Vegetable cleaning is one of the essential processes in vegetable processing and vegetable production. At present, vegetable cleaning relies mainly on manual processing, and its mechanization procedure is very low. The existing vegetable washing machines have two types: vibration spray type and drum type. There are two cleaning pools in the vibratory spray vegetable cleaning machine. The vegetables are used in the vibratory cleaning pool for repeated movement, and the initial cleaning is carried out. Then the shower pool is sprinkled with clean water to complete the whole cleaning process.
The washing machine has large water consumption and has great damage to leafy vegetables. The main body of the drum type cleaning machine is a tilted metal mesh cylindrical revolving body. The center axis of the cylinder is equipped with a number of spray pipes of the nozzle. The vegetables are scoured by the jet flow at the same time as the cylinder rotates, so as to achieve the purpose of cleaning. The washing machine can only finish the cleaning of root vegetables such as potatoes and potatoes, and the damage to vegetables is large when it is washed. It can not be applied to the cleaning of leafy vegetables. Therefore, a new vegetable washing machine with ultrasonic and bubble as vegetable cleaning power was designed. Experiments show that the cleaning machine can effectively remove the contaminants on the surface of vegetables, and has little damage to vegetables.
In liquid containing many bubbles, the instantaneous pressure will be generated when the bubble collapses and springback is regenerated. When the collapsing bubbles are near the solid boundary of the over current, the high pressure and repeated action produced by the ceaselessly collapsing bubbles in the flow can destroy the surface of the solid, thus producing cavitation. The bubble ruptures near the vegetable surface, and the nearly spherical bubbles move along the jet to the rigid solid surface. As the submerged jet forms a thin layer of flow on the surface of the solid, the lateral flow of liquid flow between the surface of the bubble and the vegetable surface makes the liquid pressure of the bubble wall near the vegetable surface (called the near wall) at the far end (called the far wall), and the velocity of the centripetal movement is slower than that of the other parts. At the center of the bubble moving to the vegetable surface, the distance between the near wall and the vegetable surface is basically the same. In order to maintain the conservation of momentum (without considering the effect of liquid viscosity), the bubbles must be accelerated, the far wall is inward inward, near the near wall, and the near wall is penetrated to form a very high velocity microjet. This micro jet points to the surface of the vegetable. Bad and erosion ability is very strong.
Through calculation and measurement, it is found that when the wandering bubble collapses, the velocity of the micro jet near the solid wall can reach 70~180MPa. Such high dynamic pressure can completely remove the contaminants on the vegetable surface and shorten the cleaning time. Moreover, this is only the pressure of a micro jet on the surface of the vegetable. When the bubbles in the water continue to produce, increase, and disintegrate, the impact pressure of the bubble collapse continuously acts on the vegetable surface, effectively removing the contaminants on the vegetable surface.
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