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Flow control with pressure regulation in an isothermal liquid system

**Library:**Simscape / Fluids / Isothermal Liquid / Valves & Orifices / Flow Control Valves

The Pressure-Compensated Flow Control Valve (IL) block provides constant-pressure flow
control through an Orifice (IL) block via a Pressure Compensator Valve (IL) connected in
series. When the control pressure over the orifice,
*p*_{A} –
*p*_{B}, meets or exceeds the **Set
orifice pressure differential**, the reducing valve in the pressure
compensator component begins to close, which maintains the pressure in the orifice. For
systems with venting or redirection of fluid to another part of the system, see the
Pressure-Compensated 3-Way Flow Control Valve (IL) block.

The valve opening and closing is controlled by a physical signal received at port
**S**. A positive signal opens the valve.

**Flow Control Valve Schematic**

At the extremes of the orifice area and valve pressure range, you can maintain
numerical robustness in your simulation by adjusting the block **Smoothing
factor**. A smoothing function is applied to all calculated areas and
pressures, but primarily influences the simulation at the extremes of these ranges.

The normalized orifice area is calculated as:

$$\widehat{A}=\frac{\left(A-{A}_{leak}\right)}{\left({A}_{\mathrm{max}}-{A}_{leak}\right)}.$$

where:

*A*is the_{leak}**Leakage area**.*A*is the cushion_{max}**Maximum orifice area**.

The **Smoothing factor**, *f*, is
applied to the normalized area:

$${\widehat{A}}_{smoothed}=\frac{1}{2}+\frac{1}{2}\sqrt{{\widehat{A}}_{}^{2}+{\left(\frac{f}{4}\right)}^{2}}-\frac{1}{2}\sqrt{{\left(\widehat{A}-1\right)}^{2}+{\left(\frac{f}{4}\right)}^{2}}.$$

The smoothed orifice area is:

$${A}_{smoothed}={\widehat{A}}_{smoothed}\left({A}_{\mathrm{max}}-{A}_{leak}\right)+{A}_{leak}.$$

Similarly, the normalized valve pressure is:

$$\widehat{p}=\frac{\left(p-{p}_{set}\right)}{\left({p}_{\mathrm{max}}-{p}_{set}\right)}.$$

where:

*p*is the_{set}**Set orifice pressure differential**.*p*is the sum of the_{max}**Set orifice pressure differential**and the**Pressure compensator valve regulation range**.

Smoothing applied to the normalized pressure is:

$${\widehat{p}}_{smoothed}=\frac{1}{2}+\frac{1}{2}\sqrt{{\widehat{p}}_{}^{2}+{\left(\frac{f}{4}\right)}^{2}}-\frac{1}{2}\sqrt{{\left(\widehat{p}-1\right)}^{2}+{\left(\frac{f}{4}\right)}^{2}},$$

and the smoothed pressure is:

$${p}_{smoothed}={\widehat{p}}_{smoothed}\left({p}_{\mathrm{max}}-{p}_{set}\right)+{p}_{set}.$$

Setting **Orifice parameterization** to:

`Linear - area vs. control member position`

assumes that the spool position and the orifice opening area are related linearly.`Tabulated data - Area vs. control member position`

interpolates user-provided data between the orifice opening area and the control member position with a potentially nonlinear relationship.`Tabulated data - Volumetric flow rate vs. control member position and pressure drop`

interpolates the orifice volumetric flow rate directly from user-provided data between the control member position, orifice pressure drop, and orifice volumetric flow rate.

Orifice (IL) | Pressure Compensator Valve (IL) | Pressure-Compensated 3-Way Flow Control Valve (IL) | Pressure-Reducing 3-Way Valve (IL) | Shuttle Valve (IL)