Simplified route key
Center bore down; outer annulus back up. The 3D view above contains the resolved CFD paths.
OpenFOAM • sealed epoxy-clearance model
Coolant flow is dominated by the printed turnaround.
Cold water now enters through the center bore, turns through the printed tip, and returns through the outer annulus. The 148,460-cell model remains almost purely quadratic.
Reversed-flow CFD completed — 1, 2 and 3 L/min
Drag to interpolate the CFD resistance curve
Tip pressure loss81.7 kPa11.9 psi
Equivalent water head8.3 mtip assembly only
Heat carried, 20→90 °C9.76 kWenthalpy ceiling
Estimated peak speed10.6 m/sprinted restriction
Minimum vs outlet−31 kPastatic pressure
Actual 3D coolant path at 2 L/min
Drag or use one finger to rotate; scroll or pinch to zoom. The animated traces are integrated through the OpenFOAM velocity field—not drawn from the center-plane slice.
Central-bore inletOuter-annulus outlet−31 → 82 kPa
OUTLET
outer annulus
outer annulus
INLET
central bore
central bore
Pressure resistance curve
Smooth interpolation through CFD points; quadratic fit Δp ≈ 20.44 Q²
What was sealed
The 0.30 mm radial clearances around the sensor, printed insert, inner tube and outer tube were treated as solid epoxy. No coolant leakage into the combustor was permitted.
What the pump must overcome
At 2 L/min the reversed tip consumes 0.82 bar before adding the remaining tubes, hoses, fittings or desired outlet backpressure. At 3 L/min it consumes 1.84 bar.
Cavitation margin
At 2 L/min the local minimum is about 31 kPa below the outer outlet. If the water actually approaches 90 °C, atmospheric discharge leaves almost no boiling margin; modest outlet backpressure is prudent.
Best geometry change
Enlarge the narrow center feed and curved crossover slots, and add generous fillets. As-printed roughness will raise resistance above this smooth-wall result.