamic and acoustic test facilities within FDAO including the 48-inch diameter Garfield Thomas Water Tunnel. During his 30+ years at Penn State ARL, Mr. Straka has also served as Principal Investigator or Co-Investigator on over 75 U.S. government or industrial sponsored research programs. These include projects relating to hydrodynamics, propulsor design and performance, cavitation, and marine hydrokinetic devices. Mr. Straka’s technical focus has mostly been centered on propulsor evaluations and cavitation assessments including performance predictions, measurement methodologies, inception, erosion, supercavitation and acoustic and hydrodynamic scaling. He has conducted or supported numerous captive model, wind tunnel, water tunnel and field demonstrations including full-scale acoustic trials. In 2021, Mr. Straka was selected as a PSU/ARL Research Fellow (for Cavitation Research). He graduated with B.S. degree in Aerospace Engineering from Penn State University and M.S. degree in Aeronautics from George Washington University.