用Tam-Thies湍流模型研究带小突片的喷管流场特性

Numerical Simulation of Flow Field of Nozzles with Tabs Using Tam-Thies Turbulence Model

首先,采用标准k-ε模型、可实现(realizable)k-ε模型、重正化群(RNG)k-ε模型和Tam-Thies模型4种湍流模型模拟了不同工况下的两种轴对称喷管和带有4片小突片的喷管流场,并将计算结果与实验值进行对比。结果发现:Tam-Thies模型所得出的模拟结果与实验值符合最好。然后,用Tam-Thies模型模拟了小突片后倾角不同的喷管的流场,和没有小突片的喷管的计算结果对比,发现:带有小突片的喷管的尾喷流的核心区长度变短,喷管出口下游气体的混合加剧;而当小突片后倾角增大时,核心区长度先减小后增大;在每个小突片下游产生一对方向相反、强度相同的流向涡,当小突片后倾角增大时,流向涡强度呈现出先增大后减小的趋势,而喷管的引射系数增益和推力损失系数都逐渐减小。

First,the flow fields of two axisymmetric nozzles and a nozzle with four tabs are simulated using different turbulence models：the standard k-ε model,the realizable k-ε model,the renormalization-group（RNG） k-ε model,and the Tam-Thies model.The results are compared with experimental data and it is found that the Tam-Thies model provides the best results that exhibite the closest agreement with the experimental data.Then,the Tam-Thies turbulence model is applied to simulate the flow fields of several nozzles with tabs whose orientation angles varied, and the results are also compared with a nozzle with no tab. The comparison shows that, due to the effect of the tabs, the length of the core zone decreases and the mixing of the shear layer is enhanced. As the orientation angle increases, the length of the core zones decreases first and then increases. A pair of counter-rotating streamwise vortices with the same strength is generated downstreams each tab. As the orientation angle rises, the strength of streamwise vortices increases first and then decreases, while both the entrainment gain of the nozzle and the thrust loss coefficient decrease.