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Rarefaction Wave Parameters

The state of measuring parameters of rarefaction waves following the gas blast compression phase is incomplete. Expert assessment of gas explosion effects based only on compression phase parameters is not correct because the profile of a real load on a target located within a dangerous area in the vicinity of the explosive source is distorted. For definition of terms, let us designate amplitudes, impulses and compression/rarefaction phase duration as AP+ and AF, 1+ and /,  [Pg.252]

Performing calculations based on the above equations, it is necessary to remember that time here is in ms, pressure - bar, and impulse - bar ms. [Pg.253]

10 Demolition Loads Resulting from an Hydrogenous Mixture Explosion [Pg.254]

In variables, the ratio of blast wave radius P/cloud radius Rq one has  [Pg.254]

In the Sachs variables, Fig. 10.11 presents the relative blast wave pressure amplitude (at AP+) and the rarefaction wave (at AP ) versus distance R The pressure difference ratio at the blast wave front/rarefaction phase is [Pg.254]


From Figs. 10.17 and 10.18 it follows that because of the significant duration of the rarefaction phase at F < 0.7, the rarefaction wave effect is more dangerous for some targets than the pressure wave effect. Figure 10.19 presents TNT equivalents based on the rarefaction phase pressure Kp (curves 1,2) and the compression phase pressure Kp+ (curves 3, 4) at various distances from the blast epicenter. Within the accuracy of the measured rarefaction wave parameters, the pressure TNT equivalent of the rarefaction phase does not depend on the distance and everywhere is not less than the TNT equivalent for the compression phase. [Pg.258]

The peak overpressure developed immediately after a burst is an important parameter for evaluating pressure vessel explosions. At that instant, waves are generated at the edge of the sphere. The wave system consists of a shock, a contact surface, and rarefaction waves. As this wave system is established, pressure at the contact surface drops from the pressure within the sphere to a pressure within the shock wave. [Pg.189]

Gas detonation at reduced initial pressures were studied by Vasil ev et al (Ref 8). They point out the errors in glibly comparing ideal lossless onedimensional computations with measurements made in 3-dimensicnal systems. We quote In an ideal lossless detonation wave, the Chapman-Jouguet plane is identified with the plane of complete chemical and thermodynamic equilibrium. As a rule, in a real detonation wave the Chapman-Jouguet state is assumed to be the gas state behind the front, where the measurable parameters are constant, within the experimental errors. It is assumed that, in the one-dimensional model of the detonation wave in the absence of loss, the conditions in the transient rarefaction wave accompanying the Chapman-Jouguet plane vary very slowly if the... [Pg.237]

If we assume that we observe only one phase boundary when Vq and are specified in the different phases, it is plausible to employ the one-parameter (denoted as ) family of solutions of Fig. 3.1 in the isothermal case and Fig. 3.2 in the nonisothermal case when the initial data are appropriate. In these figures all the intermediate states (vl,v, Vr, etc.) are constants. The abbreviations F.W., B.W., C.D., and P.B. stand for forward wave, backward wave, contact discontinuity, and phase boundary, respectively. The forward and backward waves consist of a shock or a rarefaction wave. In the isothermal case this one-parameter family of solutions was discussed first time in [13]. We take to be Vl - Vq in the isothermal case and Ul - Ug in the nonisothermal case. Then the decay of entropy (the entropy rate) is given by... [Pg.82]

The problem of dynamic strength of a liquid was considered in a number of works, where pulse methods [l-6] were used. The amplitude of maximum tensile stresses achieved in liquid depends, as it shown in [2,3], on the parameters of rarefaction wave (RW) and on the parameters of initial gas-containing of liquid. The fast growth of cavitation nuclei in RW leading to the relaxation of tensile stresses in liquid in a time of order of 10 s [2-4]. Further two ways of the cavitation process development are possible (i) the bubble damped oscillations occur and (ii) the irreversible development of cavitation zone take place [5,6], which leads to the formation of fosuning structure and the liquid fracture into discret particles. The main principle structure peculiarities of process in the second case remain vague. The structure of flows which forms an axial explo-... [Pg.361]

Cavitation development at underwater explosion near a free surface was investigated numerically within the framework of the model (3) in an axisymmetrical statement 5,16]. The initial parameters of the incident of rarefaction wave. were determined by the method of superposition of an imaginary source. The model began to work only in the rarefaction phase. The calculation (Fig. 7) shows that in the zone of developing cavitation the value of k... [Pg.401]

Fig. 7. Explosion of 1 g charge at a depth of 5.3cm, Initial parameters of inhomogeneities R = 0.5 Jim, k = 10 ". Dynamics of bu-bDle in cavitation zone(a) and profile of rarefaction wave(b) for different steepness of front 0,0.1,1 jis. Fig. 7. Explosion of 1 g charge at a depth of 5.3cm, Initial parameters of inhomogeneities R = 0.5 Jim, k = 10 ". Dynamics of bu-bDle in cavitation zone(a) and profile of rarefaction wave(b) for different steepness of front 0,0.1,1 jis.
If the curve, presenting the impedance ratios, is plotted for a series of plates made of different materials inp - W coordinates, then the intersection of this curve with the p= p DW line represents the CJ point (Figure 4.40). At that point, the impedance of the metal plate is equal to the impedance of the detonation products. This means that there is neither rarefaction nor slowing down of the detonation products, i.e., the detonation and the shock wave parameters at the explosive/plate interface are equal to the shock wave parameters. The technique described is known as the impedance match technique. [Pg.129]

Destructive capacity of a shock wave is known to be determined not only by the overpressure at the wave front, but also by the impulse and duration of the compression phase r. . The parameter Xf depends on the motion history of the rarefaction wave during the depressurization of hot water. It is shown that the transient depressurization process consists of three phases. At the be nning, the rarefaction wave propagates into the rin e-phase liqiud medium at a typical sound veloci. The pressure decreases to a certain value Pnunt nd spontaneous evaporation starts. So at the second phase of the process the pressure increases to a constant value that is lower... [Pg.302]

Fig. 10.1 The measurable parameters of blast wave - time of arrival t+ - positive phase duration T - rarefaction wave duration SP ax overpressure wave ampUtude bJ - rarefaction wave amplitude / - compression phase impulse / - rarefaction phase impulse A/ 2 and T2 - secondary pressure rise and its duration... Fig. 10.1 The measurable parameters of blast wave - time of arrival t+ - positive phase duration T - rarefaction wave duration SP ax overpressure wave ampUtude bJ - rarefaction wave amplitude / - compression phase impulse / - rarefaction phase impulse A/ 2 and T2 - secondary pressure rise and its duration...
Figure 10.21 illustrates the change in the Kp value with distance for a reflected blast wave (curve 1) and an incident blast wave (curve 2) for Ef = 46 MJ/kg. Figure 10.22 presents similar relations for the TNT impulse equivalent Kp Comparison between parameters of incident, reflected and rarefaction waves resulting from gas detonations and HE charge explosions shows that the similarity... [Pg.261]

The diagram of wave-front motions behind the membrane in the duct is known and, by analogy with the classical shock tube [43], is presented in Fig. 11.33. If it is assumed that the membrane is removed instantaneously, then we have the classical case of a membrane rupture and a flat topped shock wave generated in the low-pressure section (air at condition 1) ahead of the membrane. A centered rarefaction wave C travels back to the combustion gas at condition 4. The solution of the problem for parameters of the incident and rarefaction waves is known [43]. As a rule, before the membrane rupture, Tj = 74. The air temperature T2 behind the incident wave at condition 2 and expanding the gas temperature behind the rarefaction wave fan at condition 3 are calculated using the following expressions ... [Pg.304]

Look familiar In order to solve for all these parameters, we need an EOS in order to eliminate E and leave us an expression, P = f v). Since we do not have the EOS, we again resort to the Hugoniot. So the rarefaction unloads isentro-pically, and we assume that the isentrope is the same as the values along the Hugoniot. Let us take a look at this process on the P-v plane. To start with. Figure 19.1, a P-x snapshot, shows a square-wave pressure or shock pulse. [Pg.224]

Failure or propagation as a function of diameter, pulse width of initiating shock, wave curvature, confinement, and propagation of detonations along surfaces are all dominated by the heterogeneous initiation mechanism. The Pop plot is the important experimental parameter that correlates with all of these explosive phenomena. The hot spot decomposition reaction dominates not only the build-up to detonation, but also the way in which the detonation propagates when side rarefactions are affecting the fiow. The consequences are important for many practical problems of detonation chemistry and physics. [Pg.223]


See other pages where Rarefaction Wave Parameters is mentioned: [Pg.252]    [Pg.253]    [Pg.255]    [Pg.257]    [Pg.260]    [Pg.252]    [Pg.253]    [Pg.255]    [Pg.257]    [Pg.260]    [Pg.189]    [Pg.133]    [Pg.414]    [Pg.235]    [Pg.269]    [Pg.295]    [Pg.297]    [Pg.298]    [Pg.173]    [Pg.412]    [Pg.211]    [Pg.38]    [Pg.282]    [Pg.32]    [Pg.262]   


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Rarefaction wave

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