System-level functional capacity assessment of dual-circuit pneumatic systems under power loss conditions using a reduced-order framework

This study presents a reduced-order engineering framework for the system-level assessment of dual-circuit pneumatic systems operating under degraded supply conditions. Such systems are relevant to aerospace support-system applications, where the ability to maintain functional capability under loss-of-supply conditions is of practical engineering importance. In contrast to conventional approaches focused on detailed actuator dynamics, the proposed method enables quantitative evaluation of system functionality based on a working-cycle-based performance indicator. The model was implemented in MATLAB and internally verified against a reference schematic simulation developed in FluidSIM. The FluidSIM model was used as a schematic system-level reference rather than as an experimental or high-fidelity validation source. Additionally, engineering consistency was assessed using catalog-based actuator characteristics to ensure realistic force levels and geometric representation. The analysis was conducted for multiple operating scenarios, including nominal conditions, loss of primary supply, and emergency operation, as well as for different numbers of active actuators. The results demonstrate a strong dependence of functional capacity on the available stored energy and the number of active receivers, revealing a nonlinear threshold behavior with respect to external load. The proposed framework provides a computationally efficient tool for preliminary system-level analysis, degraded-mode assessment, and engineering decision support. While the model does not aim to provide high-fidelity prediction of local flow phenomena, it captures the dominant mechanisms governing functional endurance of pneumatic systems under limited supply conditions.