Fluid Modeling vs. Pollution

This article reviews how computational fluid dynamics (CFD) analysis provides an enhanced understanding of a low-emission combustion system. When AlliedSignal Engines in Phoenix wanted its ASE40 industrial gas turbine to meet tough new standards for nitrogen oxide emissions, the company decided to try a design that injected water into the combustion zone so the system would burn cooler. AlliedSignal combined full-scale engine tests and computer models to study the effect of water injection on the ASE40. CFD provided detailed flow field information not available from engine tests. This information allowed engineers to verify the effectiveness of the numerous design changes made in axial air swirlers, mixing jets, and cooling flows. Work is also in progress on a dual-fuel system with water injection, using the same gas/water manifold and combustor. Oil fuel will be introduced through the original water circuit, with water being introduced into the gas side. This system will be distributed for the European market by AlliedSignal’s partner, Motoren-und Turbinen-Union (MTU) of Friedrichshafen, Germany.