Abstract
In order to understand the pressure fluctuation characteristics of a semi-open cutting pump, the three-dimensional unsteady flow fields were calculated. External and internal flow characteristics of four schemes with different relative angles between the rotary cutter and the impeller were studied. The pressure fluctuations in the lower plate, the upper plate, the clearance between the rotary cutter and the fixed cutter, the first section in volute and nearby parts of the tongue were all analyzed, which are all the places that pressure distributions are greatly affected by the static and dynamic interaction, and at the same time, the force on the impeller was also analyzed. The results show that the fluctuations at different positions change periodically; the main frequency is blade frequency. The amplitude of pressure fluctuation decreases from near the rotating part to far away, from near the tongue to far from the tongue. Due to the influence of both impeller and rotary cutter, the pressure fluctuation on the lower plate is the largest. The pressure fluctuation is affected by flow rate, the larger the flow rate, the greater the pressure fluctuation. The radial and axial forces of the impeller change periodically with time, and the number of wave peaks and wave valleys is the same as the number of blades.
Highlights
Sewage pumps are widely used in municipal engineering, environmental protection engineering, power industrial engineering, sewage treatment station, mining, metallurgy, medical and health services and many other industries
In order to improve the force on the impeller of single blade spiral centrifugal pump, Yuan et al [3] used a numerical simulation method to calculate the internal flow field of the pump, and the characteristics of pressure pulsation at the outlet of spiral centrifugal pump and the radial force acting on the impeller and volute were obtained
The experimental pump is of semitheimpeller, number the of impeller is three, andisthe number of number rotary cutter blades is three
Summary
Sewage pumps are widely used in municipal engineering, environmental protection engineering, power industrial engineering, sewage treatment station, mining, metallurgy, medical and health services and many other industries. Compared with traditional sewage pumps, the semi-open cutting pump is not easy to be blocked, which can be used to transport sewage, waste water, rainwater and urban domestic water containing solid particles and various fibers. As a kind of rotating machinery, the semi-open submersible cutting pump faces with vibration, noise, operation instability and other problems, these problems are related to the unsteady pressure fluctuations in the pump cavity, namely the axial and radial forces. Adkins et al [1] and Barrio et al [2] studied the radial force distribution of a centrifugal pump rotor through theoretical analysis and numerical calculation. González et al [4] Barrio et al [5] Solis et al [6] studied the radial force characteristics of the impeller and the pressure fluctuation at the tongue under different tongue clearance conditions of a centrifugal pump. It was found that the changes of tongue clearance had a great influence on the radial force
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