Numerical Investigation of Pressure Fluctuation Characteristics in a Centrifugal Pump with Variable Axial Clearance

Abstract

Clearance flows in the sidewall gaps of centrifugal pumps are unsteady as well as main flows in the volute casing and impeller, which may cause vibration and noise, and the corresponding pressure fluctuations are related to the axial clearance size. In this paper, unsteady numerical simulations were conducted to predict the unsteady flows within the entire flow passage of a centrifugal pump operating in the design condition. Pressure fluctuation characteristics in the volute casing, impeller, and sidewall gaps were investigated with three axial clearance sizes. Results show that an axial clearance variation affects the pressure fluctuation characteristics in each flow domain by different degree. The greatest pressure fluctuation occurs at the blade pressure surface and is almost not influenced by the axial clearance variation which has a certainly effect on the pressure fluctuation characteristics around the tongue. The maximum pressure fluctuation amplitude in the sidewall gaps is larger than that in the volute casing, and different spectrum characteristics show up in the three models due to the interaction between the clearance flow and the main flow as well as the rotor-stator interaction. Therefore, clearance flow should be taken into consideration in the hydraulic design of centrifugal pumps.

Pressure fluctuation characteristics in the sidewall gaps of a centrifugal dredging pump

“…Besides Points VC1-VC3, we simultaneously calculated and analyzed the pressure fluctuation at several points in the sidewall gaps. From our previous research (Cao et al , 2016), the strongest pressure fluctuation in the volute casing occurs near the tongue (at Point VC3 in Figure 4), and the peak–peak amplitude circumferentially decreases from the tongue to the beginning of the diffusing section and that in the diffusing section gradually increases again until the outlet. In this research, we found that the pressure fluctuations at some locations of the sidewall gaps were larger than those in the volute casing.…”

“…Based on the previous research (Cao et al , 2015; Cao et al , 2016), this paper presents a more detailed numerical study on the pressure fluctuation characteristics in the sidewall gaps of a centrifugal pump operating in a condition near the design point. The numerical model was validated by a model test conducted in a closed hydraulic machinery test rig in China Water Resources Beifang Investigation, Design and Research Co., Ltd. (Zhang, 2013).…”

The effect of wear ring clearance on flow field in the impeller sidewall gap and efficiency of a low specific speed centrifugal pump

“…Additionally, in order to model the rotor-stator interaction a frozen rotor model was utilized based on the satisfactory results in previous water pump simulations. 44,45…”

Influence of wall roughness on the static performance and pressure fluctuation characteristics of a double-suction centrifugal pump

“…Inside the pumps are several types of unsteady phenomena with different time scales, such as jet-wake flow pattern in the impeller outlet, recirculation and, eventually, a rotating stall at off-design operating conditions. 1,2 Similar to the flow within a pipe or over a flat plate, energy losses in a centrifugal pump depend on Reynolds number and relative surface roughness. Thus, the efficiency of a centrifugal pump is affected by many parameters such as size, speed, viscosity, and roughness.…”