[7; 8] further developed tube simulation techniques to effectively capture the pressure wave propagation process within the tubes [9; 10], which has been validated experimentally [11]. [PERSON] and [PERSON] [12; 13], [PERSON] and [PERSON] [14], and [PERSON] et al. [15] each established low-dimensional simulation models for cavities and applied them in low-dimensional simulations of the secondary air system; these cavity models were validated using the cavity charging and discharging tests conducted by [PERSON] and [PERSON] [16] and [PERSON] et al. [17]. Additionally, [PERSON] et al. [18] investigated the effects of the number and relative positions of cavity inlets and outlets through experiments and three-dimensional simulation methods. In the aforementioned studies, the low-dimensional models for tubes have been validated through practical internal combustion aeroengine tests; however, the establishment and validation of cavity models were conducted under conditions with relatively small inlet and outlet areas. Under these conditions, the fast transient response processes of cavities under sudden change boundaries align with the assumption proposed by [PERSON] and [PERSON] [12] during low-dimensional simulation modeling, which disregards the influence of inlet and outlet areas, specifically that the relationship between the inlet and outlet areas and the cavity volume meets criterion \(A/V_{Vessel}^{\frac{2}{3}}\ll 1\). At this point, the flow rates at the inlets and outlets are relatively small compared to the cavity volume, so fluid inertia forces within the cavity were neglected during the research process. However, the actual flow path structure of the aeroengine secondary air system is complex, and not all cavities can satisfy this assumption. To achieve a more accurate response history of axial loads under sudden change boundaries, it is essential to consider the effects of inertia forces within the cavity. For the response process of cavity-tube combination flow paths under transient boundaries, [PERSON] and [PERSON] [13] focused on a dual-cavity single-tube oscillating flow path and established a low-dimensional model to analyze the influence of tube length on the response process of the cavity-tube combination flow path. [PERSON] et al. [19], in exploring the influence of cavities on the propagation of explosive shock waves, employed a combination of experimental and three-dimensional simulation methods to investigate how cavity shape affects shock wave propagation. Although these studies have clarified the influence of geometric parameters, including tube length and cavity shape, on pressure changes within cavities during flow path response processes, the underlying mechanisms by which these parameters affect flow path responses have yet to be thoroughly investigated. In summary, while existing research has made certain advancements in related fields, key issues remain unresolved. On the one hand, the mechanisms by which inertial forces within cavities affect axial loads are not yet clear; on the other hand, there is a lack of systematic research on the mechanisms by which geometric parameters of flow path features influence axial loads during flow path responses under sudden change boundaries. To address the aforementioned issues, this study utilizes a validated three-dimensional simulation method, focusing on a single-cavity flow path. By comparing changes in the Cavity Inertial Force Dominant Zone (CIDZ), the study investigates the mechanisms through which inertial forces influence axial loads during fast transient responses under sudden change boundaries as the parameter \(A/V_{Vessel}^{\frac{2}{3}}\) increases from the order of 0.01 to 0.1. Building on this, the research examines the cavity within the cavity-tube flow path, analyzing how characteristic geometric parameters affect axial loads during fast transient responses under sudden change boundaries under condition \(A/V_{Vessel}^{\frac{2}{3}}=0.272\).