When using an air atomizing nozzle, controlling the gas-liquid flow rate plays a crucial role in the spray angle, particle uniformity and flow rate of the nozzle. So how to control the gas-liquid flow?
Taking the working condition of the gas-liquid mass flow ratio of 23% as an example, it can be seen that the air enters the nozzle and is compressed and accelerated in the nozzle. At the fan-shaped orifice, the fluid is fully squeezed and accelerated again. When it reaches the nozzle outlet (X=21.5mm), the velocity reaches the maximum value of 166m/s. After the air is ejected from the nozzle, it interacts with the surrounding air, resulting in an obvious entrainment phenomenon. After that, the airflow velocity gradually decreases due to the dissipation effect of the external gas. In the gas flow mixture, the greater the proportion of gas phase, the greater the kinetic energy of the gas-liquid mixture. As the gas-liquid mass flow ratio increases, the velocity of the airflow on the axis also increases: when the gas-liquid mass flow ratio is 17%, the airflow velocity at the nozzle outlet is 125m/s; when the gas-liquid mass flow ratio increases to At 28%, the airflow velocity at the nozzle outlet can reach 209m/s.
As mentioned above, in the case of a certain nozzle orifice width, the larger the proportion of gas in the gas-liquid mixture, the greater the kinetic energy of the mixture, the more fully the liquid is broken, and the smaller the resulting droplets will be. , but the droplet diameter is not always inversely proportional to the gas-liquid mass flow ratio. When the width of the nozzle orifice is 0.6mm, the SMD at 20mm from the nozzle outlet decreases gradually with the increase of the gas-liquid mass flow ratio. When the SMD reaches the minimum value, it starts to increase again. The minimum value of the SMD is about 39.5um. Therefore, in the actual application process, in order to obtain a good droplet size distribution, an appropriate gas-liquid mass flow ratio should be selected according to the actual nozzle orifice width.
