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"Detonation waves"
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Continuous Detonation of the Liquid Kerosene—Air Mixture with Addition of Hydrogen or Syngas
Regimes of continuous detonation of heterogeneous mixtures of aviation kerosene and air with addition of hydrogen or syngas are studied in a flow-type annular cylindrical combustor 503 mm in diameter. With variations of the flow rates of air, liquid kerosene, hydrogen, and their relationships, regimes of continuous spin detonation are obtained in the following ranges: number of detonation waves 1–5, detonation wave velocity 1.15–1.67 km/s, and wave rotation frequency 0.73–4.86 kHz. In the case with addition of syngas with the composition CO + 3H2, regimes with two opposing transverse waves are obtained; the mean velocity of wave rotation is 0.66–1.47 km/s, and the frequency is 0.85–1.87 kHz. Bubbling of the gaseous fuel (hydrogen or syngas) through liquid kerosene in the fuel injection system makes it possible to reduce the mass fraction of the gas in the two-phase fuel down to 8.4% for hydrogen and 47% for syngas with the composition CO + 3H2. It is demonstrated that the minimum fraction of syngas in kerosene that still ensures the detonation regime is determined by the amount of hydrogen. Based on the stagnation pressure measured at the combustor exit, the specific impulse in the case of continuous detonation is determined as a function of the two-phase fuel composition. The maximum value of the specific impulse (about 4000 s) is obtained for the mass fraction of hydrogen in the two-phase fuel equal to 42%. The minimum diameter of the annular detonation combustor is estimated as a function of the specific flow rate of the heterogeneous mixture.
Journal Article
Strong detonation behaviours in stratified media bound by non-reactive gases
In this study, the propagation behaviour of detonation waves in a channel filled with stratified media is analysed using a detailed chemical reaction model. Two symmetrical layers of non-reactive gas are introduced near the upper and lower walls to encapsulate a stoichiometric premixed H2–air mixture. The effects of gas temperature and molecular weight of the non-reactive layers on the detonation wave’s propagation mode and velocity are examined thoroughly. The results reveal that as the non-reactive gas temperature increases, the detonation wave front transitions from a ‘convex’ to a ‘concave’ shape, accompanied by an increase in wave velocity. Notably, the concave wave front comprises detached shocks, oblique shocks and detonation waves, with the overall wave system propagating at a velocity exceeding the theoretical Chapman–Jouguet speed, indicating the emergence of a strong detonation wave. Furthermore, when the molecular weight of non-reactive layers varies, the results qualitatively align with those obtained from temperature variations. To elucidate the formation mechanism of different detonation wave front shapes, a dimensionless parameter
$\\eta$
(defined as a function of the specific heat ratio and sound speed) is proposed. This parameter unifies the effects of temperature and molecular weight, confirming that the specific heat ratio and sound speed of non-reactive layers are the primary factors governing the detonation wave propagation mode. Additionally, considering the effect of mixture inhomogeneity on the detonation reaction zone, the stream tube contraction theory is proposed, successfully explaining why strong detonation waves form in stratified mixtures. Numerical results show good agreement with theoretical predictions, validating the proposed model.
Journal Article
Secondary waves dynamics and their impact on detonation structure in rotating detonation combustors
In this work, we experimentally investigate secondary waves in rotating detonation combustor (RDC) operation. Secondary waves are finite-strength periodic perturbations of the field, which manifest as reacting fronts and/or pressure rise rotating around the annulus superimposed to one or more detonation waves. Secondary waves interact with the detonation wave, affecting the operation of the RDC, as well as the potential of realizing pressure gain. Through analysis of high-speed end-view chemiluminescence imaging in the detonation channel, the characteristics (speed, multiplicity, and strength) of different systems of waves are identified. The analysis indicates that in addition to the main detonation wave, two secondary wave systems are present: (1) a pair of co-rotating waves moving counter to the detonation wave at a speed near the acoustic speed of the products of combustion and (2) a wave moving counter to the detonation wave at a speed near that of the detonation wave. These two types of secondary waves are consistently observed in three canonical injection schemes. We further investigated the impact of the wave pair on the structure of the main detonation wave in one inlet configuration. By constructing conditional phase-averaged distributions of the pressure and OH* emission over the interaction between the detonation and secondary waves, we reconstruct the structure of the detonation wave during the interaction. The results show that there is a nonlinear interaction between the detonation and secondary waves, which results in an augmentation of the pressure rise (increase by as much as 60%) across the detonation wave as well as partial suppression of the heat release as the two waves interact (variation up to an order of magnitude). This nonlinear interaction is supported by differences in the temporal response of the air and fuel streams subject to the propagation of secondary waves, generating fill region stratification leading to the partial suppression of heat release when the secondary wave collides with the main detonation wave.
Journal Article
Effect of oxygen rich environment on detonation characteristics of pulse detonation engine
The detonation tests of propane/air pulse detonation engine at normal temperature were carried out in this paper. The effects of chemical ratios on the detonation performance of propane/air pulse detonation engine in oxygen-rich environment were studied. The propagation modes and characteristics of detonation waves and the detonation characteristics of the engine under different conditions were analyzed. Detonation tests were conducted on propane/air mixtures with oxygen mass fraction of 20%, 25%, 30% and 35% respectively. The results showed that: In the detonation experiment of the propane/air mixture with oxygen content of 20%, 25% and 30%, the flame wave propagation velocity in the detonation tube is low, which fails to form a stable detonation wave. The detonation effect of the fuel mixture with oxygen content of 20% is the worst, and the propagation velocity of flame wave is 384.00 m/s. In the experiment of propane/air mixture with oxygen content of 35%, the detonation velocity and pressure obtained by pressure signal analysis are both greater than the theoretical CJ detonation velocity, and the detonation state is successfully reached.
Journal Article
Propagation characteristics of rotating detonation with high-temperature hydrogen gas
The rotating detonation characteristics of high-temperature hydrogen-rich gas were studied. Hydrogen-rich gas was generated by the pre-combustion of hydrogen, and a rotating detonation experiment of hydrogen-rich gas and air was subsequently performed. The auto-initiation of high-temperature hydrogen-rich gas was observed in the experiment, and the influence of pre-detonation tube ignition on the steady propagation of the detonation wave was analyzed. The results show that high-temperature hydrogen-rich gas and air have the ability to spontaneously form rotating detonation waves. The operation of the pre-detonation tube has a significant influence on the propagation mode and propagation velocity of the continuous rotating detonation wave after auto-initiation. The rotational detonation wave formed by the auto-initiation of hydrogen-rich gas and air has a short instability in the propagation process. The propagation velocity of the detonation wave before and after the unstable state is 1345.4 m/s and 1425.3 m/s, respectively, the unstable state is 1345.4 m/s and 1425.3 m/s, respectively.
Journal Article
Thermochemical study of the detonation properties of boron- and aluminum-containing compounds in air and water
Contrary to the conventional chemical propulsion systems based on the controlled relatively slow (subsonic) combustion of fuel in a combustor, the operation process in pulsed detonation engines (PDEs) and rotating detonation engines (RDEs) is based on the controlled fast (supersonic) combustion of fuel in pulsed and continuous detonation waves, respectively. One of the most important issues for such propulsion systems is the choice of fuel with proper reactivity and exothermicity required for a sustained and energy-efficient operation process. Presented in the paper are the results of thermodynamic calculations of the detonation parameters of boron- and aluminum-containing compounds (B, B
2
H
6
, B
5
H
9
, B
10
H
14
, Al, AlH
3
, Al(C
2
H
5
)
3
, and Al(CH
3
)
3
)
in air and water. The results demonstrate the potential feasibility of using the considered compounds as fuels for both air- and water-breathing transportation vehicles powered with PDEs and RDEs. As a verification of the reliability of the calculated results, the detonation parameters of diborane, aluminum, and isopropyl nitrate in air were compared with experimental data available in the literature.
Journal Article
Detonation Waves on Enhancing Aerospace Propulsion Systems Performances: A Review
Detonation-based combustion has re-emerged as a promising pathway for enhancing the efficiency and compactness of future aerospace propulsion systems, motivated by the intrinsic pressure-gain characteristics of detonative heat release. This review provides a comprehensive synthesis of the physical foundations, technological progress, and practical limitations associated with pulse detonation engines, rotating detonation engines, and standing or oblique detonation wave concepts. By tracing the evolution from early theoretical models and laboratory-scale demonstrations to engine-relevant configurations, this article highlights how detonation physics, ignition mechanisms, wave stability, and flow–structure interactions collectively govern propulsion performance. Particular attention is paid to recent experimental and numerical studies, with the review focusing on their technological impact and on the feasibility of integrating detonation-based propulsion concepts into practical aerospace systems. The analysis evaluates these approaches’ potential to enhance system-level performance compared to conventional propulsion technologies, while highlighting key challenges associated with scalability, operability, and compatibility with existing aerospace architectures. The review further identifies emerging design strategies, including geometry tailoring, adaptive flow control, and hybrid architectures, as key enablers for extending operability and system integration. Overall, the findings indicate that future progress in detonation-based propulsion will depend less on demonstrating detonation itself and more on achieving robust, controllable, and scalable implementations suitable for realistic aerospace applications.
Journal Article
Detonation behaviors in a curved tube with and without an obstacle
Experiments were conducted to investigate detonation propagation in a curved tube filled with stoichiometric 2H
2
+
O
2
+
7Ar and CH
4
+
2O
2
. The test section of the experimental setup was a semicircular channel with an internal radius of 500 mm. Detonation velocities were calculated based on the arrival time of the wave front, monitored by pressure transducers. The detonation cellular evolution was recorded using smoked foils. The results revealed that after crossing the obstacle, the detonation wave failed and promptly re-initiated. It then decayed from an overdriven detonation to a steady-state detonation. The detonation development processes were divided into five regimes. The formation of the boundary behind the obstacle and the generation mechanism of the overdriven detonation were thoroughly analyzed. The formation of the boundary behind the obstacle is associated with the curved shock front and the non-uniform cellular structure. The re-initiation distance for an unstable mixture in a curved tube was significantly shorter than that in a straight channel. In the absence of the obstacle, the cell width decreased radially outward, a linear relationship was determined. The speed of the detonation wave initially decreased and then gradually increased.
Journal Article
Perturbed Initial Value Problem for Chaplygin System with Combustion
In the present paper, the authors consider the perturbed initial value problem of the Chapman-Jouguet model for the Chaplygin gas. We obtain the unique solution by analyzing the elementary waves under the global entropy conditions. We observe that the combustion wave solution may be extinguished after perturbation which tells the instability of the unburnt gas. And we also capture the transitions between the deflagration wave and the detonation wave.
Journal Article