Accession Number : ADP009064

Title :   Investigation of Shock Ignition in the Injector Ports of an Annular (Bore Evacuator) Reservoir.

Corporate Author : ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY CLOSE COMBAT ARMAMENTS CENTER

Personal Author(s) : Andrade, Charles A. ; Clauss, Craig W. ; Nagamatsu, Henry T. ; Myrabo, Leik N. ; Messitt, Donald G.

Report Date : SEP 1993

Pagination or Media Count : 20

Abstract : We observe that at first launch of the day, e.g., after the bore evacuator reservoir is removed and resealed, peak reservoir pressures can double. As reported in Ref 1, the measured peak reservoir pressure was about 1.4 MPa (200 poi) for the M256 firing an M831 training projectile, whereas the next firing produced a reservoir peak of about 0. 7 MPa (100 poi) . The explanation proposed in that shock wave ignition occurs in the evacuator ports: fuel rich propellant gas in contact with heated air at the shock contact interface reacts exothermally at the elevated states. Since post-shock states must be established within go of projectile arrival at the ports, the proposed secondary combustion initiates during projectile travel. Air in the reservoir is depleted for subsequent firings, replaced by burnt propellant gas, so that secondary combustion is not likely then and evacuator pressures are predictable by gas dynamical methods. The initiation of lot round secondary combustion in the bore evacuator is the subject of this paper. We first cite further field test data for the 120 mm M256 evacuator. Then, using equilibrium thermochemistry, we perform shock tube analyses that predict lot round ignition in the evacuator ports of the 155 mm M284/185 at high zone. To examine the hypothesis of lst round secondary combustion in the M284/185 evacuator, and obtain measurements of the evacuator charge coefficient, a laboratory investigation by Nagamatsu et. al., Ref 2, was established in which pressure and heat transfer gauges confirm that shock processes occur in the injector ports at the port opening event.

Descriptors :   *COMBUSTION, *BACK PRESSURE, *INTERIOR BALLISTICS, COEFFICIENTS, FIELD TESTS, HEAT TRANSFER, IGNITION, INJECTORS, INTERFACES, MEASUREMENT, OPENINGS, PROJECTILES, PROPELLANTS, RESERVOIRS, SECONDARY, SHOCK TUBES, SHOCK WAVES, TEST AND EVALUATION, THERMOCHEMISTRY, GUN BARRELS.

Subject Categories : Guns
      Quantum Theory and Relativity
      Combustion and Ignition

Distribution Statement : APPROVED FOR PUBLIC RELEASE