In order to reduce the axial force on centrifugal pump impeller, it is a common measure to set sealing ring and balancing hole structure on the outside of centrifugal impeller rear cover plate. In this paper, based on the pressure distribution law of rotating fluid and through mathematical analysis and calculation, the quantitative calculation method of leakage of this structure is obtained, and the calculation theoretical formula of axial force is derived, which proves that this structure can achieve the purpose of reducing axial force. The research results are helpful to avoid blindness in the design of impeller balancing mechanism and provide reference for correctly determining the relevant geometrical dimensions of impeller.
A centrifugal pump with good performance must have not only good hydraulic performance, but also expected service life. In some continuous running production lines, such as chemical and metallurgical industries, customer requirements for reliability of critical equipment even become the main indicator for equipment selection. The stress state of parts of centrifugal pump is complicated, and the external force of some parts can reach a high order of magnitude. This is the main reason why some parts of pump, such as bearings, seals and keys, break and fail early and shorten the maintenance period of pump seriously. Therefore, high-speed rotating impellers must be corrected for dynamic balance.
When the liquid flows through the impeller, the mechanical energy of the fluid increases as the impeller works on it, and the main form of energy increase is pressure energy. The high pressure at the impeller outlet forms an axial force distribution system acting on the outside of the front and rear cover plates of the impeller with a certain distribution law in the front and rear pump cavities of the pump. Because of the asymmetry of the front and rear covers, the opposite axial forces on the outside of the front and rear covers cannot be balanced with each other, resulting in an axial force acting on the suction direction of the impeller. This axial force can not be neglected especially in high-lift low-specific-speed pumps or large-size pumps. There are several hydraulic methods to reduce the axial force of the impeller. Setting balance holes and sealing rings in the rear cover plate of impeller is a common method to achieve this goal. However, for a long time, the designer's understanding of this effective structure has remained in the qualitative stage. Up to now, no quantitative analysis of the reduction effect of this structure on axial force has been seen.
There are many reasons for unbalance of centrifugal impeller during its use, such as wear and scaling of impeller. Whether the impeller is treated by thermal spraying or by various methods, its effect will not last forever. After long-term use, the vibration will still exceed the permissible upper limit order. At this time, the imbalance of impeller can only be solved by dynamic balance correction.
A centrifugal pump with good performance must have not only good hydraulic performance, but also expected service life. In some continuous running production lines, such as chemical and metallurgical industries, customer requirements for reliability of critical equipment even become the main indicator for equipment selection. The stress state of parts of centrifugal pump is complicated, and the external force of some parts can reach a high order of magnitude. This is the main reason why some parts of pump, such as bearings, seals and keys, break and fail early and shorten the maintenance period of pump seriously. Therefore, high-speed rotating impellers must be corrected for dynamic balance.
When the liquid flows through the impeller, the mechanical energy of the fluid increases as the impeller works on it, and the main form of energy increase is pressure energy. The high pressure at the impeller outlet forms an axial force distribution system acting on the outside of the front and rear cover plates of the impeller with a certain distribution law in the front and rear pump cavities of the pump. Because of the asymmetry of the front and rear covers, the opposite axial forces on the outside of the front and rear covers cannot be balanced with each other, resulting in an axial force acting on the suction direction of the impeller. This axial force can not be neglected especially in high-lift low-specific-speed pumps or large-size pumps. There are several hydraulic methods to reduce the axial force of the impeller. Setting balance holes and sealing rings in the rear cover plate of impeller is a common method to achieve this goal. However, for a long time, the designer's understanding of this effective structure has remained in the qualitative stage. Up to now, no quantitative analysis of the reduction effect of this structure on axial force has been seen.
There are many reasons for unbalance of centrifugal impeller during its use, such as wear and scaling of impeller. Whether the impeller is treated by thermal spraying or by various methods, its effect will not last forever. After long-term use, the vibration will still exceed the permissible upper limit order. At this time, the imbalance of impeller can only be solved by dynamic balance correction.
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