This simulator models a compact recirculating test loop — variable-frequency drive, pump, adjustable resistance valve and flowmeter — to show how the intersection of a pump's head-versus-flow curve with a system's static-plus-friction resistance curve fixes the actual operating point. Change speed, reference pump coefficients, static head and valve opening, and watch the operating point move live on the H–Q graph.
• A real-time 3D cutaway workbench (variable-frequency drive and speed display, test-loop pump/motor, adjustable resistance valve, electromagnetic-style flowmeter, return loop, suction/discharge pressure station and a dedicated curve/operating-point recorder) with home view, focus-selected-part, show full enclosure, exploded view, auto-rotate, expand and hide-labels scene tools. • A dedicated 'Pump and system head curves' chart overlaying the pump curve and system curve at the current speed and marking the computed intersection point. • Experiment controls: speed demand (600–2,400 rpm), motor energized checkbox, reference-speed shutoff head, reference quadratic pump coefficient, static head requirement, fully-open system resistance and resistance-valve opening (0–100%) sliders, plus pause/resume, single-step and 1 s-step buttons and four playback speeds. • A Curves & measurements analysis tab with two further live charts (operating flow; operating head vs. static requirement), the underlying pump/system equations including the valve-opening-to-resistance relation, and snapshot readouts (shaft speed, flow, head, static requirement, friction requirement, shutoff head, best-efficiency flow, efficiency). • An Experiments tab with four guided fixtures (default intersection, throttle the system, high static requirement, zero static head) and a Model verification bench with a timestamped event log and copyable trial report. • A Learn & assess tab with four guided lessons, a knowledge-check quiz with reset, and a written model-scope statement linking to a pump affinity-laws reference.
A centrifugal pump does not deliver a fixed flow rate on its own — the actual flow is wherever the pump's available head, Hpump = H0(n/1800)² − a·Q², exactly equals what the system demands, Hsystem = Hstatic + Keffective·Q². Closing the resistance valve raises Keffective proportional to (100/opening%)², shifting the system curve upward and moving the intersection toward lower flow and higher head — exactly the throttling experiment shown in the simulator.
Changing pump speed rescales the entire pump curve by the square of the speed ratio (the affinity law), while changing valve opening or static head only moves the system curve. With zero static head, the operating flow tracks speed roughly proportionally under the model's ideal affinity relation — a distinct effect from throttling, which the simulator deliberately keeps separate via its independent controls.
This is a synthetic quadratic pump/system model with quasi-steady incompressible flow and a first-order 0.8 s motor speed response. A nonreturn valve blocks reverse flow when static head exceeds shutoff head. The pump curve is plotted only where head is non-negative, and closed-valve or insufficient-head cases are explicitly labeled rather than extrapolated.
It is wherever the pump's head-versus-flow curve intersects the system's head-versus-flow curve — the one flow rate at which the head the pump can supply exactly equals the head the system demands. The simulator plots both curves live and marks this intersection.
Closing a resistance valve raises the system's resistance coefficient, shifting the entire system curve upward. It does not change the pump curve itself — the new intersection point simply moves to lower flow and higher head along the unchanged pump curve.
Changing speed rescales the pump curve itself (head scales with the square of the speed ratio under the affinity laws), while throttling only moves the system curve. The simulator's separate speed and valve-opening controls let you isolate each effect.
Yes — if the pump's shutoff head (its maximum head at zero flow) is below the system's required static head at the chosen speed, the modeled nonreturn valve prevents any forward flow, shown in the high static requirement experiment.