Assessment of the consequences of the explosion of gas-air and fuel-air mixtures in detonation mode

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Assessment of the consequences of the explosion of gas-air and fuel-air mixtures in detonation mode

The method of calculation

As a result of the explosion of fuel assemblies or hot water, zones are formed: a blasting action, a fireball, a shock wave, and thermal damage. Each of the zones is characterized by a radius, values of excess pressure and thermal radiation.

1. Zone of blasting (shattering) action.

The radius of the zone of blasting action is determined by the formula:

                                        (6.1)

where M is the mass of the FAM  in the tank, kg; α – factor depending on the storage conditions of the substance (α = 0.5 – for single storage, α = 0.9 for group storage).

Overpressure in the zone is assumed: ΔP_f1=1750 kPa.

2. Zone of the fireball.

Radius of the fireball zone:

                             R_fb=1,7·R₁                                                 (6.2)

3. Zone of action of the shock wave.

This zone is subdivided into 4 subzones by the value of the overpressure at the boundary of zone ΔP_f:

– Subzone of maximal impact (full damage) (ΔP_f=50 kPa);

– Subzone of strong impact (intense damage) (ΔP_f=30 kPa);

– Subzone of midlevel impact (medium damage) (ΔP_f=20 kPa);

– Subzone of low level impact (little damage) (ΔP_f=30 kPa);

Little damage is damage or destruction of roofs and window and door openings. Damage is about 10–15% of the number of buildings (Table 6.1).

Medium damage is the destruction of roofs, windows, partitions, attic floors, upper floors. The damage is 10–15%.

Intense damage is the destruction of load-bearing structures and ceilings. The damage is 50%. Repair is not practical.

Full damage (complete destruction) is the collapse of buildings.

Overpressure at the explosion zone of the explosion products (at the boundary of the fireball), kPa:

.                                   (6.3)

Radius of the boundary of each subzone (full, intense, medium and little damage) can be determined by the formula:

                      (6.4)

where ΔP_f is overpressure at the boundary of zone (50, 30, 20, 10 kPa respectively).

Тable 6.1

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