16-Inch Gunblast Experiments
NAVAL SURFACE WARFARE CENTER DAHLGREN VA
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This report describes the blast wave from the 16-in. naval gun. The emphasis on this section is on the physics of the blast wave. In the following sections, the blast wave is described in sufficient detail to enable development of mathematical models for the loading and response of ships and equipment and to predict far field noise levels. One of the most interesting of all wave phenomena is the blast wave. The blast wave is discontinuous, nonlinear, and move through the medium at a speed greater than the speed of sound. Unlike sound waves, which all travel at the same speed, the stronger the blast wave, the faster it travels. Blast waves asymptotically approach the speed of sound as they weaken. The blast wave consists of a discontinuous jump in the thermodynamic properties at the wave front. Upon arrival at a point in space, the pressure, density, and temperature jump almost instantaneously to new values and the medium is instantly set in motion in the direction of propagation of the wave. Items in teh path of the blast wave experience both a discontinuous change and unbalance in pressure as the blast diffracts around them and a substantial gust-like load due to the motion of the medium. A structure that may not be sensitive to the pressure load may be quite sensitive to the gust load and vice versa.