Projectile motion under free surface after perforation of containment filled with two-phase fluid
- Paper number
IAC-10,A6,3,12,x7035
- Author
Prof. Nickolay N. Smirnov, Moscow Lomonosov State University, Russia
- Coauthor
Ms. Maria Smirnova, Moscow Lomonosov State University, Russia
- Coauthor
Mr. Kirill Kondratiev, Faculty of Mechanics and Mathematics Moscow M.V.Lomonosov State University, Russia
- Year
2010
- Abstract
The paper develops a model for evaluating results of high velocity fragment or bullet interaction with thin walled fluid-filled containments. The problem of thin body high speed motion in compressible fluid near free surface was regarded. The resistance and lift forces strongly depend on the depth of body motion under free surface. Due to that reason the response of containment on high velocity perforation depends on amount of fluid. To obtain analytical solution the fluid is assumed occupying infinite semi-space, gravity is neglected as compared with fluid inertia. The solution was obtained for a two-dimensional problem of thin body motion in compressible fluid at a definite depth, constant velocity and inclination angle. The solution allows determining drag and lift forces in the limiting cases. For relatively thin fluid layer above the moving body the resistance force depends on body thickness, inclination and Mach number, while for relatively thick fluid layer the force depends on body length, inclination angle and Mach number. To determine solution for the intermediate cases the equations were integrated numerically for dimensional values of basic variables. Then approximation formulas were developed making it possible to simulate resistance and drag forces being functions of governing parameters. Dynamics of impactor deceleration after wall perforation in fluid filled containment was studied being the function of the depth of motion under the fluid level in case the containment was partially filled with fluid and partially with gas having a distinct fluid-gas interface. The developed models were verified with results of experiments. on decreasing fragment size the slowing down distance also decreases. On slowing down the fragment conversion of its kinetic energy into the internal energy of the surrounding gas (or fluid) takes place. The rapid increase of the density of energy in a small volume inside the containment is similar to that for the local explosion. The energy release gives birth to diverging blast waves inside the containment that reflects from the walls thus producing non-uniform loading. The concentrated energy release causes blast waves of high intensity. Thus the wall being more close to the blast point exercises higher loading. The breakup of the wall causes the pressure drop and the rarefaction waves, which go inside the containment, overtaking the blast wave and lowering down its intensity. Thus the far wall will be much less loaded. The support of Russian Foundation for basic research is gratefully acknowledged (projects 09-01-13505)
- Abstract document
- Manuscript document
(absent)