基于虚拟风室模型的排气引射流动三维流场的数值计算

Numerical Analysis of 3D Entrainment Flow: Virtual Wind Chamber

提出了一种虚拟风室模型,以精确计算引射器在各种主流速度下的引射空气量.在数值建模中,将引射器置于一个仅具有主流和引射入口的虚拟整流风室内,通过人工调整引射入口空气流量直至引射器附近监测面积的平均总压与环境大气压相等,以预测该环境下引射器的引射空气量.求解了全三维N-S方程和k-ω湍流模型,并采用多孔介质模型处理虚拟风室内的整流格栅,对不同主流速度下的引射流动进行了数值模拟.结果表明,引射空气量的计算值与已有文献实验测量结果之差小于7%,所采用的虚拟风室模型能有效预测大气环境下的引射流量.并通过流向涡和正交涡等理论对引射流动的卷吸和掺混进行了分析.

A virtual wind chamber was proposed to accurately predict entrainment rate of the ejector at variable mainstream speed. The ejector is placed inside a virtual wind chamber, which is characterized by a mainstream inlet and a secondary entrainment port; the so-called entrainment flow rate is determined until the area-averaged total pressure of the entrained fluid near the ejector is equal to that at the outlet of the diffuser. The flow field at different mainstream speed was predicted by solving the 3D Navier-Stokes equation set and k-ω turbulence model. In addition, the porous zone model was used to include the influence of the honeycomb on the flow field, which straightens the flow field in the wind chamber. The discrepancy between the calculated entrained flow rate and previous experimental measurements is less than 7%, indicating validity of the virtual wind chamber. Further more, the entrainment and mixing processes were extensively analyzed in terms of streamwise vortices and normal vortices.