atomization technology covers almost all industrial fields, such as transportation, agricultural production, and people's daily life, in addition to various fuels (combustion of gases, liquids and solid fuels), atomization techniques such as granulation, non- Catalytic combustion industrial food processing, powder coatings, spraying pesticides also have a wide range of applications. The atomizing nozzle technology of liquid fuel is currently briefly introduced in the main industrial nozzles
The so-called atomization of liquid refers to the external energy, the physical process of liquid entering the liquid nozzle atomization or other small droplets in the gas environment. There are many explanations for the atomization mechanism, such as pressure shock theory, aerodynamic interference, air disturbance, and turbulent disturbance boundary conditions, which are briefly described as follows:
1 pressure oscillation says
That is a certain influence on the fluctuation of the oscillation pressure observed in the liquid pressure supply system during the atomization process. According to the general system of injection pressure oscillations, it plays an important role in nozzle atomization.
2 pneumatic interference
Castleman first proposed aerodynamic interference, he believes that due to the aerodynamic interference between the jet and the surrounding gas, the surface of the jet is unstable. As the velocity increases, the length of the unstable wave function surface becomes shorter and shorter, up to the order of micrometers, and the jet diffuses into a mist.
3 air disturbance
The air disturbance says that the turbulence disturbance is the opposite method, causing the large-amplitude pressure to disturb the cavitation phenomenon of the fuel injection system to cause nozzle atomization.
4 turbulent flow
Turbulence says that the jet atomization process takes place inside the nozzle and the turbulence itself with the fluid may play an important role. Some people think that the velocity of the radial fluid nozzle in the turbulent motion of the tube immediately causes disturbance at the nozzle outlet, resulting in atomization.
5 Mutation of boundary conditions.
The abrupt changes in the boundary conditions at the outlet of the industrial nozzle say that the boundary condition (stress) of the liquid is abrupt; or the laminar jet protrudes from the constraint of losing the wall, resulting in a sudden change in the velocity profile of the section resulting from atomization. The assumptions of the above five mechanisms of the nozzle are not enough or even contradictory. Most scholars, such as braccofv, support the aerodynamic interference. Assuming that the development is more adequate and better explained the reason for the low-speed jet fracture, this reasoning high-speed jet can be used for the basic reasons of nozzle atomization. At present, the research on the atomization mechanism of fuel injection nozzles mainly comes from two aspects: one is the calculation technology, the various hypothesis models are established, and the numerical simulation is used; on the other hand, the photoelectric test technology uses advanced capture to the detailed In order to provide a hypothetical or comprehensive support during nozzle atomization