This extends GunnsGasFan with a model of liquid cavitation. This can be used to model all types of liquid axial, radial, or mixed-flow centrifugal (constant-head) pumps. If a cavitation model is not needed, you can use the GunnsGasFan link instead ("Gas" and "Liquid" in these link names only distinguish which has the liquid cavitation model.) This link should not be used for positive displacement (constant-volume) pumps such as pistons, etc. For those types of pumps, use the GunnsLiquidDisplacementPump link instead.

The only difference between this link and the GunnsGasFan is the inclusion of the liquid cavitation model. In all other respects, this is identical to the GunnsGasFan with similar set-up, tuning and issues.

The cavitation effect can be triggered by user command and automatically when the pump inlet pressure drops below the liquid vaporization pressure. Note that this link doesn't have a direct parameter for pump NPSH. Instead, the inlet network node is assumed to be at the lowest-pressure point in the pump inlet, and its pressure is used to model the cavitation. The pump's suction head can be tuned relative to the rest of the system via the conductivity of links flowing into the inlet node.

The cavitation model has two components, both of which are configured in the GunnShow drawing:

• Full cavitation: A long-period degrade of the pump pressure rise and flow rate, starting from the onset of cavitation and ending with a complete or partial reduction in pressure and flow after a configured duration. This simulates a buildup and complete flooding of the impeller with gas bubbles.
• Partial cavitation: A random noise on the pressure and flow with a sudden onset that washes out over time. This simulates the forming or arrival of gas bubbles at the pump inlet creating turbulence and vibrations in the pump, which are then gradually cleared downstream.

This link has the same connection rules as GunnsGasFan.

Port Connection Rules (These are limitations on the port connection to nodes that the link enforces in run-time):

• Same as GunnsFluidConductor.

Other Rules (These are extra rules you should always try to follow):

• Same as GunnsGasFan.
• Additionally, you should always include a GunnsFluidAccum or similar link near the pump inlet to maintain the pump inlet pressure. This is a real-world design practice, enables realistic triggering of the cavitation model, and avoids unrealistic problems with inlet pressures (see the note on negative inlet pressures in GunnsGasFan.

Configuration Data Parameters:

• maxConductivity: Same as GunnsFluidPotential.
• expansionScaleFactor: Same as GunnsFluidConductor.
• referenceDensity: Same as GunnsGasFan.
• referenceSpeed: Same as GunnsGasFan.
• referenceCoeff0: Same as GunnsGasFan.
• referenceCoeff1: Same as GunnsGasFan.
• referenceCoeff2: Same as GunnsGasFan.
• referenceCoeff3: Same as GunnsGasFan.
• referenceCoeff4: Same as GunnsGasFan.
• referenceCoeff5: Same as GunnsGasFan.
• bestEfficiency: Same as GunnsGasFan.
• referenceQBep: Same as GunnsGasFan.
• filterGain: Same as GunnsGasFan.
• driveRatio: Same as GunnsGasFan.
• thermalLength: Same as GunnsFluidValve.
• thermalDiameter: Same as GunnsFluidValve.
• surfaceRoughness: Same as GunnsFluidValve.
• checkValveActive: Same as GunnsGasFan.
• liquidType (default = FluidProperties::NO_FLUID, must be a GUNNS liquid fluid type): The liquid type that is used in this pump. In general, liquid types should not be mixed in nodes, and the pump should only see this one type.
• autoCavitationDuration (default = 0 s, must >= 0): This sets the default duration of the full and partial cavitation effects when they are triggered automatically by the model.
• autoCavitationAmplitude (default = 0 kPa): This sets the amplitude of the partial cavitation pressure noise effect when it is triggered automatically by the model.

Input Data Parameters:

• malfBlockageFlag: Same as GunnsFluidConductor.
• malfBlockageValue: Same as GunnsFluidConductor.
• sourcePressure: Same as GunnsFluidPotential.
• motorSpeed: Same as GunnsGasFan.
• wallTemperature: Same as GunnsFluidValve.
• enableAutoCavitation (default = false): This sets whether the auto-cavitation model is initially enabled. We recommend you set this to enabled (true), as modeling cavitation helps avoid unrealistic signatures when the pump inlet is starved.

• Same as GunnsGasFan. Additionally, the negative inlet pressure problem can be further avoided by enabling the auto-cavitation model (set enableAutoCavitation = true). In reality all liquid pumps will cavitate before their inlet pressures can reach zero. Enabling this model causes the pump to cavitate, and the resulting source pressure drop reduces the suction pulled on the inlet.

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