Study On The Mechanism Of Effervescent Atomization And The Effect Of Ambient Pressure On The Spray Characteristics

Compared with the traditional atomization methods, effervescent atomization has tremendous advantages. So the use of effervescent atomization technology has covered almost all the industrial fields, in addition to the thermal industrial equipment, such as boilers, gas turbines and internal combustion engines, in fire suppression, industrial spray, food drying and other fields also have a wide range of applications. However, the mechanism of effervescent atomization is not yet been fully understood, and there is also no a formula for the spray particle that can be widely accepted.This thesis proposed a new understanding of effervescent atomization process, and divide the effervescent atomization process into three steps. Wherein the first step is the process of the formation of annular liquid film, the second step is the process of the formation of liquid ligament, and the third step is the process of the formation of the final atomization droplets. And view the thickness of the annular liquid film as the key factors in the decision of the ultimately atomized droplets size(represented by SMD).Believe that the film thickness directly determines the range of SMD, the third step just have a revision effet on the final SMD, and the second step is the transition of the first step and the third step. According to the new understanding, this thesis also deduce the formulas of effervescent atomization spray particle from theoretically. The new definition of the effervescent atomization process together with the formulas of spray particle constitute the mechanism of effervescent atomization.In order to prove the formula and the effervescent r atomization mechanism is right, we conducted a lot of experiments. Verified its correctness from angles of gas-liquid mass ratio(GLR), atomization pressure, nozzle outlet hole diameter, atomized liquid viscosity and density as well as gas-liquid mass flow. The results showed that: all the experiments data can comply with the particle formula. This fully shows that the particle formula and mechanism of effervescent atomization is correct.Using a self-designed pressurized atomizing platform, the effect of ambient pressure on the spray characteristics were studied by experiments. Experimental results and theoretical analysis show that: ambient pressure have a very big effect on the effervescen atomization, with the increasing of ambient pressure, spray SMD will be significantly increased, and the ambient pressure have a much larger effect than the atomization pressure on the spray SMD. Meanwhile, ambient pressure also have some influence on the spray angle, with increasing the ambient pressure, the spray cone angle appeared decreas at first, and then increases after the ambient pressure continue rising, and with the increasing of atomization pressure the transition point ambient pressure has a trend to increase.