一种超声速状态下机载推进系统模型的建模方法

为了满足机载航空推进系统模型对精度、实时性及数据存储量的苛刻要求，提出了一种机载模型建模方法.对传统的机载稳态模型建立过程中使用的相似准则进行了充分讨论，得出了一种具备更高建模精度的相似准则.在新的相似准则基础上，建立了包含泰勒展开式中非线性2阶项的高精度稳态变量模型，有效解决了分段线性稳态变量模型在大包线、变状态条件下精度难以保证的问题；为了解决超声速状态下安装推力与发动机净推力差别较大的问题，建立了考虑外流特性的简化进气道模型，给出了一种计算安装推力的方法，即由简化发动机模型计算安装推力中符合相似准则的部分，由进气道模型计算溢流阻力、放气阻力及发动机推力中不符合相似准则的部分.仿真结果表明:基于新的相似准则所建立的机载模型具有大包线、变状态适应性，输出参数误差均在0.5%以内. 

A novel method for on-board propulsion system modelling under supersonic state

In order to meet the high requirements of precision, timeliness and data storage of on-board aero propulsion model, a new method of onboard modeling was proposed. The similarity criterions used in traditional on-board steady-state model were deeply discussed, and a similarity criterion with higher modeling accuracy was obtained. Based on the new similarity criterion, a high precision steady state variable model was established, which includes the nonlinear 2 order term in the Taylor expansion, and the inaccuracy problem of the traditional piece-wise linear method in the condition of large flight envelope and variable state was solved effectively. In order to solve the problem of the prominent difference between engine installed thrust and net thrust under supersonic state, the simplified inlet model considering the outflow characteristics is established, and a method is given to calculate the installed thrust, the part of the installed thrust compatible with the similarity criterion was computed by the above simplified engine model, while the spilled air fluid resistance, the deflation resistance and some part of engine net thrust incompatible with the similarity criterion were calculated by the simplified inlet model. The simulation results show that the error of the on-board propulsion system model based on the new similarity criterion has the advantages of large flight envelope and variable state adaptability, and the error of output parameters are within 0.5%.