受涡轮动、静叶片影响的轴向轮缘密封非定常封严特性研究

Unsteady Sealing Characteristics of Axial Rim Seal Affected by Turbine Vane and Blade

关键词:  涡轮  轮缘密封  燃气入侵  封严效率  非定常流动

Key words:  Turbine  Rim seal  Gas ingestion  Sealing efficiency  Unsteady flow

摘要:

为探究受涡轮动、静叶片单独及共同作用下的轮缘密封结构封严与入侵的精细流动机理，通过SST湍流模型，对处于无叶片、仅存在动叶、仅存在静叶、动静叶均存在的4个不同环境中的典型轴向密封结构进行非定常数值模拟。结果表明：动、静叶片通过改变轮缘密封间隙出口处高、低压区之间的面积与压差，和增加间隙内的再循环及泰勒-库特型流动强度，以及使盘腔内回流涡的位置沿径向下移等方式对间隙和盘腔内的封严性能产生负面影响；且动叶的存在可抬高出流冷气进入主流时的径向高度，静叶的存在可导致入侵区中大尺度间隙涡的出现并使其在近静盘顶部位置的封严性能急剧恶化；相比于无叶片结构，受动、静叶单独及共同作用的间隙中部的最小封严效率分别降低约0.22，0.25和0.44，间隙底部的最小封严效率分别降低约0.08，0.13和0.36。间隙中部及近静盘顶部位置监测点的静压频谱结果显示，无叶片、仅有动叶和仅有静叶结构的特征频率分别为转盘旋转频率的77.7，75.6和60倍，动静叶均存在结构的特征频率则为转盘旋转频率的54倍，对应着转子旋转频率。

Abstract:

In order to investigate the fine flow mechanism of the sealing and ingestion in the rim sealing structure under the effect of turbine vane and blade， URANS simulations using SST turbulence model were used to investigate the characteristics of typical axial rim seal in four different environments with only platform rings model， only blades， only vanes and both turbine vanes and blades. The results show that by changing the area and pressure difference between high and low pressure areas at the outlet of the rim seal clearance， increasing the recirculation and Taylor-Coulter type flow strength in the clearance， and making the position of the backflow vortex in the disk cavity move down radially， both vanes and blades have a negative impact on the sealing performance of the clearance and disk cavity. Besides， the blade can be lifted higher than the radial height when the coolant enters the annulus， and the vane can lead to the appearance of large gap vortices in the invasion area and deteriorate the sealing performance of them near the top of the vane disk. Compared with platform rings model， the minimum sealing efficiency in the mid gap was reduced by about 0.22， 0.25 and 0.44 for the blades and vanes alone and together， and the minimum sealing efficiency in the bottom of gap is reduced by about 0.08， 0.13 and 0.36， respectively. The static pressure spectrum of the monitoring points in the middle of the gap and near the top of the vane disk showed that the characteristic frequencies of the structures only platform rings， blades and vane were 77.7， 75.6 and 60 times of the blade disk rotation frequency，respectively. The characteristic frequency of the structure with both turbine vanes and blades were 54 times the rotating frequency of the blade disk， corresponding to the blade passing frequency.