硕士论文代写：动力机械及工程专业硕士论文代

　　硕士论文代写：动力机械及工程专业硕士论文代写范文《变轴向间隙对采用直、弯静叶压气机性能影响的数值研究》

        目录：　　
　　摘要 4-5
　　Abstract 5-6
　　第1章绪论 10-27
　　1.1引言 10-11
　　1.2课题来源及背景 11-12
　　1.3弯曲叶片在压气机内的应用研究 12-19
　　1.3.1叶片弯曲的定义 12-13
　　1.3.2弯叶片在叶轮机械中的作用机理 13-15
　　1.3.3弯曲叶片在压气机中的研究现状 15-19
　　1.4变轴向间隙在叶轮机械中的研究进展 19-25
　　1.4.1尾迹干扰的研究 20-22
　　1.4.2变轴向间隙的研究现状 22-25
　　1.5本论文的主要研究内容 25-27
　　第2章数值方法 27-39
　　2.1引言 27
　　2.2商用软件NUMECA简介 27-32
　　2.2.1控制方程 28-29
　　2.2.2计算方法 29-30
　　2.2.3湍流模型 30-31
　　2.2.4边界条件处理 31
　　2.2.5前处理与后处理 31-32
　　2.3数值模拟 32-37
　　2.3.1叶片及压气机设计参数 32-33
　　2.3.2网格生成、湍流模型及进出口边界条件 33-35
　　2.3.3数值模拟方案的划分 35-37
　　2.3.4计算公式 37
　　2.4本章小结 37-39
　　第3章直、弯叶片对压气机性能影响的数值研究 39-62
　　3.1引言 39
　　3.2直、正弯曲静叶压气机的特性线 39-40
　　3.3设计工况下采用直、正弯静叶对压气机性能影响 40-49
　　3.3.1压气机出口节距平均参数对比 40-42
　　3.3.2压气机出口截面总压升系数 42-43
　　3.3.3压气机出口截面流线 43-44
　　3.3.4总压损失系数 44-45
　　3.3.5型面静压 45-46
　　3.3.6不同叶高处熵分布 46-47
　　3.3.7静叶吸力面静压等值线 47-49
　　3.4最大流量工况下采用直、正弯静叶对压气机性能影响 49-54
　　3.4.1压气机出口节距平均参数对比 49
　　3.4.2压气机出口截面总压升系数 49-50
　　3.4.3压气机出口截面流线 50
　　3.4.4总压损失系数 50-51
　　3.4.5型面静压 51-52
　　3.4.6不同叶高处熵分布 52-53
　　3.4.7静叶吸力面静压等值线 53-54
　　3.5近喘工况下采用直、正弯静叶对压气机性能影响 54-60
　　3.5.1压气机出口节距平均参数对比 54-55
　　3.5.2压气机出口截面总压升系数 55
　　3.5.3压气机出口截面流线 55-56
　　3.5.4总压损失系数 56
　　3.5.5型面静压 56-57
　　3.5.6不同叶高处的流线 57-59
　　3.5.7静叶吸力面静压等值线 59-60
　　3.6本章小结 60-62
　　第4章变轴向间隙对压气机性能影响的数值研究 62-91
　　4.1引言 62
　　4.2直静叶压气机变轴向间隙的数值研究 62-75
　　4.2.1数值模拟与实验的总参数对比 62-64
　　4.2.2设计流量工况 64-71
　　4.2.3最大流量工况 71-73
　　4.2.4近喘工况 73-75
　　4.3正弯曲静叶压气机变轴向间隙的数值研究 75-85
　　4.3.1数值模拟与实验的总参数对比 75-76
　　4.3.2设计流量工况 76-82
　　4.3.3最大流量工况 82-83
　　4.3.4近喘工况 83-85
　　4.4轴向间隙变化对压气机性能影响的机理探讨 85-90
　　4.4.1轴向间隙变化对压气机性能影响机理分析 85-86
　　4.4.2气流周向分速度C_u值随轴向间隙的变化 86-87
　　4.4.3下游静叶对上游动叶的势流干扰 87-88
　　4.4.4尾迹的耗散 88-89
　　4.4.5分析总结 89-90
　　4.5本章小结 90-91
　　结论 91-92
　　参考文献 92-98
　　攻读学位期间发表的学术论文 98-100
　　致谢 100

硕士论文代写【摘要】 航空发动机的高效率以及高推重比的发展方向对压气机部件性能提出了更高的要求。通过改变压气机通流部分的几何形状来提升压气机气动性能将会是一个有前途的发展方向。基于这种认识,本论文采用三维数值模拟的方法研究了一台低速重复级压气机,研究的过程中通过变化其静叶类型(分别使用直叶片与正弯曲叶片)以及动、静叶间轴向间隙来改变压气机通流部分的几何形状。本文首先研究了原始轴向间隙下分别采用直静叶和正弯曲静叶的两台压气机的气动性能。结果表明:正弯曲静叶压气机的轴功与直静叶压气机相比有所减小,轴功的减小对效率的提升是一个积极因素,从另一个侧面也说明正弯曲静叶弱化了级间势流干扰的强度。正弯曲静叶的采用在全工况范围内都不同程度地提升了压气机的效率,同时喘振裕度也获得提高。但是,与直静叶压气机相比,气流的折转能力与通流能力有所下降。静叶正弯曲改变了叶片表面的静压分布,在吸力面表面建立起了“C”型压力分布,即沿径向两端压力高,中间压力低。端区的低能流体在压差的作用下向中径处移动,从而有效地防止了边界层内流体在端区的聚积。本文在原始轴向间隙的基础上构造了两种轴向间隙减小的方案,分别对采用直、正弯曲静叶的压气机进行了研究。结果表明,无论是采用直静叶还是正弯曲静叶的压气机,轴向间隙的减小使得压气机扭矩增加,说明小轴向间隙增强了叶列间的势流干扰,减小轴向间隙有助于提升压气机的总性能。但是,过小的轴向间隙又会恶化压气机的气动性能,使得压气机的喘振裕度降低。这说明存在使得压气机获得最佳气动性能的最佳轴向间隙。此外,近喘工况时,压气机性能对轴向间隙变化的敏感程度最高,最大流量工况时最低,设计工况居中。直静叶压气机较正弯曲静叶压气机对轴向间隙的变化更为敏感。

【Abstract】 The development of higher efficiency and larger thrust-weight ratio of aeroengine has put a further demand on the aerodynamic performance of compressor component. The method improving the compressor’s aeroperformance by changes of geometrical shape among flow passage will be promising. Based on this understanding, the method of 3-D numerical simulation is adopted to investigate the two stages of a low speed compressor in the dissertation, and it was by means of changing the type of stators(straight blade and positive dihedral blade) and varying the axial gap between rotor and stator to realize the changes of geometrical shape among flow passage through the research.Firstly,the performance of the two original axial gap compressors which used straight stator and the positive dihedral stator was investigated. The result shows that the shaft work of the compressor with positive dihedral stator is less than the compressor with straight stator, and the reducing of the shaft work is a positive element for the efficiency rising, and it also proved that positive dihedral stator weakened the potential flow interference. The efficiency of the compressor with positive dihedral stator is all higher than that with straight stator at all working conditions in different degree, and the positive dihedral stator also increases the stall margin of the compressor. However, comparing to the straight stator the positive dihedral stator reduced the turning angel of the air flow and the mass flow rate of the compressor. The positive dihedral stator changed the static pressure distribution on the surface of blade, and it establishs the C-type pressure distribution on the suction surface, which means that the static pressure near end wall is higher than that far from the end wall in radial direction. Thus, the boundary layer fluid would move to middle region of blade under the psid, which could restrain the boundary layer fluid’s accumulation on the blade surface near end wall effectively.This dissertation establishes two methods which also be investigated with straight stator and positive dihedral stator to reduce the axial gap based on original axial gap. The result shows that reducing the axial gap increased the torque, and that proved that small axial gap strengthen the potential flow interference. Smaller axial gap is helpful to improve the aerodynamic performance of compressor. however, it will worsen the aerodynamic performance of a compressor if the axial gap is too small, such as it reduce a compressor’s stall margin. This also proved that there is a certain axial gap with which a compressor can achieve optimal aerodynamic performance. Further, the performance of the compresspor works at the near stall condition is the most sensitive to axial gap varying, the maximum flow rate condition is the least one, and the design condition take the middle place. Comparing to the compressor with positive dihedral stator, the compressor with straight stator is sensitive to axial gap varying.

硕士论文代写【关键词】 压气机； 正弯曲叶片； 轴向间隙； 叶列间干扰； 气动性能；

【Key words】 Compressor； Positive dihedral blade； Axial gap； Interference between blade rows； Aerodynamic performance；