离心通风机旋转失速的特征分析

对采用进口导流器调节的离心通风机的旋转失速问题进行了试验研究，并借助谐波小波对旋转失速的频率、幅值特性及动态过程进行了时频分析和特征提取，揭示了旋转失速发展的规律及对风机性能的影响。     

电站离心通风机旋转失速的试验研究及特征提取

通过对试验室4—73№8D离心通风机的旋转失速的试验研究，得出了风机性能和失速脉动幅值、频率随旋转失速发展的规律，采用谐波小波对失速动态过程以及弱失速阶段进行了时频分析，提取了特征。试验证实，风机旋转失速边界线与风机最高效率线比较接近，弱失速阶段是应该引起足够重视的运行区域。     

共振解调技术在风机旋转失速故障诊断中的应用

风机旋转失速故障的振动特征通常出现在较低的频段。容易淹没在噪声或转子失衡等其它零部件的故障特征中。难以分析和诊断。共振解调技术对低频冲击的高频共振波形进行包络检波,可以有效地提取低频冲击特征。本文提出基于共振解调技术的风机旋转失速故障诊断方法,并成功应用于某炼铁厂废气风机旋转失速的故障诊断中。     

离心引风机旋转失速的故障诊断及现场处理方法

针对锅炉离心引风机机壳及进出口管道振动剧烈的问题,使用 CSI2130振动分析仪进行了频谱分析.频谱显示0.7倍转频的幅值较大,基本符合风机旋转失速的故障特征.依据引起旋转失速故障的机理,将风机进口管道的人孔盖打开后,彻底解决了此问题.     

静叶摆动辅助轴流压气机退出旋转失速过程的数值模拟

采用数值模拟的方法,对轴流压气机进入旋转失速、退出旋转失速过程以及加入叶片摆动耦合使压气机退出旋转失速的过程进行了三维数值模拟。对比了加入与未加入叶片摆动对压气机退出旋转失速状态过程中的流量影响。数值计算表明,在加入合适的叶片摆动耦合后,可以使得压气机退出旋转失速状态的流量减小1.6%,压比上升1.7%。结合两种退出方式的旋转失速过程对比,得到该压气机失速团破碎的条件:部分叶片通道全叶高消除显著的流动分离,出现具有一定"稳定裕度"的优质流动,导致失速团传播途径受阻,使失速团迅速破碎、消失。     

基于共振解调技术的风机旋转失速故障诊断方法

风机旋转失速故障的振动特征通常出现在较低的频段,容易淹没在噪声或转子失衡等其他零部件的故障特征中,难以分析和诊断.共振解调技术对低频冲击的高频共振波形进行包络检波,可以有效地提取低频冲击特征.提出基于共振解调技术的风机旋转失速故障诊断方法,并成功应用于鞍钢股伤有限公司炼铁厂废气风机旋转失速的故障诊断中.     

旋转机械转速波动检测及故障诊断

针对旋转机械运行转速波动导致信息获取及诊断决策困难问题,以非平稳信号的瞬时频率估计为切入点,结合快速路径优化算法进行非平稳信号的瞬时频率估计,以实现转速波动信息的准确获取。基于参数化时频分析理论的短时阶比原理,依据估计的振动信号瞬时频率变化函数构造匹配旋转算子,将转速波动信号的时频特征进行旋转,获得各时频窗内的短时阶次谱,进而完整保留转速波动信号的瞬态信息。仿真及实验结果表明,该方法可以准确提取出旋转机械转速波动工况下的状态信息及故障特征,为后续故障精密诊断奠定基础。     

基于迭代广义同步压缩变换的时变工况行星齿轮箱故障诊断

同步压缩变换在分析频率恒定的单分量信号时改善时频可读性的效果显著,而在分析多分量频率时变信号时存在时频模糊现象,为了解决这一问题,提出迭代广义同步压缩变换方法。通过迭代广义解调分离出各单分量成分,并将时变频率变换为恒定频率。应用同步压缩变换精确估计瞬时频率和时频分布幅值。将各单分量的时频分布叠加获得信号的时频分布。该方法有效改善了同步压缩变换在分析频率时变信号时的时频可读性,并且将其推广应用于多分量信号。应用该方法有效识别了时变工况下行星齿轮箱振动信号的频率组成及其时变特征,准确诊断了齿轮故障。     

基于频率成比例重分配线性Chirplet变换的时频分析方法

齿轮故障信号具有典型的调制特征，其各个频率分量的瞬时频率轨迹具有成比例特征；同时，传统的时频方法存在时频能量集中度低、弱分量信号被淹没的问题。为此，提出了一种频率成比例重分配线性Chirplet变换(PFSRLCT)的时频分析方法。首先，修改了线性Chirplet变换，利用新的核函数来匹配信号的瞬时频率轨迹，以获得时频域表示，利用脊线搜索方法提取了时频脊线；然后，利用时频脊线和狄拉克函数构造了同步重分配算子，对所得到的时频结果进行了重分配，进一步提高了时频能量集中度；最后，利用模拟信号验证了PFSRLCT方法的有效性，并将其与其他方法进行了比较；此外又将该方法应用于实际齿轮箱故障信号的诊断，从所得到的时频结果中可以清楚地分辨出啮合频率fm及其谐波和边频带，所诊断出的故障类型与预设故障类型符合，验证了该方法的适用性。研究结果表明：PFSRLCT在处理具有瞬时频率轨迹成比例特征的信号时，显示出了良好的性能，在信噪比为-2 dB～10 dB时，所得的频率估计误差均小于0.01,在信噪比为-1 dB时，所得Rényi熵仅为4.745 1,均明显小于其他方法，证明该方法的噪声鲁棒性相较于其他方法...     

基于微分局部均值分解的旋转机械故障诊断方法

提出一种基于微分局部均值分解(Differential local mean decomposition,DLMD)的旋转机械故障诊断方法。该方法在局部均值分解(Local mean decomposition,LMD)过程中融入微分和积分运算。对原始信号进行k阶微分,然后对微分后信号进行LMD分解,对分解得到的各乘积函数(Production function,PF)分量循环进行一次积分和一阶LMD分解,直至循环k次,得到m个PF分量和残余分量,将所有PF分量的瞬时幅值和瞬时频率组合,便可以得到原始信号完整时频分布。将该方法应用于旋转机械故障诊断研究中,通过仿真和试验进行分析研究,结果表明,基于微分局部均值分解的旋转机械故障诊断方法能够有效地抑制虚假干扰频率,提高旋转机械故障诊断准确性。     

Inlet Recirculation Influence to the Flow Structure of Centrifugal Impeller

Inlet recirculation is proved as an effective way for centrifugal compressor surge margin extension,and is successively used in some engineering applications.Unfortunately its working mechanism is still not being well understood,which leads to redesigning of inlet recirculation mostly by experience.Also,most study about inlet recirculation is steady to date.It is necessary to study surge margin extension mechanism about inlet recirculation.To expose the mechanism in detail,steady and unsteady numerical simulations were performed on a centrifugal compressor with and without inlet recirculation.The results showed that,with inlet recirculation,the inlet axial velocity is augmented,relative Mach number around blade tip leading edge area is significantly reduced and so is the flow angle.As the flow angle decreased,the incidence angle reduced which greatly improves the flow field inside the impeller.Moreover,inlet recirculation changes the blade loading around blade tip and restrains the flow separation on the blade suction side at the leading edge area.The unsteady results of static pressure around blade surface,entropy at inlet crossflow section and vorticity distributions at near tip span surface indicated that,at near stall condition,strong fluctuation exists in the vicinity of tip area due to the interaction between tip leakage flow and core flow.By inlet recirculation these strong flow fluctuations are eliminated so the flow stability is greatly enhanced.All these improvements mentioned above are the reason for inlet recirculation delays compressor stall.This research reveals the surge margin extension reason of inlet recirculation from an unsteady flow viewpoint and provides important reference for inlet recirculation structure design.     

横流风机内部流动试验研究

利用激光多普勒测速（LDV）技术,测量并分析在不同叶轮直径和结构尺寸时,横流风机在稳定工况和失速工况下,风机内部流场的相似与差异,通过对几组试验数据的比较,对横流风机特有的偏心涡的成因进行了理论分析,并对偏心涡的主要参数特点作了深入的探讨,同时总结了偏心涡的位置随流量变化的规律。     

非设计工况下带分流叶片半开式离心叶轮内部流动特性数值研究（英文）

In order to investigate the complex flow characteristics inside an unshrouded centrifugal impeller with splitter blades at off-design conditions, and analyze its influence on pump operation stability, a numerical simulation study was carried on using the curvature-corrected SST-CC turbulence model; the head and efficiency accorded with experimental results. The pressure fluctuation, unsteady radial force and velocity were analyzed quantitatively and the numerical results indicate this: the peak to peak value of pressure fluctuation in the impeller channel gradually increases in the flow direction and at 0.49 Qn, the slope of peak to peak value to normalized impeller channel behind the splitter blade is 8.57 times greater than that before the splitter blade. The greater the flow rate deviates from the design condition, the larger the peak to peak value of the pressure fluctuation and radial force; in particular at 0.27 Qn, the maximum radial force is 194.29% greater than that of the design condition. When the operating flow rate is smaller than0.83 Qn, the stall occurs and the stall vortex could block the impeller discharge; as the flow rate decreases further, the pressure amplitude at rotational frequency gradually increases in the impeller channel and the prevailing frequency changes from the blade passage frequency(BPF) to the rotating stall frequency in the diffuser. The tip leakage vortex(TLV) is generated in the tip region and rotated move downstream in the impeller flow channel, and the backflows appear on the blade suction side and in the tip and the tongue regions; the smaller the flow rate, the more serious the TLV and backflow phenomenon. The rotating stall causes uneven flow in the impeller channel, increasing the pressure fluctuation and the radial force, and resulting in an imbalance of the impeller rotation.     

Behavior of rotating stall cell in a high specific-speed diagonal flow fan

An experimental investigation was carried out to clarify unsteady flow fields with rotating stall cell, especially behavior of stall cell, in a high specific-speed diagonal flow fan. As its specific-speed is very high for a diagonal flow fan, its pressure-flow rate curve tends to indicate unstable characteristics caused by rotating stall similar to axial flow fan. Although for an axial flow fan many researchers have investigated such the flow field, for a diagonal flow fan little study has been done. In this study, velocity fields at rotor inlet in a high specific-speed diagonal flow fan were measured by use of a single slant hot-wire probe. These data were processed by using the ““Double Phase-Locked Averaging“ (DPLA) technique, i. e. phases of both the rotor blade and the stall cell were taken into account. The behaviors of stall cell at rotor inlet were visualized for the meridional, tangential and radial velocity.     

EXPERIMENTAL INVESTIGATION OF ROTATING STALL FOR A LOW-SPEED CENTRIFUGAL COMPRESSOR

Unsteady flows and rotating stall of a low-speed centrifugal compressor are investigated by measuring vaneless diffuser wall static pressure fluctuation and internal flow fields at different small flow fluxes. During the experiment, firstly the real time static pressure fluctuations on the vaneless diffuser shroud at different circumferential and radial position were acquired by high-frequency dynamic pressure transducers. Discrete Fourier transformation analysis and cross-correlation analysis were applied to the experimental results to ascertain the rotating stall beginning operation conditions and stall cells numbers and rotating speed. Secondly, the vaneless diffuser inlet flow angle distribution along diffuser width direction was acquired by single hotwire, which was compared with SENOO＇s analysis results. At last, the internal flow fields of the centrifugal compressor were investigated with a particle image velocimetry （PIV） system at different small flow fluxes. The flow field development of vaneless diffuser and blade flow passage are given at rotating stall conditions. The experiments enrich the understanding of rotating stall flow phenomenon of the low-speed centrifugal compressor and provide full experiment data for designing high performance centrifugal compressor.     

涡流发生器对动态失速影响的模拟研究

基于风力机专用翼型DU91-W2-250直叶片段,采用延迟分离涡模拟（Delayed detached-eddy simulation,DDES）与k-ω SST两种CFD模拟方法,研究了涡流发生器（Vortex generators,VGs）对动态失速的影响,并对两种模拟方法的表现进行了比较。结果表明：动态失速下,光滑叶片段的分离与重新附着均出现延迟;加VGs后,上仰阶段叶片段的气动分离更加延迟,下俯阶段叶片段上表面附着流动重建的更早,气动力的迟滞现象得到明显改善。VGs对DU91-W2-250叶片段增升减阻的效果明显,其中最大升力系数增加10%,周期平均升力系数增加17.9%,最大阻力系数减少56.3%,周期平均阻力系数减少40.3%。DDES模型能更细致地反映VGs对动态失速抑制作用下叶片段表面复杂流动分离现象,k-ω SST模型则难以捕捉小尺度涡结构,模拟得到的涡结构展向呈二维分布。     

EXPERIMENTAL INVESTIGATION OF PASSIVE CONTROL ON UNSTABLE CHARACTERISTICS IN AXIAL FLOW FAN

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离心式压缩机旋转失速的故障机理研究

介绍了离心式压缩机旋转失速的故障机理及故障特征，充分利用升降速三维功率谱阵等数字信号处理方法对现场拾取的轴位移信号及振动加速度信号等有用信息进行了分析，根据测试结果，对某公司的DH－80离心式压缩机旋转失速的故障现象进行了诊断，实践证明，诊断结果是正确的，保证了机组的安全，连续运行。     

主/被动流动联合控制技术对高负荷扩压叶栅流场结构及损失的影响*

为精简附面层抽吸结构、提升吸附式压气机的工程应用性,提出将串列叶栅技术与端壁附面层抽吸技术相结合的主/被动流动联合控制技术。以某多级高负荷吸附式压气机末级静子作为研究对象,借助数值模拟的方法,探讨串列叶栅技术、端壁附面层抽吸技术以及主/被动流动联合控制技术对原型扩压叶栅内部流场结构及气动损失的影响。研究结果表明,主/被动流动联合控制技术结合了两种流动控制技术的优势,对原型高负荷扩压叶栅内部复杂流动的控制效果明显优于单一流动控制技术,通过应用更少的附面层抽吸量,有效地抑制了角区失速的促发,缓解了二维叶型分离流动,叶栅出口参数沿展向分布更为均匀,当端壁附面层抽吸总量为进口流量的0.90%时,总压损失降低了59%。