Continuous, high-repetition rate planar laser induced fluorescence system
Abstract
In this proposal, we request funds to purchase a state-of-the-art, continuous, high-repetitionand framing rate planar laser induced fluorescence (PLIF) system that is capable of tracking OH*,CH* and fuel tracers (such as acetone) at 50 kHz. Additionally, the PLIF system can also tracksoot using laser induced incandescence (LII). The system is chosen based on specific goals ofboth current and pending grants at the University of Cincinnati (UC) that are sponsored by varioussub-entities of the Department of Defense. Currently, we have multiple projects that cover threemain research areas, namely: a) rotating detonation combustors (RDC), b) supersonic jet noise,and c) afterburner combustion instabilities. The RDC grant, pertaining to the experimental researchon the various modes of operation at diverse operating conditions and geometries, is funded by theOffice of Naval Research and we have also been granted an additional Phase-I grant from the AirForce Office of Scientific Research to perform preliminary studies to affirm the possibility of usingRDCs in an afterburner setting, i.e. a rotating detonation afterburner (RDA). Currently, we areworking with the Naval Research Laboratory to investigate the behavior of hollow and flowthroughRDCs, which lack the typical annular geometry while also possessing a mean core-flow.The supersonic jet noise topic is subdivided into two different projects, with one dealing with theflow dynamics and acoustic spectra of twin-rectangular jets, whereas the other pertains to the moreconventional circular jets. Both these projects are funded by ONR, and we work closely with NRLto provide benchmark results to compare NRLs JENRE code against. Finally, we are workingwith Knite Inc. for a Small Business Innovation Research project that is funded by the Naval AirSystems Command to experimentally analyze the suppression of afterburner combustioninstabilities using a novel plasma actuator. At present, we are also awaiting decision on a $1.5million grant from ONR to perform in-depth research on RDAs, by harnessing our expertise withead in all the projects described above is the presence of highly threedimens For instance, rotating detonationspropagate at more than 1 kHz and can extend to more than 10 kHz based on their number (up to10 waves are known to exist simultaneously within the combustor). The screech noise insupersonic jets is also known to occur in the kHz regime and causes very strong sound amplitudesthat produces a tonal acoustic spectra in both the near- and far- field. Combustion instabilities inafterburner environment couple strongly with the chamber acoustics and produce instabilities atmore than 500 Hz. To understand the fundamental physics responsible for these complex fluidandcombustion- dynamic phenomena, we need a visualization system that can track differentelements (OH*, CH*, acetone tracker, soot) of these mechanisms at distinct planes (not line-ofsightaveraged) in a time-resolved fashion (satisfying the Nyquist criterion of sampling frequency).The currently proposed high-speed PLIF system is contended to satisfy all these requirements,thereby contributing immensely to DoD-sponsored research. We note that this system can be easilyconverted to a high-speed PIV system (oriented towards supersonic jet noise) by using the otherinstruments and software already present at UC. If granted, the cutting-edge system is expected toremain relevant for at least the next two decades, and can be used in conjunction with UCs otherresearch facilities (see Project Narrative), fostering not only DoDs research, but also otherresearch endeavors relevant to the country.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 09, 2021
- Source ID
- N000142112348
Entities
People
- Ephraim Gutmark
Organizations
- Office of Naval Research
- United States Navy
- University of Cincinnati