This research investigation encompasses experimental tests demonstrating the control of a high-frequency combustion instability by acoustically modulating the propellant flow. This investigation complements an accompanying theoretical study implementing linear modal analysis [Bennewitz, J. W., Rani, S. L., Cranford, J. T., and Frederick, R. A., Jr., “Combustion Instability Control Through Acoustic Modulation at the Inlet Boundary: Analysis,” Journal of Propulsion and Power, (to be published)]. A model rocket combustor burned gaseous oxygen and methane using a single-element pentad-style injector. Flow conditions were established that spontaneously excited a 2430 Hz first longitudinal combustion oscillation at an amplitude up to p / p c 4 % . An acoustic speaker was placed at the base of the oxidizer supply line to modulate the flow and alter the oscillatory behavior of the combustor. Two speaker modulation approaches were investigated: 1) bands of white noise, and 2) pure sinusoidal tones. The first approach adjusted 500 Hz bands of white noise ranging from 0–500 to 2000–2500 Hz, whereas the second approach implemented individual harmonic signals with arbitrary phase swept from 500 to 2500 Hz. The results show that, above a modulation signal amplitude threshold, both approaches suppressed 95 + % of the spontaneous combustion oscillation. By increasing the applied signal amplitude, a wider frequency range of instability suppression became present for these two acoustic modulation approaches. Thus, this work further supports the strategic application of acoustic modulation within an injector as a potential method to control high-frequency combustion instabilities for liquid rocket engine applications.


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    Titel :

    Combustion Instability Control Through Acoustic Modulation at the Inlet Boundary: Experiments


    Beteiligte:

    Erschienen in:

    Erscheinungsdatum :

    2015-07-03


    Format / Umfang :

    17 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch