Transient Combustion Dynamics.
Abstract
Characteristics of pressure fluctuations due to the instability of the shear layer at the sudden expansion step of a dump combustor are being studied experimentally. Results show that the disturbances induced by the step are centered around a characteristic frequency which is a function of the shape of the chamber. The center frequency appear to be independent of either the step height of the free stream velocity within the range of the experimental variables. The step height and the free-stream velocity affect only the amplitude and not the frequency of the disturbance. Closely spaced frequencies around the center frequency lead to a low frequency 'beating' phenomenon which is clearly seen on a oscilloscope. Axisymmetric and two-dimensional chambers have different characteristic center frequencies and beat frequency distributions, This coherent beating appears to be responsible for the low frequency combustion instability in dump combustors. Work is continuing in order to understand the nature of the coherent beating and its influence on the combustor. A feedback control is to be used to destroy the coherence of the critical 'beating' and minimize the effect of combustion instability.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 26, 1984
- Accession Number
- ADA154430
Entities
People
- M. Gerstein
- P. R. Choudhury
Organizations
- University of Southern California