Experiments with Liquid Propellant Jet Ignition in a Ballistic Compressor.
Abstract
This report describes a series of tests that inaugurated the use of a ballistic compressor-based apparatus for the research of liquid propellant (L2) jet combustion. The apparatus consists of an inline ballistic compressor and LP injector. The rebound of the ballistic compressor piston was arrested, trapping 40 to 55 MPa of 750 to 8500 C argon for ignition of circular jets in a windowed test chamber. The LP jets ignited in less than 2 ms as indicated by a steep rise (ca. 3 MPa/ms) in the chamber pressure. The elevated combustion pressure ruptured a disk above 70 MPa, venting the combustion gas into the compressor's barrel. The rupture of the disk did not always stabilize the combustion pressure; with 3.5-mm jets, we obtained both quasi-steady combustion at about 80 MPa and nonsteady combustion with steep pressure rise-rate (ca. 100 MPaIms) that culminated in peak combustion pressures over 100 MPa. The nonsteady combustion occurred because LP accumulated excessively in the test chamber and burned rapidly once the combustion pressure exceeded 75 MPa. The accumulation impeded the visualization, obscuring the jet before ignition, and burned in a fireball fashion once ignited. Nevertheless, we could determine from film records that the penetration of l-mm and 3.5-mm circular XM46 jets with injection velocities over 200 m/s exceed 5 cm when the combustion pressure is below 80 MPa. Large millimeter size drops were observed burning at 80 MPA, indicating that, even at this pressure, XM46 combustion is subcritical. The operation of the piston arrest mechanism was problematic.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1998
- Accession Number
- ADA342579
Entities
People
- Avi Birk
- Marek Tarczynski
Organizations
- United States Army Research Laboratory