), which is specific to each impeller type (e.g., Rushton turbine, hydrofoil, pitched blade turbine) and varies with the Reynolds number. The Power Equation In the fully turbulent regime ( ), the Power Number ( Npcap N sub p
A dimensionless constant specific to the impeller type (e.g., turbine, paddle, anchor). (Density): The specific gravity of the liquid. (Rotational Speed): The speed in revolutions per second. cap D sub a (Impeller Diameter):
. The operating speed should typically be at least 20% away from the shaft's natural frequency to avoid catastrophic vibrations. Impeller Tip Speed: Calculated as agitator design calculation xls repack
The fundamental calculation for an agitator is the power needed to rotate the impeller through a fluid. This is influenced by the fluid's viscosity and density, as well as the impeller's geometry. IQS Directory Power Formula: cap N sub p (Power Number):
A reliable calculation spreadsheet uses a sequential workflow. Each step feeds data into the next mechanical or process formula. Step 1: Define Input Parameters ), which is specific to each impeller type (e
Automated calculation cells for Reynolds number, flow regime text indicator, calculated pure process power, and raw torque.
Calculated based on hydraulic side loads acting on the impeller blades. Critical Speed ( Nccap N sub c (Rotational Speed): The speed in revolutions per second
Evaluation of hydraulic forces, shaft bending moments, minimum shaft diameter matching standard commercial bar stock sizes, and weight calculations. Safety Check Guard: A pass/fail summary box displaying: Actual Speed vs. Critical Speed ratio. Combined stress vs. Allowable material stress limit. Impeller tip speed class (low, medium, or high shear).
): Viscous forces dominate. Mixing is localized around the blades. Transitional Flow (
Typically, these spreadsheets are designed to have input areas (often colored yellow) and output areas.