Annex60.Fluid.Movers.BaseClasses.Characteristics.pressure

# .Annex60.Fluid.Movers.BaseClasses.Characteristics.pressure

Pump or fan head away from the origin without correction for mover flow resistance

## Information

This function computes the fan static pressure raise as a function of volume flow rate and revolution in the form

Δp = rN2 s(V̇/rN, d),

where Δp is the pressure rise, rN is the normalized fan speed, V̇ is the volume flow rate and d are performance data for fan or pump power consumption at rN=1.

#### Implementation

The function s(·, ·) is a cubic hermite spline. If the data d define a monotone decreasing sequence, then s(·, d) is a monotone decreasing function.

The function allows rN to be zero.

#### Interface

>     function pressure
>       extends Modelica.Icons.Function;
>       input Modelica.SIunits.VolumeFlowRate V_flow "Volumetric flow rate";
>       input Real r_N(unit = "1") "Relative revolution, r_N=N/N_nominal";
>       input Real d[:] "Derivatives of flow rate vs. pressure at the support points";
>       input Modelica.SIunits.PressureDifference dpMax(displayUnit = "Pa") "Maximum pressure drop at nominal speed, for regularisation";
>       input Modelica.SIunits.VolumeFlowRate V_flow_max "Maximum flow rate at nominal speed, for regularisation";
>       input Annex60.Fluid.Movers.BaseClasses.Characteristics.flowParametersInternal per "Pressure performance data";
>       output Modelica.SIunits.PressureDifference dp(displayUnit = "Pa") "Pressure raise";
>     end pressure;

## Revisions

- September 8, 2016, by Michael Wetter and Filip Jorissen:
  Changed implementation to allow `r_N = 0`.
  This is for #458.
- September 7, 2016, by Michael Wetter:
  Moved function which was a protected function to make it public, as it is now called by Annex60.Fluid.Movers.BaseClasses.FlowMachineInterface.

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