Burst-Mode Laser System for Temporally and Spatially Resolved Non-Intrusive Laser Diagnostics in Supersonic Flows
Abstract
The continued development of non-intrusive diagnostics will be critical to the advancement of aerothermodynamics research. Significant strides have been made in this field over the past fifty years but further progress is required to provide the temporally and spatially resolved measurements that will be necessary to advance the state-of-the-art in hypersonics. As the developers of emerging hypersonic concepts strive to reduce design margin and uncertainty by accounting for dynamic and transient aerothermodynamic phenomena, the demand for diagnostics with enhanced spatial and temporal resolution is increasing. Four key technology challenges faced by the diagnostics community include collecting (i) time-resolved measurements in high-speed flows, (ii) spatially-resolved measurements in high-speed flows, and (iii) 4-D measurements (3-D space + time) in supersonic flows and (iv) the development of high-repetition rate, high-energy, laser systems with tunable access to UV wavelengths necessary for many diagnostics (not currently available on the commercial market). Recent advances in imaging and laser technology???such as cheaper high-speed cameras, development of plenoptic cameras, and advances with pulse-burst lasers???have increased the potential capabilities for non-intrusive diagnostics such as particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF). The improved resolution and faster frame rates now available for cameras, coupled with state-of-the-art high-power highrepetition rate lasers has allowed researchers to begin to address the temporal and spatial resolution issues that make measurements in high-speed flows difficult. For example, tomographic reconstruction of two- and three-dimensional measurements from techniques such as PLIF and TDLAS is a growing area of interest. Time-resolved, ???4-D??? imaging of turbulent flows has also been realized over the past several years, and should lead to an improved understanding of the temporal evolution of turbulent structures. Given the opportunity provided by the recent availability of new technology and the demand from simulations and aggressive design to reduce margins of uncertainty, an investment in diagnostics technology that enables temporally and spatially resolved measurements in supersonic flows is needed to help address key issues and lead to game-changing breakthroughs in aerothermodynamics research. This effort seeks to develop cutting-edge advancements in non-intrusive diagnostics that will enable temporally and spatially resolved measurements of velocity, temperature, pressure, and species concentration in supersonic flows. Therefore, funds are sought for the purchase of a highpowered burst-mode Nd:YAG laser with repetition rates up to 500 kHz as well as the equipment necessary to construct a compatible optical parametric oscillator (OPO) that will permit tunable access to UV wavelengths necessary for the excitation of many key laser-induced fluorescence (LIF) tracers such as nitric oxide (NO), krypton, atomic oxygen, and atomic nitrogen and will be a one-of-a-kind technology not currently available in the academic community. This system will allow time-resolved PIV measurements to be made at supersonic Mach numbers as well as timeresolved PLIF and molecular tagging velocimetry (MTV). Furthermore, the laser will produce sufficient laser energy to develop point, planar, and volumetric applications of these diagnostics. It is also anticipated that this system will be sufficiently portable so that it can be used at the various experimental facilities at UTSI.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 27, 2018
- Source ID
- N000141812688
Entities
People
- John D. Schmisseur
Organizations
- Office of Naval Research
- United States Navy
- University of Tennessee