Effects of Debris Entrainment and Multi-Phase Flow on Plug Loading in an MX Trench.
Abstract
The 1 - 1/2-D version of the multi-phase DICE code was used to analyze the flow of hot air and wall debris in covered MX trenches after an on-line burst. In DICE, debris particles are coupled to the air flow by thermal and drag mechanisms. The objective was to examine the effects of major uncertainties in the timing and magnitude of wall removal and debris entrainment upon the pressure and impulse loading on a rigid plug in the trench. The contributions to impulse due both to pressure loading and the momentum of the debris mass were considered. Transfer of momentum and energy from the hot gas flow to the debris attenuates pressures and velocities. In all cases treated, the maximum pressure and impulse calculated on the plug were substantially lower than would be the case if no debris were present (i.e., if the flow in the trench consisted only of hot air). Where debris mass became entrained near the shock (say within 20-50 feet after the shock passes), plug loading was reduced by orders of magnitude. For example, entrainment of the debris from 0.15-in. of wall recession (with entrainment starting 18 feet behind the shock) reduced the maximum pressure on the plug from 6800 to 78 bars and the impulse from 24 to 3 bar-sec (as compared to air-only flow in the trench). Techniques to enhance early entrainment would be useful in reducing the design load on plugs. Debris not entrained until 100 feet or more behind the shock front has a much smaller effect on plug loading.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 15, 1978
- Accession Number
- ADA086218
Entities
People
- Gene E. Carpenter
- Martin Rosenblatt
- Robert P. Bilyeu