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Fluctuating wall pressure measurements have been made upstream of the corner line in Mach 5 compression ramp interactions generated by unswept and 10-, 20-, 25-, 30-, 40-, and 50-deg swept models. The streamwise ramp angle was 28 deg in all cases. The results show the following: 1) In highly swept interactions the rms distributions of pressure fluctuations as well as the mean distributions are essentially quasiconically symmetric. The rms levels decrease globally with increasing sweep as does the maximum rms generated by the translating separation shock. 2) The length of the intermittent region, over which the separation shock foot translates, decreases with increasing sweep. In a given interaction, the length of the intermittent region grows spanwise. 3) Dominant separation shock frequencies increase from about 0.3-0.5 kHz in unswept flows to about 2-7 kHz in highly swept flows. In a given interaction, shock frequencies decrease spanwise. 4) The higher frequencies are shown to be a direct result of the decrease in the length scale of the separation shock motion.

The U.S. Navy is considering the development of electromagnetic railguns for future ships for naval surface-fire support (NSFS) and other missions. To reach long ranges, muzzle velocities in excess of 2000 m/s with projectile flight mass of 16 kg and above are needed. Relatively high firing rates are desired; typically 6-12 rounds per minute, so substantial power demands will be made on the ship. For an electrically driven ship, as in the DD(X) concepts presently being explored by the Navy, an existing electrical infrastructure would be in place that could be modified to recharge the pulsed power supplies for the railgun. This study focused on the railgun, the pulsed power system needed to drive the gun, the power system needed to restore the energy required to match the firing rate, and special ship interfaces. Railgun concepts and sizing for the NSFS mission were undertaken, and research and development issues of importance for the success of a future system were identified. Recommendations for analytical and experimental studies that should be undertaken to further address these issues are provided.Index Terms-Electromagnetic railgun, fire support, kinetic energy, projectile, pulsed power.

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