Session: 04-27 Atomization and Spray Combustion III
Paper Number: 123836
123836 - Advancements in Wall Film Thickness Measurement Under High Pressure and High Temperature Conditions for Gas Turbine Applications
Gas turbines play a pivotal role in various industrial applications, including power generation and aviation. In the face of continued diversification of conventional and sustainable fuels, optimizing gas turbine performance and efficiency over a wide operating range is paramount to meet growing energy demands while minimizing carbon emission. One critical factor affecting stationary gas turbine performance operated with liquid fuels is the formation and behavior of wall films in certain combustor designs/spray configurations, e.g. long mixing ducts under high-pressure, high-temperature conditions. In this study, the high-pressure combustion test rig (HBK-S) at DLR Stuttgart was modified to accommodate a non-reacting, optical spray chamber, where liquid film was generated in a jet-in-crossflow configuration on the surface of a long metal plate. Owing to restricted optical access, high turbulence and high spray particle loading as encountered in this study, quantitative measurement of wall film thickness proved extremely challenging if at all feasible for conventional imaging- or sensor-based techniques. In this paper, we present a novel approach for quantifying wall film thickness from images obtained using a standard laser shadowgraphy setup. This image-processing approach involves programmatically distinguishing wall film from flying-by particles, surfaces and other shadow-inducing objects to achieve reproducible extraction of wall film thickness down to tens of micro meters. This shadowgraphy-based technique was validated in a controlled lab environment against a commercial laser-triangulation-based sensor for determining film thickness, showing high reliability over a wide range of film conditions relevant to gas turbine applications.
Specifically, detailed measurements were carried out at 10 bars with the highspeed air cross-flow maintained at a preheating temperature of up to 500 °C for a variety of liquids and liquid flow rates. Film thicknesses between 50 and 1000 micrometers were observed at these conditions. The measured results revealed a strong correlation between wall film thickness (as well as its development along the metal plate) and liquid properties (Weber number), demonstrating the effectiveness of the measurement technique. The implications of these results on gas turbine combustor design and performance will be addressed in the full paper.
Presenting Author: Zhiyao Yin German Aerospace Center (DLR)
Presenting Author Biography: After obtaining his PhD in Mechanical Engineering at the Ohio State University, Zhiyao Yin joined the department of combustion diagnostics at the German Aerospace Center (DLR) in Stuttgart in 2014. His research centers on the development and application of non-intrusive laser diagnostics in various combustion enviroments utilizing both gaseous and liquid fuels. He is also actively engaged in developing tools and methods to analyze diverse experimental data.
Authors:
Zhiyao Yin German Aerospace Center (DLR)Oliver Lammel German Aerospace Center (DLR)
Rainer Lückerath German Aerospace Center (DLR)
Holger Ax German Aerospace Center (DLR)
Dennis Poulios German Aerospace Center (DLR)
Advancements in Wall Film Thickness Measurement Under High Pressure and High Temperature Conditions for Gas Turbine Applications
Paper Type
Technical Paper Publication