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Generate time-varying pressure differential

**Library:**Simscape / Foundation Library / Gas / Sources

The Controlled Pressure Source (G) block represents an ideal
mechanical energy source in a gas network. The pressure differential is controlled by
the input physical signal at port **P**. The source can maintain the
specified pressure differential across its ports regardless of the mass flow rate
through the source. There is no flow resistance and no heat exchange with the
environment. A positive signal at port **P** causes the pressure at
port **B** to be greater than the pressure at port
**A**.

You can choose whether the source performs work on the gas flow:

If the source is isentropic (

**Power added**parameter is set to`Isentropic power`

), then the isentropic relation depends on the gas property model.Gas Model Equations Perfect gas $$\frac{{\left({p}_{A}\right)}^{Z\cdot R/{c}_{p}}}{{T}_{A}}=\frac{{\left({p}_{B}\right)}^{Z\cdot R/{c}_{p}}}{{T}_{B}}$$ Semiperfect gas $${\int}_{0}^{{T}_{A}}\frac{{c}_{p}\left(T\right)}{T}}dT-Z\cdot R\cdot \mathrm{ln}\left({p}_{A}\right)={\displaystyle {\int}_{0}^{{T}_{B}}\frac{{c}_{p}\left(T\right)}{T}}dT-Z\cdot R\cdot \mathrm{ln}\left({p}_{B}\right)$$ Real gas $$s\left({T}_{A},{p}_{A}\right)=s\left({T}_{B},{p}_{B}\right)$$ The power delivered to the gas flow is based on the specific total enthalpy associated with the isentropic process.

$${\Phi}_{work}=-{\dot{m}}_{A}\left({h}_{A}+\frac{{w}_{A}^{2}}{2}\right)-{\dot{m}}_{B}\left({h}_{B}+\frac{{w}_{B}^{2}}{2}\right)$$

If the source performs no work (

**Power added**parameter is set to`None`

), then the defining equation states that the specific total enthalpy is equal on both sides of the source. It is the same for all three gas property models.$${h}_{A}+\frac{{w}_{A}^{2}}{2}={h}_{B}+\frac{{w}_{B}^{2}}{2}$$

The power delivered to the gas flow

*Φ*_{work}= 0.

The equations use these symbols:

c_{p} | Specific heat at constant pressure |

h | Specific enthalpy |

$$\dot{m}$$ | Mass flow rate (flow rate associated with a port is positive when it flows into the block) |

p | Pressure |

R | Specific gas constant |

s | Specific entropy |

T | Temperature |

w | Flow velocity |

Z | Compressibility factor |

Φ_{work} | Power delivered to the gas flow through the source |

Subscripts A and B indicate the appropriate port.

There are no irreversible losses.

There is no heat exchange with the environment.