Unveiling Pressure Spikes and Shock Structures in a Concentric Vertical Launch Rocket System

This study presents a detailed computational investigation into the early-stage transient flow behavior of hot-launch missile systems in a concentric vertical tube. Emphasizing the critical milliseconds before thrust build up and missile liftoff, the work captures the formation and evolution of pressure spikes and shock structures through high-resolution, twodimensional axisymmetric simulations using a pressure-based solver with the k-ω SST turbulence model. The simulations focus on the effects of nozzle inlet pressure and shock interactions on the launch tube wall during the initial seconds of the exhaust gas evolution. Three distinct pressure and temperature peaks are identified, with characteristics resembling Friedlander-type waveforms, driven primarily by bow shock impingement and subsequent wave reflections within the annular gap of the launch tube. Furthermore, the study investigates the influence of nozzle inlet pressure on the pressure and temperature distribution along the launch tube wall. It was observed that while the timing of pressure spike occurrences varied with inlet pressure, the magnitude of the maximum peak pressure remained nearly constant. In contrast, higher inlet pressures resulted in more pronounced temperature spikes, which increased in intensity and propagated further downstream along the launch tube wall. This study offers valuable insights into the design and safety assessment of hot-launch vertical missile systems, aiding the optimization of lightweight launch tubes for high-speed deployment.