针栓式喷注单元雾化角模型分析

为了实现不同径向孔形的针栓式喷注器雾化角的准确预测，从动量守恒方程出发建立了液膜撞击液膜和液膜撞击液束的雾化角理论修正模型。对于液膜撞击液膜的喷注单元，模型中通过理论推导引入了2个变形因子，将撞击的几何变形效应与雾化角关联；对于液膜撞击液束，通过引入阻塞率定义有效撞击动量比，同时将液束入口孔形的影响隐含考虑在变形因子中，最后根据高速摄影试验结果和数值仿真结果获得了对应的变形因子组合系数，使得新的雾化角模型适应性更广、准确性更高。结果表明：引入变形因子和阻塞率的理论模型预测值与试验及数值仿真结果吻合很好；对于液膜撞击液膜，变形因子基本维持在0.9~1.1，根据试验结果及仿真结果，变形因子推荐值为C₁=0.99和C₂=1.06；对于液膜撞击液束，变形因子推荐值为C₁=0.75和C₂=1.25。该模型根据实际出口的轴向动量和合成总动量计算雾化角，隐含考虑了撞击作用造成的影响，较根据撞击前入口的轴向动量和合成总动量计算雾化角的常用模型预测值准确度显著提高，为针栓式喷注器的理论研究和工程设计提供了重要参考。

Analysis on spray angle model for pintle injector element

In order to accurately predict the spray angle of pintle injector of different radial orifice shapes, the theoretical models of the spray angles of one liquid sheet impinging on another liquid sheet and a liquid sheet impinging on a liquid jet are modified based on the momentum conservation equation. For the injection unit of one liquid sheet impacting another liquid sheet, two deformation factors are introduced in the model by theoretical derivation, which associates the geometric deformation effect of the impact with spray angle. For a liquid sheet impact a liquid jet, the effective impinging momentum ratio is defined by introducing the blocking rate. At the same time, the influence of the inlet hole shape of the liquid jet is implicitly considered in the deformation factors. Finally, according to the results of high-speed photography test and the numerical simulation results, the corresponding combination coefficients of deformation factors are obtained, which makes the new spray angle model more adaptable and more accurate than the original model. The results show that the predicted values of the theoretical model with the introduction of deformation factors and blocking rate are in good agreement with the experimental and numerical simulation results. For one liquid sheet impinging on another liquid sheet, the deformation factors are basically maintained at 0.9~1.1, and the recommended values of the deformation factors are C₁=0.99 and C₂=1.06, according to the experimental results and simulation results. For a liquid sheet impinging on a liquid jet, the recommended values of the deformation factor are C₁=0.75 and C₂=1.25. This model calculates the spray angle according to the actual axial momentum and the actual synthetic total momentum at the exit, which implicitly considers the influence of the impact effect. Compared with the common model that calculates the spray angle based on the axial momentum and the synthetic total momentum at the entrance before the impact, the accuracy of the new model is significantly improved, which provides an important reference for the theoretical research and engineering design of pintle injectors.