Mechanisms of Geometric Parameter Influence on Fast Transient Response Process of the Flow Path Under Inertial Forces  
[PERSON]  
1 Research Institute of Aeron-Engine, Shahe Campus, Beihang University, Beijing 102206, China; [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (J.W. ); [PERSON]ADDRESS] (Z.L.) Shuiting Ding  
2C Civil Aviation University of China, Tianjin 300300, China; [EMAIL_ADDRESS]  
increases friction between the fractured shaft rotor and the stator through axial loads to decelerate the turbine [3]. Additionally, limiting bearings are employed at the compressor end of the rotor to restrict compressor displacement following shaft failure, thereby preventing contact between the compressor rotor and stator [4]. Regardless of the type of passive safety design, the evolution of axial loads following a shaft failure serves as a critical basis for the design. Accurately understanding the evolution of axial loads in the aeroengine after a shaft failure is essential for ensuring the effective functioning of passive safety designs. The axial loads in an aeroengine arise from the pressure differentials at the compressor and turbine inlets and outlets. To mitigate these axial loads during operation, specific designs have been implemented for both the mainstream flow path and the secondary air system, including a twin-rotor configuration for the mainstream flow path and the integration of a relief cavity within the secondary air system. The turbine shaft of the aeroengine is situated within the secondary air system, and a shaft failure directly modifies the geometric configuration of the flow path in the secondary air system, thereby affecting its capacity to balance axial loads and subsequently influencing the evolution of axial loads following a shaft failure [5]. Consequently, an in-depth investigation into the evolution of axial loads in the secondary air system after a shaft failure is crucial for accurately understanding the load dynamics within the aeroengine. The turbine shaft is situated within the secondary air system of the aeroengine. A shaft failure can result in a sudden connection between the internal and external flow paths of the turbine shaft. Due to the pressure differential on both sides of the shaft, this failure introduces a geometric and sudden pressure change boundary in the secondary air system, lasting no longer than 10 ms [5]. During the transient response process of the secondary air system triggered by this sudden change boundary, the axial load within the secondary air system also fluctuates. Components exhibiting transient effects within the secondary air system can further influence its transient response process. According to relevant studies, the components that exhibit transient effects and impact the axial load response primarily include the compressor, turbine disk cavity, and various tubes within the secondary air system [6]. The compressor and turbine disk cavity possess a large projected area and serve as the primary sources of axial load in the secondary air system. The tube components affect the evolution of axial load by influencing the pressure response time within the compressor and turbine disk cavity. Since the various cavities are interconnected by tubes, the key to investigating the evolution of axial load in the secondary air system following a shaft failure lies in exploring the response mechanisms of axial load in the combined flow paths of the cavity and tubes under the sudden change boundary. Existing research has focused on the fast transient response processes of cavities and tubes under sudden change boundaries, yielding significant results. Given that these fast transient response processes primarily occur within complex flow paths under sudden change boundaries, system-level studies have predominantly employed low-dimensional simulations and experiments, while component-level investigations have incorporated three-dimensional simulation methods. After initially proposing low-dimensional simulation methods for cavities and tubes, [PERSON] et al.