9.8 Rotodynamic Pumps For Pump Intake Design: Ansi Hi

This article is intended for civil, mechanical, and chemical engineers involved in water/wastewater, power generation, and industrial pumping systems. Always consult a licensed hydraulic engineer for final design verification.

Your (e.g., vertical turbine, submersible, or horizontal split-case) The flow rate per pump Any specific space limitations you are facing

A triangular or flat vertical plate centered directly underneath the suction bell. This device physically splits the incoming fluid stream, preventing a single, large sub-surface vortex from anchoring to the floor. ansi hi 9.8 rotodynamic pumps for pump intake design

Triangular corner fillets smooth out sharp 90∘90 raised to the composed with power

The 2018 revision of HI 9.8 formally introduced guidance on using for intake design validation. Instead of a one-time physical model, owners now build a real-time CFD model connected to SCADA. This article is intended for civil, mechanical, and

), length, and the distance from the pump centerline to the back wall ( ) and the floor (

Funnel-shaped whirlpools that pull air from the surface into the pump, leading to cavitation, vibration, and drop-offs in discharge capacity. This device physically splits the incoming fluid stream,

Computational Fluid Dynamics (CFD) has emerged as a powerful complementary tool. CFD can analyze general approach flow, help determine the necessary extent of physical modeling, and assess velocity distributions throughout the intake. However, the standard recognizes that CFD has limitations for demonstrating full compliance, and a physical model study remains the standard method for acceptance. In practice, the most rigorous design approach involves a hybrid strategy: using CFD to optimize the intake geometry, then validating the final design with a physical model study.

Adequate submergence is vital to suppress surface vortices. ANSI/HI 9.8 uses a formula based on the dimensionless Froude Number ( FRcap F sub cap R

: These draw air or floating debris from the water surface down into the pump suction. Air entrainment as low as 1% to 2% can severely degrade pump performance, induce severe vibrations, and break the pump's prime.

S=D(1+2.3FD)cap S equals cap D open paren 1 plus 2.3 cap F sub cap D close paren Where the Froude number ( FDcap F sub cap D ) relative to the bell diameter is calculated as: