基于改进雅克比–旋量模型的航空发动机转子–叶片结构装配精度分析

Assembly Precision Analysis for Rotor–Blade Structure of Aero-Engine Based on Improved Jacobian–Torsor Model

转子–叶片是航空发动机的核心部件,具有装配结构复杂、装配难度大等特点,在高温高压条件下,转子–叶片装配误差被催化放大,容易导致疲劳裂纹等故障,严重影响整机安全性和可靠性。针对转子–叶片结构,传统的装配偏差分析方法常采用多特征并联结构中的一条支链作为单一主链来建立偏差传递模型,难以综合考虑转子–叶片复杂定位结构和局部并联关系。本文提出了基于改进的雅可比–旋量(Jacobian–Torsor,J–T)模型的转子–叶片装配偏差分析方法。首先分析了转子–叶片多级回转结构、止口定位结构和榫头榫槽结构,建立了考虑转子–叶片多特征局部并联关系的整机装配尺寸链;然后采用不完全定位策略将转子–叶片装配结合面表达为基于点接触形式的偏差旋量,建立了基于定位点系统的转子–叶片联合定位基准方案;最后提出转子–叶片装配精度指标及基于改进的雅克比–旋量模型的求解方法。以某航空发动机转子–叶片的径向、轴向和周向装配偏差分析为例,将传统雅克比–旋量模型、基于蒙特卡洛法的仿真模型、改进雅克比–旋量模型及实测结果进行了对比分析。结果表明,本文方法相较其他方法预测精度更高,与实测结果误差率不超过9%,提出了榫头榫槽更合理的装配连接方式。

Rotor–blade parts are the core components of aero-engines,which have the characteristics of complex assembly structure and difficult assembly.Under high temperature and pressure conditions,the rotor-blade assembly error is catalytically amplified,resulting in fatigue cracks and other failures,which seriously affects the stability and reliability of the whole engine.For the rotor-blade structure,traditional variation analysis method cannot comprehensively consider the complex positioning structure and the partial parallel relation,as a result of that a branch chain in the multi-feature parallel structure is often used as a series relationship in a single direction.This paper proposed a variation analysis method of rotor-blade assembly based on the improved Jacobian–Torsor(J–T)model.Firstly,the multi-stage rotational structure,stop positioning structure and tenon tongue-groove structure were analyzed,and the assembly dimension chain considering partial parallel relationship of the rotor-blade with multi-feature was established.Then the assembly joint surface of rotor�blade was expressed as the deviation torsor based on the points contact form by using the incomplete positioning strategy,and a united positioning reference scheme based on the positioning point system was established.Finally,the rotor–blade assembly precision index and the solution method based on the improved J–T model was proposed.Taking the assembly precision analysis for radial,axial and circumferential variation of the rotor-blades as an example,the calculation results of the traditional J–T model,Monte Carlo simulation model,and the improved J–T model were compared with the measured data.The results show that the proposed method has higher prediction accuracy than other methods.Compared with the measured results,the error rate is less than 9%.A more reasonable assembling and connecting mode of tenon tongue-groove structure was put forward.