Detonation Wave Propagation Research Articles

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This paper proposes to use the detonation process to solve the problem of controlling highly maneuverable flying vehicles. The goal of the work is to study a new way of the thrust vector control of a rocket engine using the effect of a detonation shock wave on the gas flow in the nozzle. It is known that the method of thrust vector control by gas injection into the supersonic nozzle area of a rocket engine features one of the lowest losses of specific momentum and a high response speed and produces a significant lateral force. However, for the current level of rocket technology, there is a need to improve these characteristics. Detonation is considered as a method to intensify processes that affect the main gas flow and produce a lateral force. Its features make it possible to develop a system for pulse trajectory correction. In order to study the features of such a system, experimental studies of the detonation wave effect on a supersonic nozzle flow were conducted. A nozzle model and a gas generator for initiating a detonation wave interacting with the main supersonic air flow were developed and made. In the course of experiments, the effect of separation of the main flow from the nozzle wall by the detonation wave during the nozzle operation in the overexpansion mode was revealed. The duration of this effect was much longer than that of the detonation product effect on the main air flow in the nozzle, thus allowing it to be used in the development of a new thrust vector control method. To better understand the experimental results, a numerical simulation of the detonation wave propagation in a supersonic flow was carried out for the test conditions. The simulation was carried out in a non-stationary 2D formulation using the Solid Works software package. The goal of the simulation was to estimate the flow structure and the value of the relative lateral force produced by the change of this structure during detonation product injection into the supersonic nozzle area. The time evolution of the pressure field was obtained. The relative lateral force produced by detonation product injection into the supersonic air flow in the nozzle was determined. The presented features and method of jet engine thrust vector control may be used in unmanned systems operating in a wide range of speeds.

Imploding Detonation Waves in Self-gravitating Ideal Gas

In the present paper, the propagation of strong spherical imploding detonation waves in a reacting ideal gas under the effect of self-gravitation of the non-homogeneous medium has been investigated, by the help of Chester-Chisnell-Whitham (CCW) theory. It is considered that detonation wave is initially Chapman-Jouguet. Initial taking the density distribution law as power decreasing with distance, the analytical expressions for the detonation velocity just behind the front along with other flow variables are derived. Neglecting the effect of overtaking disturbances the variation of non-dimensional detonation velocity, the pressure and density with the propagation distance have been calculated numerically. The effect of change in density parameter at different Alfven Mach number on the convergence of detonation front have been discussed through graphs in details. Finally, it is found that density parameter and Alfven Mach number of gas have a significant role on propagation of strong spherical detonation front in reacting ideal gas with gravitation effect on all the post-flow variables. The software MATLAB have been used for computation of the problem. Keywords: Self-gravitating gas, Strong detonation waves, CCW theory.

The Mechanism of Resonant Amplification of One-Dimensional Detonation Propagating in a Non-Uniform Mixture

The propagation of detonation waves (i.e., supersonic combustion waves) in non-uniform gaseous mixtures has become a matter of interest over the past several years due to the development of rotating detonation engines. It was shown in a number of recent theoretical studies of one-dimensional pulsating detonation that perturbation of the parameters in front of the detonation wave can lead to a resonant amplification of intrinsic pulsations for a certain range of perturbation wavelengths. This work is dedicated to the clarification of the mechanism of this effect. One-dimensional reactive Euler equations with single-step Arrhenius kinetics were solved. Detonation propagation in a gas with sine waves in density was simulated in a shock-attached frame of reference. We carried out a series of simulations, varying the wavelength of the disturbances. We obtained a non-linear dependence of the amplitude of these pulsations on the wavelength of disturbances with resonant amplification for a certain range of wavelengths. The gain in velocity was about 25% of the Chapman–Jouguet velocity of the stable detonation wave. The effect is explained using the characteristic analysis in the x-t diagram. For the resonant case, we correlated the pulsation period with the time it takes for the C+ and C− characteristics to travel through the effective reaction zone. A similar pulsation mechanism is realized when a detonation wave propagates in a homogeneous medium.

NUMERICAL INVESTIGATION ON PULSE DETONATION ENGINE PERFORMANCE UNDER DIFFERENT EQUIVALENCE RATIO

Detonation-based engines have a higher thermal efficiency than deflagration-based engines and are therefore widely studied. In this study, the effect of initiation conditions on the detonation wave propagation and the performance of a pulse detonation engine, one type of detonation-based engine, was numerically investigated. Hydrogen-oxygen mixtures with equivalence ratios of φ=0.8, 1.0, and 1.2 were defined as initiation conditions with constant pressure and temperature. The numerical simulations were conducted using the transient explicit density-based solver in the ANSYS Fluent commercial software. The adaptability of the adaptive mesh refinement method in detonation-based engines was explored in the numerical studies, reducing the average total cell count by a factor of 2.617, and obtaining consistent results according to validation studies. The adaptive mesh refinement method was also used in numerical simulations where different equivalence ratios were defined. It was determined that an increase in the equivalence ratio resulted in an increase in the detonation wave velocity. Also, an increase in thrust distribution at the nozzle exit was observed before the blowdown stage, and the calculated thrust values for φ=0.8, φ=1.0, and φ=1.2 were 248.28 N, 264.5 N, and 270.83 N, respectively.

A high-order simulation method for compressible multiphase flows with condensed-phase explosive detonation in underwater explosions

This study introduces an efficient method designed for the simulation of compressible multiphase flows associated with explosive detonation, primarily in the context of underwater explosions. The proposed approach integrates three core components: the compressible Euler equations, the level-set equation, and the program burn model. Spatial terms of the compressible Euler equations undergo discretization using a fifth-order accuracy weighted essentially non-oscillation reconstruction, while the third-order total variation diminishing Runge–Kutta scheme manages the temporal terms. The level-set method ensures accurate tracking of the multiphase interface. To detail the transition from solid, non-reactive explosives to gaseous detonation products in the condensed charge's detonation reaction zone, the program burn model based on Zeldovich, von Neumann, Doering theory. The efficacy and accuracy of the incorporated program burn model and the multiphase interface capture method are employed through four benchmark tests, exhibiting excellent agreement with previously published data from alternative numerical methods or commercial software. In conclusion, applying the proposed method to four distinct engineering scenarios facilitates a comprehensive understanding of the inherent dynamics associated with detonation and shock wave generation and propagation.

Numerical study on the reinitiation mechanism of detonation propagating through double slits in a planar channel

In this study, numerical simulations were performed to investigate the reinitiation of diffracted detonation waves through a double-slit-plate. A planar detonation wave was set to propagate through a channel of a height of 50 mm filled with the stoichiometric mixture of hydrogen and oxygen at 20 kPa. Several slit-plates with different slit widths and slit spacing were considered to explore the effects of slit geometry on reinitiation and its underlying mechanisms. For this, two-dimensional multi-species reactive Navier–Stokes equations were solved using a finite volume solver. The results revealed that upon diffraction, the detonation waves become decoupled and subsequently exhibit one of three distinct phenomena depending on the specific slit geometry. These phenomena include reinitiation by shock–shock interaction (RSSI), reinitiation by shock-wall interaction (RSWI), and complete suppression. It was found that a residual transverse wave is crucial in generating a detonation kernel. In cases where this residual transverse wave is absent, the detonation kernel fails to develop. As a result, only complete suppression of the detonation wave was observed. The narrow slit widths effectively suppress residual transverse waves through the steep expansion that occurs as the detonation front passes through the slit. Moreover, larger slit spacing resulted in further expansion of the shock front before the collision, due to the increased time delay for the shock waves to intersect. As a result, it was found that a larger slit spacing is unfavorable for the formation of a detonation kernel. Yet, in this regard, it is important to note that the onset of RSSI was not guaranteed even with a detonation kernel. Rather, the onset of RSSI was highly dependent on the curvature of the main detonation trajectory. RSSI was inhibited in cases where the forward propagating detonation wave experienced significant expansion due to the large curvature of the main detonation wave trajectory. Smaller slit spacing was found to be particularly unfavorable for RSSI as they exhibit more divergent curves. Overall, this study illustrates that the reinitiation mechanisms of detonation show two different pathways in the transition to detonation from decoupled shock waves and reaction fronts upon diffraction propagating through double slit configurations, and enhances understanding of RSSI by providing insights into the complex interplay between slit geometry, detonation kernel formation, and curvature of detonation wave based on highly-resolved numerical simulations using detailed chemistry. The findings from this study have implications towards the design and optimization of systems involving detonation propagation and suppression.Novelty and significanceThis study focuses on the reinitiation mechanism of detonation propagating through double slits in a planar channel. Specifically, this numerical study aims to understand the critical behaviors that occur when the slit width and the cell width of the detonation are comparable, based on the previously reported experiment. Reinitiation by shock–shock interaction which had previously been limited in understanding was explained in detail and the effects of slit geometry were examined. It is worth noting that there is a lack of in-depth explanations in the literature regarding the double slit configuration with various dimensions of slit-plates. Moreover, this investigation deals with smaller scales of slit width compared to the well-known critical length scale of a planar channel which is about ten times of cell width. As a result, the findings of this study offer further insights for optimizing the design of detonation arrestors.

Experimental study on detonation characteristics of liquid kerosene/air rotating detonation engine

Thermal experiments were conducted to investigate the characteristics of rotating detonation waves in a Liquid Kerosene/Air Rotating Detonation Engine featuring gas-liquid two-phase non-premixed injection. The annular combustion chamber for the rotating detonation had inner and outer diameters of 206 mm and 144 mm, respectively. To mitigate pressure back-propagation of detonation waves, a 3 mm high annular gap structure was employed. The fuel injection system utilized an integrated structure for fuel atomization and mixing, which was designed by our research group based on high-speed shear flow and fuel injection principles. The experiment successfully initiated and sustained a single-wave mode rotating detonation wave with tangentially arranged kerosene/air pre-detonators. The frequency of detonation wave propagation ranged from 2.4 kHz to 2.5 kHz, with a detonation wave velocity of up to 1600 m/s. The initiation delay time of the detonation wave varied between 1600 ms and 400 ms. Within the experimental conditions, as the equivalence ratio increased, the detonation wave velocity increased while the stable establishment time of the detonation wave decreased. However, the overall stability of the detonation wave exhibited a decreasing trend. Additionally, a long-term test of the kerosene/air rotating detonation engine was conducted for 4 s, confirming the engine's ability to operate continuously over an extended period. The frequency of the rotating detonation wave obtained during the long-term test differed by only 0.2 % from the results of the short-term experiments, validating the accuracy and universality of the conclusions drawn from the short-term experiments.

Experimental Study on Combustion Efficiency and Pressure Gain Characteristic of RDC with Guide Vanes

ABSTRACT The influence of guide vanes on the combustion efficiency and pressure gain characteristic of rotating detonation combustor was studied. In this experiment, aviation kerosene (RP-3) was used as fuel and hot air was used as oxidant under the condition of maintaining a certain air flow of 1.5 kg/s. The Temperature rise method was used and the combustion products were analyzed by the flue gas analyzer to calculate the combustion efficiency. Pressure gain characteristic of the rotating detonation combustor was calculated by the mass flow function method (MFFM). The detonation was successfully initiated and operated stably in two rotating detonation combustor configurations without guide vanes and with guide vanes installed. Without the guide vanes, the equivalent ratios for reliable operation of the rotating detonation combustor were relatively small, and the mode of detonation wave propagation is mainly two-counter rotating wave mode. Behind the guide vanes were installed, the range of equivalent ratios for reliable operation of the rotating detonation combustor moved to the appropriate chemical equivalent ratio, and the main mode of detonation wave propagation is two-co rotating wave mode. When the guide vanes were installed, the combustion efficiency of the rotating detonation combustor reached the maximum value of 60.29% when the equivalence ratio is 0.78. In both combustor structures, the pressure gain characteristic increased with the increase of equivalence ratio.

On the interaction between a detonation wave and an inert gas plug: A numerical investigation

Employing inert gases to attenuate and obstruct the propagation of detonation waves has proven to be an effective strategy for mitigating potential damage in the realm of industrial safety, which involves complex physical and chemical mechanisms. This study utilizes an in-house solver built on the OpenFOAM platform to examine the interaction between a detonation wave and an inert gas plug of various lengths. The results reveal that as the length of the inert gas plug increases, various detonation states emerge downstream of the gas plug, and an exponential relationship is observed between the detonation re-initiation distance and the gas plug's length. In the process of detonation re-initiation, the non-isentropic process within the viscous boundary layer plays a crucial role in initiating the flames at the upper and lower channel walls. Later, the collision between flames initiates the detonation wave. Additionally, a localized detonation can also be triggered through the interaction between the compression wave and the wall. Notably, the impingements of the detonation wave and the transmitted shock wave induce the mixing and downstream motion of the gas plug. In the presence of the detonation re-initiation, the motion patterns of the left and right interfaces of the gas plug can be categorized into two distinct stages, which are mainly because of the impingement of backpropagation expansion waves and the hindrance of the high pressure generated by the detonation re-initiation, respectively. Also, as the length of the inert gas plug increases, the velocity difference between the two stages gradually decreases.

Enhancing overpressure and velocity of methane detonation by adding sodium chlorate with a view to fracturing shale

Contamination and inefficiency of combustion improver is an unaddressed issue in emerging in-situ methane explosive fracturing. In this work, a cleaner oxidant with higher oxygen content, NaClO3, was employed as an alternative to KMnO4. Explosion experiments on a series of NaClO3 and CH4-O2-air mixtures were conducted in a 500 L pipeline setup, whereby the influences of NaClO3 intrinsic parameters including particle diameter, specific surface area and loading concentration on the enhanced effects were first explored. It is discovered that there is a critical parameter that maximizes the specific surface area of NaClO3 after adsorption and agglomeration, thereby significantly promoting explosion. Two samples closest to it with a diameter of 22.4 and 11.9 μm, corresponding to concentrations of 0.2 and 0.1 g/L, respectively. Furthermore, the influences of equivalence ratios on the enhanced effects of two NaClO3, and the underlying improved mechanisms, were investigated. Results indicate that NaClO3 can provide sufficient O2 to promote the development of flame fronts and thus boost the wall impact and horizontal propagation of detonation waves; meanwhile, an oxygen-rich atmosphere created by decomposition can cause violent explosions in originally fuel-rich mixtures. In methane with a volume fraction of 16% and an equivalence ratio of 1.25, NaClO3 can generate an explosion overpressure of up to 33.197 MPa with a rise rate of 2.221 GPa/s, and a detonation velocity of 1.359 km/s.

Effect of equivalence ratio on rotating detonation combustion with n-heptane sprays

Three-dimensional simulations are conducted for rotating detonative combustion fueled by n-heptane sprays without any fuel pre-vaporization. Parametric studies are performed to study the influences of equivalence ratio on the rotating detonation wave. The decoupled process of the detonation wave with lean equivalence ratio is also been analyzed. It is found that when the global equivalence ratio is lower than 0.6, a stable propagating detonation wave cannot be observed in the combustion chamber. With the gradual increase of the global equivalence ratio, the detonation wave can stably propagate in the combustion chamber after ignition. When the global equivalence ratio is 0.8–1.5, the propagation mode of the detonation wave in the combustion chamber is one-way propagation mode. When the global equivalence ratio gradually increase from 0.8 to 1.5, the formation time of the detonation wave first decreases and then increases with the increase of the equivalence ratio. Besides, the stability of the detonation wave first increases and then decreases with the increase of the equivalence ratio. Moreover, the thrust of the rotating detonation chamber fueled by n-heptane increases gradually with the increase of the equivalence ratio. The specific impulse of the combustion chamber first increases and then decreases with the increase of the equivalence ratio.

Three-dimensional Numerical Simulations of a Liquid RP-2/O[formula omitted] based Rotating Detonation Engine

Rotating detonation engines (RDEs) offer increased thermal efficiencies and continuous thrust in a compact design. While non-premixed RDEs, where fuel and oxidizer are injected into the combustor through separate streams, have been extensively studied through experiments and numerical simulations, practical realizations of this technology mandate the use of the liquid fuels that power propulsion devices today. As a result, the strength and stability of the detonation wave are heavily influenced by not only the injection scheme but also the quality of the fuel mixture prepared for detonation. This mixture is a product of the dispersion and evaporation dynamics of liquid droplets in the presence of propagating detonation waves. To this end, the multiphase RDE system is investigated through high-fidelity simulations of a rocket-type RDE (RDRE) with liquid RP-2 fuel and gaseous oxygen. The Eulerian-Lagrangian compressible flow solver developed here provides detailed insight into the physical mechanisms important in a multiphase environment. A series of simulations are employed to understand both the droplet dynamics and mechanisms that lead to stable multiphase detonations and their resulting detonation structure. The interaction of the oxidizer injector, liquid droplets, and the detonation wave is discussed extensively. The injector dynamics lead to variations in droplet motion, where the injector recovery process enforces recirculation zones. Most importantly, the penetration of the injected droplets is crucial in their ability to evaporate; the lack thereof can quench detonation and result in a chaotic, deflagration-like mode. The injection scheme is crucial in the dispersion and evaporation of liquid droplets and the formation of detonable mixtures, perhaps more so than in gas-phase systems. The simulations provide detailed insight into the design of liquid-fueled RDE systems.

Experimental study on the influence of cracked kerosene gas temperature on the propagation characteristics of rotating detonation waves

The product of kerosene pre-combustion pyrolysis is typically used as the fuel for rotating detonation, and pure air at an ambient temperature is used as the oxidizer. The temperature of cracked kerosene gas (CKG) is determined by changing the supply conditions of the pre-combustion chamber. Therefore, the influence of the CKG temperature on the detonation range and rotating detonation wave (RDW) propagation was determined in this study. The experimental results show that the initiation delay time decreases with increasing CKG temperature. The temperature of CKG increased from 633 to 980 K, and two modes of RDW propagation appeared: the single rotating detonation wave (SRDW) and intermittent single rotating detonation wave (ISRDW) modes. In the temperature range of each propagation mode, the RDW velocity increased with the CKG temperature. Moreover, the average pressure of RDW propagation decreased with increasing CKG temperature. The stability of RDW propagation was reduced mainly because the propagation mode was changed to ISRDW. Thus, increasing the CKG temperature widens the range of CKG and air initiation. Moreover, the equivalent ratio interval of RDW propagation in the SRDW mode increases from low to high with an increase in the CKG temperature.

Wave mode analysis of a turbine guide vane-integrated rotating detonation combustor based on instantaneous frequency identification

Owing to the pressure gain combustion characteristics, the gas turbine can enhance the system thermodynamic cycle efficiency by integrating a rotating detonation combustor (RDC). In this study, an experimental model of a hydrogen/air RDC with a variant installation of turbine guide vanes (TGVs) was developed. A mathematical model was proposed to identify the rotating detonation wave (RDW) propagation direction. The accuracy of the calculated RDW instantaneous velocity was improved, and the range of velocity fluctuations narrowed from 200 to 1700 m s−1 to 800–1600 m s−1. The impact of TGV installation on the rotating detonation characteristics was investigated. Both the RDW frequency and static pressure increased by installing the TGV at the combustor outlet. The propagation direction of the initial detonation wave induced the RDW to propagate along the same direction. TGV installation reduced the discrepancy in the RDW velocity between two opposite directions as well as the propagation direction changing frequency, while the inverse TGV installation achieved better optimization. The high-frequency pressure oscillations attenuated at the downstream of the TGV, and the amplitude varied depending on the TGV installation options. The static pressure decreased by 14%–16% in both TGV installation options when the combustion flow travelled through the TGV.

Operation and Power Generation of a Disk-Shaped Pressure Gain Combustor

The objective of this experimental study is to evaluate the power generation capability of an ethylene–air disk-shaped pressure gain combustor (DPGC). The main content of this paper focuses on discussing the DPGC testing results, consisting of detonation wave dynamics, power generation, and accompanying combustion instabilities. The experiments can be grouped into two stages. In the first stage, the DPGC was tested under atmospheric back condition. Continuous detonation wave dynamics were evaluated among various testing conditions. Evolution of the detonation wave velocity with respect to changes in the equivalence ratio has been discussed. In the second stage of the experiments, the DPGC was tested with a turbocharger installed. Shaft power extracted by the turbocharger turbine from the DPGC exhaust was used as a metric for evaluating the DPGC power output. During the operation of the DPGC and turbocharger, low- and intermediate-frequency combustion instabilities were observed, which coexisted with the high-frequency component associated with the circumferentially propagating detonation wave. The experimental results suggest that the DPGC shows superiority in compactness relative to conventional combustion power systems. However, more improvements need to be made with regard to overall thermal efficiency in order to achieve the benefits from detonation combustion.

Experimental study on tesla valve and bypass manifold to suppress feedback of rotating detonation engine fuel by kerosene

In this paper, the effects of the Tesla valve intake structure with or without bypass manifold on suppressing pressure feedback and combustion product backflow in rotating detonation engine fueled by kerosene and enriched air with 29% oxygen content are investigated, with the configuration of convergent–divergent intake without bypass manifold being used for comparison. The working range, detonation wave propagation characteristics, and propulsion performance for the three configurations are evaluated. It is found that the Tesla valve intake structure can effectively improve the suppression of pressure feedback and combustion product backflow through the diversion function of the Tesla valve bypass channel and that the addition of the bypass manifold further improves the suppression of pressure feedback. The Tesla valve intake with bypass manifold configuration has the best ability to suppress pressure feedback, with a minimum value of pressure feedback percentage of about 6.5% and a minimum value of air plenum pressure fluctuation percentage of about 6.7%. By comparison, the minimum value of pressure feedback percentage of the convergent–divergent intake without bypass manifold configuration is about 29.8%, and its minimum value of pressure feedback percentage is about 7.8%. The Tesla valve intake without bypass manifold configuration is most effective in suppressing combustion product backflow, with the effective inlet area ratio of about 95.7%. Under the same conditions, the minimum effective inlet area ratio of the convergent–divergent intake without bypass manifold configuration is about 90.2%. Ultimately, optimizing the engine structure leads to a broader working range and higher propulsion performance. The Tesla valve intake structure broadens the working range by suppressing the generation of the longitudinal pulsed detonation mode. When the bypass manifold is incorporated, some combustible reactants directly enter the rear of the combustion chamber from the head of the chamber, and the working range is reduced. Compared with the convergent–divergent intake without bypass manifold configuration, the working range of the Tesla valve intake with bypass manifold configuration is widened by 383.3%, and that of the without bypass manifold configuration by 700%. Both the Tesla valve intake and bypass manifold increase the strength of detonation waves and improve propulsion performance. The Tesla valve intake with bypass manifold configuration has the highest specific thrust, at about 90.1 N s3/(kg·m). This is increased by an average of 10% compared with the Tesla valve intake without bypass manifold configuration, and by an average of 30.1% compared with the convergent–divergent intake configuration.

Numerical Investigation into the Propagation of Detonation Waves in Inhomogeneous Gas Suspensions of a Monofuel in Abruptly Expanding Tubes

Numerical Investigation into the Propagation of Detonation Waves in Inhomogeneous Gas Suspensions of a Monofuel in Abruptly Expanding Tubes

Detonation stabilization in supersonic expanding channel with velocity gradients

The present work aims at exploring the stabilization mechanism of detonation propagating in a supersonic expanding channel with inflow velocity gradients. To achieve this, two-dimensional numerical simulations of a stoichiometric hydrogen–oxygen mixture are performed by solving the Navier–Stokes equations with a one-step two-species reaction model. A hybrid sixth-order weighted essentially non-oscillatory centered difference scheme is utilized to solve the governing equations. The results show that the detonation wave reaches a dynamic stabilization in a supersonic expanding channel affected by the inflow velocity gradients. By contrast, the detonation wave fails to self-sustain propagation in the channel with uniform inlet velocity for the same average velocity, highlighting the significant role of inlet velocity gradients in controlling the propagation and attenuation of detonation waves in confined channels. The mechanism of the dynamic detonation stabilization with the inflow velocity gradients is related to the compression of the flow field by large-scale unburned jets and the interactions of transverse waves and shear layers, which are conducive to improving the pressure and combustion rate of the unburned gases behind the detonation wave. Additionally, to a certain extent, the larger the inflow velocity gradient, the easier it is for the detonation wave to achieve dynamic stabilization at a certain position in the expanding channel.

Numerical Analysis on Detonation Wave and Combustion Efficiency of Pulse Detonation Combustor With U-Shape Combustor

Abstract The research work is carried out for deflagration and detonation combustion processes at different equivalence ratios of hydrogen–air mixtures in a pulse detonation combustor (PDC). Furthermore, the U-shape channel curvature radius and thickness effect on detonation wave propagation are also investigated. This numerical simulation has been done using a SIMPLE algorithm with the finite volume discretization method and laminar finite rate chemistry for volumetric reaction in the Ansys Fluent platform. The numerical result shows that the U-bend radius of R = 3.5 cm can enhance the faster deflagration-to-detonation transition. So far, the fully developed detonation wave was found near the curvature area of the detonation tube having a width of W = 8 cm. This enhanced detonation wave velocity reaches 2775 m/s, which is higher than the C-J detonation velocity. Furthermore, the entropy generation has been analyzed in two modes of the combustion process. The entropy generation number of 0.76 and 0.7 is obtained from the deflagration and detonation combustion processes. However, the entropy production rate is less in the detonation combustion process, but thermal entropy generation is more in the deflagration combustion process with a magnitude of 3.5 kJ/kg K for an equivalence ratio of φ = 1.5. A combustion efficiency of 78% is found in the detonation combustion process, which is comparatively higher than the deflagration process.

Formation and Evolution of the Numerical Air-Breathing Rotating Detonation Fueled by C12H23

ABSTRACT Conducting an in-depth study of the characteristics of a two-phase rotating detonation combustor is crucial for developing a new type of air-breathing engine that can be used for wide-range flight. This study established the first full-process air-breathing two-phase rotating detonation numerical combustor, based on published experimental data, using the Euler-Lagrangian method to simulate the complete process of fuel injection, breaking, evaporation, blending, and combustion. The simulation model analyzed the cold flow and the combustion flow field after detonation ignition, providing insight into the interaction mechanism between the two-phase detonation wave and fuel. The simulation results showed that the secondary heat release after the detonation wave was caused by the secondary combustion of unburned droplets. The working frequency of the detonation combustor was found to be 2301 Hz, and the propagation speed was 1228.89 m/s. Compared to the experiment, the simulation showed a deviation of approximately 19.5% in terms of frequency and detonation wave propagation velocity. When the Sauter-mean diameter of the droplets D 32 was around 25 μm, the combustor was able to operate stably. The thrust generated by the engine was approximately 1009 N, and the fuel-specific impulse was about 1767.5 s. These findings have significant theoretical value in designing a two-phase air-breathing rotating detonation combustor and engine.