| After the jet fuel enters the combustion,it is broken and atomized under the combined action of aerodynamic force,surface tension and viscous force,forming droplets to accelerate the evaporation.The initial atomization process is hard to accurately summarize the law due to the complicated gas flow,short occurrence time and the influence of various forces.This paper uses a combination of experiment and numerical simulation to study the phenomenon of cross jet atomization in non-uniform flow field.An experimental system is designed to construct two non-uniform flow fields,shear mode and rotation mode.The gas flow velocity is 10-30 m/s,the liquid velocity is 4-9 m/s,the jet angle is-15°～15°,and the experiment liquids are water and glycerin.The research results are as follows:The axial and longitudinal column breaking position and the liquid to air momentum ratio of the shear-laden crossflow field satisfy the exponential function relationship,the longitudinal breaking position has a more obvious change range.The penetration depth and air momentum ratio also satisfy the exponential function relationship,and the relationship between longitudinal and axial displacement is roughly a quadratic function.Increasing the up to down air velocity ratio from 0.5 to 2,the penetration depth and breakup position increase,the negative gradient shear-laden crossflow field accelerates the jet breakup.Increasing the jet angle from-15° to 15°,the axial breakup position increases,the longitudinal breakup distance first increases and then decreases,the 0°jet angle reaches its maximum value,and the upwind longitudinal breakup distance is reduced by 52.44% ～ 77.13%.The initial breakup diameter is 0.468～1.007 times the nozzle diameter;Increasing the jet viscosity,the initial breakup diameter of the droplets increases,and the liquid column breakup mode does not change.The swirling crossflow field is axisymmetrical,forming a recirculation zone in the central of the flow field.Increasing the swirl number from 0.49 to 1.25,the position of the recirculation zone moves forward,and its length decreases.As the radius of the swirling crossflow field increases,the axial velocity firstly decreases,then increases and end of decreasing,the tangential velocity increases slowly and then decreases rapidly,the radial velocity gradually increases and decreases slowly,which is one order of magnitude less than the axial velocity.Increasing the inlet velocity from 10m/s to 20m/s,the axial velocity in the main flow direction and the counter-main flow direction will increase,whose direction changes in the 40%-60% longitudinal distance;The tangential velocity increases,and the maximum position gradually approaches the center of the flow field.The three liquid column breaking positions and the liquid to air momentum ratio of the swirling crossflow field satisfy the exponential function relationship,so as the penetration depth.The liquid to air momentum ratio has the greatest influence,and the penetration of the xz plane changes significantly more than the yz plane.In this paper,the non-uniform characteristics of the shear-laden crossflow and swirling crossflow are finally obtained,so as the basic laws and dominant factors of the liquid jet breakup under the above-mentioned non-uniform flow field,which provides an important reference for the design of the combustion chamber atomization device. |
