The Response of Cryogenic H2/O2 Coaxial Jet Flames to Acoustic Disturbances

Abstract

An experimental study has been conducted to explore the coupling between a coaxial gaseous hydrogen / liquid oxygen jet flame and transverse acoustic perturbations. A variety of chamber conditions including acoustic frequency, amplitude, and the location of the pressure node / antinode with respect to the flame were examined. The flame response was documented using high-speed imaging including backlit visualization and unfiltered chemiluminescence. Dynamic mode decomposition was used to isolate the spatial structure of the flame response at the forcing frequency. The results indicate that the flame response to forcing is qualitatively similar to previous results of nonreacting coaxial jet flows; the pressure node forcing appears to generate in-plane flapping of the flame while pressure antinode forcing induces a helical structure in the flame.

Wave Dynamic Mechanisms in Coaxial Hydrogen/Liquid-Oxygen Jet Flames

“…A significant amount of work was performed at the U.S. Air Force Research Laboratory [23][24][25][26][27]. The majority of the research was performed on a single coaxial jet using liquid nitrogen and gaseous nitrogen as propellant stimulants for rocket injector studies.…”

“…The majority of that work, however, concerned nonreacting flows; but, it did investigate the effects of subcritical and supercritical pressures and effects of acoustic forcing. The most recent work considered reacting flows, however [24,27]. From the experimental efforts, different flow dynamics were observed when the flame was present and when it was not.…”

Acoustically Coupled Combustion of Liquid Fuel Droplets

“…While in many practical systems involving liquid spray combustion the flame envelops the spray itself [21], the behavior of individual droplets is a necessary component of twophase models for the reactive spray [22,23]. Moreover, many flow and reactive processes associated with single droplet combustion are relevant to and consistent with those of reactive multiphase jets, especially for configurations found in LREs [4], including shear coaxial jets, which have been shown in the past to selfexcite combustion instabilities [24][25][26][27][28][29][30].…”

Transverse Acoustic Forcing of Gaseous Hydrogen/Liquid Oxygen Turbulent Shear Coaxial Flames

“…Experimental and computational research on shear coaxial injectors using a gaseous annular propellant and a central cryogenic jet for liquid rocket engine applications were carried out by Poinsot et al [4], Rey et al [5], Richecoeur et al [6][7][8], Méry et al [9], Hakim et al [10,11], Urbano et al [12], Gonzalez-Flesca et al [13], Urbano et al [14], Hardi et al [15,16], Gröning et al [17], Armbruster et al [18], Mayer and Krülle [19], Mayer and Tamura [20], Mayer et al [21], Oefelein and Yang [22], Zong and Yang [23,24], Roa and Talley [25], Roa et al [26], Forliti et al [27], Hua et al [28], Graham et al [29], Levya et al [30,31], Rodriguez et al [32], Wegener et al [33], and Davis and Chehroudi [34]. Aspects of those studies that focused largely on characterizing and understanding the atomization, flame locations, and average global behavior for shear coaxial flows that are not experiencing combustion instabilities were reviewed by Roa and Talley.…”