MHz-rate optical pressure sensing in supercritical detonation environments
Abstract
The goal of this project is to enable MHz-rate optical measurement of gas-pressure, as well as temperature and species, across detonation waves up to 100 bar in order to quantify pressure gain and performance in advanced propulsion systems that operate in a supercritical regime. Traditional mechanical pressure transducers have poor performance and durability in detonation environments, thus motivating the need for a non-intrusive optical sensing method. Such highspeed optical measurement capability has proven elusive at extreme pressures. These challenges are expected to worsen as operating pressures are increased for higher thrust and higher performance detonation systems. This project will advance state-of-the-art MHz-rate laser absorption spectroscopy methods to supercritical conditions to enable time-resolved measurements of gas pressure from collisional line broadening and mixing directly across detonation waves. To achieve this new diagnostic capability, the proposed project will consist of- (1) characterizing spectral line mixing and broadening of select methane, carbon monoxide, and carbon dioxide rovibrational transitions up to 100 bar, (2) extending wavelength tuning of interband and quantum cascade lasers at MHz rates via opto-electronic modulation, (3) analyzing thermal shock of infrared-transmissive optical materials subject to cyclic impulsive heating, and (4) sensor validation in controlled laboratory impulse facilities as well as continuous or rotating detonation systems up to 100 bar. It is expected that achieving the research objectives will provide a new generation of quantitative high-speed diagnostics for supercritical combustion systems capable of resolving ultra-fast transients associated with detonation, ignition, and extinction events, ultimately enabling progress in development of advanced rocket and aircraft propulsion systems relevant to future U.S. Air Force vehicles.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 14, 2024
- Source ID
- FA95502310729
Entities
People
- R. Mitchell Spearrin
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of California, Los Angeles