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One-dimensional and three-dimensional computational thermal fluid hybrid analysis-aided air distribution pipeline system design

The air distribution system is an essential aircraft system, helping to create a safe, healthy and thermally comfortable cabin environment for large-scale aircraft. This complex pipe network system contains a large number of pipes, valves, elbows, joints and flow devices. The enormous number of components poses a severe challenge to the efficiency, accuracy and convergence of system thermal fluid analysis. Traditional three-dimensional (3D) computational fluid dynamics (CFD) methods can describe the system internal flow and heat transfer performance in detail with complex mesh models and extremely low calculation efficiency, while one-dimensional (1D) fluid system simulation methods have better computational efficiency but insufficient calculation accuracy. This study proposes a method to implement efficient and accurate simulation to solve this problem. 1D fluid system analysis models are established to obtain the P-Q characteristic curve of each pipeline subsystem. These 1D models are also used to evaluate the uniformity of air flow into each compartment of the aircraft cabin and the thermal insulation performance of system pipelines. The 3D CFD model is built to evaluate the air distribution performance of the mix manifold using the subsystem P-Q characteristics as the boundary conditions. The air distribution analysis based on the CFD model is compared with that using the 1D fluid system model in the same boundary conditions. The results show that more than 7% deviation occurs if the influence of the mix manifold structure on its internal flow is ignored.