| Popis: |
This research tested a swirl-coaxial injector, originally designed to use liquid oxygen and liquid methane, using gaseous oxygen and gaseous methane under scaled mass flow rates in an atmospheric resonance chamber made of fused silica for CH* chemiluminescence imaging and contained ports for high-frequency pressure measurements. The methane mass flow rates varied from 0.122 g/s to 0.259 g/s, and the oxygen mass flow rates varied from 0.318 g/s to 0.777 g/s. The parameters scaled from the original LOX/LCH4 design were the total velocity, axial velocity, OF ratio, and momentum ratio. Discrete frequencies based on dynamic pressure data were present at 2.6 kHz, 5.1 kHz, 9.5 kHz, 10.5 kHz, and 11.0 kHz, with a maximum amplitude of 2% of chamber pressure. The 2.6 kHz instability was determined to be a second tangential mode, but the other instabilities were inconclusive. CH* chemiluminescence images were phase-locked to the dynamic pressure and showed a stark difference in intensity and flame structure between flames with and without discrete instability frequencies. |
