Accession Number:

ADA413863

Title:

Vented Fixture Modeling

Descriptive Note:

Final rept. Oct 2000-Oct 2001

Corporate Author:

ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD

Personal Author(s):

Report Date:

2003-04-01

Pagination or Media Count:

24.0

Abstract:

Vented fixtures have been used extensively for erosionerosivity investigation for many years. The fixtures can assist in quickly assessing materialspropellants and interactions as well as understanding mechanisms of erosion. In this report, two fixtures are modeled a 37-mm fixture at the U.S. Army Research Laboratory and a 2OO-mm bomb with a l-mm vent hole, located in Canada. Both fixtures erode a nozzle-type insert. The 37-mm fixture is designed to maintain a steady erosion quantity over repeated firings, with relatively small throat cross- sectional area change, which enables some insight into possible mechanisms. Each interior ballistic model required modifications to the interior ballistic code to enable a variable throat exit for the orifice. The Canadian fixture has a 1 -mm vent hole, which has a tendency to enlarge considerably during firing. The dominant erosion mechanism for the Canadian fixture is shown to be melt wipe, while for the 37-mm fixture, it is primarily thermochemical. A redesign of the Canadian fixture to permit a larger exit orifice with a rupture diaphragm would enable thermochemical differences in the propellants to reveal themselves better.

Subject Categories:

  • Ballistics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE