测量叶轮机振动叶片表面非定常气动响应的实验技术——影响系数法

详细论述了一种适用于叶轮机叶片气动弹性基础性研究的实验技术——影响系数法。以一种简单的方式考虑叶片与叶片之间的气动耦合效应,从而获得叶盘耦合系统在不同叶片间相位角下,叶片表面非定常气动响应(非定常压力和非定常气动功),用于气动弹性机理性研究并校核数值模拟程序。指出影响系数法气动弹性基础实验与传统气动弹性实验的区别,介绍了国外以及作者已经取得的研究成果,其中也涉及到高低速不同流动状态下,叶片表面非定常压力测量的实验设备。通过这一综述,以期推动国内叶轮机气动弹性基础实验的开展,为正在发展的气动弹性数值模拟工具提供详细、有效的实验验证数据。

非定常压力测量中信号失真的管传递函数修正方法(英文)

使用外置压力传感器测量非定常压力会造成非定常测量信号失真。这是由连接外置传感器和测点之间的管道传压系统引成的。阐述了一种修正这种非定常信号失真的方法。从而使得运用外置传感器测量非定常压力成为可能。这种技术使用已知的管传递函数在频域中修正非定常测量信号的失真。同时修正失真信号振幅的变化和相位角的偏移。给出了这种修正技术的运用实例:在叶轮机颤振试验中测量叶片表面非定常压力和在非定常旋涡脱落试验中测量尾迹。

两种动态压力测量装置试验对比研究

针对齐平安装与准无限长管两种动态压力测量装置的结构特征,设计了多种动态压力探针。采用正弦压力发生器进行动态压力特性标定,量化了工程应用中两种结构的不同感压管腔对动态压力测量误差的影响,并在发动机总压畸变试验中进行了对比研究。结果表明,齐平安装结构中,传感器安装引起的小容腔对动态压力测量误差影响不大;准无限长管结构中,感压管腔的存在会导致动态压力幅频特性波动、相位滞后,且波动量与感压管腔长度正相关,相位滞后与感压管腔大小呈线性特征。

高频响气动探针研究综述

为了应对高效发电趋势,提高汽轮机和燃气轮机的效率,必须对动叶流场气动性能进行准确的测量和分析。高频响气动探针可以有效的对涡轮机械中三维非定常流场进行时间分辨测量。而探针的研制主要涉及探头形状、大小,气动腔动态特性,标定以及数据后处理。文中对这几个方面的国内外研究现状和发展趋势进行了详细阐述,总结了它们各自的特点、适用范围和局限性,并指出了今后的研究方向以及难点所在,为相关科研人员进一步开展探针理论分析、数值模拟研究和应用设计提供参考。

低速三角翼滚摆试验研究

对80°和8O°／45°尖前缘平板三角器模型在低速风洞中进行滚摆试验，包括自激滚摆角时间历程测量，强边滚摆流动显示和翼面非定常压力测量。分析滚摆流动机理以及运动参数对涡流场的影响。

基于数字信号处理实现的三维动态探针研制

以气动多孔探头与微型压力传感器为基础的高频响测试技术是进行叶片式转动机械实验研究的主要测试手段,一直是内部流动测试技术研究的国际热点问题。本文从交叉学科的角度出发,尝试采用DSP(动态数据处理)与高频响测试技术的融合,试图将零点漂移、线性度修整、动态海量测试数据储存、增益宽范围可调等先进数据处理方法融为一体,实现高频响测试(总压、静压、速度)的系统化、智能化和便捷化。

脉动背压下涡轮增压离心压气机入口流场试验

为了研究离心压气机在强脉动背压下的入口流场分布,研制了用于非定常流场测量的全自动二维步进装置。使用该装置结合一维热线风速仪测量了不同脉动频率、时均流量下离心压气机入口非定常流场分布。结果表明:背压脉动时,离心压气机入口速度与气流角在周向及径向分布形态均随背压变化呈大幅周期性振荡,且气流角在叶尖处的变化幅度显著高于叶根处。蜗壳上游周向角区内轴向速度显著低于下游,且该周向畸变强度随频率及时均流量增加而增强。径向气流角最大差异出现在约85%叶高处:小流量时最大气流角差异为8°,大流量时为12°。研究探明了脉动背压工况下离心压气机入口流场的非定常演化规律,为针对实际工况的压气机优化设计理论提供了试验基础。

Experimental and Numerical Investigation of the Unsteady Tip Leakage Flow in Axial Compressor Cascade

For convenience of both measurement and adjusting the clearance size and incidence, the current research is mainly conducted by experiments on an axial compressor linear cascade. The characteristics and the condition under which the unsteadiness of tip leakage flow would occur were investigated by dynamic measuring in different clearances, inlet velocities and incidences. From the experiment it is found that increasing tip clearance size or reducing rotor tip incidence can affect the strength of the tip clearance flow. Then the experimental results also indicate the tip leakage shows instability in certain conditions, and the frequency of unsteadiness is great influenced by inflow angle. The condition of occurrence of tip leakage flow unsteadiness is when the leakage flow is strong enough to reach the pressure side of the adjacent blade. The main cause of tip leakage flow unsteadiness is the tip blade loading.

Unsteady Pressure Measurements in a High-Speed Centrifugal Compressor

This paper presents the unsteady data acquisition system used to measure the pressure field in high speed compressors.Details and electronic sketches are given for the conditioners developed in-house that have been used to amplify and to filter the pressure signal with the aim of acquiring data up to 150 kHz.A discussion of the experimental results carried out in a centrifugal compressor is proposed.Through different processing of the pressure signals and a comparison with URANS simulations,the excitation of the pressure transducers by the pressure waves generated by shock waves that occur between the impeller and the diffuser is highlighted.The levels of pressure fluctuations measured when entering into surge are also presented and reveal very repetitive behaviour of the flow instabilities.

Exact Boundary Observability of Unsteady Supercritical Flows in a Tree-Like Network of Open Canals

The author establishes the exact boundary observability of unsteady supercritical flows in a tree-like network of open canals with general topology. An implicit duality between the exact boundary controllability and the exact boundary observability is also given for unsteady supercritical flows.