柴油机涡轮增压器转子动力学特性研究
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摘要
涡轮增压器是一种能够在不改变发动机体积和重量的前提下，提高发动机功率、降低排放，同时还能降低油耗的装置。涡轮增压器的基本工作原理主要是利用发动机的废气来推动涡轮旋转，然后带动压气机叶轮旋转，从而达到增压的目的。从空气滤清器送来的新鲜空气经压气机压缩后再经过中冷器进入到汽缸，因此提高了发动机的进气充量系数以及空气和燃料的混合比，从而提高内燃机的功率、提高燃油经济性和减少发动机有害排放。
涡轮增压器是发动机重要的子系统之一，它工作的可靠性、稳定性以及使用寿命对发动机有着重大影响。转子系统是涡轮增压器的核心部件，它的性能和寿命直接影响着增压器的运转性能。本论文旨在研究涡轮增压器转子系统的动力学建模和分析方法，通过计算模拟与实验校核相结合的方法来证明我们的建模方案的有效性以及分析结果的正确性。
本文主要工作有：
第一，使用LMS Test Lab测试分析系统测得涡轮增压器转子和壳体的自由模态频率和振型，用声学测试的方法测得压气机长叶片和涡轮叶片的模态频率范围，主要为后面建立正确的涡轮增压器有限元模型提供参考依据。
第二，将涡轮增压器分为壳体和转子系统两大部分，将涡轮增压器几何模型导入到HyperMesh软件划分网格，建立有限元模型。其中转子的轴部分划分六面体网格，其它部分划分四面体网格。分别将涡轮增压器的压气机叶轮、涡轮、转子和壳体的有限元模型导入ANSYS软件进行自由模态计算，得到各部分的模态频率及振型。将计算结果与实验测试的结果进行比较，校核有限元模型有效性。在正确有限元模型基础上计算了转子有预应力的模态和壳体约束状态下的模态。
第三，搭建涡轮增压器试验台架，进行转子动力学特性实验。测得转子在各稳定转速下的轴心轨迹和降速过程中中间壳上X、Y、Z三个方向的振动曲线。分析振动瀑布图和order1图得到转子的临界转速，为校核转子动力学计算方法正确性打下基础。
第四，把涡轮增压器转子系统的轴承简化为弹簧单元，建立转子系统动力学模型，分别计算出转子取不同弹簧刚度时的Campbell图，发现转子临界转速随轴承支承刚度的增大而增大，当支承刚度大到一定程度，临界转速趋于某一个值，不再增加。将转子有限元模型简化为梁单元进行瞬态分析，得到转子的轴心轨迹以及弹簧支反力随转速变化的曲线。
The turbocharger is a device which can increase engine power, reduce emissions andreduce the fuel consumption without changing the engine size and weight. The basicworking principle of the turbocharger is using the high temperature and high pressureexhaust gas discharged from the cylinder to drive the turbine, so as to drive the compressorimpeller connected to the turbine coaxial. The fresh air sent from the air filter is compressedby the compressor and then sent through the intercooler into the cylinder, thereby increasingthe engine’s intake charge coefficient, as well as air and fuel mixture ratio, thereforeenhancing the power of the internal combustion engine, increasing fuel economy and reduceharmful engine emissions.
The turbocharger is one of the important subsystems of the engine, the reliability,stability and service life of its work has a significant impact on the engine. The rotor systemis the core component of the turbocharger, its performance and life expectancy has a directimpact on the operational performance of the turbocharger. The purpose of this paper isstudying the methods of rotor dynamics modeling and analysis on turbocharger, to prove thevalidity of our modeling scheme and the correctness of the analysis results by the method ofcombining simulation and experiment.
The main content of this paper include:
First, the modal analysis of turbocharger rotor and shells were carried out by using theLMS Test Lab Test System. The modal frequencies of compressor long blades and turbineblades were measured by the method of acoustic test.
Second, the turbocharger was divided into shells and rotor system. The finite elementmodel of turbocharger was created by HyperMesh program. Hexahedral and tetrahedral wereused in the finite element model. The modal analysis of all parts of turbocharger was carried out by ANSYS program. The results of calculation were compared with experimental resultsto check the finite element models of turbocharger. The prestressed modal of rotor andconstraint modal of shells were calculated based on the correct finite element model.
Third, the test bed of turbocharger was established and the experiments of rotordynamic characteristics were carried out. The orbits of rotor and the vibration of shells weremeasured. The critical speed of the rotor was got through analyzing the waterfall plot andorder1figure.
Fourth, the bearings of the turbocharger rotor system were simplified into springs andthe dynamic model of rotor system was established. Campbell diagrams of the rotor fordifferent spring stiffness were calculated. From which we found that the critical speed ofrotor gain in the increase of the bearing stiffness, when the support stiffness increase to acertain extent, the critical speed tends to a value no longer increasing. A transient analysiswas calculated with a simplified model of rotor and the orbits and the curve of the springreaction force were measured.
涡轮增压器是发动机重要的子系统之一，它工作的可靠性、稳定性以及使用寿命对发动机有着重大影响。转子系统是涡轮增压器的核心部件，它的性能和寿命直接影响着增压器的运转性能。本论文旨在研究涡轮增压器转子系统的动力学建模和分析方法，通过计算模拟与实验校核相结合的方法来证明我们的建模方案的有效性以及分析结果的正确性。
本文主要工作有：
第一，使用LMS Test Lab测试分析系统测得涡轮增压器转子和壳体的自由模态频率和振型，用声学测试的方法测得压气机长叶片和涡轮叶片的模态频率范围，主要为后面建立正确的涡轮增压器有限元模型提供参考依据。
第二，将涡轮增压器分为壳体和转子系统两大部分，将涡轮增压器几何模型导入到HyperMesh软件划分网格，建立有限元模型。其中转子的轴部分划分六面体网格，其它部分划分四面体网格。分别将涡轮增压器的压气机叶轮、涡轮、转子和壳体的有限元模型导入ANSYS软件进行自由模态计算，得到各部分的模态频率及振型。将计算结果与实验测试的结果进行比较，校核有限元模型有效性。在正确有限元模型基础上计算了转子有预应力的模态和壳体约束状态下的模态。
第三，搭建涡轮增压器试验台架，进行转子动力学特性实验。测得转子在各稳定转速下的轴心轨迹和降速过程中中间壳上X、Y、Z三个方向的振动曲线。分析振动瀑布图和order1图得到转子的临界转速，为校核转子动力学计算方法正确性打下基础。
第四，把涡轮增压器转子系统的轴承简化为弹簧单元，建立转子系统动力学模型，分别计算出转子取不同弹簧刚度时的Campbell图，发现转子临界转速随轴承支承刚度的增大而增大，当支承刚度大到一定程度，临界转速趋于某一个值，不再增加。将转子有限元模型简化为梁单元进行瞬态分析，得到转子的轴心轨迹以及弹簧支反力随转速变化的曲线。
The turbocharger is a device which can increase engine power, reduce emissions andreduce the fuel consumption without changing the engine size and weight. The basicworking principle of the turbocharger is using the high temperature and high pressureexhaust gas discharged from the cylinder to drive the turbine, so as to drive the compressorimpeller connected to the turbine coaxial. The fresh air sent from the air filter is compressedby the compressor and then sent through the intercooler into the cylinder, thereby increasingthe engine’s intake charge coefficient, as well as air and fuel mixture ratio, thereforeenhancing the power of the internal combustion engine, increasing fuel economy and reduceharmful engine emissions.
The turbocharger is one of the important subsystems of the engine, the reliability,stability and service life of its work has a significant impact on the engine. The rotor systemis the core component of the turbocharger, its performance and life expectancy has a directimpact on the operational performance of the turbocharger. The purpose of this paper isstudying the methods of rotor dynamics modeling and analysis on turbocharger, to prove thevalidity of our modeling scheme and the correctness of the analysis results by the method ofcombining simulation and experiment.
The main content of this paper include:
First, the modal analysis of turbocharger rotor and shells were carried out by using theLMS Test Lab Test System. The modal frequencies of compressor long blades and turbineblades were measured by the method of acoustic test.
Second, the turbocharger was divided into shells and rotor system. The finite elementmodel of turbocharger was created by HyperMesh program. Hexahedral and tetrahedral wereused in the finite element model. The modal analysis of all parts of turbocharger was carried out by ANSYS program. The results of calculation were compared with experimental resultsto check the finite element models of turbocharger. The prestressed modal of rotor andconstraint modal of shells were calculated based on the correct finite element model.
Third, the test bed of turbocharger was established and the experiments of rotordynamic characteristics were carried out. The orbits of rotor and the vibration of shells weremeasured. The critical speed of the rotor was got through analyzing the waterfall plot andorder1figure.
Fourth, the bearings of the turbocharger rotor system were simplified into springs andthe dynamic model of rotor system was established. Campbell diagrams of the rotor fordifferent spring stiffness were calculated. From which we found that the critical speed ofrotor gain in the increase of the bearing stiffness, when the support stiffness increase to acertain extent, the critical speed tends to a value no longer increasing. A transient analysiswas calculated with a simplified model of rotor and the orbits and the curve of the springreaction force were measured.
引文
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[2]孟光.转子动力学研究的回顾与展望[J].振动工程学报，2002，15（1）：1-9.
[3]许涛.弹性支承一柔性轴转子系统动力学研究[D].西安：西安电子科技大学，2010.
[4] Rankine W JM. On the centrifugal force of rotating shafts[J]. The Engineer, April,1869,27.
[5] Parkinson A G, Schneider H. Balancing of flexible rotors—some considerations onmodal convergence[C]. In: Proc.5th International Conf. on Rotor Dynamics, IFToMM,Germany, Sep t.1998:653—663.
[6]马玉星.涡轮增压器振动和噪声在线监测及转子动力学分析[D].北京：北京理工大学，2005.
[7]周骊麟.涡轮增压器转子动力学分析与研究[D].北京：北京理工大学，2007.
[8]谢里阳.现代机械设计方法[M].北京：机械工业出版社，2010.
[9]李德葆.振动模态分析及其应用[M].北京：宇航出版社，1989.
[10] Yuan Zhaocheng, Zhang Liang. Modal analysis and structure analysis for oil pan of4118Zdiesel engine[J]. Automotive Engineering，2001.
[11]张义民.机械振动力学[M].吉林：吉林科学技术出版社，2000.
[12]庞剑，谌刚，何华.汽车噪声与振动—理论与应用[M].北京：北京理工大学出版社，2006.
[13]岳玉梅.涡轮增压器转子动力分析[J].航空制造技术，2004（4）：92-94.
[14]曹树谦.振动结构模态分析[M].天津：天津大学出版社，2001.
[15]杨建刚.旋转机械振动分析与工程应用[M].北京：中国电力出版社，2007.
[16]闻邦椿，等.高等转子动力学-理论、技术与应用[M].北京：机械工业出版社，2000.
[17] Prohl M A. A general method of calculating critical speeds of flexible rotors[J]. Appl.Mech. Trans. ASME,1945,67:142-146.
[18]张虹，马朝臣.车用涡轮增压器压气机叶轮几何参数优化设计和性能分析[J].北京理工大学学报，2005，25（1）：22-26.
[19]张虹，马朝臣.车用涡轮增压器压气机叶轮强度计算与分析[J].内燃机工程，2007，28（1）：62-66.
[20]单颖春，刘献栋，张洪亭.涡轮增压器转子的振动分析及故障诊断[J].噪声与振动控制，2006，26（1）：73-76.
[21]宫志国，魏名山.涡轮增压器转子动平衡技术研究[J].车用发动机，200（56）：46-49.
[22]李德生.含裂纹的涡轮增压器转子-轴承系统非线性动力学研究[D].上海:上海交通大学，2008.
[23]黄文虎，武新华，焦映厚，等.非线性转子动力学研究综述[J].振动工程学报，2000，13（4）：497-509.
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