Dynamic simulation of three-wheel bleed air environment control system for the civil aircraft
摘要
The Environmental Control System (ECS) is essential for maintaining a safe and comfortable cabin environment in aircraft by managing temperature, pressure, and airflow, typically using bleed air from the engines. While most research has focused on steady-state ECS performance, limited attention has been given to transient behaviour, particularly the impact of shaft mass moment of inertia on the dynamic response of three-wheel bleed air ECS configurations. This study addresses this gap through a detailed dynamic analysis using the ECS library in Dymola®, considering both thermal and mechanical system performance. Simulations are conducted under realistic transient conditions derived from a real-time flight profile, including altitude and flight speed variations, as well as under representative steady conditions at sea level (Mach 0.50) and high altitude (11 km, Mach 0.85). Thermal performance is evaluated through transient heat flow rates and outlet temperatures of four compact heat exchangers, while mechanical performance is assessed via Cold Air Unit (CAU) parameters, including outlet temperature, shaft power, torque, angular speed, corrected flow, and corrected speed. Results show that the shaft's mass moment of inertia significantly influences the dynamic response, with stabilisation occurring around 30 s for 0.01 kg m2, 50 s for 0.02 kg m2, and 70 s for 0.03 kg m2. The validated model also supports health monitoring and fault diagnostics by accurately predicting time-dependent ECS behaviour under varying operating conditions. These findings provide critical insights for the design optimisation of ECS, control strategies, and real-time diagnostics in civil aviation.