本研究使用OpenFOAM建立適用於不同噴嘴幾何和工作流體三維數值模型，配合多相流模型中之流體體積法(Volume of fluid,VOF)描述兩相間界面，並且考慮表面張力之作用，以及採用大渦模型(Large eddy simulation)模擬紊流流場，在計算中使用自適應網格法(Adaptive mesh refinement,AMR)加密網格得到清晰的界面和減少計算所需資源。另外將噴嘴內外的流場以尤拉 - 尤拉描述法並使用流體體積法(VOF)進行模擬，雖能準確捕捉噴嘴內外之流動情形，但在描述兩相界面時或進行後續大尺度的計算時需要耗費大量計算資源。因此本研究藉由把液相之流體體積耦合成拉格朗日粒子，並加入破裂模型來模擬噴霧二次破裂，取得噴霧中粒子參數的資訊來分析粒徑大小和分布。
由模擬結果在噴嘴不同高度截面採樣所得到切向速度和渦度分布可將噴嘴內部流場區分出邊界層、位勢錐和空氣柱之區域。在空氣柱區域氣體受到液體的帶動而旋轉往下噴出，而在噴嘴中心處會將外部空氣吸進噴嘴以滿足質量守恆。當液體噴出後，液膜受到渦流拉伸之影響，隨著旋轉半徑隨著越往下游增加導致沿中心軸轉動趨勢逐漸減緩，最後液膜將漸漸變薄且不再旋轉僅朝徑向方向前進。觀察模擬噴霧中存在直向以及橫向交錯排列之韌條，直向韌條為液膜上受橫向傳遞不穩定性影響所形成，而橫向韌條則為受直向傳遞不穩定性影響所形成。針對模擬噴霧二次破裂結果發現使用Pilch-Erdman模型及Reitz-Diwakar模型噴霧D32之值相近，主要原由為模擬中噴霧粒子之Oh數皆小於液滴受黏性影響之標準。

In this study, we use OpenFOAM to create a three-dimensional numerical model applicable to different injector geometries and working fluids. The model incorporate the Volume of Fluid method for multiphase flow, considering surface tension effects. Large Eddy Simulation captures turbulent flow, while adaptive mesh refinement (AMR) refines grids. By coupling VOF with Lagrangian particles, we simulate secondary breakup in droplets through Pilch-Erdman and Reitz-Diwakar breakup model. The calculation results show the same trend as the experimentally measured spray angle and Sauter mean diameter.
As the liquid is ejected, the liquid film is stretched by vortices. The rotational radius increases downstream, leading to a gradual decrease in rotational trend along the central axis. Eventually, the liquid film thins out and ceases to rotate, advancing only in the radial direction. The simulated spray exhibits longitudinal and transverse interlaced ligaments. The longitudinal ligaments are formed due to the influence of transverse instability on the liquid film, while the transverse ligaments result from the influence of longitudinal instability. Regarding the secondary breakup of the spray, it is found that using the Pilch-Erdman model and the Reitz-Diwakar model yields similar values for the spray D32.This similarity is primarily because the Ohnesorge number of the spray particles in the simulation is below the threshold where droplet viscosity effects become significant.

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