Abstract:

Heat exchanger is the fundamental equipment of industry, which is important for the air vehicle, widely used in engine and ECS subsystem which is needed for it. The heat exchangers are usually used for passenger safety and comfort, which is also the important device for other equipment to keep normal and efficient work. The references of heat exchanger design and hydrodynamics have been contrasted and analyzed, some concepts and definitions are different from each other, the engineering calculation expressions of pressure characteristic of plate-fin heat exchangers have been put forward on the basis of hydrodynamics. One type of offset strip fin has been chosen for air-air heat exchanger, the one-pass and two-pass heat exchanger was set, which contained sudden expansion and contraction and 90°^{elbow and 180° elbow for the local pressure drop computation, the heat transfer is not considered, the Halton sequence is used for quasi-Monte Carlo, which is for heat exchanger at some temperature and pressure and Re outlet conditions computation, the probabilistic analysis is worked for the conclusions. As the two kinds of calculation examples shown, the header pressure loss and drop are little part to total heat exchanger pressure drop at most conditions, and the most probability density is about 0.05, the ratios of the total pressure drops to outlet pressures are very little, the constant pressure can be used for calculation of the fluids property.}

Key words: porous media, product design, Monte Carlo simulation, pressure loss, pressure drop, resistance

摘要：

换热器是工业的基础设备，也是飞行器中的重要设备，其广泛应用于发动机、飞行器环境控制等飞机需要换热的系统中，用于维持人员舒适安全和设备高效正常运行，其准确工程设计方法影响设备及系统的可靠运行，很多换热器设计文献对其压力相关计算问题进行了详细说明，但将换热器设计和流体力学文献进行对比和分析，发现两者在一些概念和定义上存在差异，根据流体力学文献中的概念提出了相应的换热器压力特性工程计算公式。具体选取了一种空气换热器常用的锯齿翅片作为算例，不考虑散热的绝热情况，构建单流程及双流程板翅式换热器，以涵盖突扩、突缩、90°和180°局部等结构变化的压力变化特性计算，运用Halton序列进行拟Monte Carlo对一定跨度内的温度、压力、Re的单流程、双流程换热器出口条件进行计算，经过这两类换热器计算统计发现：封头压降和压力损失在整个换热器压损中占比概率情况下较小，概率密度最大在0.05附近，换热器总压降在大部分情况下较出口压力小，流体性质可按固定压力计算。

关键词: 多孔介质, 产品设计, Monte Carlo模拟, 压力损失, 压降, 阻力