Attenuation of shock waves in a duct. Effects of mounted wedge shapes

When vacuum accidents occur in beam lines in a synchrotron radiation facility, shock waves will be generated with hazard of damaging the experimental apparatus. To protect them from shock waves, acoustic delay lines (ADLs) are installed in the beam lines. In this study, noticing the diverging type, converging type and square type as basic elements of ADLs, we considered three models of single element type (backward slope model, forward slope model, and square model for comparison) and four models of composite type (double backward slope model, double forward slope model, central concave model, and central convex model). Each element consists of wedges, angle of which is 30deg, 45deg, or 60deg. Experiments were carried out using a shock tube with a blast-wave generator. The pressure decay was evaluated by transmissive factor and reflective factor for the incident blast wave. As the results, composite type models showed higher pressure decay than single element types. Above all, the central concave type were best with regard to the transmissive decay. (author)