This study investigated the effects of backpressure and operating conditions on the self-pulsation characteristics of a liquid-centred swirl coaxial (LCSC) injector. To this end, a three-dimensional numerical simulation via octree adaptive mesh refinement as well as coupled level-set and volume of fluid method were employed. Self-pulsation is suppressed by backpressure for a constant gas–liquid momentum flux ratio (MFR). When backpressure is constant, the strength of self-pulsation varies with the mass flow rate of the gas (${\dot{m}}_g$), which is constant with experimental data due to the variation in the flow patterns in the recess chambers. The self-pulsation frequency increases with backpressure and ${\dot{m}}_g$. The trends of the spray angle and intensity of self-pulsation are consistent. As backpressure increases, the radial distribution of the mass flow rate of the liquid changes from a double- to single-peak. The central mass flow rate increases with backpressure and ${\dot{m}}_g$, which also affect the pressure oscillations inside and outside the liquid film in the injector. We proposed a self-pulsation mechanism, in which self-pulsation is closely related to the dominant surface wave and Kelvin–Helmholtz (K–H) instability. Self-pulsation under the critical mixing flow pattern is stronger than that under inner or outer mixing flow patterns. Under the critical mixing flow pattern, the K–H vortex is relatively strong, and the spray oscillation is not restricted by the wall of the recess chamber.

这项研究调查了背压和工作条件对液心旋流同轴（LCSC）喷油器自脉冲特性的影响。为此，采用了八叉树自适应网格细化的三维数值模拟，以及液位和体积的耦合方法。对于恒定的气液动量通量比（MFR），背压可抑制自脉动。当背压恒定时，自脉动的强度会随气体的质量流量而变化（${\dot{米}}_G$），由于凹室中流动模式的变化，该值与实验数据一致。自脉动频率随着背压的增加而增加。${\dot{米}}_G$。喷雾角度和自脉动强度的趋势是一致的。随着背压的增加，液体质量流率的径向分布从双峰变为单峰。中心质量流率随着背压的增加而增加。${\dot{米}}_G$，这也会影响注射器中液膜内部和外部的压力振荡。我们提出了一种自脉冲机制，其中自脉冲与主表面波和开尔文-亥姆霍兹（K-H）不稳定性密切相关。临界混合流模式下的自脉动要强于内部或外部混合流模式下的自脉动。在临界混合流模式下，K–H涡旋相对较强，并且喷雾振荡不受凹室壁的限制。