In-Situ Measurement of 3-Dimensional Fluid Flow and Temperature in a Geometrically Complex Duct for Characterization of Heavy-Duty Gas Turbine Inlet Air Compressor Bleed Heat Systems

As demands for increased operational flexibility are placed on heavy-duty gas turbines, the usage of inlet air compressor bleed heating devices has been expanded to increase the emissions-compliant operating envelope. To ensure that these devices maintain acceptable flow-field characteristics at the compressor face, a method to accurately determine the flow field characteristics at the compressor face is required. In the past, Computational Fluid Dynamics (CFD) analysis has been used to predict flow field characteristics at the compressor face. As a means by which to make a comparison between analytical predictions and empirically determined characteristics, a scale model direct measurement arrangement was devised and tested. Given the high flow speed and complex geometry in the vicinity of the compressor face, accurate in-situ measurement of the flow profile presents many challenges. The measurement arrangement must provide sufficient data density such that flow-field gradients are fully captured, while simultaneously maintaining a minimum level of obstruction attributable to the sensors. One of the end goals is to ensure that the measured flow is representative of the system in its final configuration. Measurement systems of sufficiently small size to minimally influence the flow, but of sufficiently high accuracy must be employed. Advances in the design and usage of a measurement system to empirically determine the flow field characteristics in the inlet air system of a heavy-duty industrial gas turbine are presented. This system was used to characterize a number of competing inlet air compressor bleed heating systems. The results of this characterization are compared qualitatively and quantitatively, with a specific focus on the technology of the measurement system and measurement techniques.