Blast Wave Parameters

Response to Blast Waves The effect of blast waves upon eqmp-ment and people is difficult to assess because there is no single blast wave parameter which can fully describe the damage potenti of the... 

The most important blast-wave parameters are peak overpressure and positive impulse i, as shown in Figure 6.11. The deep negative phase and second shock are clearly visible in this figure. 

Both scaling laws apply to reflected blast wave parameters, as well as side-on parameters. (Note that, if charge weight W is used instead of energy E, these parameters have dimensions.)... 

The Hopkinson-Cranz scaling law described earlier applies to scaling of reflected blast wave parameters just as well as it does to side-on waves. That is, all reflected blast data taken under the same atmospheric conditions for the same type of explosive source can be reduced to a common base for comparison and prediction. Sachs law for reflected waves fails close to high explosive blast sources but it does apply beyond about ten charge radii. 

Response to Blast Waves The effect of blast waves upon equipment and people is difficult to assess because there is no single blast wave parameter which can fully describe the damage potential of the blast. Some targets respond more strongly to the peak incident overpressure and others to the impulse (J p dt) of the blast. The blast parameters are usually based on the conservative assumption that the... 

The blast wave attenuates as it propagates outward from the explosion epicenter. Consequently, the values of peak overpressure and impulse decrease with distance while the duration tends to increase. Values for these blast wave parameters can be... 

In addition to peak overpressure, duration, and impulse, other blast wave parameters that may enter into the determination of the blast loads for a structure include ... 

Usually these secondary parameters can be determined from the primary blast wave parameters as discussed below. 

The following loads are computed from free field blast wave parameters. Refer to Chapter 3 for load determination procedure. 

D.R. Richmond et al, "The Relationship between Selected Blast Wave Parameters and the Response of Mammals Exposed to Air Blast", See Ref 8, pp 103-121)... 

Self-Consistent Blast Wave Parameters , Rept ER 3589, Aircraft Armaments Inc, Cockeys-ville, Md (1964) 16) J.M. Dewey, The Air... 

Figure 2 shows the most sensitive effect of the asymmetry of the flowfield on the blast wave parameters. For the noncentered explosion, the positive phase duration is shorter compared with the centered explosion results. The relative situation is ti o.s. ( -20%) < ti s.s. ( -10%) < ti centered. 

EXAMPLE PROBLEMS Example 19 Blast Wave Parameters... 

Effect of Gas Volume Geometry on Blast Wave Parameters 263... 

Characteristic Sachs dimension Re = [P/Pol was taken as a reference scale to neglect the shape of the explosive volume in determining the relative distance R =R/Re. That approach does not imply analysis of blast wave parameters at distances of 1 < P/Py < 3. In experiments described in [1], the radius of the cylinder filled with HAM was Py = 1.7 m. In mixtures with less than 28.7% H2 content the pressure and impulse values became lower. 

Pressure and impulse in the pressure wave determine the danger level resulting from an explosion of hydrogenous combustible mixtures. The main measurable blast wave parameters are presented in the diagram (Fig. 10.1). The blast wave pressure in a gas explosion is a function of the energy release rate and it reaches a maximum at the detonation mode of combustion [1 ]. 

In Fig. 10.2 lines 1 and 2 present the dependence of the incident wave parameters as a function of distance for a gas detonation (1) and a TNT detonation (2). Line 3 and line 4 show the refiected blast wave parameters for gas (3) and TNT (4) detonations. The argument P/Pq refers to the gas explosion only. 

Using measured incident blast wave parameter data, the basic dependence of the TNT pressure equivalent Kp of a gas explosion on the relative blast wave pressure... 

Fig. 10.2 Relative blast wave amplitude versus relative (R/Rq) and scaled (A) distances for a gas detonation (lines 1, 3) and a TNT explosion (lines 2,4). Lines I, 2 - incident blast wave parameters lines 3,...

The diagrams in Fig. 10.7a, b, the gas detonation blast wave parameters are presented in non-dimensional Sachs variables ... 

At R/Rq > 1 the pressure wave parameter fields outside the cloud are of the greatest interest. Curves 1, 2, 3 were obtained for a propane + air stoichiometric mixture. Curves 1 were plotted for the detonation of a mixture of C2H2 + 2.5O2. The least decrease in blast wave parameter values with the distance was recorded for a plane explosion. In the diagram P =f (R/Ro) for the case of a plane explosion, the region A of the quasi-stationary blast wave motion with a constant velocity and intensity, was observed in the length range 5 < i / < 8 [41 3]. Origination of... 

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