What are the similar conditions of centrifugal pump impellers?
Similarity theory is widely used in pump design and experiment. Generally speaking, similarity design and model experiment are carried out under the guidance of similarity theory. According to the similarity theory, the model experiment results can be converted to the solid pump, and the parameters of the solid pump can be converted into the parameters of the model, and the model design and experiment can be carried out. Using a small model experiment than the real machine experimental economy much, and due to the limitation of conditions, when the machine size is too large, excessive speed or other special pumping such as high temperature liquid, it is often difficult to analyze real experiments, only with model test generation.
The pump impeller outlet geometry similarity crowding coefficients are equal if the size ratio is not large, meet the centrifugal pump V = eta 'three similar conditions V
Geometric similarityThe two pumps are similar in structure, the same in size, and equal in number of blades and corresponding angles.Motion similarityThe flow rate of the corresponding liquid in the two pumps is similar. The velocity ratio is the same and the direction is the same (i.e. the velocity triangle is similar).Motion similarity is the inevitable result of geometric similarity and dynamic similarity.Dynamic similarityTwo pumps in the corresponding point of the liquid inertia force, viscous force and so on the ratio of the same.To meet the above 3, the two pumps are similar. Generally, two pumps satisfy the similar conditions as long as they meet geometric similarity and motion similarity.Similarity lawSimilar to the conditions of the two pumps, can be approximately similar to two similar pump volume efficiency, hydraulic efficiency, mechanical efficiency equal, at this time there are all kinds of the following set up, known as the law of similarity.
