When a physical model study is required, the standard method involves constructing a scaled physical model (typically 1:10 to 1:12 scale) and observing vortex formation using dye injection, as well as measuring swirl and velocity distributions.
The approach flow configuration is highly non-uniform, asymmetrical, or restricted (e.g., a cross-flow intake or an intake fed by a 90-degree angled canal). ansi hi 9.8 rotodynamic pumps for pump intake design
If you are involved in the specification, design, or operation of pumping systems, is not just a recommendation—it is an essential resource for ensuring the success and longevity of your projects. When a physical model study is required, the
Though the 2018 edition acknowledges CFD, the standard is historically rooted in physical scale-model testing. Novice users may not realize that poorly executed CFD is worse than no analysis. The standard lacks prescriptive best practices for mesh quality, turbulence models, and validation. Though the 2018 edition acknowledges CFD, the standard
A vertical wedge installed against the back wall behind the pump column. It fills the hydraulic dead-zone, preventing rotational wake patterns from developing behind the suction pipe.
Recognizing the increasing power of computer simulation, the latest versions of have significantly expanded their guidance on the use of Computational Fluid Dynamics (CFD) for pump intake analysis. CFD is now an accepted engineering tool, often used to refine a design before a physical model is built, or in some cases, to validate a design that does not meet the strict criteria for a physical model. The standard even provides acceptance criteria for swirl angles and velocity profiles that a CFD model must meet to be considered valid.
The clearance between the pump suction bell and the floor of the sump or wet well (C_f) is critical for preventing submerged vortices and ensuring uniform inflow. ANSI/HI 9.8 recommends floor clearance between 0.3 and 0.5 times the bell diameter (D). Excessive floor clearance can create stagnant zones where solids accumulate, while insufficient clearance can cause increased inlet head loss, flow separation, and submerged vortices that negatively impact pump performance.