Incorporation of a Variable Discharge Coefficient for the Primary Orifice into the Benet Labs Recoil Analysis Model via Results from Quasi-Steady State Simulations Using Computational Fluid Dynamics
Abstract
The design and analysis of recoil systems for direct fire weapons has been conducted at Benet for the last 25 years. The model developed employs the Bernoulli Equation to establish the relationship between flow rate and back pressure within the internal paths and through the primary orifice of the recoil brake. This displacement varying orifice provides the throttling mechanism needed to generate back pressure which opposes the ballistic driving load and arrests the gun in recoil. An orifice is designed to maintain constant upstream pressure over the complete length of recoil, thus minimizing the load transferred to the gun support and vehicle. The equation which models this type of orifice requires an discharge coefficient (Cd) which 'lumps' all of the flow losses due to contraction and directional change of the fluid stream. This coefficient is constant regardless of fluid properties, flow regimes and geometries. Test data from firing tests and research experiments indicate that this may not be the case. This report presents the details of using an offline CFD analysis to establish the flow response characteristics of a typical recoil brake orifice and a methodology of incorporating these results via a lookup table of Cd values into the lumped parameter recoil analysis model developed at Benet Labs.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2008
- Accession Number
- ADA640099
Entities
People
- Ronald Gast
- Steven Morris
- Timothy Gedney
Organizations
- United States Army Armament Research, Development and Engineering Center