BuildingSystems.Fluid.Actuators.Dampers.Exponential

# .BuildingSystems.Fluid.Actuators.Dampers.Exponential

Air damper with exponential opening characteristics

## Information

Model of two flow resistances in series:

- one resistance has a fixed flow coefficient;
- the other resistance represents a damper whose flow coefficient is an exponential function of the opening angle.

The lumped flow coefficient k(y) (function of the fractional opening y) is used to compute the mass flow rate versus pressure drop relation as:

ṁ = sign(Δp) k(y) √ Δp

with regularization near the origin.

For a description of the damper opening characteristics and typical parameter values, see the partial model BuildingSystems.Fluid.Actuators.BaseClasses.PartialDamperExponential.

## Revisions

- June 10, 2021, by Michael Wetter:
  Changed implementation of the filter and changed the parameter `order` to a constant as most users need not change this value.
  This is for #1498.
- April 12, 2021, by Michael Wetter:
  Guarded against division by zero if the pressure equation is removed. This then leads to a more meaningful error message.
  This is for IBPSA, #1243.
- December 23, 2019, by Antoine Gautier:
  Added the pressure drop calculation as it is no longer in the base class.
  This is for IBPSA, #1188.
- March 22, 2017, by Michael Wetter:
  Updated documentation.
- April 14, 2014 by Michael Wetter:
  Improved documentation.
- September 26, 2013 by Michael Wetter:
  Moved assignment of `kDam_default` and `kThetaSqRt_default` from `initial algorithm` to the variable declaration, to avoid a division by zero in OpenModelica.
- December 14, 2012 by Michael Wetter:
  Renamed protected parameters for consistency with the naming conventions.
- June 22, 2008 by Michael Wetter:
  Extended range of control signal from 0 to 1 by implementing the function BuildingSystems.Fluid.Actuators.BaseClasses.exponentialDamper.
- June 10, 2008 by Michael Wetter:
  Introduced new partial base class, PartialDamperExponential.
- June 30, 2007 by Michael Wetter:
  Introduced new partial base class, PartialActuator.
- July 27, 2007 by Michael Wetter:
  Introduced partial base class.
- July 20, 2007 by Michael Wetter:
  First implementation.

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