机匣周向槽对跨声速涡轮叶顶泄漏流结构和气动特性影响的研究

Effects of Circumferential Casing Groove on Tip Leakage Flow Structures and Aerodynamic Characteristics of Transonic Turbine

关键词:  跨声速涡轮级  动叶叶顶  泄漏流控制  机匣周向槽造型  气动特性

Key words:  Transonic turbine stage  Rotor blade tip  Control of leakage flow  Circumferential casing groove configuration  Aerodynamic characteristics

摘要:

为了控制涡轮叶顶间隙泄漏流以改善叶顶区域的流动状况，提出了机匣周向槽造型方法。以典型跨声速涡轮级（Thermal Turbomachinery and Machine Dynamics，TTM）模型为对象，研究了不同高度的机匣周向槽造型对涡轮叶顶流动结构和气动特性的影响。结果表明，引入机匣周向槽造型后，近叶顶涡系结构发生了显著变化，叶顶泄漏涡（TLV）分为前后两部分，TLV-1穿过上通道涡（UPV）并逐渐被消耗，TLV-2则在周向槽之后重新形成并发展至尾缘，导致TLV的强度减弱，尺度减小。此外，由于周向槽的卷吸削弱了马蹄涡压力侧分支（HVP）的强度，加上TLV-1的压制和消耗，UPV更为远离机匣，与TLV的交互作用减弱，其强度减弱，尺度减小。总体而言，随着造型高度增大，叶顶间隙泄漏率逐渐减小，涡轮级总静效率先增大后减小。相比于无周向槽设计，当造型高度为2倍叶顶间隙时，叶顶泄漏率可降低0.15%，涡轮级总静效率可提升0.31%。

Abstract:

In order to control the tip leakage flow and improve the flow field quality of the turbine blade tip， a circumferential casing groove configuration was proposed. Taking the typical transonic turbine stage TTM （Thermal Turbomachinery and Machine Dynamics） as the research object， the effects of circumferential casing grooves （CG） with different heights on tip leakage flow structures and aerodynamic characteristics of turbine were investigated numerically. The results show that due to the introduction of CG， the vortex system topology in the tip region changes a lot. The tip leakage vortex （TLV） is divided into two parts， with the TLV-1 passing through the upper passage vortex （UPV） and being consumed gradually and the TLV-2 rebuilding behind the CG and extending to the trailing edge. As a result， the strength and size of the TLV are reduced. In addition， due to the weakening of the pressure side leg of horseshoe vortex （HVP） caused by the swirling of the CG and the suppression and consumption of the TLV-1， the UPV is far away from the casing and the interaction between the UPV and the TLV is weakened， leading to the reduction of the strength and size of the UPV. Overall， as the height of CG increases， the tip leakage rate decreases gradually， and the total-to-static efficiency of the turbine stage increases first and then decreases. Compared with the casing without any treatment， when the height of CG equals twice the tip gap， the tip leakage rate decreases by 0.15%，and the total-to-static efficiency of the turbine stage increases by 0.31%.