Airblast Attenuation Experiments for the M-X Trench.
Abstract
A series of experiments were performed in the NASA Ames Electric Arc Shock Tube to investigate the propagation of strong shock waves in tubes with transverse ribs. The experiments were designed to measure shock attenuation, end wall reflected pressures, wall drag and flowfield structure to provide a basis for development of computer models for analysis of blast wave propagation in the M-X trench. Shock attenuation was found to be dependent on shock strengths but apparently not strongly dependent on rib design. Entrance region effects appeared to play a strong role in the attenuation; no effect of flow Reynolds number was observed. Laser shadowgrams and interferograms revealed a complex two-dimensional flowfield in the vicinity of the shock with no indication of fully developed pipe flow seven diameters behind the shock. Wall drag measurements exceeded estimates from steady flow theory; a simple wave drag model gave estimates somewhat closer to the measurements. End wall measurements were initially higher than expected from conventional reflection factors presumably due to the nonuniform flowfields. Test data should be applicable to the prototype trench since scale effects were not observed. Two-dimensional flowfield calculations are required to understand the entrance region and shock attenuation process. Design tools developed for prototype assessment should be able to predict the experimental shock wave time of arrival, strength attenuation, and waveforms.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1978
- Accession Number
- ADA085725
Entities
People
- Duane T. Hove
- James E. Craig