Atmospheric Tests of a Variable Combustor Geometry for Reducing Gas Turbine Emissions

Current concern with reduction of pollution from combustion systems resulted in a research program being undertaken to evaluate the potential of variable combustor geometry for reducing emissions from an annular reverse flow gas turbine combustor. A device which simulated a variable baffle in the annulus surrounding the combustor was investigated. Results indicated a good potential for this approach, if the combustor was specially developed for low emissions. The fluid dynamics of this concept were investigated in a model using flow visualization techniques. The hot tests under this program were carried out at atmospheric pressure with full simulation of combustor flows. Significant reductions in emissions and corresponding improvements in combustion efficiency were observed when a baffle was incorporated in the combustion system. It is recognized that all important pressure effects are absent in this work, but a subsequent program is planned to demonstrate the variable geometry concept on an engine over a full range of operation.