【作者】 李成勤；

【导师】 黄伟光；

【作者基本信息】 中国科学院研究生院（工程热物理研究所） ， 工程热物理， 2011， 博士

【摘要】 叶顶泄漏流对压气机的性能和稳定性都有着重要影响,近十多年来,人们又发现叶顶泄漏流与压气机的旋转失速现象有着密切的关系,并在近失速的工况下会表现出明显的非定常波动特性。由此促使人们去探究这种泄漏流的非定常特性的流动特征、形成机理进而发掘其与失速之间潜在的联系,以期找到有效的扩稳方法。叶顶泄漏为压力驱动,同时也受到诸多因素的影响,包括叶顶间隙的大小、叶片的负荷、叶片的几何造型、进口气流角、环壁附面层等。但由于在模拟真实流动环境的转子内部测量泄漏流非常困难,而且对于各种影响因素的变化也不方便考察,为了克服这些难题,采用叶栅试验台来研究泄漏流动成为重要的手段。本文以叶栅实验为主要手段,辅以数值模拟,针对两套不同折转角的叶栅的叶顶泄漏流动进行研究,考察叶顶泄漏流的定常流动特征,验证其非定常性的存在及发生条件并分析其非定常波动产生的机理。本文第一部分首先介绍了对本文实验所进行的实验环境的搭建及相关测量手段的完善,包括采用隔板对风洞进口边界层进行处理；设计加工了叶栅间隙可调装置；考核了风洞的品质；选取、调试并确定本文所用到流动显示方法——墨迹法,设计和加工了三孔探针和七孔探针,并建设了一标准校准风洞对二者进行了校准,标定了稳态和动态传感器,采用Labiew编写了数据采集程序等。本文第二部分考察了叶顶泄漏流的定常特性。通过墨迹法、七孔探针等实验手段和数值模拟方法研究了间隙大小、攻角、来流速度和折转角等因素对叶顶泄漏流动的影响,结果表明：(1)间隙增大使泄漏流的起始点明显向下游移动,泄漏流的轨迹逐渐向相邻叶片的压力面移动,同时泄漏涡在展向上的尺度增大。当间隙大到一定程度时,泄漏流会到达相邻叶片的压力面。(2)攻角与来流速度的影响都可归结为流量对泄漏流的影响。随着流量的减小(攻角增大或者来流速度降低),叶顶泄漏流的起始点逐渐向前缘移动,泄漏流轨迹也逐渐向相邻叶片的压力面移动。(3)当叶栅折转角增大时,叶顶泄漏流的轨迹相对于间隙大小、攻角以及来流速度等的变化都会变得不敏感。本文第三部分研究了叶顶泄漏流的非定常特性。通过Kulite动态传感器对叶顶泄漏流的端壁压力进行了测量,并对相应工况进行了非定常的数值模拟,发现(1)叶顶泄漏流在某些工况下存在非定常性。速度及攻角的变化都会影响该非定常性的频率特征,但相对来流速度影响较大。(2)叶顶泄漏流非定常性的发生需要泄漏流轨迹到达相邻叶片的压力面。(3)大折转角有助于抑制泄漏流非定常性的发生。在大折转角叶栅中,即使间隙和攻角较大,泄漏流轨迹依然被限制在叶片通道内,从而阻碍了非定常性的发生。更多还原

【Abstract】 Tip leakage flow has significant effects on the performance and stability of compressor operation. In recent years, it has been found that tip leakage flow is closely related with the phenomena of rotating stall. And tip leakage flow will oscillate unsteadily when compressor is throttled close to the stability limit. In order to develop effective control techniques to delay the onset of rotating stall, the research on the unsteady flow features of tip leakage flow, its triggering mechanism and relationship with rotating stall is motivated.Tip leakage flow is driven by the pressure difference between pressure and suction sides of compressor blade, and is affected by many other factors, such tip clearance size, blade loads, blade shape, inlet flow angle and annular boundary layer. Due to the great difficulty to measure the compressor inner flow field in real rotating environment, and also to consider the effects of different factors, the compressor plane cascade is an important method to study the unsteady tip leakage flow.In this dissertation, the research is mainly conducted by experiments on compressor plane cascade, and numerical simulation also is adopted to validate the experiment results. For two sets of compressor plane cascades with large turning angles, the existence of tip leakage flow unsteadiness is confirmed, and its unsteady flow field features, occurrence condition and triggering mechanism are also explored.In the first section, the construction of the experiment test rig and development of corresponding measurement systems are introduced, during which the inlet boundary layer of wind tunnel is treated by the diaphragm, the adjustable device of cascade tip clearance size is designed and manufactured, the flow quality of the wind tunnel is checked, the ink traces method is used for flow visualization, the three-hole and seven-hole pressure probes are designed and manufactured and a standard wind tunnel is built to calibrate the two probes, the steady and unsteady pressure sensors are calibrated, the data acquisition program is written by the computer language of Labview.In the second section, the steady features of tip leakage flow are investigated. The effects of tip clearance size, attack angle, inlet flow velocity and turning angles on the tip leakage flow is studied by the ink traces method, measurement of seven-hole pressure probes and numerical simulation. The results showed that:(1) The originating location of tip leakage flow moves downstream obviously when the tip clearance size increases. The trajectory of tip leakage flow moves toward the neighboring blade pressure side. And at the same time, the radial range of tip leakage flow also expands. When the tip clearance size is increased to a certain extent, the trajectory of tip leakage flow impinges on the neighboring blade pressure side. (2) The effects of stack angle and velocity of inlet flow on tip leakage flow are equivalent to that of mass flow rate. With mass flow rate decreased (stack angle increased or inlet velocity decreased), the originating location of tip leakage flow moves upstream towards blade leading edge. And the trajectory of tip leakage flow also moves toward the neighboring blade pressure side. (3) When the turning angle is increased, the trajectory of tip leakage flow is not sensitive to the change of tip clearance size, stack angle and inlet velocity.In the third section, the unsteady features of tip leakage flow are studied. The casing pressure is measured by Kulite unsteady pressure transducers. And the numerical simulation is also the conducted for the corresponding operating points. It has been found that:(1) The unsteadiness of tip leakage flow occurs under some certain conditions. The changes of inlet velocity and stack angle will affect the unsteady frequency of tip leakage flow, and the effect of inlet velocity is relatively larger. (2) It is necessary for the occurrence of tip leakage flow unsteadiness that the trajectory of tip leakage flow arrives at the neighboring blade pressure side. (3) The large turning angle will restrain the occurrence of tip leakage flow unsteadiness. For the cascade with large turning angle, even if the tip clearance size and inlet stack angle are larger, the trajectory of tip leakage flow is still restrained within the blade passage. And thus the triggering of tip leakage flow unsteadiness is controlled.更多还原