Swirl Coaxial Injector Element Research Articles

Experimental Study of Major Species and Temperature Profiles of Liquid Oxygen/Gaseous Hydrogen Rocket Combustion

Understanding thefundamentalsofhigh-pressure, high-temperaturecombustion of practical rocketpropellants is key to improving rocket engine performance and efe ciency. The application of Raman spectroscopy for making detailed species concentration measurements of oxygen, hydrogen, and water vapor in the elevated-pressure, combusting e owe eld downstream of a liquid-oxygen/gaseous-hydrogen swirl-coaxial injector element at fuel-rich conditionsispresented.Detailsregardingmeasurementerroranalysisandrecommendationsforfurtherree nement ofthediagnostictechniquearealsopresented.To theauthors’ knowledge,theseexperimentsrepresentthee rsttime that instantaneous temperature and major species proe les have been successfully made in such an environment. Theseresults,whichincludebothinstantaneousand time-averagedtemperatureand speciesconcentrationproe les, impact both rocket fuel preburner design and computational e uid dynamic code validation activities. Nomenclature f .T/ = temperature dependent function that relates the spectral bandwidth strength to the signal strength = focal length =# = focal length divided by the diameter of the lens K = constant that accounts for the laser pulse energy, species Raman cross section, optical collection efe ciency, and optical solid angle N = measurement uncertainty n = number density S = Raman signal intensity aeB = background shot noise due to e ame luminosity aeD = dark current noise of the intensie er aeR = Readout noise aeS = signal shot noise due to Raman signal