Unsteadiness of the Port Feed and Jet Flows Within a Gas Turbine Combustion System

Abstract

This paper describes an experimental investigation on a gas turbine combustor geometry that is typical of current aerospace applications. The isothermal investigation has concentrated on the flow approaching and passing through a primary port, and the subsequent jet formed by this flow within the flame tube. It is widely accepted that the jet formed by a port in such a geometry is influenced by the mean approach flow conditions. This paper, though, addresses whether the high levels of turbulence and unsteadiness, as is typically found within the approach flow of these systems, can also affect the time dependent jet and flow field generated by the port. Measurements using both hot wire anemometry (HWA) and a three component Laser Doppler Anemometry (LDA) system were therefore used to characterize the flow field. Cross correlation of simultaneous measurements indicated that velocity fluctuations in the feed annulus correlate with fluctuations inside the port and flame tube. The sign and magnitude of the correlations are presented between various feed annulus, port and flame tube spatial locations. The results suggest the time dependent external flow field can influence the flow field within the flame tube and hence, potentially, flame stability, mixing and emissions.