FLASHBACK PREVENTION IN A HYDROGEN-FUELED REHEAT COMBUSTOR BY WATER INJECTION OPTIMIZED WITH GLOBAL SENSITIVITY ANALYSIS

Pousada, PR and Doan, NAK and Aditya, K and Düsing, M and Ciani, A and Langella, I (2024) FLASHBACK PREVENTION IN A HYDROGEN-FUELED REHEAT COMBUSTOR BY WATER INJECTION OPTIMIZED WITH GLOBAL SENSITIVITY ANALYSIS. In: 69th ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition, GT 2024, 24 June 2024 through 28 June 2024, London.

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Abstract

This paper presents an investigation of the effects of water injection within a simplified version of the Ansaldo GT36 reheat system. The investigation is carried out under realistic operating conditions of 20 atm and using large eddy simulation (LES) coupled with the thickened flame model (TFM) and an adaptive mesh refinement. The water injection conditions are optimized by performing a parametric study based on global sensitivity analysis and a surrogate model based on Gaussian process is employed as a way to reduce computational cost. In particular, the influence on the system performance of four design parameters, namely Sauter mean diameter, water mass flow and the angles of the spray's hollow cone, is tested to achieve an optimized solution. In the 'dry' case, the LES simulations show several flashback events, which are a defining aspect of the considered conditions, and attributed to compressive pressure waves resulting from autoignition in the core flow near the crossover temperature. The use of water injection is found to be effective in suppressing the flashback occurrence. In particular, the global sensitivity analysis shows that the external angle of the spray cone and the mass flow of water are the most important design parameters for flashback prevention. Moreover, NOx was shown to be reduced by about 17 by the use of the water injection at the tested conditions. Once an optimised condition with water injection is found, a recently proposed method to downscale the combustor to lower pressures is applied and tested. Additional LES are performed for this purpose at the 'dry', unstable condition and the 'wet', stable condition. Results show that similar dynamics, respectively unstable and stable, is predicted at 1 atm, suggesting the robustness of the method. This provides avenues for experimentally testing combustion dynamics at simplified conditions which are still representative of high-pressure practical configurations. Copyright © 2024 by ASME.

Item Type:	Conference Paper
Publication:	Proceedings of the ASME Turbo Expo
Publisher:	American Society of Mechanical Engineers (ASME)
Additional Information:	The copyright for this article belongs to the publishers.
Keywords:	Aerodynamics; Combustors; Flow of water; Gas turbines; High pressure effects; Preignition; Reheat cycle; Surface diffusion; Vortex flow; Wind turbines, 'Dry' ; Ansaldo; Condition; Design parameters; Effect of water; Flashback; Global sensitivity analysis; Hydrogen-fuelled; Large-eddy simulations; Reheat combustor, Sensitivity analysis
Department/Centre:	Division of Interdisciplinary Sciences > Computational and Data Sciences
Date Deposited:	06 Nov 2024 17:40
Last Modified:	06 Nov 2024 17:40
URI:	http://eprints.iisc.ac.in/id/eprint/86731

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