| POWER AND ENERGY |
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Impact of inlet distortion on the flow characteristics of a heavy-duty gas turbine cylinder pressure |
| SHI Yunjiao, ZHAO Ningbo, ZHENG Hongtao |
| College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China |
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Abstract [Objective] During the operation of a heavy-duty gas turbine, the flow field at the compressor outlet is impacted by the blade wakes and boundary layers. Consequently, the flow field entering the combustor becomes nonuniform, which can negatively impact the performance of the combustion chamber. Unfortunately, the existing design of combustion chambers often ignores the influence of this nonuniform inlet air, which is inconsistent with the actual operating conditions of a gas turbine, May cause poor uniformity of combustion chamber outlet temperature distribution or an increase in pressure loss. Therefore, we must consider the cylinder pressure as a crucial rectification component within the combustion chamber of a heavy-duty gas turbine. We can use the cylinder pressure to effectively address these issues and enhance the overall performance through performance analysis conducted under distortion conditions.[Methods] In this study, we conducted numerical simulations to investigate the flow characteristics of the cylinder pressure under various inlet distortions as well as the parameter response patterns associated with different distortion modes. The realizable k-ε turbulence model was employed, and a SIMPLE pressure-velocity coupling algorithm was applied. Second-order convergence precision was implemented to ensure accurate calculation of all physical quantities. We compared the calculated results with experimental data to validate the reliability of our numerical simulation method. The agreement between the two confirmed the credibility of our approach. We explored radial distortions at different levels of distortion and positions, as well as circumferential distortions under varying degrees of distortion. Our findings indicated that the appropriate range for inlet distortion degrees was between 0.18 and 0.47.[Results] The inlet distortion of the gas turbine combustion induced a more intricate vortex system within the cylinder pressure and altered the airflow separation position in the inlet section. Both the position and shape of the high-speed region with speeds greater than 80 m/s, were affected upon modifying the inlet distortion mode. Circumferential distortion resulted in the expansion of the high-speed area near the gas turbine combustion chamber flame tube, with a distortion degree approximately twice that of the uniform incoming flow and radial distortion. The rectification effect diminished when the inlet was circumferentially distorted, leading to increased pressure loss. The airflow separation position advanced with the upward movement of the peak position of radial distortion velocity, enlarging the high-speed area beneath the combustion chamber. This caused an increase in the total pressure loss, and the peak distortion value progressed along the path. Additionally, the high-speed area on the upper side of the cylinder pressure outlet diminished, nearly disappearing in the presence of high speed on the inner side under inlet conditions. Within the same distortion mode, augmenting the degree of distortion exerted a minimal impact on the vortex structure and flow field distribution characteristics. However, augmenting the degree of distortion exerted a minimal impact and elevated the maximum airflow velocity within the combustion diffuser, resulting in an increased total pressure loss and outlet distortion.[Conclusions] Both the inlet distortion mode and its degree considerably impact the velocity distribution within the combustion diffuser as well as the structure of the vortex structure. In particular, when circumferential distortion occurs at the inlet, the rectification effect of the diffuser deteriorates. Consequently, we must prioritize the design process of the combustion chamber with regard to the structure's capability to withstand circumferential distortion.
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| Keywords
heavy-duty gas turbine
cylinder pressure
inlet distortion
numerical simulation
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Issue Date: 30 November 2023
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2024,
Vol. 64
