Enhancement of flow characteristics in a pump sump using anti-vortex external vaned suction pipe

The current study investigates a new anti-vortex device (AVD) for improving flow characteristics in a pump intake sump and suction pipe. Steady-state CFD simulations (RANS with the realizable k-ε turbulence model) are validated against previous experimental work as a base-case. A nine-cases are introduced by installing four external vanes on the suction pipe to form an External Vaned Pipe Anti-Vortex Device (EVP-AVD). Vane length and height are varied from L/Dpipe = 0.25–1.0 and Z/S = 0.25–1.0. The intent of the new AVD is generating small vortices bounded within the external vanes to damp the larger vortices and reduce their strength and size, and hence the air entrainment. Flow vorticity is evaluated using streamlines and velocity fields at several planes, while suction performance is quantified by the swirl angle and mass-weighted axial velocity uniformity. Results indicate that vane height is the dominant parameter for swirl mitigation. The optimal EVP-AVD configuration (L = 0.25Dpipe, Z = S) suppresses surface and subsurface vortices and reduces the mean swirl angle from 18.79° (no AVD) to 4.26° (77% reduction) while Velocity uniformity is generally maintained, with the largest reductions limited to 16% and 14% for cases 3 and 8, respectively.