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Laser Absorption Measurements of Equivalence Ratios Studied Along With Their Coupling to Pressure Fluctuations in Lean Premixed Prevaporized (LPP) CombustionConcerns about damaging the Earth's ozone layer as a result of high levels of nitrogen oxides (known collectively as NOx) from high-altitude, high-speed aircraft have prompted the study of lean premixed prevaporized (LPP) combustion in aircraft engines. LPP combustion reduces NOx emissions principally by reducing the peak flame temperatures inside an engine. Recent advances in LPP technologies have realized exceptional reductions in pollutant emissions (single-digit ppm NOx for example). However, LPP combustion also presents major challenges: combustion instability and dynamic coupling effects between fluctuations in heat-release rate, dynamic pressure, and fuel pressure. These challenges are formidable and can literally shake an engine apart if uncontrolled. To better understand this phenomenon so that it can be controlled, we obtained real-time laser absorption measurements of the fuel vapor concentration (and equivalence ratio) simultaneously with the dynamic pressure, flame luminosity, and time-averaged gaseous emissions measurements in a research-type jet-A-fueled LPP combustor. The measurements were obtained in NASA Glenn Research Center's CE-5B optically accessible flame tube facility. The CE-5B facility provides inlet air temperatures and pressures similar to the actual operating conditions of real aircraft engines. The laser absorption measurements were performed using an infrared 3.39 micron HeNe laser in conjunction with a visible HeNe laser for liquid droplet scattering compensation.
Document ID
20050196682
Acquisition Source
Glenn Research Center
Document Type
Other
Authors
Nguyen, Quang-Viet
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 23, 2013
Publication Date
March 1, 2001
Publication Information
Publication: Research and Technology 2000
Subject Category
Propellants And Fuels
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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