Theoretical Performance Model and Initial Experimentation of a Baffled-Tube Ram Accelerator

Abstract

The baffled-tube ram accelerator is an innovation in hypervelocity launch technology that allows the acceleration of axisymmetric projectiles in the velocity range of 500 to 3000 meters per second. This device has the potential to double the thrust performance of the conventional smooth-bore ram accelerator while reducing its minimum starting velocity. The baffled-tube ram accelerator utilizes a series of internal baffles to suppress the forward surge of a combustion driven shock wave, thus enabling operation in propellants having two to three times the energy release of those used with conventional smooth-bore ram accelerators. An experimental and theoretical investigation of this device is currently on-going at the University of Washington. Operation at velocities between 620 and 1220 meters per second has been demonstrated to date. Theoretical modeling indicates that momentum loss due to baffle interactions is a key factor in the baffled-tube ram accelerator, which reduces its performance. Nevertheless, baffled-tube experiments have demonstrated thrusts 30-100\% greater than that of a smooth-bore ram accelerator operating at the same fill pressure. The design, modeling, and experimental results from a 38-mm-bore, two-meter-long baffled-tube ram accelerator apparatus are presented.