低雷诺数涡轮流动损失控制技术

Control of separation losses on turbine blade with low Reynolds number

关键词:  涡轮喷气发动机  涡轮叶片  流动分布  流动特性  控制

Key words:  Turbojet engine  Trubine blade  Flow distribution  Flow characteristic  Control

摘要:

针对高空、低雷诺数条件下涡轮损失显著增大、效率显著降低的问题, 应用理论分析与数值计算相结合的方法, 从流动控制原理、设计方法、流场数值计算等多个方面研究了“微球窝” (Dimple) 流动控制技术在航空燃气涡轮中应用的问题, 分析了“微球窝”表面处理控制流动分离的基本原理, 数值计算表明, 围绕球窝周围的气流参数具有明显的变化, 球窝对叶片表面流动过程的扰动, 使得流动分离点向后推移, 雷诺数在 12208 ~15611范围的流动情况, 分离点分别向后推迟 3% ~5%的叶片弦长。

Abstract:

The Reynolds number of turbine, especially the low-pressure turbine, of turbofan engine is very low during the long loiters at high altitudes for the Unmanned Aerial Vehicles (UAVs), and this low Reynolds number results in the notable drop of efficiency of turbine. The objective of the present work was to explore the control method of flow separation on the turbine blades with the low Reynolds number. In the current investigation, the available and contemplated flow-control methods particularly suited for low-Reynolds number airfoils were first surveyed. Dimpled blade, which is one of the surface treatments based on the golf-ball dimple structure, was investigated in present study. The horseshoe vortices created behind the dimples are the main cause for the delay and elimination of flow separation. Numerical simulation results for the dimpled airfoil of the mid-span section of the low-pressure turbine rotor blade of a turbofan engine are inspiring.