Realization and application evaluation of near-wall mesh in centrifugal pumps

To investigate effects of grid quality on the calculation accuracy for flow field simulation in centrifugal pumps, taking structured grid as research objects, the near-wall mesh of centrifugal pumps were constructed and evaluated in three aspects from the number of gird, subdivision of near-wall mesh and blocking strategies. Based on the grid independence analysis, the standard k-ε model, RNG k-ε model, standard k-ω model and SST k-ω model were used to simulate the flows in the centrifugal pump with ns=103 respectively. Compared to the measured values, the prediction accuracy of numerical results obtained by coarse grid and fine grid were higher than the grid without near-wall mesh. The results showed that when near-wall mesh was added, the prediction accuracy of the pump head increased by 1.19%. The relationship between the near-wall mesh and the turbulence models were also analyzed to find a reliable and feasibility numerical method for the centrifugal pump. To accommodate the use of k-ε model based scalable wall function, grid near-wall points were established at locations yielding dimensionless, grid wall spacing of Y+＜200 was appropriate, while Y+≤100 was a must for the k-ω model with automatic wall function.