2013. – 30 p.
This report summarize a computational study of unsteady gun tube flows based on a Large Eddy Simulation (LES) model coupled with a deformation and regeneration technique for handling the motion of the projectile. A generic, and rather simple, gun tube configuration, without rifling and muzzle brake, has been used to demonstrate this approach. In addition to using the deformation and regeneration technique, semiadaptive grid refinement is also used to improve the spatial resolution between the precursor bow shock and the gun tube. From the simulation results some analysis is presented regarding the flow within the gun tube and just outside the muzzle. A precursor shock wave driven by the projectile propagates through the gun tube and ahead of the projectile that acts like a piston. When the precursor shock wave discharges from the open end, the first blast develops, which results in shock-wave diffraction with an associated initiation of a vortex ring and a jet flow. Later, the projectile itself moves out and away from the gun tube and interacts with the diffracting shock system and the jet flow. Meanwhile, the high-pressure high-temperature propellant gas behind the projectile expands out of the shock tube and the second blast develops.Contents:.
Introduction.
Generic gun tube configuration.
Large eddy simulation.
Numerical methods.
Computational set-up.
Results.
Concluding remarks.
References.
