Research on pneumatic hammer effect and transient structural response characteristics of natural gas pipeline in gas turbine based on coupled fluid-structure interaction simulations

As a core component of the fuel supply system, the natural gas pipeline of a gas turbine is responsible for the stable delivery of high-pressure gas during start-up and load regulation. With the increasing penetration of renewable energy into power grids, gas turbines are required to operate more frequently under start–stop conditions and rapid load fluctuations. As a result, valve operations in fuel supply pipelines occur more frequently, inducing transient pressure surges that may threaten system safety. The evolution of pneumatic hammer is strongly affected by gas compressibility, valve opening characteristics, and pipeline structural properties. Therefore, a clear understanding of pneumatic hammer propagation and the associated transient structural response under sudden flow variations is essential. In this study, a 300 MW-class F-type heavy-duty gas turbine fuel supply pipeline system is investigated. A fully coupled fluid–structure interaction model is established based on computational fluid dynamics and transient structural dynamics to analyze pressure wave propagation and pipeline structural responses under different valve opening strategies. The results show that, unlike liquid hammer, pneumatic hammer in natural gas pipelines does not exhibit an initial sharp pressure peak but instead features a long-period decay process. The pressure peak typically occurs as the valve approaches the fully open position, followed by multi-cycle oscillations caused by rarefaction waves and reflection interference. Both the valve opening duration and opening pattern significantly influence the pneumatic hammer intensity and structural response. Appropriately extending the valve opening time or optimizing the opening pattern can effectively reduce peak gas pressure and equivalent structural stress, thereby mitigating pipeline vibration. From a phase-response perspective, pipeline stress is nearly in phase with the pressure wave, whereas the pipe supports exhibit a time lag of approximately 0.2 s accompanied by dynamic amplification. High stress is localized at connection edges, while the overall structural stress remains below the allowable material limit, indicating good system safety. This study provides theoretical guidance and engineering references for valve control optimization, pipeline support design, and the safe operation of gas turbine natural gas supply systems.