Critical conditions for gas detonation in sharply expanding channels

Васильев, А. А.; Григорьев, В. В.

doi:10.1007/bf00794938

Cited by 11 publications

(7 citation statements)

References 7 publications

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“…Only few experiments were devoted to the determination of the constant A (Vasiliev and Grigor'ev 1980, B enedick et al 1986, Desbordes 1990) and it should be noticed that previous comparisons between computed and experimental values of the initiation energy usually exhibits discrepencies of one order of magnitude as shown in the paper of Benedick et al (1986).…”

Section: Discussionmentioning

confidence: 93%

Direct initiation of detonation in cryogenic gaseous H2-O2 mixtures

et al. 1995

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Abstract. Critical conditions for the direct initiation of selfsustained detonation in cryogenic hydrogen-oxygen mixtures are examined experimentally. These initial conditions are expected to depend mainly on four parameters: the equivalence ratio of the mixture, the amount of the initial energy deposition, the initial temperature and pressure of the mixture. These critical conditions are determined by fixing alternatively three of these parameters and varying the fourth one from subcritical to supercritical detonation conditions. Results are presented for initial pressures t:'o and equivalence ratios 9 ranging from 0.3 to 1 bar and from 1 to 2 respectively, for the two initial temperatures To, 123 K and 293 K. These results indicate that for the lowest values of the initial pressure, a decrease of initial temperature may favour the onset of detonation. Whatever the initial conditions, the measured detonation pressures and velocities are in reasonably good agreement with the corresponding Chapman-Jouguet values computed using the idealgas equation of state.

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Section: Discussionmentioning

confidence: 93%

Direct initiation of detonation in cryogenic gaseous H2-O2 mixtures

et al. 1995

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“…The complex three-dimensional and time-dependent structure of the front of these waves propagating in constant cross-section channels shows some order, whose geometrical parameter is the size of the elementary cell of the DW a 0 . Based on this value, it is possible to determine such parameters of detonation as critical conditions of detonation combustion, the critical energy of initiation (Vasil'ev and Grigor'ev, 1980), detonation propagation limits, etc., i.e. to estimate the detonation hazard of gaseous mixture.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of cellular detonation structures of methane mixtures

Trotsyuk

Fomin

Васильев

2015

Journal of Loss Prevention in the Process Industries

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“…The assumption of d =a const for different mixtures is widely used for calculating the main dynamic parameter of a DW [34,35,95]. This assumption, however, may be used only for approximate estimations [96][97][98][99][100]. The associated errors may be considerable, in particular, for fuel-air mixtures and for marginally detonable reactive mixtures.…”

Section: A Critical Diameter Of Dw Diffractionmentioning

confidence: 98%

“…where c x is the aerodynamic drag coefficient of the HVB, w is the relative velocity between the HVB and mixture, d is the HVB midsection diameter (the maximum cross section of HVB in a plane normal to the flight direction), is the effectiveness ratio of spatial initiation, A 2 f; E act =Q; ; 2 is the coefficient from the multipoint initiation model (see, e.g., [30,32,33,96,111,112]). After some straightforward manipulations, the following expression can be obtained:…”

Section: Critical Diameter Of Bullet For Dw Initiationmentioning

confidence: 99%

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Cell Size as the Main Geometric Parameter of a Multifront Detonation Wave

Васильев

2006

Journal of Propulsion and Power

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The concept of the cell size of multifront gaseous detonation proposed about 40 years ago is used widely to estimate other detonation parameters: the critical initiation energy and critical diameters. In this paper the review of all known models for calculation of the cell size as the main detonation parameter is presented. Models were analyzed on their physical basis and basic assumptions. All models were checked also on their correctness to estimate the cell size for different mixtures. The calculated values of cell size were compared with available experimental data. On the basis of such comparison only some models are recommended for engineering calculations in practical applications. The formulas for estimating important detonation parameters with the dimension of length are proposed. Nomenclature A = preexponential factor, sec mol=cm 3 a, b = transverse and longitudinal cell sizes, respectively c 1 , P 1 = sound velocity and pressure in the induction zone D 0 = Chapman-Jouguet detonation wave velocity (chemical equilibrium calculation) D 2 , D ? = velocities of shock wave and transverse wave at collision E = effective activation energy, kcal=mol E 0 = collision energy [f], [o], [in] = concentrations of fuel, oxidant, and inert; mol cm 3 M = Mach number (M D 0 =c 0 , M 2 D 2 =c 0 , M ? D ? =c 0 ) P 0 , c 0= initial pressure and sound speed Q = specific chemical heat release R; r = shock front radii from two neighboring microexplosions at a certain time instant (R 0 r 0 at collision moment) r = coordinate of shock front r 2 , t 2 = shock wave radius and instant of transverse wave collision r , t = shock wave radius and instant when the latest particle crosses the shock front, for the latest particle the ignition delay is over at instant of transverse wave collision T = temperature t = time u = particle velocity in the laboratory frame of reference x = r =b y = =2b = parameter of the model of a strong point explosion = parameter of the model of a detonation wave with instantaneous chemical reaction behind the shock front = adiabatic exponent of initial mixture e = equilibrium adiabatic exponent of detonation products " = E 0 =4 0 D 2 0 b 2 p = transverse wave size at collision moment ij = P i =P j 0 = initial mixture density = = 0 = ignition delay

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Critical conditions for gas detonation in sharply expanding channels

Cited by 11 publications

References 7 publications

Direct initiation of detonation in cryogenic gaseous H2-O2 mixtures

Direct initiation of detonation in cryogenic gaseous H2-O2 mixtures

Numerical study of cellular detonation structures of methane mixtures

Cell Size as the Main Geometric Parameter of a Multifront Detonation Wave

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