Numerical study on initiation of oblique detonations in hydrogen–air mixtures with various equivalence ratios

Zhang, Yining; Gong, Jishuang; Wang, Tao

doi:10.1016/j.ast.2015.11.035

Cited by 40 publications

(15 citation statements)

References 29 publications

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“…In other words, the induction zone length increases either by increasing or decreasing the overall mixture ER. This agrees with the previous study [35] and the effect is attributed to the increase in ignition delay time when the global mixture ER deviates away from stoichiometric condition ER = 1.0.…”

Section: Basic Odw Structure and Resolution Studysupporting

confidence: 93%

“…This numerical methodology has been used previously to investigate the ODW with homogeneous inflow [35,39], i.e., fixed ER. In this study, the inflow ER inhomogeneity is introduced by assuming a lateral linear distribution.…”

Section: Physical and Numerical Modelsmentioning

confidence: 99%

“…Sislian et al [34] described the effects of incomplete fuel/air mixing on two types of ramjets performance characteristics by assuming a Gaussian distribution of equivalence ratio in the combustible mixture flow, and the deflagration distortion is observed clearly. Zhang et al [35] studied the formation of ODW with various ER and found that the initiation length as function of ER displays a classical "V-shaped" curve, similar to the relation between detonation cell size and initiation energy [36]. Iwata et al [37] simulated the shock-induced combustion from a supersonic spherical projectile, illustrating several shock-flame configurations induced by inflow ER inhomogeneity.…”

Section: Introductionmentioning

confidence: 95%

“…Based on the previous studies on how the ER inhomogeneity influences ODW structures [35,37], the emphasis of this work is on how such inhomogeneity in the initiation region changes the characteristic parameters, such as the initiation length and ODW position, under practical operating conditions of ODW engines. Our previous study [39] demonstrates that considering the high flight altitude of ODW engines, the transition from OSW (oblique shock wave) to ODW is achieved by a curved shock, different from the abrupt transition structure studied widely [9].…”

Section: Introductionmentioning

confidence: 99%

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Numerical study of inflow equivalence ratio inhomogeneity on oblique detonation formation in hydrogen–air mixtures

Fang

Teng

et al. 2017

Aerospace Science and Technology

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In this study, numerical simulations using Euler equations with detailed chemistry are performed to investigate the effect of fuel-air composition inhomogeneity on the oblique detonation wave (ODW) initiation in hydrogen-air mixtures. This study aims for a better understanding of oblique detonation wave engine performance under practical operating conditions, among those is the inhomogeneous mixing of fuel and air giving rise to a variation of the equivalence ratio (ER) in the incoming combustible flow. This work focuses primarily on how a variable equivalence ratio in the inflow mixture affects both the formation and characteristic parameters of the oblique detonation wave. In this regard, the present simulation imposes initially a lateral linear distribution of the mixture equivalence ratio within the initiation region. The variation is either from fuel-lean or fuel-rich to the uniform stoichiometric mixture condition above the oblique shock wave. The obtained numerical results illustrate that the reaction surface is distorted in the cases of low mixture equivalence ratio. The so-called "V-shaped" flame is observed but differed from previous results that it is not coupled with any compression or shock wave. Analyzing the temperature and species density evolution also shows that the fuel-lean and fuel-rich inhomogeneity have different effects on the combustion features in the initiation region behind the oblique shock wave. Two characteristic quantities, namely the initiation length and the ODW surface position, are defined to describe quantitatively the effects of mixture equivalence ratio inhomogeneity. The results show that the initiation length is mainly determined by the mixture equivalence ratio in the initiation region. Additional computations are performed by reversing ER distribution, i.e., with the linear variation above the initiation region of uniform stoichiometric condition and results also demonstrate that the ODW position is effectively determined by the ER variation before the ODW, which has in turn only negligible effect on the initiation length.

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Section: Basic Odw Structure and Resolution Studysupporting

confidence: 93%

Section: Physical and Numerical Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Numerical study of inflow equivalence ratio inhomogeneity on oblique detonation formation in hydrogen–air mixtures

Fang

Teng

et al. 2017

Aerospace Science and Technology

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“…Using high-resolution numerical simulations, various formation structures of wedge-induced oblique detonation waves, i.e., the transition from the oblique shock wave (OSW) to the oblique detonation wave (ODW), have been revealed in recent investigations, e.g., References [35][36][37][38][39][40]. Hysteresis phenomenon of the ODW structure related to initial condition and ODW responses subject to inflow non-uniformities and turbulences have also been investigated [41][42][43][44][45]. Fundamentally, there exists two key transition types, namely, the abrupt transition from OSW to ODW where a nonreactive oblique shock, a set of deflagration waves, and the oblique detonation surface, all united on a multi-wave point; and the smooth transition characterized by a smoothly curved shock [35,36,46,47], see Figure 1.…”

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confidence: 99%

The Effect of Chemical Reactivity on the Formation of Gaseous Oblique Detonation Waves

Yan

Teng

et al. 2019

Aerospace

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High-fidelity numerical simulations using a Graphics Processing Unit (GPU)-based solver are performed to investigate oblique detonations induced by a two-dimensional, semi-infinite wedge using an idealized model with the reactive Euler equations coupled with one-step Arrhenius or two-step induction-reaction kinetics. The novelty of this work lies in the analysis of chemical reaction sensitivity (characterized by the activation energy E a and heat release rate constant k R ) on the two types of oblique detonation formation, namely, the abrupt onset with a multi-wave point and a smooth transition with a curved shock. Scenarios with various inflow Mach number regimes M 0 and wedge angles θ are considered. The conditions for these two formation types are described quantitatively by the obtained boundary curves in M 0 -E a and M 0 -k R spaces. At a low M 0 , the critical E a,cr and k R,cr for the transition are essentially independent of the wedge angle. At a high flow Mach number regime with M 0 above approximately 9.0, the boundary curves for the three wedge angles deviate substantially from each other. The overdrive effect induced by the wedge becomes the dominant factor on the transition type. In the limit of large E a , the flow in the vicinity of the initiation region exhibits more complex features. The effects of the features on the unstable oblique detonation surface are discussed.Aerospace 2019, 6, 62 2 of 17 the conditions and interpret the observed flow field regimes in terms of competing reactions and flow-quenching effects.Alternatively, an oblique detonation wave can be induced by a wedge in an incoming reactive flow [20][21][22]. A standing oblique detonation wave attached to the wedge tip presents a more practical configuration for engine operation [23][24][25]. There has been indeed a remarkable progress in understanding the fundamental aspects of oblique detonation waves induced by a semi-infinite, two-dimensional wedge. Analytical solutions such as wave angles and steady structures as the basic foundation were sought in a number of pioneering works using detonation polar analysis by approximating the ODW as an oblique shock wave (OSW) coupled with an instantaneous post-shock heat release [26][27][28][29]. In later studies, it has been demonstrated that the ODW formation structure induced by the wedge is more complex. In many cases, an oblique shock wave first forms upon the flow interaction with the wedge igniting the combustible flow mixture, and subsequently transits into an oblique detonation wave [30]. Due to the strong coupling sensitivity between fluid dynamics and chemical reactions, as well as the inherent unstable nature of detonation waves [31], it remains technically challenging to establish steady oblique detonations in high-speed combustible mixtures for practical propulsion applications, and such success requires fundamental understanding of the initiation structure of oblique detonation waves. To this end, the dynamics of ODW formation has recently drawn significant research attention...

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Energy Output of High‐speed Flowing Two‐phase IPN/Air in the Combustion Chamber

Wan

Wen

Zhang

2022

Propellants Explo Pyrotec

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Fuel-air cloud explosions or detonations are often affected by initial ambient conditions. A two-dimensional (2D) semi-confined model was established to study the effects of the inflowing air temperature and initial temperature of the combustor on the explosion process of isopropyl nitrate (IPN)/air mixture. The results showed that at different initial temperatures (1000-3000 K), the first peak pressure (P 1 ) and second peak pressure (P 2 ) decreased with the increase in initial temperature; the maximum flame temperature (2338-3534 K) increased with the increasing initial temperature; the explosion pressure and temperature had the opposite trends with the initial temperature, indicating that the oxygen content in the combustor had a greater impact on the explosion pressure, while the initial temperature had a more significant effect on the flame temperature. Under different incoming air temperatures (1000-3000 K), the flame temperature (~2700 K) of the two-phase explosion had a small difference at the incoming temperature of � 2500 K, signifying that the airflow temperature (< 3000 K) and the oxygen content in air jointly dominated the flame temperature; the flame temperature was 3100 K at the incoming temperature of 3000 K, which was about 300 K higher than other incoming flow temperatures, indicating that the flame temperature was more sensitive to the incoming air temperature (� 3000 K). At 600 m/s airflow, the explosion parameter curves at the inflow temperatures of 300 K and 600 K were compared, and the critical inflow temperature of the explosion process was also investigated.

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Numerical study on initiation of oblique detonations in hydrogen–air mixtures with various equivalence ratios

Cited by 40 publications

References 29 publications

Numerical study of inflow equivalence ratio inhomogeneity on oblique detonation formation in hydrogen–air mixtures

Numerical study of inflow equivalence ratio inhomogeneity on oblique detonation formation in hydrogen–air mixtures

The Effect of Chemical Reactivity on the Formation of Gaseous Oblique Detonation Waves

Energy Output of High‐speed Flowing Two‐phase IPN/Air in the Combustion Chamber

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