Session: Student Poster Competition

Submission Number: 186788

Numerical Study on the Influence of Swirl Intensity on the Effusion Cooling Characteristics Under Lean-Premixed Swirl-Stabilized Flame 

Lean-premixed combustion has been widely adopted in gas turbine combustors due to its advantages in enhancing combustion efficiency and reducing exhaust emissions. However, this combustion mode significantly increases the thermal load on the combustor liner. To address this, effusion cooling, which utilizes numerous small holes to form a protective cooling film, has emerged as a promising technology. While the interaction between effusion cooling jets and swirling mainstream flows has been studied, the influence of reacting swirl flows (swirl-stabilized flames) on cooling performance remains inadequately explored, particularly regarding the role of flame structure modulated by swirl intensity.

This study numerically investigates the influence of swirl intensity on the effusion cooling characteristics in a lean-premixed, swirl-stabilized gas turbine combustor model. A three-dimensional computational model incorporating coupled fluid-solid heat transfer and the Flamelet Generated Manifold (FGM) combustion model is established. The swirl intensity is systematically varied (Swirl Number, SN, from 0 to 1.23) at two equivalence ratios (ϕ = 0.575 and 0.675). The model is validated against experimental data for overall cooling effectiveness.

The results reveal a dual influence mechanism of the swirl-stabilized flame on wall cooling. Firstly, the swirling flow impingement significantly alters the near-wall flow field. With increasing swirl intensity, the impingement point of the swirling jet moves upstream, creating a stagnation zone that entraps cooling air upstream and reduces local cooling air mass flow rates. Secondly, the chemical reaction progress, manifested by the flame structure, critically determines the local thermal environment. At a lower equivalence ratio (ϕ = 0.575), the flame impinging on the wall is not fully reacted, surrounding the impingement zone with a relatively low-temperature unburned mixture. Conversely, at a higher equivalence ratio (ϕ = 0.675), the flame length decreases, and the impingement zone is exposed to high-temperature combustion products, leading to a severe thermal load. This chemical effect interacts with flow impingement, resulting in distinct patterns of cooling effectiveness distribution.

The analysis of cooling effectiveness reveals a non-monotonic relationship with swirl intensity. The cooling performance first deteriorates and then improves as the Swirl Number increases, reaching its minimum at SN = 0.86. The initial degradation (from SN = 0.60 to 0.86) is primarily driven by intensified swirl impingement effects, where stronger normal velocity components disrupt the cooling film formation and enhance local heat transfer. However, at even higher swirl intensities (SN = 1.23), the cooling effectiveness recovers. This is attributed to the shortened flow distance, which results in the flame impinging on the wall earlier and the near-wall mainstream temperature becomes lower.

This work elucidates the coupled thermo-fluid mechanisms governing effusion cooling under reacting swirl conditions and provides insights for the synergistic design of swirl nozzles and cooling systems to optimize combustor liner thermal protection.

Presenting Author: Xiang Lu ShangHai Jiaotong University

Presenting Author Biography: Dr. Xiang Lu is a Ph.D. candidate n the School of Mechanical Engineering at Shanghai Jiao Tong University. His doctoral research focuses on the intricate coupling mechanisms between combustion and heat transfer in gas turbines. Utilizing advanced computational fluid dynamics (CFD) simulations and experimental diagnostics, his work aims to develop innovative cooling strategies and optimize combustion chamber design. He has authored several publications in renowned journals and international conferences in the field of energy and propulsion.

Authors:

Xiang Lu ShangHai Jiaotong University
Lei He Shanghai XuanYuan Power Technology Co., Ltd.
Liping Xiong Shanghai XuanYuan Power Technology Co., Ltd.
Yunlai Xiao Shanghai Jiao Tong University
Bing Ge Shanghai Jiao Tong University