【作者】 戴军；

【导师】 王艳华； 周少伟；

【作者基本信息】 哈尔滨工程大学 ， 能源动力（专业学位）， 2023， 硕士

【摘要】 压气机作为燃气轮机的核心部件,对燃气轮机性能优劣有决定性影响。压气机工作时,动叶受到内部气流激振力,出现振动响应,产生高周疲劳失效,出现裂纹,导致叶片断裂。因此探究双向流固耦合作用时裂纹叶片的振动特性,对叶片裂纹的识别,避免发生重大事故具有十分重要的意义。本文通过数值模拟的方法对动叶前缘存在矩形开口裂纹的压气机进行研究。以下是本文的主要研究内容:首先,建立裂纹动叶模型,对动叶固体域和压气机流体域进行网格划分。对不同动叶进行模态计算和分析,得到固有频率和模态振型,绘制动叶的坎贝尔图,进行共振分析,最后研究裂纹分布位置对动叶模态和等效应力分布的影响。其次,对压气机流体域模型进行定常数值模拟,利用流体域定常数值模拟结果对压气机叶片进行单向流固耦合计算。分析静力和叶片变形情况,探究在单向流固耦合下裂纹分布对叶片结构性质的影响。最后,对压气机进行双向流固耦合数值模拟,分析动叶振动响应、静应力响应和裂纹分布位置对叶片振动特性的影响。本文研究发现,在仅受到离心载荷作用时,0.1叶高位置出现裂纹对动叶的最大形变量影响最大,而在0.5、0.7和0.9叶高位置出现裂纹时,对动叶的平均形变影响较大。另外,裂纹的出现会略微降低动叶的固有频率。在动叶受到低频激励时,裂纹分布位置的不同,会产生不同的振动响应和静应力响应。双向流固耦合数值数值模拟结果表明,0.7和0.9叶高裂纹动叶的振动幅度最为明显,裂纹更容易发现。本文研究能较真实模拟压气机动叶实际工作情况,较精确地研究裂纹动叶的振动和静应力特性,对工程实际中,动叶裂纹的检测与诊断提供一定的理论依据,对后续的双向流固耦合数值模拟下的损伤叶片力学、振动特性研究有一定的参考价值。更多还原

【Abstract】 As the core component of gas turbine,compressor has a decisive influence on the performance of gas turbine.When the compressor is working,the rotor blade is stimulated by the internal air flow and appears vibration response,resulting in high-cycle fatigue failure and cracks,leading to blade fracture.Therefore,it is of great significance to explore the vibration characteristics of cracked blades under two-way fluid-structure interaction,so as to identify cracks and avoid serious accidents.In this paper,moving blades and compressors with rectangular open cracks in the leading edge are studied by numerical simulation.The main research content of this paper is as follows:Firstly,a cracked rotor blade model was established to mesh the solid domain of the rotor blade and the fluid domain of the compressor.The modal calculation and analysis of different moving blades were carried out to obtain the natural frequency and mode shapes.The Campbell diagram of moving blades was drawn to conduct resonance analysis.Finally,the influence of crack distribution location on the modal and equivalent stress distribution of moving blades was studied.Secondly,the steady numerical simulation of the compressor fluid domain model is carried out,and the one-way fluid-structure coupling calculation of the compressor blade is carried out by using the results of the steady numerical simulation of the fluid domain.The static force and blade deformation were analyzed,and the influence of crack distribution on blade structural properties under unidirectional fluid-solid coupling was investigated.Finally,the effects of the vibration response,static stress response and crack distribution on the vibration characteristics of the rotor blades were analyzed by the bidirectional fluidstructure coupling numerical simulation.In this paper,it is found that cracks at 0.1 blade height have the greatest influence on the maximum shape variable of moving blades under centrifugal load only,while cracks at 0.5,0.7and 0.9 blade height have a greater influence on the average deformation of moving blades.In addition,the appearance of cracks will slightly reduce the natural frequency of moving blades.When the rotor blade is under low frequency excitation,the different crack distribution location will produce different vibration response and static stress response.The bidirectional fluidstructure coupling numerical simulation results show that the vibration amplitude of 0.7 and 0.9blades with high cracks is the most obvious,and the cracks are easier to be found.The research in this paper can simulate the actual working conditions of pneumatic maneuvering blades and accurately study the vibration and static stress characteristics of cracked rotor blades.It provides certain theoretical basis for the detection and diagnosis of cracks in rotor blades in engineering practice,and has certain reference value for the subsequent research on the mechanics and vibration characteristics of damaged blades under the bidirectional fluid-structure coupling numerical simulation.更多还原