Dense core response to forced acoustic fields in oxygen-hydrogen rocket flames

Youhi Morii, Scott Beinke, Justin Hardi, Taro Shimizu, Hideto Kawashima, Michael Oschwald

Research output: Contribution to journalArticlepeer-review

Abstract

Oscillatory combustion representative of thermo-acoustic instability in liquid rockets is simulated by experiment and LES calculation to investigate the flame behavior in detail. In particular, we focus on how the velocity and pressure fluctuations affect the behavior of the dense oxygen jet, or ‘LOx core’. The test case investigated is a high pressure, multi-injector, oxygen-hydrogen combustor with a siren for acoustic excitation. First, the LES calculation is validated by the resonant frequencies and average flame topology. A precise frequency correction is conducted to compare experiment with LES. Then an unforced case, a pressure fluctuation case, and a velocity fluctuation case are investigated. LES can quantitatively reproduce the LOx core shortening and flattening that occurs under transverse velocity excitation as it is observed in the experiments. On the other hand, the core behavior under pressure excitation is almost equal to the unforced case, and little shortening of the core occurs. The LOx core flattening is explained by the pressure drop around an elliptical cylinder using the unsteady Bernoulli equation. Finally, it is shown that the shortening of the LOx core occurs because the flattening enhances combustion by mixing and increase of the flame surface area.

Original languageEnglish
Pages (from-to)197-215
Number of pages19
JournalPropulsion and Power Research
Volume9
Issue number3
DOIs
Publication statusPublished - 2020 Sep

Keywords

  • Combustion instability
  • Computational fluid dynamics (CFD)
  • Large eddy simulation (LES)
  • Liquid rocket engine
  • Supercritical fluid

ASJC Scopus subject areas

  • Automotive Engineering
  • Aerospace Engineering
  • Fuel Technology
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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