飞机换热器故障诊断仿真研究

Research on Simulation of Fault diagnosis of Aircraft Heat Exchangers

为准确判定飞机环境控制系统关键部件换热器的故障发生情况,针对飞机在运行状态下进行实验的难度,应用计算机仿真技术,为准确进行故障诊断。在建立换热器动态模型的基础上,为克服普通最小二乘法,参数估计是静态,使故障诊断延迟大的缺点,提出采用递推增广最小二乘法对换热器物理参数进行辨识,主要分析单一故障时,换热器物理参数变动情况进行仿真。结果表明,递推增广最小二乘法可以准确辨识换热器物理参数变动,实现换热器故障诊断,验证了方法的有效性和正确性,同时得到了换热器物理参数与故障模式的对应关系,对实际工程中换热器故障诊断有一定的指导作用。

For the purpose of ascertaining fault changes and the practical experiment difficulty considered in this paper,in order to accurately determine the key components of the aircraft environmental control system （AECS） fail- ure occurrence of heat exchanger, a simulation technology of microcomputer is applied. Dynamic simulation of a trian- gle fin heat exchanger utilized in AECS was performed. To overcome the ordinary least squares method, parameter es- timation is static, a big disadvantage of delay fault diagnosis, and the physical parameters of heat exchanger have been identified using the Recursive Extended Least Squares method. Then the behaviors of the heat exchanger with single/double faults were simulated and changes of the physical parameters from normal to fault conditions were ana- lyzed. It is indicated that the Recursive Extended Least Squares method is feasible for fault diagnosis. The relation- ship between the changes of physical parameters and the fault modes provides a useful approach to define the faults and can be extend to heat exchangers applied in practical engineering.