无导叶对转涡轮高压级动叶换热特性的研究

发布时间：2018-09-11 19:48

【摘要】：由于在提高推重比等方面的潜在优势,无导叶对转涡轮将会在未来高性能推进系统中发挥重要作用。根据气动布局特征,无导叶对转涡轮高压级具有高负荷和高反力度的特点,在此情况下,气流在高压级动叶内的膨胀程度很高,出口相对马赫数会达到1.3-1.5,动叶叶道内气流的高加速性以及与之相关的激波结构势必会对动叶表面的换热特性产生重要影响。为了研究无导叶对转涡轮高压级动叶的换热特性,本文研制了适用于旋转测量的双面薄膜式热流计,组建了高速旋转动态测量系统,并发展了相应的薄膜式热流计设计和旋转测量方法。在上述工作基础上,本文依托于中国科学院工程热物理研究所(IET)短周期涡轮试验台开展了对全尺寸无导叶对转涡轮试验件的高速旋转换热试验,并结合试验结果和CFD对无导叶对转涡轮高压级动叶在不同进口雷诺数下的换热特性进行了研究。本文涉及的主要研究内容及结论如下:1.系统的分析了薄膜式热流计薄膜厚度对热流计性能的影响,分析表明膜厚增加有利于提高信噪比,但是会导致高频热流结果所被引入的不确定度增大。本文提出了一种基于系统辨识理论的动态标定方法,能够有效降低薄膜厚度增加对高频热流结果所造成的影响。2.基于磁控溅射技术研制了双面薄膜式热流计,并形成了完整的设计、制造和标定方法,同时基于数字遥测技术组建了高速旋转动态测量系统,并在此基础上发展了适用的旋转测量方法。实践表明整个旋转测量系统运行可靠,各项参数均能够满足实际应用需求。3.基于全尺寸高速旋转换热试验结果和CFD对无导叶对转涡轮高压级动叶的静态换热特性进行了分析,发现吸力面气流加速极快,局部加速系数K会超过3×10-6,此时边界层具备"再层流化"的条件。在气流的强加速性下,动叶叶表边界层在吸力面大部分区域维持为层流边界层,这导致吸力面叶表换热从前缘开始随着边界层增厚而不断降低。在吸力面后半段,相邻叶片尾缘投射的斜激波与叶表发生干涉而致使边界层分离,这直接促成边界层由层流转捩为湍流,即发生"分离转捩",此时叶表换热会急剧升高。同时,随着进口雷诺数增加,吸力面表面的换热会整体增强,尤其对于分离转捩之后的湍流边界层,换热的增强效应更加明显。4.基于全尺寸高速旋转换热试验结果对无导叶对转涡轮高压级动叶的动态换热特性进行了研究,发现在吸力面前半段,叶表换热随着上游导叶排尾迹的通过会呈现出明显的周期性脉动现象。随着尾迹向下迁移,尾迹所引起的局部湍流区逐渐变宽,叶片后半段换热会因尾迹而持续得到增强,但周期性脉动现象会得到减弱。在吸力面后半段,叶片表面的换热除了受上游尾迹的影响外,还会受到下游叶排的影响。同时,随着进口雷诺数的增加,吸力面叶表非定常换热的脉动幅值会整体降低。
[Abstract]:Because of its potential advantages in improving the ratio of thrust to weight, the unguided vane pair turbine will play an important role in the future high performance propulsion system. According to the characteristics of aerodynamic layout, the unguided vane has the characteristics of high load and high reactivity to the rotating turbine high pressure stage. In this case, the expansion degree of the airflow in the high pressure turbine stage is very high. The relative Mach number of the outlet will reach 1.3-1.5. The high acceleration of the airflow and the associated shock wave structure will have an important influence on the heat transfer characteristics of the moving blade surface. In order to study the heat transfer characteristics of rotating turbine high pressure stage moving vane without guide vane, a double side thin film heat flow meter suitable for rotating measurement is developed in this paper, and a high speed rotating dynamic measuring system is constructed. The design and rotation measurement method of thin film heat flow meter are developed. On the basis of the above work, the high-speed rotating heat transfer test of full-size non-guide vane rotating turbine was carried out on the (IET) short-period turbine test-bed of the Institute of Engineering Thermal Physics of the Chinese Academy of Sciences. Combined with the experimental results and CFD, the heat transfer characteristics of the unguided vane counterrotating turbine high pressure moving vane at different inlet Reynolds numbers were studied. The main contents and conclusions of this paper are as follows: 1. The effect of film thickness on the performance of thin film heat flux meter is analyzed systematically. It is shown that the increase of film thickness is helpful to improve SNR, but the uncertainty of high frequency heat flux is increased. In this paper, a dynamic calibration method based on system identification theory is proposed, which can effectively reduce the effect of film thickness increase on the results of high frequency heat flux. Based on the magnetron sputtering technology, a double-sided thin film heat flux meter is developed, and a complete design, fabrication and calibration method is formed. At the same time, a high-speed rotating dynamic measurement system is constructed based on the digital telemetry technology. On this basis, a suitable rotation measurement method is developed. Practice shows that the whole rotating measurement system is reliable and all parameters can meet the practical application requirements. 3. Based on the results of full-scale high-speed rotating heat transfer test and CFD, the static heat transfer characteristics of the high pressure rotor blades of a turbine with no guide vane are analyzed. It is found that the suction surface airflow accelerates extremely quickly. The local acceleration coefficient K will exceed 3 脳 10 ~ (-6), and the boundary layer has the condition of "relayer fluidization". Under the strong acceleration of airflow, the blade surface boundary layer is maintained as laminar flow boundary layer in most areas of suction surface, which leads to the decrease of blade surface heat transfer from the front edge to the thickening of the boundary layer. In the latter half of the suction surface, the oblique shock projected from the tail edge of the adjacent blade interferes with the blade surface and results in the separation of the boundary layer, which directly contributes to the boundary layer transition from laminar flow to turbulence, that is, "separation transition", in which the heat transfer on the blade surface increases sharply. At the same time, with the increase of inlet Reynolds number, the heat transfer on the surface of suction surface will be enhanced as a whole, especially for turbulent boundary layer after separation transition, the enhancement effect of heat transfer is more obvious. Based on the results of full-scale high-speed rotating heat transfer test, the dynamic heat transfer characteristics of the high pressure rotor blade of a turbo with no guide vane are studied. It is found that in front of the suction, the dynamic heat transfer characteristics of the rotor blade are studied. The heat transfer of the blade surface shows obvious periodic pulsation with the passage of the upstream guide vane wake. With the wake moving downwards, the local turbulence caused by the wake gradually widens, and the heat transfer in the second half of the blade continues to increase because of the wake, but the periodic pulsation will be weakened. In the latter half of the suction surface, the heat transfer on the blade surface is affected not only by the upstream wake, but also by the downstream blade row. At the same time, with the increase of inlet Reynolds number, the pulsation amplitude of unsteady heat transfer on the suction surface blade surface will be reduced as a whole.
【学位授予单位】：中国科学院工程热物理研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：V231.1

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