This extends GunnsFluidSource with a generic model of a positive displacement (constant-volume) pump. These are pumps that move a constant volume of fluid per revolution, such as gear, screw & rotary vane pumps. This link is mainly used for gas pumps, but it can also be used for liquid displacement pumps if liquid cavitation is not desired. If cavitation is desired, use the GunnsLiquidDisplacementPump instead. (We recommend that you do use cavitation for liquids). This link should not be used for centrifugal (constant-head) pumps & fans. For those types of pumps, use the GunnsGasFan link instead.

This link forces a specified volume of flow for every revolution of the pump. Care must be taken by the user to ensure that the network can accommodate the flow. This is especially true for liquids -- since liquids are (nearly) incompressible, forcing a volume of liquid into a fixed volume container causes the node pressure to "blow up" to astronomically large values.

This link is designed to interface with a motor model. The motor supplies a shaft rotational speed to the pump, and the pump returns a shaft torque to the motor. The shaft torque is due to the useful work applied to the fluid. Unlike the fan & centrifugal pump links, this link does not model hydraulic losses.

This link models isentropic expansion and convection heat transfer between the fluid and the fan/pipe wall, similar to other pipe & HX links. This link does not modify the mixture of the fluid passing through it.

This link has the same connection rules as GunnsFluidSource. Multiple pumps can be staged in any combination, either in parallel or series, and in sympathetic or opposing directions and interact in a realistic manner.

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

• Same as GunnsFluidSource.

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

• Do not mix fluid phases across the link. That is, both nodes should contain the same phase (gas or liquid), and not different phases.
• When using this pump for liquids, you should always use accumulators in the network on both sides of the pump, to provide flexible volume to accommodate the pump flow out of the inlet side and into the exit side. Failure to use accumulators or isolating them from the pump leads to pressure instability in the network. See the discussion on Pressure Stability below.
• Always finish tuning this link and the system that it flows through before you attempt to hook up and tune a motor model.

Configuration Data Parameters:

• cycleVolume (default = 0 m3, must be > 0): This is the true volume of fluid forced from inlet to exit nodes per revolution of the pump.
• driveRatio: Same as GunnsGasFan.
• thermalLength: Same as GunnsFluidValve.
• thermalDiameter: Same as GunnsFluidValve.
• surfaceRoughness: Same as GunnsFluidValve.
• checkValveActive: Same as GunnsGasFan.

Input Data Parameters:

• malfBlockageFlag: Same as GunnsFluidSource. This malfunction reduces the flow rate per revolution of the pump.
• malfBlockageValue: Same as GunnsFluidSource.
• flowDemand: This inherited term from the base class is not used by this model, and it can be left zero.
• motorSpeed: Same as GunnsGasFan.
• wallTemperature: Same as GunnsFluidValve.

• Pressure Stability: This is a particular risk when using liquid. See the discussion of this problem in the GunnsFluidSource. Use of a parallel conductor to model seal leakage and a relief valve is highly recommended - not only do real systems almost always have similar hardware, but this helps avoid pressure spikes in the model.
• Negative Inlet Pressure: This is a particular risk when using liquid. See the discussion of this problem in the GunnsGasFan. Use of accumulators on both sides of the pump is highly recommended. Real systems almost always have some flexible volume on both sides of the pump to accommodate the forced flow - so using them in your network is not only realistic, but also helps to avoid unrealistic pressure spikes.

• N/A