Nuclear EFP, Gurney equations, kinetic energy discrepancy.
May 17, 2017 14:35:29 GMT
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Post by matterbeam on May 17, 2017 14:35:29 GMT
Hello!
I'm having trouble with a set of equations meant to describe the velocity of an Explosively Formed penetrator, called the Gurney equations. Specifically, the kinetic energy delivered by the explosive charge, and the kinetic energy contained in the EFP, do not add up.
Here is the set-up:
M is the metal plate, or the 'flyer'. C is the explosive charge. N is the tamper or backplate.
In our scenario, M is the projectile, C is the beryllium filler and N is the nuclear warhead of mass about 10 times greater than explosive charge. It allows us to consider the metal plate as infinitely tamped.
Here is the equation:
Vm: Velocity of the metal plate
E: yield energy converted into thermal energy within the filler. (2E)^0.5 is the specific velocity of our device.
M: mass of metal plate
C: mass of filler
Let's use a 1 kiloton yield warhead, massing 100kg. It is configured like a pulse propulsion unit for an Orion driver, delivering about 85% of its energy into heating a beryllium filler. This is 3.56 TJ.
The beryllium masses 10kg.
The metal plate is 10kg.
Using the equation, we get an EFP flying out at 2311km/s.
The problem:
10kg at 2311km/s contains 26TJ of kinetic energy. This is higher than the energy delivered by the warhead.
What could be the problem?
I'm having trouble with a set of equations meant to describe the velocity of an Explosively Formed penetrator, called the Gurney equations. Specifically, the kinetic energy delivered by the explosive charge, and the kinetic energy contained in the EFP, do not add up.
Here is the set-up:
M is the metal plate, or the 'flyer'. C is the explosive charge. N is the tamper or backplate.
In our scenario, M is the projectile, C is the beryllium filler and N is the nuclear warhead of mass about 10 times greater than explosive charge. It allows us to consider the metal plate as infinitely tamped.
Here is the equation:
Vm: Velocity of the metal plate
E: yield energy converted into thermal energy within the filler. (2E)^0.5 is the specific velocity of our device.
M: mass of metal plate
C: mass of filler
Let's use a 1 kiloton yield warhead, massing 100kg. It is configured like a pulse propulsion unit for an Orion driver, delivering about 85% of its energy into heating a beryllium filler. This is 3.56 TJ.
The beryllium masses 10kg.
The metal plate is 10kg.
Using the equation, we get an EFP flying out at 2311km/s.
The problem:
10kg at 2311km/s contains 26TJ of kinetic energy. This is higher than the energy delivered by the warhead.
What could be the problem?
