Abstract Rotating detonation combustors are prone to a wide range of off-design behaviors during both atmospheric and pressurized operation. The current manuscript deals with the transient mean pressure change seen in back-pressurized combustors after ignition. Using experimental high-speed pressure data acquired during this transience, we report two distinct, but overlapping, mechanisms that are well-known in deflagrative rocket combustors, but are not currently considered in rotating detonation combustors: DC shift and chugging. The former is characterized by sudden and seemingly random alterations of the time-averaged chamber pressure during operation, not unlike the same behavior observed in conventional rockets during instability onset. The latter is a low frequency instability that is inherently coupled to the reactants feed, causing significant oscillations of the mean chamber pressure. We show that these phenomena are strongly linked, where onset of chugging oscillations alter the frequency and pressure of the operating mode, which in turn produces a DC shift of the mean chamber pressure. To discern this complex interaction, we use multivariate polynomial curve-fitting, considering all the appropriate parameters to arrive at an empirical formulation that is seen to reasonably match the observed pressure transience after ignition.
Highlights The transient pressure increase after RDC ignition is studied. The low frequency oscillations accompanying this transience is also investigated. These two behaviors in RDCs are linked to DC shift and chugging instability in rocket engines. These two phenomena are also interlinked between themselves. An empirical correlation is proposed to discern the pressure evolution after ignition.
Observations of DC shift and chugging in a pressurized rotating detonation combustor
Acta Astronautica ; 187 ; 362-369
2021-06-12
8 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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