Thermomechanical and Magnetohydrodynamic Stability in Shaped-Charge Jets
Abstract
In this study the stability characteristics of shaped-charge jets when exposed to axial electric currents are investigated. The objective of this study is to expand the results of previous analyses by Littlefield to include high levels of electric current, where thermal energy effects must be included. Coupling of the magnetohydrodynamic and thermal characteristics of the flow is accomplished solely through the variation of mechanical, thermal and electrical properties with temperature. Phase change effects are also included. The jet is assumed incompressible and perfectly plastic, with the Levy-von Mises criterion imposed to limit the effective stress. A linear variation of the effective stress with temperature is employed to simulate effects of thermal softening. Electrical resistivity and specific heat are permitted to vary linearly with temperature, coupled with associated jump values that occur as the jet changes phase. Solutions to the appropriate base flow are subjected to small axisymmetric disturbances, and linear perturbation theory is employed to determine the time evolution of these disturbances. Perturbations that grow the fastest in magnitude as time progresses are identified as the most unstable. Results of the analysis indicate that thermal effects can dramatically alter both the base and perturbed flow fields, as well as the growth rate of perturbations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 23, 1993
- Accession Number
- ADA271369
Entities
People
- David L. Littlefield
Organizations
- Southwest Research Institute