Characterization of Turbulent Unsteady Separation Using Photonic Micro-Skin Friction and Wall Pressure Sensors
Abstract
The goal of this study is to investigate the structure and the dynamics of unsteady/transient separated turbulent boundary layers for 4x103 < ReÀ < 1.4x104. Central to the study is the characterization of the streamwise and spanwise fluctuating skin friction (direct measurements) and wall pressure fluctuations in and around the separation zone using a novel micro-optical sensor with high spatial resolution and bandwidth. At the same time, detailed high fidelity measurements of velocity, and high order moments will be measured and analyzed. The ultimate goal is to analyze the data in order to understand the dynamics and the prediction of the onset and extent of stall in transient separated turbulent boundary layer. The experiments will be carried out in a specially designed test section of the wind tunnel. The initial region of the test section of the wind tunnel is designed to develop a nearly steady state two-dimensional turbulent boundary layer with a zero pressure gradient. The benefit of growing a steady state boundary layer under a zero pressure gradient is that the net spanwise vorticity would remain constant except at the beginning of the development region. Free transition and development of the turbulent boundary layer using a tripping device will be investigated. A forced local flow unsteadiness will be generated after the initial development region. Different adverse pressure gradient distributions in space and time will be investigate. Experiments will be carried out with harmonic and impulsive adverse pressure gradients. Several frequencies will be covered to provide a wide range of the Strouhal number. The proposed research offers a new opportunity to improve the current State of the Art on flow diagnostics, and provide an unprecedented capability to the experimental, theoretical and computational fluid dynamics community as well as engineering designers. This research will also lead to better computational tools for the design of high efficiency devices and techniques for flow control. The sensor concept can be extended into distributed sensor arrays relatively easily and inexpensively.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810341
Entities
People
- Tindaro Ioppolo
Organizations
- Army Contracting Command
- Southern Methodist University
- United States Army