压气机叶尖泄漏流动中基于旋转的κ-ε模型修正

Modification of Realizable κ-ε Model for Tip-leakage Flow in an Axial Compressor Rotor

本研究采用了Realizable k-ε模型(RKE)对低速大尺寸压气机转子的叶尖泄漏流动进行模拟,并提出了一种新的湍流模型修正思路,在湍动能输运方程中将旋转效应引入生成项,从而改善模型对湍动能输运特性的模拟。本文对比了数值模拟与实验的结果,通过对使用修正前后模型得到的平均流场和湍流场进行分析,可以发现原始RKE模型无法准确预测泄漏流动中的湍流结构,基于螺旋度修正模型得到的流场湍流特性与实验结果更为接近,湍动能的生成得到加强,分布也更为合理。这表明在叶尖泄漏流动中,湍流的非平衡输运特性起到了非常大的作用。

A new method of modifying the Realizable k-ε(RKE) model for tip-leakage flow is proposed in this paper. The production term is modified using mean rotation rate and normalized helicity. A set of numerical simulations employing the original and modified RKE models are carried out on an axial compressor rotor. The results of the calculations are compared with experimental results, focusing on mean flow field and turbulent quantities. The measurements show high level of turbulent kinetic energy and high anisotropy in the tip-leakage flow which cannot be simulated precisely by eddy-viscosity turbulence models. The modified model can significantly correct the prediction of turbulent kinetic energy and its transport process by enhancing the turbulence production in the center of the tip-leakage vortex. This indicates that the non-equilibrium transport process is important in the tip-leakage flow.