Mechanisms of Exciting Pressure Oscillations in Ramjet Engines.
Abstract
Analytical work devoted to the global acoustics has been concerned with both linear and nonlinear behavior. Good agreement has been found between calculations of the mode shapes and data taken at the Naval Weapons Center. Numerical calculations are in progress to provide representation of the nonlinear unsteady behavior of a normal shock wave in an inlet diffuser, including viscous effects. Experimental investigations of combustion have been carried out with pressure, spectral line intensity and flow visualization techniques in a burner equipped with a bluff body flameholder. When the combustion is stable, the flow in the flameholder shear layers has many of the characteristics of isothermal shear layers. When unstable combustion occurs, the shear layers are characterized by large vortices which are shed from the flame holder lip. the self excited oscillations appear to result from a coupling between the vortex production mechanism and nonsteady heat addition in the vortex. Both steady and nonsteady processes are being studied. Calculations of the combustion augmentation associated with the interaction of a burning vortex with a wall show a well-defined combustion rise but somewhat less marked than was expected on the basis of experimental observations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 18, 1985
- Accession Number
- ADA173573
Entities
People
- E. E. Zukoski
- F. E. Culick
- Frank E. Marble
Organizations
- California Institute of Technology