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Standard package icon.

Extends from `Modelica.Icons.Package`

(Icon for standard packages).

Name | Description |
---|---|

`BladderAccumulator` | |

`OpenTank` | |

`PistonAccumulator` | |

`Volume` | |

`VolumeExt` |

Model of a gas-loaded accumulator with a bladder separating the media. Fluid inertia or the stiffness of the bladder is not considered. The gas is modelled as an ideal gas.

The parameters `Biasing pressure`, `Nominal volume` and `Dead volume`
describe the accumulator in the unconnected state. At the beginning of a simulation,
the state variables of the accumulator are computed depending on the parameter
`Initial pressure of the hydraulic volume` and `Isothermal start`.

If the bladder expands to its maximum volume, only the `Dead volume` remains in the
accumulator. Due to the typically small dead volume, a high mathematical stiffness
of the accumulator can result. This behavior might require choosing a
correspondingly small timestep.

The parameter `Polytropic exponent` characterizes how pressure changes affect the
volume and stiffness of the gas bladder. If `Polytropic exponent` is set to unity,
the change of state within the gas is isothermal. This implies perfect heat
transfer between the gas in the bladder and the environment such that no change
of temperature occurs in the gas. This situation is encountered in hydraulic
accumulators if the load cycles of the liquid are lengthy.

If the `Polytropic exponent` is set to the isentropic exponent (1.4 for air), the
gas undergoes an adiabatic change of state which means that no heat exchange
with the environment can occur. This is typically the case for very short
load cycles.

If `Isothermal start` is set to true, it is assumed that the change from biasing
pressure to the initial pressure happened at constant temperature. If
`Isothermal start` is set to false, a polytropic process incorporating the parameter
`Polytropic exponent` is assumed.

Type | Name | Default | Description |
---|---|---|---|

`Volume` | `nominalVolume` | `0.005` | Nominal volume |

`Volume` | `deadVolume` | `1e-4` | Dead volume |

`AbsolutePressure` | `relBiasingPressure` | `5e+6` | Biasing pressure (rel.) |

`Temperature` | `biasingTemperature` | `293.1` | Biasing Temperature |

`Real` | `polytropicExponent` | `1.4` | Polytropic exponent |

`Boolean` | `isothermalStart` | `true` | Isothermal start |

`AbsolutePressure` | `initialPressure` | `environment.pAmbient` | Initial pressure of the hydraulic volume |

`Boolean` | `FixedInitialPressure` | `false` | fixed initial pressure |

`Boolean` | `enableVolumeOutput` | `false` | Enable fluid volume output |

Type | Name | Description |
---|---|---|

`FluidPort` | `fluidPort` | Hydraulic port |

`RealOutput` | `fluidVolume` | Fluid volume |

Model of a gas-loaded accumulator with a piston separating the media. Fluid inertia is not considered. The gas is modelled as an ideal gas.

The parameters `Biasing pressure`, `Nominal volume`, `Dead volume`,
and `Additional gas volume` describe the accumulator in the unconnected state.

At a piston stroke of 0 m only the `Dead volume` remains in the
accumulator. Due to the typically small dead volume, a high mathematical stiffness
of the accumulator can result. This behavior might require choosing a
correspondingly small timestep.

The parameter `Polytropic exponent` characterizes how pressure changes affect the
volume and stiffness of the gas volume. If `Polytropic exponent` is set to unity,
the change of state within the gas is isothermal. This implies perfect heat
transfer between the gas in the bladder and the environment such that no change
of temperature occurs in the gas. This situation is encountered in hydraulic
accumulators if the load cycles of the liquid are lengthy.

If the `Polytropic exponent` is set to the isentropic exponent (1.4 for air), the
gas undergoes an adiabatic change of state which means that no heat exchange
with the environment can occur. This is typically the case for very short
load cycles.

The `Biasing pressure (rel.)` is converted according to the ratio of
`Biasing Temperature` and fluid temperature and the `Polytropic exponent`
at the beginning of the simulation.

The parameters `Breakaway friction force`, `Constant friction/Coulomb force`, `Velocity dependent friction`
and `Velocity parameter for Stribeck friction` (velocity where the friction force begins to grow linearly) characterize
the velocity dependence of the friction force between piston and cylinder.

Type | Name | Default | Description |
---|---|---|---|

`Length` | `pistonDiameter` | `0.2` | Diameter of piston |

`Volume` | `nominalVolume` | `0.005` | Nominal volume |

`Volume` | `gasDeadVolume` | `5e-4` | Additional gas volume |

`Volume` | `deadVolume` | `1e-4` | Fluid dead volume |

`Angle` | `angle` | `0` | Inclination angle |

`Mass` | `massPiston` | `1` | Piston mass |

`Pressure` | `relBiasingPressure` | `5e+6` | Biasing pressure (rel.) |

`Temperature` | `biasingTemperature` | `293.1` | Biasing Temperature |

`Real` | `polytropicExponent` | `1.4` | Polytropic exponent |

`Real` | `fProp` | `10000` | Velocity dependent friction |

`Force` | `fCoulomb` | `25` | Constant friction/Coulomb force |

`Force` | `fBreakaway` | `50` | Breakaway friction force |

`Velocity` | `vM` | `0.005` | Velocity parameter for Stribeck friction |

`Boolean` | `enableStrokeOutput` | `false` | Enable stroke output |

`Boolean` | `enableVelocityOutput` | `false` | Enable velocity output |

`Boolean` | `enableVolumeOutput` | `false` | Enable fluid volume output |

Type | Name | Description |
---|---|---|

`FluidPort` | `fluidPort` | Hydraulic port |

`RealOutput` | `strokeOut` | Stroke of piston |

`RealOutput` | `velocityOut` | Velocity of piston |

`RealOutput` | `volumeOut` | Fluid volume |

Model of a simple hydraulic capacity. It can be used to represent the volume of adjacent components that lack
any spatial expansion, e. g. the *IdealResistor* component. The temporal change rate of pressure equals the net mass
flow into the capacity.

The capacity *C* used to calculate the rate of pressure change takes into account the compression modulus of the fluid.
The housing is assumed to be ideally rigid (in comparison to fluid). If the housing is to be taken into account,
component *VolumeExt* must be used.

Type | Name | Default | Description |
---|---|---|---|

`Volume` | `capacity` | `0.001` | Size of the volume |

Type | Name | Description |
---|---|---|

`FluidPort` | `fluidPort` | Hydraulic port |

Model of a simple hydraulic capacity with consideration of surrounding housing. It can be used to represent the volume of adjacent components that lack
any spatial expansion, e. g. the *IdealResistor* component. The temporal change rate of pressure equals the net mass
flow into the capacity.

Type | Name | Default | Description |
---|---|---|---|

`Volume` | `capacity` | `0.001` | Size of the volume |

`BulkModulus` | `bulkModulus` | `2.1e+11` | Bulk modulus housing |

Type | Name | Description |
---|---|---|

`FluidPort` | `fluidPort` | Hydraulic port |

The OpenTank component is the model of an open tank with unlimited volume in the sense of a line
termination. The pressure at *fluidPort* can either be set to *environment.pAmbient*
pressure or a different pressure.

Type | Name | Default | Description |
---|---|---|---|

`Boolean` | `useEnvironmentPressure` | `true` | Pressure at the fluid port equals environment.pAmbient |

`AbsolutePressure` | `pressure` | `environment.pAmbient` | Pressure at the fluid port if useAmbientPressure = false |

Type | Name | Description |
---|---|---|

`FluidPort` | `fluidPort` | Hydraulic port |