Abstract
The current investigation is aimed to simulate the complex internal flow in a centrifugal pump impeller with six twisted blades by using a three-dimensional Navier-Stokes code with a standardk-εtwo-equation turbulence model. Different flow rates were specified at inlet boundary to predict the characteristics of the pump. A detailed analysis of the results at design load,Qdesign, and off-design conditions, Q = 0.43Qdesignand Q = 1.45Qdesign, is presented. From the numerical simulation, it shows that the impeller passage flow at design point is quite smooth and follows the curvature of the blade. However, flow separation is observed at the leading edge due to nontangential inflow condition. The flow pattern changed significantly inside the volute as well, with double vortical flow structures formed at cutwater and slowly evolved into a single vortical structure at the volute diffuser. For the pressure distribution, the pressure increases gradually along streamwise direction in the impeller passages. When the centrifugal pump is operating under off-design flow rate condition, unsteady flow developed in the impeller passage and the volute casing.
Highlights
The complex flow pattern inside a centrifugal pump is strong three-dimensional with recirculation flows at inlet and exit, flow separation, cavitations, and so on
Liu et al [1], Akhras et al [2], and Pedersen et al [3] have made the measurement on centrifugal pumps and reported that impeller flow separation was observed on blade surface at off-design flow rate as compared to smooth flow within the impeller passage at design point
The complex pump internal flow field is investigated by using numerical methods and compared well with experimental data over the wide flow range
Summary
The complex flow pattern inside a centrifugal pump is strong three-dimensional with recirculation flows at inlet and exit, flow separation, cavitations, and so on. Liu et al [1], Akhras et al [2], and Pedersen et al [3] have made the measurement on centrifugal pumps and reported that impeller flow separation was observed on blade surface at off-design flow rate as compared to smooth flow within the impeller passage at design point. Ziegler et al [6], Shi and Tsukamoto [7], Shum et al [8], and Akhras et al [9] studied impeller diffuser interaction on the pump performance and showed that a strong pressure fluctuation is due to the unsteadiness of the flow shedding from impeller exit. To further improve the pump performance for design and off-design operating conditions, it will become extremely difficult Complex flow field such as the boundary layer separation, vortex dynamics, interactions between the impeller and diffuser are difficult to control due to the rotating and stationary components. Asuaje et al [17] and Goto et al [18] have analyzed flow in centrifugal pump impeller by using an inversed design method
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