Operando Spectroscopic Characterization of Otto Fuel Combustion
Abstract
Operando Spectroscopic Characterization of Otto Fuel CombustionAbstract: ONR support is requested to fund collaborative research focused on understanding reactive intermediates and terminal gas phase and solid-state products in the combustion of Otto Fuel II (OF II) and other monopropellants. Motivating this research is the need to characterize critical chemical species responsible for the formation of carbonaceous deposits during OF II engineoperation. Work will proceed on two fronts and integrate results from operan"do measurements infunctional flames, ex situ analyses of exhaust and deposited materials, and kinetic modeling topredict flame tem"peratures and product distributions. Two identical high-pressure combustionreactors will be constructed and used for these studies. One assembly will operate at MontanaState where operando laser diagnostics including vibrational Raman scattering will resolveintermediates in flames formed by monopropellant fuel combustion. The second reactor willoperate at Brown University where researchers will use gas sampling methods to inventory gasphase exhaust products and develop predictive models intended to optimize Otto fuel combustion. This two-pronged approach leverages the individual expertise of two accomplished researchers who have complementary skills and a demonstrated commitment to strong scholarship and personnel development.Activities will address an ONR-identified need to increase the range of the US Navy~s Mark-48torpedoes. Current engine designs produce large molecular weight combustion by-products"(commonly referred to as engine ~gunk~), and these by-products are evidence of incomplete fuelconsumption that limits torpedo rang""e. The ONR currently funds the development of acomputational model describing Otto Fuel combustion, but given the absence of experi""mentaldata including heats of combustion, product distributions, and reactive intermediates, predictionsfrom this model cannot be"" validated. By identifying and quantifying the reactive intermediatesthat reduce engine performance, the proposed research will ena""ble development of new strategiesto improve combustion efficiency and, ultimately, increase Mark 48 capabilities. Specific mileston""es of this Phase I project at Montana State include the following:~ Design, construction and characterization of a combustion assem""bly capable supporting astable, monopropellant flame~ Adapting an existing Raman microscope to perform Raman spectroscopy experime""nts withthe combustion assembly~ Quantifying sensitivity and detection limits of the Raman spectrometer for small, stablegas phas"e species and determine the temperature dependence of these detection limits.~ Identifying by their vibrational signatures gas phas"e carbon-forming precursors and carbonaccumulation kinetics using a model pyrolysis mixture (e.g. ethylene, butane, toluene etc.)~" Test the Raman spectrometer~s ability to measure flame temperature using ratios of Stokesand anti-Stokes vibrational band intensities.Work will be performed at Montana State University (Professor Rob Walker) and BrownUniversity (Professor C. Franklin Goldsmith). The PI~s will closely coordinate their activities sothat results from vibrational Raman experiments can be compared directly to" data from massspectrometric exhaust inventories. Should Phase I be successful and the reactor meetspecifications, Phase II activi"ties will address specific monopropellant combustion behaviors.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 29, 2017
- Source ID
- N000141712957
Entities
People
- Robert A Walker
Organizations
- Montana State University
- Office of Naval Research
- United States Navy