Abstract
Pressure fluctuation may cause high amplitude of vibration of double-suction centrifugal pumps, but the impact of impeller stagger angles is still not well understood. In this paper, pressure fluctuation experiments are carried out for five impeller configurations with different stagger angles by using the same test rig system. Results show that the stagger angles exert negligible effects on the characteristics of head and efficiency. The distributions of pressure fluctuations are relatively uniform along the suction chamber wall, and the maximum pressure fluctuation amplitude is reached near the suction inlet tongue region. The pressure fluctuation characteristics are affected largely by impeller rotation, whose dominant frequencies include impeller rotation frequency and its harmonic frequencies, and half blade passage frequency. The stagger angle exerts a small effect on the pressure fluctuations in the suction chamber while a great effect on the pressure fluctuation in volute casing, especially on the aspect of decreasing the amplitude on blade passage frequency. Among the tested cases, the distribution of pressure fluctuations in the volute becomes more uniform than the other impeller configurations and the level of pressure fluctuation may be reduced by up to 50% when the impeller stagger angle is close to 24° or 36°. The impeller structure pattern needs to be taken into consideration during the design period, and the halfway staggered impeller is strongly recommended.
Highlights
Double-suction centrifugal pumps are widely used in various fields, such as water diversion, farm irrigation, urban water supply, and process industry
This study showed that the impeller–volute tongue interaction and the asymmetric outflow from the impeller are the two main sources of high-level pressure fluctuations
Spence et al [20] numerically simulated a double-suction centrifugal pump with impeller staggered at 0°, 15°, and 30°, and found that the stagger impeller largely affects the characteristics of pressure fluctuation
Summary
Double-suction centrifugal pumps are widely used in various fields, such as water diversion, farm irrigation, urban water supply, and process industry. Chu et al [11, 12] tested a single centrifugal pump; built relationships among unsteady flow, pressure fluctuation, and noise; and inspected the interaction effect between the impeller and the volute. Spence et al [20] numerically simulated a double-suction centrifugal pump with impeller staggered at 0°, 15°, and 30°, and found that the stagger impeller largely affects the characteristics of pressure fluctuation. For such impeller configurations, looking from the pump outlet section toward the twin impellers, the blades of both impellers can be aligned along the exit width or staggered. The influence of impeller stagger angles on pressure fluctuations is obtained successfully
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