Numerical study on the hydrodynamic performance and internal flow of an axial-flow pump with various inlet flow angles.

In this study, numerical simulation was employed to predict the performance and internal flow characteristics of the inlet of an axial-flow pump by assigning an absolute flow angle to the inlet guide vane (IGV) trailing-edge flow. Further, the finite volume method based on the three-dimensional Reynolds-averaged Navier-Stokes equations was employed to discretize the governing equations. The shear stress transport model was used as the turbulence model, and an appropriate number of nodes were selected for the hexahedral grid system through a grid-dependency test. The performance curve and changes in the internal flow field were investigated based on the variation in the flow angle at the inlet of the axial-flow pump. These results can be used to establish an efficient operational plan by adjusting the IGV angle of IGV when installing a variable IGV for an axial-flow pump.

Numerical investigation on functional limitations of the anti-stall fin for an axial fan: one-factor analyses.

The stall in an axial fan is directly related to detrimental phenomena such as performance degradation, vibration, noise, and flow instability at low flow rates. As a kind of passive control method to handle the stall, two-dimensional plates so-named anti-stall fin (ASF) were suggested by ourselves and were attached inside the casing. In this study, the ASF's effect on the internal flow pattern was visually investigated in the flow passage, and its tendency was discussed with the performance curve. Subsequently, the ASF's functional limitations for various design parameters, which the ASF can derive aerodynamically, were presented as the primary focus of this study. Each one-factor analysis was performed, and the internal flow pattern was observed in parallel at the point where the ASF lost its function. For the radial length, axial length, number of fins, and positive-tangential angle, the ASF almost retained its function up to the limitation to prevent instability but radically lost its function at a certain flow rate. For the axial gap and negative-tangential angle, the ASF gradually lost its function. Mostly, this study was based on numerical analysis, and the performance was validated through experimental tests.