A Fast Transient Low-Dimensional Cavity Modeling Methodology Incorporating the Coupled Effects of Volume Compliance and Inertial Forces

Existing low-dimensional cavity element models developed under the lumped-parameter assumption, which neglect cavity geometric parameters and inertial effects within the cavity, cannot meet the simulation requirements of aircraft-engine secondary air systems (SAS) during the fast transient response processes. To address this gap, this study proposes a modular modeling methodology for a fast transient cavity low-dimensional model. The cavity is partitioned into modules according to the internal flow features during the fast transient response, and the partition ratios are determined by evaluating how different geometric parameters affect these flow characteristics. Using this method, low-dimensional models are constructed for single-port cavities and dual-port cavities under various geometric parameters, and the fast transient depressurization response is investigated. In parallel, corresponding three-dimensional models are established using a validated simulation approach, and three-dimensional computations are performed. Comparison between the low-dimensional and three-dimensional results confirms that the proposed method effectively reproduces the key flow phenomena in the cavity during the fast transient events with credible predictive accuracy. This work optimizes existing low-dimensional simulation algorithms for air systems and provides technical support for studying fast transient responses in aircraft-engine SAS.