Presentation on theme: "The Nature of the Blast Efficiency of explosion Kind and shape of blasts Blast effects, range & damage Thermal effects Radiation effects The."— Presentation transcript:
The Nature of the Blast Efficiency of explosion Kind and shape of blasts Blast effects, range & damage Thermal effects Radiation effects The results of the weapons test programs Blast—40-60% of total energy Thermal radiation—30-50% of total energy Ionizing radiation—5% of total energy Residual radiation (fallout)—5-10% of total energy
Classifications of blasts Surface Blast: fireball in touch with surface vaporization of surface structures through blast and firestorm, immediate radioactive fallout High Altitude Air Blast: fireball > 100,000 ft (>3000m) interrupts satellite based communication through electromagnetic pulse (EMP) Low Altitude Air Blast: fireball < 100,000 ft (without touching ground) generates shock waves, pressure difference artificial for large areal damage, sea battle Subsurface Blast: Underwater burst generates surge
Surface Blast – the fireball Central temperature: ~10,000,000 K Immediate vaporization of material! Central pressure:~33000 atm Radiation release & absorption in surrounding matter generates red-glow intense luminosity. Expansion of fireball through internal pressure Fireball rises like hot air balloon Stokes August 1957 1500 Foot Balloon 19 kt
Fireball expansion Pressure evolution within the fireball: temperature pressure Sedov Taylor approximation (valid of first 0.1s) allowed Russians to estimate the power of the Trinity bomb from the expansion time conditions t r 0.1 ms24 m 0.4 ms42 m 0.7 ms52 m 0.9 ms60 m
Expansion speed Initial expansion speed v (T≈1,000,000 K) c s is the speed of sound in the vaporized gas is the specific heat ratio of the gas R is the gas constant: 287 [J/kg K]; T is temperature [K] Cool-down to T≈3,000 after 15 ms due to radiation losses Ideal gas Fully ionized plasma
The shock front development After ~10 second the fireball expands with constant rate of ~300 ft/s After ~ 1minute fireball has cooled and radiation emission ceases!
General Features – the mushroom the emergence of the mushroom shape Absorption of cool air triggers fast toroidal circulation of hot gases and causes upward motion forming the stem and mushroom. Condensation of water changes red brownish color of cloud towards white! Strong upward wind Drags dirt and debris Into the cloud mixing with radioactive material Cloud rises in height with ~ 440 ft/s
Cloud Altitude Maximum altitude for cloud rise is reached after ~ 4min. RATE OF RISE OF THE RADIOACTIVE CLOUD FROM a I-MEGATON AIRBURST Height Time Rate of Rise (miles) (min) (mph) 2.0 0.3 330 3.0 40.7 270 4.0 61.1 220 5.0 102.5 140 6.0 123.8 27 Cloud height & cloud radius depend on the magnitude of the explosion, increase of both radius & height scales with explosion yield.
Chimney effect again! v=wind velocity in m/s g=9.8 m/s 2 earth acceleration H=height of heat column in [m] T o =outside temperature, K T i =inside temperature in K For typical firestorm: H ≈ 10,000 m T i ≈ 1,000,000 K T o ≈ 300 K ➱ v ≈ 288m/s = 647 miles/h Hurricane speeds ~100 miles/h Conventional firestorm ~220 miles/h