Design and Development of a Low Emission Combustor for a Car Gas Turbine

Abstract

The limit levels for pollutant emissions of automotive vehicles of 0.41 g/mile HC, 3.4 g/mile CO and 0.4 g/mile NOx which have been set in the USA up to the 80s may be likely achieved or even bettered by an appropriately designed gas turbine. Premixing of the fuel with air and its prevaporization before entering the combustion zone, in conjunction with continuous adjustment of the fuel/air ratio in this zone to the respective operation condition, seems to be the favorable approach for attaining this goal. Losses in output and economy are not to be expected; but as compared to spark-ignition and diesel engines, competitive fuel economy can only be reached at turbine inlet temperatures higher than presently obtainable, which call for ceramic components. The problems which are to be solved are treated and the results of the evaluation of a variable geometry combustor are presented on the basis of projected pollutant concentrations along a steady-state turbine operating line. The methods of water channel and electrical analogies which have been applied for optimizing the flow-contours in the premixing and combustion zones and their results are discussed, and the various principles investigated for mixture preparation are described in brief. In the second part, the results of experiments and measurements which have been performed, and the influences of the various parameters on pollutant emissions are shown in detail. Finally, results of particle and aromatic compound measurements are reported. The aim of the work is a combustor whose pollutant emissions at a specified maximum permissible pressure loss do not exceed the half-limit levels of the Muskie Standards at any steady-state point of operation.