Abstract: A study is presented to understand both the flow characteristics and the vibration characteristics of the in-line circulator pump with different blades numbers. The 3D unsteady flow numerical simulations are executed both on 6 blades and 7 blades of in-line circulator pumps for successfully capturing the flow characteristics inside the impeller, static pressure characteristics inside the volute and torque fluctuation characteristics of impeller, in the different flow rates conditions, which is based on the standard k-ε turbulence model and sliding mesh technique provided by CFX. In comparison with numerical simulation results of both two different blades numbers in the condition of 0.1qV, the findings show that both the “jet-wake” effect and gradient of static pressure of 6 blades are higher than 7 blades’, and the amplitude of torque fluctuation of 6 blades is higher than 7 blades’. Moreover, the laws of both relative velocity changes and static pressure changes inside the impeller and the law of low pressure region changes near the tongue of the volute, which are corresponding to the relative position changes between the tongue and the blade. Additionally, the experimental vibration tests are conducted to measure the vibration level of in-line circulation with different blades numbers. By analyzing the experimental results and simulation results, it is revealed that vibration amplitudes of 6 blades are higher than 7 blades’ in different flow rates conditions because of stronger pressure pulsation and unsteady fluid forces, and blade passing frequency and its harmonic are the domain active frequencies for the pump vibration. Therefore, both the unsteadiness of flow and vibration level of in-line circulator pump can be reduced by means of optimizing the blade parameters(Z, β2, β1).

Key words: Blades numbers, Flow characteristics, In-line circulator pump, Vibration characteristics