Modal Transitions in Rotating Detonation Rocket Engines

Bennewitz, John W.; Bigler, Blaine R.; Pilgram, Jessica; Hargus, William A.

doi:10.1615/intjenergeticmaterialschemprop.2019027880

Cited by 49 publications

(23 citation statements)

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“…The modular RDRE tested in this study is the same laboratory engine used in our previous work [5,13,14]. It was originally designed and tested by Smith and Stanley [2,15] using empirical guidelines developed by Bykovskii et al [1], and contains a 76.2 mm diameter annulus with a 5 mm annular width, and a 76.2 mm long annular channel (see Figure 1).…”

Section: Experiments Setupmentioning

confidence: 99%

“…Combining these two parameters, the accompanying wave speed is determined using U wv = πd f det |m| , where d is the midchannel diameter of the annulus. This process has been shown to adequately extract modal properties throughout periods of steady-state propagation [5,13], as well as during transition events and counter-propagating phenomena [14,22]. Example data for a case exhibiting counter-propagating behavior with the c = 2.40 nozzle (see Figure 10) show that there is complex wave motion in both the clockwise (CW) and counterclockwise (CCW) directions as evidenced by the image sequence (Figure 10a) and detonation surface (Figure 10b).…”

Section: Detonation Mode Characteristicsmentioning

confidence: 99%

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Performance of a Rotating Detonation Rocket Engine with Various Convergent Nozzles and Chamber Lengths

et al. 2021

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A rotating detonation rocket engine (RDRE) with various convergent nozzles and chamber lengths is investigated. Three hundred hot-fire tests are performed using methane and oxygen ranging from equivalence ratio equaling 0.5–2.5 and total propellant flow up to 0.680 kg/s. For the full-length (76.2 mm) chamber study, three nozzles at contraction ratios ϵc = 1.23, 1.62 and 2.40 are tested. Detonation is exhibited for each geometry at equivalent conditions, with only fuel-rich operability slightly increased for the ϵc = 1.62 and 2.40 nozzles. Despite this, counter-propagation, i.e., opposing wave sets, becomes prevalent with increasing constriction. This is accompanied by higher number of waves, lower wave speed Uwv and higher unsteadiness. Therefore, the most constricted nozzle always has the lowest Uwv. In contrast, engine performance increases with constriction, where thrust and specific impulse linearly increase with ϵc for equivalent conditions, with a 27% maximum increase. Additionally, two half-length (38.1 mm) chambers are studied including a straight chamber and ϵc = 2.40 nozzle; these shortened geometries show equal performance to their longer equivalent. Furthermore, the existence of counter-propagation is minimized. Accompanying high-fidelity simulations and injection recovery analyses describe underlying injection physics driving chamber wave dynamics, suggesting the physical throat/injector interaction influences counter-propagation.

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Section: Experiments Setupmentioning

confidence: 99%

Section: Detonation Mode Characteristicsmentioning

confidence: 99%

Performance of a Rotating Detonation Rocket Engine with Various Convergent Nozzles and Chamber Lengths

et al. 2021

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“…Modal transitions have been experimentally observed by Suchocki et al, Rankin et al, Stechmann et al, and Bennewitz at al. [10][11][12][13]. Figure 2 shows an example of a DMT from three to two waves captured from the RDRE exhaust plane during an experimental run [13].…”

Section: Introductionmentioning

confidence: 99%

Descending Modal Transition Dynamics in a Large Eddy Simulation of a Rotating Detonation Rocket Engine

et al. 2021

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Rotating detonation rocket engines (RDREs) exhibit various unsteady phenomena, including modal transitions, that significantly affect their operation, performance and stability. The dynamics of the detonation waves are studied during a descending modal transition (DMT) where four co-rotating detonations waves decrease to three in a gaseous methane-oxygen RDRE. Detonation wave tracking is applied to capture, visualize and analyze unsteady, 3D detonation wave dynamics data within the combustion chamber of the RDRE. The mechanism of a descending modal transition is the failure of a detonation wave in the RDRE, and in this study, the failing wave is identified along with its failure time. The regions upstream of each relative detonation show the mixture and flow-field parameters that drive detonation failure. Additionally, it is shown that descending modal transitions encompass multiple phases of detonation decay and recovery with respect to RDREs. The results show high upstream pressure, heat release and temperature, coupled with insufficient propellants, lead to detonation wave failure and non-recovery of the trailing detonation wave during a descending modal transition. Finally, the Wolanski wave stability criterion regarding detonation critical reactant mixing height provides insight into detonation failure or sustainment.

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“…In this manner, the steady operation of the RDE is the point at which the rates of gain depletion (combustion), gain recovery (injection), and dissipation balance. For these to exist in an unbalanced state induces a degree of unsteadiness, typically manifested as a transition to a different number of waves or modulation of wave speed [3][4][5]12]; i.e., the system bifurcates.…”

Section: Introductionmentioning

confidence: 99%

“…In laboratory experiments, typical observables are wave count, speed, and direction as captured by pressure sensors or optical instruments. Common in experimental literature are a few themes: (i) the observed detona- tion wave speeds are significantly less than the Chapman-Jouget (CJ) velocity (the steady shock-induced combustion wave in which the combustion products are sonic relative to the wave front) for the propellant mixture [13,14], (ii) the number of waves is tied to the mass flow rate of the engine and the propellant injection scheme [11,15], and (iii) para-wave combustion, meaning deflagration not associated with a traveling wave, is ubiquitous [5,12,14]. Additionally, we acknowledge the prevalence of counter-propagating waves in literature (see [5] and [14]).…”

Section: Introductionmentioning

confidence: 99%

Mode-locked rotating detonation waves: Experiments and a model equation

et al. 2020

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Direct observation of a Rotating Detonation Engine combustion chamber has enabled the extraction of the kinematics of its detonation waves. These records exhibit a rich set of instabilities and bifurcations arising from the interaction of coherent wave fronts and global gain dynamics. We develop a model of the observed dynamics by recasting the Majda detonation analog as an autowave. The solution fronts become attractors of the engine; i.e., mode-locked rotating detonation waves. We find that denotative energy release competes with dissipation and gain recovery to produce the observed dynamics and a bifurcation structure common to driven-dissipative systems, such as mode-locked lasers.

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Modal Transitions in Rotating Detonation Rocket Engines

Cited by 49 publications

References 0 publications

Performance of a Rotating Detonation Rocket Engine with Various Convergent Nozzles and Chamber Lengths

Performance of a Rotating Detonation Rocket Engine with Various Convergent Nozzles and Chamber Lengths

Descending Modal Transition Dynamics in a Large Eddy Simulation of a Rotating Detonation Rocket Engine

Mode-locked rotating detonation waves: Experiments and a model equation

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