On the transition pattern of the oblique detonation structure

Teng, Honghui; Jiang, Zhang

doi:10.1017/jfm.2012.478

Cited by 151 publications

(68 citation statements)

References 18 publications

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“…For convenience, the coordinate is rotated to the direction along the wedge surface, and simulations are carried out in the region enclosed by the dashed line. Similar to previous numerical studies on oblique detonations (Li, Kailasanath & Oran 1993;Grismer & Powers 1996;Papalexandris 2000;Choi et al 2007;Gui et al 2011;Teng & Jiang 2012;Verreault et al 2013), the present study is also based on the inviscid assumption. In the present study, non-dimensional Euler equations with one-step irreversible Arrhenius kinetic model are used as the governing equations, i.e.…”

Section: Methodsmentioning

confidence: 61%

“…Figueira da Silva & Deshaies (2000) studied the transition distance, and indicated that the smooth transition appeared when the induction time became trivial in total chemical reaction time. Recently, Teng & Jiang (2012) compared results with various chemical and gas dynamic parameters, and demonstrated that the transition type was controlled by the difference of oblique shock and detonation angles.…”

Section: Introductionmentioning

confidence: 99%

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Numerical study on unstable surfaces of oblique detonations

2014

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In this study, the onset of cellular structure on oblique detonation surfaces is investigated numerically using a one-step irreversible Arrhenius reaction kinetic model. Two types of oblique detonations are observed from the simulations. One is weakly unstable characterized by the existence of a planar surface, and the other is strongly unstable characterized by the immediate formation of the cellular structure. It is found that a high degree of overdrive suppresses the formation of cellular structures as confirmed by the results of many previous studies. However, the present investigation demonstrates that cellular structures also appear with degree of overdrive of 2.06 and 2.37, values much higher than ∼1.8 suggested previously in the literature for the critical value defining the instability boundary of oblique detonations. This contradiction could be explained by the use of differently shaped walls, a straight wall used in this study and a custom-designed curved wedge system so as to induce straight oblique detonations in previous studies. Another possible reason could be due to the low and possibly insufficient resolution used in previously published studies. Hence, simulations with different grid sizes are also performed to examine the effect of resolution on the numerical solutions. Using the present results, analysis also shows that although the characteristic lengths of unstable surfaces are different when the incident Mach number changes, these length scales are proportional to tangential velocities. Hence, the interior time determined by the overdrive degree is identified, and its limitation as the instability parameter is discussed.

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Section: Methodsmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Numerical study on unstable surfaces of oblique detonations

2014

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“…Generally there are two kinds of transition structures, the abrupt one and the smooth one. The transition structures have been studied and the criterions on the transition type have been proposed [13][14][15]. However, most of previous researchers studied on the static structures, which are assured by the high incident Mach numbers (Ma).…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on the induction zone structure of the oblique detonation waves

2014

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a b s t r a c tOblique detonation waves are simulated to study the induction zone structures with different incident Ma numbers. Three kinds of shock configurations are observed at the end of the induction zone, which are the k-shaped shock, the X-shaped shock and the Y-shaped shock. The X-shaped and Y-shaped shocks appear when the incident Ma is low, and the Y-shaped shock associated with the complicated unstationary process. The induction zone length reaches the maximum value when the X-shaped shock changes into the Y-shaped shock, which indicates different mechanisms deciding the induction zone. The oblique shock wave dominates the induction zone when the incident Ma is high, while the oblique detonation wave dominates the induction zone when the incident Ma is low.

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“…Specific pulse of traditional engines, such as turbo fan and ramjet, decreases dramatically when the flight Mach rises. To resolve this problem, the concept of supersonic combustion is proposed, including the Scramjet [1] and detonation engines [2]. However, the residence time of supersonic combustion is only a few milliseconds, which has the same time scale as the ignition delay time of hydrocarbon fuels.…”

Section: Introductionmentioning

confidence: 99%

“…The ignition characteristics of fuels are more sensitive to the ignition environment such as temperature, pressure and the composition of airflow. The contaminants of H 2 O and CO 2 can change the thermodynamic properties and the composition of test gas mixtures, which may obviously affect the ignition characteristics of fuels.…”

Section: Introductionmentioning

confidence: 99%

The vitiation effects of water vapor and carbon dioxide on the autoignition characteristics of kerosene

et al. 2014

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In ground tests of hypersonic scramjet, the highenthalpy airstream produced by burning hydrocarbon fuels often contains contaminants of water vapor and carbon dioxide. The contaminants may change the ignition characteristics of fuels between ground tests and real flights. In order to properly assess the influence of the contaminants on ignition characteristics of hydrocarbon fuels, the effect of water vapor and carbon dioxide on the ignition delay times of China RP-3 kerosene was studied behind reflected shock waves in a preheated shock tube. Experiments were conducted over a wider temperature range of 800-1 500 K, at a pressure of 0.3 MPa, equivalence ratios of 0.5 and 1, and oxygen concentration of 20%. Ignition delay times were determined from the onset of the excited radical OH emission together with the pressure profile. Ignition delay times were measured for four cases: (1) clean gas, (2) gas vitiated with 10% and 20% water vapor in mole, (3) gas vitiated with 10% carbon dioxide in mole, and (4) gas vitiated with 10% water vapor and 10% carbon dioxide, 20% water vapor and 10% carbon dioxide in mole. The results show that carbon dioxide produces an inhibiting effect at temperatures below 1 300 K when φ = 0.5, whereas water vapor appears to accelerate the ignition process below a critical temperature of about 1 000 K when φ = 0.5. When both water vapor and carbon dioxide exist together, a minor inhibiting effect is observed at φ = 0.5, while no effect is found at φ = 1.0. The results are also discussed preliminary by considering both the combustion reaction mechanism and the thermophysics properties of the fuel mixtures. The current measurements demonstrate vitiation effects of water vapor and carbon dioxide on the autoignition characteristics of China RP-3 kerosene at air-like O 2 concentration. It is important to account for such effects when data are extrapolated from ground testing to real flight conditions.

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On the transition pattern of the oblique detonation structure

Cited by 151 publications

References 18 publications

Numerical study on unstable surfaces of oblique detonations

Numerical study on unstable surfaces of oblique detonations

Numerical investigation on the induction zone structure of the oblique detonation waves

The vitiation effects of water vapor and carbon dioxide on the autoignition characteristics of kerosene

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