轴流压气机角区分离的研究进展

角区分离是一种常发生于轴流压气机"吸力面-端壁"角区的三维分离现象,该现象以及随之产生的流场堵塞和流场损失会对压气机的稳定工作和效率造成不良影响,严重时会发展为"角区失速"。随着现代轴流压气机单级负荷的提升,角区分离所产生的负面影响日益突出,严重阻碍了高负荷压气机的发展,各种主动、被动流动控制方法也因此被广泛应用于角区分离的流动控制。首先,从角区分离对轴流压气机性能的影响、角区分离的流场特征和角区失速的判别准则3个方面对轴流压气机角区分离的流动机理研究进行了回顾,详细讨论了角区分离的影响因素、角区分离的流动拓扑分析以及角区失速的定义与判别方法。其次,对三维叶片设计、翼刀与凹槽、旋涡发生器、非轴对称端壁造型、射流式旋涡发生器、等离子体气动激励以及附面层抽吸与附面层射流7类流动控制方法的研究进展进行了回顾,重点探讨了这些流动控制方法在抑制角区分离方面的应用,并给出了这些流动控制方法的对角区分离的作用机制。最后,对角区分离领域的研究现状进行了简要地总结,指出了现有角区分离的机理研究和流动控制研究所存在的不足,并对该领域未来的发展进行了展望。     

Tracking characteristics of tracer particles for PIV measurements in supersonic flows

The tracking characteristics of tracer particles for particle image velocimetry (PIV) mea-surements in supersonic flows were investigated. The experimental tests were conducted at Mach number 4 in Multi-Mach Wind Tunnel (MMWT) of Shanghai Jiao Tong University. The motion of tracer particles carried by the supersonic flow across shockwaves was theoretically modelled, and then their aerodynamic characteristics with compressibility and rarefaction effects were evalu-ated. According to the proposed selection criterion of tracer particles, the PIV measured results clearly identified that the shockwave amplitude is in good agreement with theory and Schlieren visu-alizations. For the tracer particles in nanoscales, their effective aerodynamic sizes in the diagnostic zone can be faithfully estimated to characterize the tracking capability and dispersity performance based on their relaxation motion across oblique shockwaves. On the other hand, the seeding system enabled the tracer particles well-controlled and repeatable dispersity against the storage and humidity.     

现代超声速战斗机横航向模态特性计算

首先推导了适用于某第三代超声速战机横航向运动方程的传递函数,然后对三种等效系统方法进行了对比分析,选用了效果较好的方法,并验证了计算模型,最后,对某战斗机的横航向模态特性进行了计算,结果表明,推导了模型正确,控制系统对某点头机横航向飞行吕质的改善作用明显。     

Robust Navier-Stokes method for predicting unsteady flowfield and aerodynamic characteristics of helicopter rotor

A robust unsteady rotor flowfield solver CLORNS code is established to predict the complex unsteady aerodynamic characteristics of rotor flowfield. In order to handle the difficult problem about grid generation around rotor with complex aerodynamic shape in this CFD code,a parameterized grid generated method is established, and the moving-embedded grids are constructed by several proposed universal methods. In this work, the unsteady Reynolds-Averaged Navier-Stokes(RANS) equations with Spalart-Allmaras are selected as the governing equations to predict the unsteady flowfield of helicopter rotor. The discretization of convective fluxes is accomplished by employing the second-order central difference scheme, third-order MUSCL-Roe scheme, and fifth-order WENO-Roe scheme. Aimed at simulating the unsteady aerodynamic characteristics of helicopter rotor, the dual-time scheme with implicit LU-SGS scheme is employed to accomplish the temporal discretization. In order to improve the computational efficiency of holecells and donor elements searching of the moving-embedded grid technology, the ‘‘disturbance diffraction method and ‘‘minimum distance scheme of donor elements method are established in this work. To improve the computational efficiency, Message Passing Interface(MPI) parallel method based on subdivision of grid, local preconditioning method and Full Approximation Storage(FAS) multi-grid method are combined in this code. By comparison of the numerical results simulated by CLORNS code with test data, it is illustrated that the present code could simulate the aerodynamic loads and aerodynamic noise characteristics of helicopter rotor accurately.     

SFD用于某导弹发动机的改型研究

以某导弹发动机双转子系统为研究对象，将弹支挤压油膜阻尼器（简称ＳＦＤ）用于内转子进行了动力特性分析。应用传递矩阵和线性迭代方法，分别计算了发动机用与不用ＳＦＤ的转子系统的临界转速、不平衡响应和外传力。结果表明：弹支挤压油膜阻尼器大大减小了转子振动的振幅和外传力。特别是该发动机的工作转速为２５０００ｒ／ｍｉｎ，不用弹支挤压油膜阻尼器时，其二阶临界转速为２２６００ｒ／ｍｉｎ，与工作转速相当接近，用了我们设计的弹支挤压油膜阻尼器后，二阶临界转速降低到１５４００ｒ／ｍｉｎ，显然，发动机工作时的振动性能会大大改善。     

高职高专院校学报对科研工作的积极影响

在我国高职高专教育事业蓬勃发展的同时,高职高专教育教学研究室院校学报已成长为一支生力军。高职高专院校学报既是各高职院校学术交流的宣传交流窗口,又是广大教师展示科研成果与技术创新成果的有效平台。学报的论文发表与交流,既可以提高教师的业务水平,又可以进一步提升学校教学、科研的整体水平,使学校形成一个良好的学术氛围,对推动高职高专教育的发展起到良好的促进作用。虽然高职高专院校学报起步晚,底子薄,经验少,但是依据自身的优势和地方特点,坚持特色办刊的理念,多数学报已经成为了独树一帜的学术交流平台。     

1+3/2无导叶对转涡轮设计特点分析

无导叶对转涡轮的结构形式是减轻发动机质量、提高发动机推重比的有效技术途径之一。以现有1＋2对转涡轮为平台,在保持总体性能参数不变的前提下,进行了1＋3／2无导叶对转涡轮初步设计,并对无导叶对转涡轮的设计特点进行了分析。研究结果表明,1＋3／2无导叶对转涡轮设计中必须以合适的高压涡轮为基础;其低压涡轮特性与常规涡轮的基本一致,第1级低压涡轮转子叶片在各工作状态下效率水平均较高。     

来流边界层厚度对开式空腔气动声学特性的影响分析

分析了不同来流边界层厚度与空腔深度比(δ/D)对长深比(L/D)为8的开式空腔内不同测点的声压级分布和声压频谱特性的影响。试验马赫数是0.6和1.5,相应的Re为1.23×107和2.26×107(基于每米)。结果表明,δ/D减小,导致开式空腔内不同测点声压级均有不同程度的增大;导致空腔上方剪切层与腔内流动或腔后壁相互作用能量增加,引起腔内同一测点不同离散频率对应的声压级增大。可见,δ/D减小,腔内流动自激振荡更易引起空腔自身结构和腔内储藏物结构振动和疲劳破坏。     

火花型合成射流激励器流动特性及其激励参数数值研究

利用能量方程中的源项模拟电火花能量的输入,数值模拟了火花型合成射流激励器的流场,获得了激励器的能量蓄积、喷射和吸入过程.结果表明:电火花瞬间能量的输入产生了腔体内的高温、高压环境,从而诱发合成射流的形成;在周期性激励下,合成射流在3个周期后稳定,喷口处的速度呈现非正弦的周期性变化,射流喷射过程时间极短,吸入外界环境气体...     

静电驱动悬臂梁式微开关的动态特性分析

通过建立静电驱动悬臂梁式微开关的非线性动力学简化模型,利用数值方法求解出系统的动态响应特性,得到了动态吸合电压和开关吸合时间的关系,并详细分析了其动态响应中的非线性现象以及动态特性和静态特性的不同。计算结果表明,动态吸合电压并不是唯一的;随着动态吸合电压的增大,吸合时间逐渐变小;微悬臂梁的动态响应周期随着驱动电压的增大而增大;动态临界电压低于静态临界电压,这些动态特性与静态特性有着明显的不同。