Engineering topics
Publications and source records attributed to Glenn, L. A..
This was a collaborative effort between Lawrence Livermore National Security, LLC/Lawrence Livermore National Laboratory (LLNL) (formerly the University of California) and Jet Research Center, a wholly owned division of Halliburton Energy Services, Inc. to design and prototype an improved explosive cutter for cutting the support legs of offshore oil and gas platforms.
The problem of a spherical blast in air is solved using the STUN code. For bare charges, the calculations are shown to be in excellent agreement with previous published results. It is demonstrated that, for an unconfined (uncased) chemical explosive, both range and time to effect scale inversely as the cube root of the yield and directly as the cube root of the ambient air density. It is shown that the peak overpressure decays to roughly 1/10 of ambient pressure in a scaled range of roughly 10 m/kg 1/3 at sea level. At a height of 30 km, where the ambient density is a factor of 64 less, the range to the same decay increases to 40 m/kg 1/3 . As a direct result of the scaling a single calculation suffices for all charge sizes and altitudes. Although the close-in results are sensitive to the nature of the explosive source and the equation of state of the air, this sensitivity is shown to virtually disappear at scaled ranges > 0.5 m/kg 1/3 .
The case of an explosion in a tunnel where the blast wave encounters a sudden decrease in cross section is studied with quasi-one-dimensional (1D) and two-dimensional axisymmetric codes (2D) and the results are compared to experimental data. It is found that the numerical results from both codes are in good agreement until the interface at the change in cross section is encountered. Thereafter, however, the peak pressure derived with the codes is found to be significantly higher than the experimental results although the agreement between the 2D result and the experiment improves with increasing distance down the tunnel. Peak pressure and impulse per unit area obtained downstream of the interface with the 1D analysis are found to be substantially higher than with either the experiment or the 2D results. The reason for this is the time delay for the shock reflecting off the (vertical) rigid wall between the inner and outer tunnel radii to interact with the (supersonic) core flow into the decreased cross section. In the 1D case the reflected and transmitted shocks are formed instantaneously across the entire cross section resulting in higher pressure and increased shock speed downstream of the interface.
Water vapor recondensation effect on structure of liquid particle flow into vacuum
Stationary radial source flow of liquid particles into vacuum, discussing boundary value problem equations, parameters effects on flow structure and flow field characteristics