Base Drag Reduction Using Angled Injection
Abstract
Drag reduction of cannon launched artillery shells is a potential way to increase their range. Base drag of the shell is directly related to the base pressure that exists on the base region area. A potential method to reduce base drag is to use a solid propellant gas generator in the shell aft end that injects gas into the base region. The mass injected can be distributed through the center of the projectile, near the edge of the projectile or by a combination of these techniques. This study analyzed the effects of central injection or edge injection and the effect on base drag. The injectant, injected at subsonic velocities, was considered to be either air or a mixture of air and hydrogen. The effect of injectant temperature was considered for the air injection case. The air hydrogen mixture was considered to be both non reacting and reacting. A flame sheet combustion model was used for the reacting flow case. Free stream Mach numbers considered were 1.4, 1.8, and 2.2. The effect of spin on base drag was investigated by including a spin term in the axisymmetric flow equations. Results indicate that subsonic base injection can be beneficial in reducing base drag. Use of edge injection gives higher values of base drag reduction than center injection. Use of higher temperature injectant gas also gives larger values of base drag reduction. Small injection amounts of burning gas in the base region appear to be more beneficial than large amounts.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 08, 1987
- Accession Number
- ADA196404
Entities
People
- R. J. Cavalleri