Accession Number : ADA299679

Title :   Numerical Studies of the Ram Accelerator.

Descriptive Note : Final rept. 1 Oct 94-1 Oct 95,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC

Personal Author(s) : Oran, Elaine S. ; Li, Chiping ; Kailasanath, K. ; Boris, Jay P.

PDF Url : ADA299679

Report Date : AUG 1995

Pagination or Media Count : 5

Abstract : Multidimensional, reactive flow simulations were used to provide the pressure information on the projectile for studying the projectile stability and the starting process of the thermally choked ram accelerator. The results showed that the pressure distribution on the front part of the projectile was controlled by a series of reflected shock and expansion waves. These reflected pressure waves were quite stable and virtually steady. A perturbation in the projectile position could result in significant changes in the strength of these shock and expansion waves, but the overall structure of these pressure waves remained the same; On the rear part of projectile, there was a normal shock generated by the thermally choked combustion behind the projectile. This shock maintained the high pressure needed for the projectile acceleration. Unlike the reflected shock on the front part, this shock was transient. A perturbation in projectile position could change both the strength and location of this shock; When the center of projectile mass was in the middle of the projectile, the pressure imbalance created by the perturbation in the position stabilized the projectile if a normal shock was maintained on the rear of projectile by the thermally choked combustion. The pressure imbalance further destabilized the projectile if the normal shock was absent. The study on the starting process showed that the thermally choked combustion and the associated normal shock could be generated by either a pressure pulse, resembling that created by the obturator, or an ignition process on the rear part of projectile, resembling that generated by an on projectile ignitor.

Descriptors :   *ACCELERATION, *PROJECTILES, *NUMERICAL ANALYSIS, *SUPERSONIC COMBUSTION, STABILIZATION, MATHEMATICAL MODELS, SIMULATION, POSITION(LOCATION), STABILITY, REACTION KINETICS, HIGH PRESSURE, REFLECTION, PULSES, SHOCK, PRESSURE, IGNITION, EXPANSION, SUPERSONIC FLOW, PRESSURE DISTRIBUTION, WAVES, MECHANICAL WAVES.

Subject Categories : Ammunition and Explosives
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE