BuildingSystems.Fluid.Movers.BaseClasses.Euler.power

# .BuildingSystems.Fluid.Movers.BaseClasses.Euler.power

Computes power as well as its derivative with respect to flow rate using Euler number

## Information

This function outputs power values as well as its derivative versus volumetric flow rate in the following steps:

- It first interpolates the input pressure curve to find a new pressure curve of 11 points on 10% increments of max flow rate. It assumes that the last point on the input pressure curve corresponds to Δp = 0, which is ensured when this function is called by BuildingSystems.Fluid.Movers.BaseClasses.FlowMachineInterface.
- It then computes power using efficiency evaluated with the Euler number from 10% to 90% of max flow rate on 10% increments.
- With the incomplete power curve it computes the spline derivatives with respect to flow rate at the same points.
- Once the derivatives are available, the power values at the two boundary points are found through linear extrapolation.

These steps are designed to ensure that power and efficiency computation with the Euler number is handled correctly near zero flow or zero pressure, where

Ẇflo = 0,
η = 0,
P > 0

in the equation

η = Ẇflo ⁄ P.

#### Interface

>     function power
>       extends Modelica.Icons.Function;
>       input BuildingSystems.Fluid.Movers.BaseClasses.Euler.peak peak "Peak operation point";
>       input BuildingSystems.Fluid.Movers.BaseClasses.Characteristics.flowParametersInternal pressure "Pressure curve with both max flow rate and max pressure";
>       output BuildingSystems.Fluid.Movers.BaseClasses.Euler.powerWithDerivative power(V_flow = zeros(11), P = zeros(11), d = zeros(11)) "Power and its derivative vs. flow rate";
>     end power;

## Revisions

- December 13, 2022, by Hongxiang Fu:
  First implementation. This is for #2668.

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