caa a22 4500 606244921 CHVBK 20210128101332.0 cr unu---uuuuu 210128e20150301xx s 000 0 eng 10.1007/s12567-015-0079-z doi (NATIONALLICENCE)springer-10.1007/s12567-015-0079-z Characterisation of acoustic energy content in an experimental combustion chamber with and without external forcing [Elektronische Daten] [S. Webster, J. Hardi, M. Oschwald] The influence of injection conditions on rocket engine combustion stability is investigated for a sub-scale combustion chamber with shear coaxial injection elements and the propellant combination hydrogen-oxygen. The experimental results presented are from a series of tests conducted at subcritical and supercritical pressures for oxygen and for both ambient and cryogenic temperature hydrogen. The stability of the system is characterised by the root mean squared amplitude of dynamic combustion chamber pressure in the upper part of the acoustic spectrum relevant for high frequency combustion instabilities. Results are presented for both unforced and externally forced combustion chamber configurations. It was found that, for both the unforced and externally forced configurations, the injection velocity had the strongest influence on combustion chamber stability. Through the use of multivariate linear regression the influence of hydrogen injection temperature and hydrogen injection mass flow rate were best able to explain the variance in stability for dependence on injection velocity ratio. For unforced tests turbulent jet noise from injection was found to dominate the energy content of the signal. For the externally forced configuration a non-linear regression model was better able to predict the variance, suggesting the influence of non-linear behaviour. The response of the system to variation of injection conditions was found to be small; suggesting that the combustion chamber investigated in the experiment is highly stable. CEAS, 2015 Combustion instabilities nationallicence Liquid propellant rocket engines nationallicence Coaxial injection nationallicence Cryogenic propellants nationallicence Webster S. Institute of Space Propulsion, German Aerospace Center (DLR), Lampoldshausen, 74239, Hardthausen, Germany aut Hardi J. Institute of Space Propulsion, German Aerospace Center (DLR), Lampoldshausen, 74239, Hardthausen, Germany aut Oschwald M. Institute of Space Propulsion, German Aerospace Center (DLR), Lampoldshausen, 74239, Hardthausen, Germany aut CEAS Space Journal Springer Vienna 7/1(2015-03-01), 37-51 1868-2502 7:1<37 2015 7 12567 https://doi.org/10.1007/s12567-015-0079-z text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s12567-015-0079-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Webster S. Institute of Space Propulsion, German Aerospace Center (DLR), Lampoldshausen, 74239, Hardthausen, Germany aut NATIONALLICENCE 700 1- Hardi J. Institute of Space Propulsion, German Aerospace Center (DLR), Lampoldshausen, 74239, Hardthausen, Germany aut NATIONALLICENCE 700 1- Oschwald M. Institute of Space Propulsion, German Aerospace Center (DLR), Lampoldshausen, 74239, Hardthausen, Germany aut NATIONALLICENCE 773 0- CEAS Space Journal Springer Vienna 7/1(2015-03-01), 37-51 1868-2502 7:1<37 2015 7 12567