Fluid Dynamic Investigation of Projectile Movement Inside and Outside of the Tube: Numerical-Experimental Assessments and Two Equations of State Comparison

In the current research, 3D simulation of the projectile movement with a diameter of 5.56 mm, has been considered in the barrel with 48.26 cm length. The ideal gas and Abel-Nobel equations of state have been used to solve the gas phase equations. 6DOF solver has been applied to evaluate the projectile- fluid interaction and solved in the coupled manner with continuity, momentum, and energy equations. To reduce the computational time, the projectile initial position was considered 15cm farther from the breech and initial conditions have been obtained from Quickload software and introduced into Fluent. In the experimental study, two light screens and an electrically insulated firing pin have been used to measure the muzzle velocity and projectile exiting time. The relative deviations of the ideal gas and Abel-Nobel equations of state were almost 6.38, 0.76 percent in muzzle velocity, and 1.1, 0.21 percent in residence time computations respectively. The simulated transient velocity of the projectile was also compared with Quickload software results and the close agreement was achieved. Simulation results include temperature, velocity, and pressure contours inside and outside of the barrel during the projectile movement. Temperature-time, pressure-time, displacement-time, and velocity-time curves of projectile were reported using ideal and Abel-Nobel gas equations of states and compared. Also, one of the important results of the simulation was the computation of force exerted on breech which was obtained 5341 N in the present study.