Accession Number : ADA193577

Title :   Investigation of the Hypersonic Flowfield Surrounding a Shaped Charge Jet.

Descriptive Note : Technical rept.,

Corporate Author : ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD

Personal Author(s) : Meyer, Hubert W , Jr

PDF Url : ADA193577

Report Date : Dec 1987

Pagination or Media Count : 192

Abstract : Explosively formed hypervelocity shaped charge jets for the defeat of armored targets have been the subject of a considerable amount of research, but little of this effort has been devoted to studying the aerodynamic forces acting on the jet particles, particularly the interference caused by nearby surfaces. The object here is to develop numerical methods and apply them to this problem. A Godunov inviscid technique is developed, modified to include high temperature thermodynamic properties, and used to obtain the flow field in front of a hemisphere. This solution is used as the initial condition for the computation of the flow field in the annular region between the jet and a surrounding cylindrical tube. Computations for Mach number 4.00 are compared to experimental data in order to validate the numerical technique. The actual shaped charge jet case at a Mach number of 20.45 is then solved. The predictions are compared to the results of an experiment under corresponding conditions. Excellent correlation was obtained between the code prediction and experimental radiographic data, with the predicted shock propagation shock propagation characteristics being within 8% of the data. The computed pressure on the tube wall behind the reflected shock wave was 27% of the measured value, with poor repeatibility in the measurement. Computations indicated the pressure on the side of the jet is 34 atm for a tube diameter of 2.50 jet diameters. This is insufficient to cause observed perturbations in the jet. A hypothesis was proposed to account for the perturbations; it considers the effect of the flow field on a cloud of particles, resulting from the explosive formation process, that surrounds the jet tip.

Descriptors :   *SHAPED CHARGE JETS, AERODYNAMIC FORCES, ARMOR, CLOUDS, CODING, COMPUTATIONS, CYLINDRICAL BODIES, DIAMETERS, EXPERIMENTAL DATA, EXPLOSIVE FORMING, FLOW FIELDS, HIGH TEMPERATURE, HYPERSONIC FLOW, HYPERSONIC VELOCITY, HYPOTHESES, INVISCID FLOW, NUMERICAL METHODS AND PROCEDURES, PARTICLES, PERTURBATIONS, MATHEMATICAL PREDICTION, PRESSURE, RADIOGRAPHY, REFLECTION, SHOCK WAVES, TARGETS, THERMODYNAMIC PROPERTIES, TUBES, WALLS

Subject Categories : Ammunition and Explosives
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE