建模和仿真在热-流体系统设计和控制中起着关键作用。随着飞机功能需求的不断增加，燃油系统等机载热-流体系统的拓扑结构变得越来越复杂， 系统仿真的难度和重要性也随之增大。因此，热-流体系统的高效建模和求解算法已经成为高性能飞机的重要研究内容之一。本文针对航空发动机的燃油热管理系统，研究一维热-流体系统的建模与简化方法、稳态及瞬态的求解算法和燃油、滑油及空气流路的联合仿真方法。 论文首先给出了基于关联矩阵定义的一维热-流体系统的网络建模方法。通过对热-流体网路流动控制方程组和拓扑结构的分析，提出了一种基于关联矩阵特征识别和操作的热-流体网络自动简化方法。某燃油热管理系统运用简化算法后流动控制方程的数量减少了约45 %，仿真消耗的时间平均减少了32 %。 其次，针对含有多个泵和多条回油支路的热-流体系统在仿真时存在的流向变化问题，从简化假设和基本部件的流动计算数学模型出发，建立了基于流动方程组自动生成方法和热-流体网络拓扑结构重构方法的流动换热求解算法。通过算例验证了该算法能够自适应热-流体系统在仿真过程中的支路流向和拓扑结构的改变。 之后，论文搭建了模型库和物性库，并基于求解算法和面向对象设计自主编程开发了燃油热管理系统的稳态仿真系统。基于架构清晰、修改便捷和扩展自由的设计思路，将仿真系统在组件、支路、求解器和系统层面分别进行封装。不同层级之间用标准化定义的数据接口连接，仿真系统具有便于修改和扩展灵活的优点。通过大量的算例仿真检验了仿真系统的可靠性。 最后搭建了包含油箱、滑油加热和空气冷却换热单元的燃油热管理系统的瞬态仿真系统，系统时间步长的取值范围为0.1 s ~ 1.0 s。通过对比不同电子设备热载荷和不同电子设备冷却回路布置下燃油热管理系统在同一个巡航任务中的温度变化，燃油进入燃油热管理系统后先冷却电子设备再冷却滑油的方案比从油箱内额外引一股燃油冷却电子设备的方案燃油不超温的时间更长。
Modeling and simulation of thermal-fluid systems play key roles in their design and control. With the increasing functional requirements of aircraft, the topological structure of aviation onboard thermal-fluid systems, such as a thermal management system, is becoming increasingly complicated, which results in the difficulty and importance of simulation. Therefore, efficient modeling and solution algorithm for thermal-fluid system, as one of the important technologies in high performance aircraft, has become a research focus. This thesis dedicates to the simulation method of aeroengine fuel thermal management system, including simplification method of one-dimensional thermal-fluid network, solution methods for the steady-state, transient solution algorithm and the joint simulation method of fuel, lubricating oil and air flow path. Firstly, the modeling and simplification method of one-dimensional thermal-fluid network are presented. The simplification method of the thermal-fluid network is based on the feature recognition and operation of incidence matrices. The example of fuel thermal management system shows that the number of the governing equations for flow is reduced by about 45 % and the calculation time is reduced by an average of 32 % after the simplification. Secondly, an algorithm for solving the flow and heat transfer based on the automatic generation method of the flow equations and the reconstruction method of the thermal-fluid network topology is established. The calculation example verifies that the algorithm can adapt to the changes of the flow direction and topological structure of the thermo-fluid system in the simulation process. After that, the model library and the physical property library are built. A steady-state simulation system of the fuel thermal management system is developed based on the solution algorithm and object-oriented design independent programming. Based on the design ideas of clear architecture, convenient modification and free expansion, the simulation system is encapsulated at the component, branch, solver, and system level. Different levels are connected with standardized data interfaces, which makes the simulation system easy to modify and expand flexibly. The reliability of the simulation system is verified through a large number of simulation examples. Finally, a transient simulation system of a fuel thermal management system including a fuel tank, a simple lubricating oil pipeline and a simple air pipeline is built. The solution time step of system is between 0.1 s ~ 1.0 s. The scheme for cooling electronic equipment and lubricating oil successively after the fuel enters the fuel thermal management system is better than that for cooling the electronic equipment separately with fuel directly from the fuel tank by comparing the temperature change of the fuel thermal management system in the same cruise mission under different heating power of electronic equipment and electronic equipment cooling circuit arrangements.
