20TH INTERNATIONAL SYMPOSIUM ON BALLISTICS
ORLANDO, FL, 23­27 SEPTEMBER 2002
THE PROBLEM OF TWO FLOW COLLISION ­ A
GENERALIZED EXTENSION TO THE BASIC MODEL
D. Mordehai1 and E. Hircsh1
1Mil. P.O. Box 01055, IDF, ISRAEL
In this work an extension for the model of two colliding flows
is developed. The widths and angles of the outgoing flows are
calculated both numerically and analytically as a function of the
flow's width ratio of the incoming flows. The model results for
various widths ratio are comparable with respect to hydrocode
calculations. Moreover, a basic evaluation of the flow
compressibility is engaged in the model. The model lacks a
good description of the curvature around the small stream and
the stagnation point, with respect to the hydrocode calculation.
INTRODUCTION
The abundance of problems in ballistics related to the collision between two
impinging flows yielded analytical and simulation research of the problem. Most of
the interest has been focused in and near the symmetric geometry due to its relation to
shaped charge jets formation. Several models were developed however to study the
problem of asymmetric flows collision (e.g. [1-12]). Miller and Ceder [13] pointed
out that a general analytic solution for that problem doesn't exist. They also stated that
the results of the numerical study were highly dependent on the specific material
description, namely its EOS.
In this work we suggest a different approach to solve the problems of the
collision between two asymmetric flows when their velocities toward the collision
region V are the same. This problem can be solved avoiding most of the problems
pointed out in [13] and get analytic expressions for the outgoing streams' width and
flow direction.
First the assumptions and the model will be presented. Then we will compare its
predictions with numerical simulation in several examples, using Autodyn 2D.