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Hydrodynamic calculation Gate valve (through conduit)

Gate valve (through conduit) Q air D Q max 1,1D 0,3D 1,5D 4D 1,2D 2D +F by +F bx +F x +F y L Q air D Q max 1.2 D +F by +F bx +F x +F y 1.1 D 0.3D 1.5D 4D 2D
Gate valve (through conduit)

Values for calculation

$ D $ $ \mathrm{mm} $
$ Q_{max} $ $ \mathrm{m^3/s} $
$ H $ $ \mathrm{m} $
$ g $ $ \mathrm{m/s^2} $
$ T $ $ \mathrm{°C} $
$ ρ $ $ \mathrm{kg/m^3} $
$ P_{SV} $ $ \mathrm{Pa} $
$ ΔP $ $ \mathrm{m} $
$ h $ $ \mathrm{m} $
$ ρ_{air} $ $ \mathrm{kg/m^3} $
$ p_{air} $ $ \mathrm{Pa} $
$ n $
$ t $ $ \mathrm{s} $
$ L $ $ \mathrm{m} $

Calculation

Velocity in valve

$$v_{max}=\cfrac{4\cdot 10^6\cdot Q_{max}}{π\cdot D^2}$$

Theoretical pressure in the valve at full opening

$$Δ_h=\cfrac{v_{max}^2}{2\cdot g}\cdot \left({\min\left(ζ\right)}+1\right)$$

Pressure parameter

$$p=\cfrac{Δ_h}{H}$$

$$0 < p \le 1$$

Effective closing time factor

$$c_{ef}=0.1/\max_{i=1}^{10}{\left(Q_p[i]-Q_p[i+1]\right)}$$

$$c_{ef}\le 1$$

Under-pressure behind the valve

$$P_{u}=\max\left(-\cfrac{L\cdot v_{max}}{g\cdot t\cdot c_{ef}}, -\cfrac{p_{air}}{ρ\cdot g}\right)$$
Stroke from open position
Flow coefficient
Coefficient of hydraulic force on a sliding plate in the axis x
Coefficient of hydraulic force on a sliding plate in the axis y
Coefficient of hydraulic force on body in the axis x
Coefficient of hydraulic force on body in the axis y
$ s $ $ K_Q $ $ K_x $ $ K_y $ $ K_{bx} $ $ K_{by} $
$ \mathrm{\%} $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $
No data

$ K_x\ [-] $
$ K_y\ [-] $
$ K_{bx}\ [-] $
$ K_{by}\ [-] $
No data
$ s\ [\mathrm{\%}] $
Coefficient of force

$ K_Q\ [-] $
No data
$ s\ [\mathrm{\%}] $
Flow coefficient

Stroke from open position
Loss coefficient
Reduced free flow area in the throttle control system
Relative flow
Flow of water in the pipeline
Water velocity in pipeline
$ s $ $ ζ $ $ f_r $ $ Q_p $ $ Q $ $ v $
$ \mathrm{\%} $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{m^3/s} $ $ \mathrm{m/s} $
No data

$ ζ\ [-] $
No data
$ s\ [\mathrm{\%}] $
Loss coefficient

$$ζ=\cfrac{1-K_Q^2}{K_Q^2}$$

$ f_r\ [-] $
$ Q_p\ [-] $
No data
$ s\ [\mathrm{\%}] $
Coefficients

$$f_r=\cfrac{K_Q}{K_{Qmax}}$$
$$Q_p=\cfrac{f_r}{\sqrt{p+f_r^2\cdot \left(1-p\right)}}$$

$ Q\ [\mathrm{m^3/s}] $
$ v\ [\mathrm{m/s}] $
No data
$ s\ [\mathrm{\%}] $
Flow and speed of water in the pipeline

$$Q=Q_p\cdot Q_{max}$$
$$v=Q_p\cdot v_{max}$$
Stroke from open position
Loss of pressure on the valve
Pressure on the valve
Cavitation number
$ s $ $ H_L $ $ H_v $ $ σ $
$ \mathrm{\%} $ $ \mathrm{m} $ $ \mathrm{m} $ $ \mathrm{\ } $
No data

$ H_L\ [\mathrm{m}] $
$ H_v\ [\mathrm{m}] $
No data
$ s\ [\mathrm{\%}] $
Loss of height on valve and pressure height on Gate valve

$$H_L=\cfrac{v^2}{2\cdot g}\cdot ζ$$
$$H_v=H_L+\cfrac{v^2}{2\cdot g}+\left(1-Q_p\right)\cdot\left(ΔP-P_{u}\right)$$

$ σ\ [-] $
No data
$ s\ [\mathrm{\%}] $
Cavitation number

$$σ=\cfrac{\cfrac{p_{air}-P_{SV}}{ρ\cdot g}+H-H_L}{H_v}$$
Stroke from open position
Forces on sliding plate in axis x
Forces on sliding plate in axis y
The force at the valve axis x
The force at the valve axis y
$ s $ $ F_x $ $ F_y $ $ F_{bx} $ $ F_{by} $
$ \mathrm{\%} $ $ \mathrm{kN} $ $ \mathrm{kN} $ $ \mathrm{kN} $ $ \mathrm{kN} $
No data

$ F_x\ [\mathrm{kN}] $
$ F_y\ [\mathrm{kN}] $
No data
$ s\ [\mathrm{\%}] $
Forces on sliding plate

$$F_x=\cfrac{π\cdot D^2}{4\cdot 10^9}\cdot ρ\cdot g\cdot H_v\cdot K_x$$
$$F_y=\cfrac{π\cdot D^2}{4\cdot 10^9}\cdot ρ\cdot g\cdot H_v\cdot K_y$$

$ F_{bx}\ [\mathrm{kN}] $
No data
$ s\ [\mathrm{\%}] $
The force at the valve axis x

$\text{if }\ α=90$
$$F_{bx}=\cfrac{π\cdot D_s^2}{4\cdot 10^9}\cdot ρ\cdot g\cdot H_v\cdot K_{bx}$$
$\text{else}$
$$F_{bx}=\cfrac{π\cdot D^2}{4\cdot 10^9}\cdot ρ\cdot g\cdot H_v\cdot K_{bx}$$

$ F_{by}\ [\mathrm{kN}] $
No data
$ s\ [\mathrm{\%}] $
The force at the valve axis y

$$F_{by}=\cfrac{π\cdot D^2}{4\cdot 10^9}\cdot ρ\cdot g\cdot H_v\cdot K_{by}$$
Stroke from open position
Coefficient of under-pressure of aerated hole
Under-pressure in the aerated pipeline
Air flow
$ s $ $ f_{air} $ $ p_{air} $ $ Q_{air} $
$ \mathrm{\%} $ $ \mathrm{\ } $ $ \mathrm{Pa} $ $ \mathrm{m^3/s} $
No data

$ f_{air}\ [-] $
No data
$ s\ [\mathrm{\%}] $
Coefficient of under-pressure of aerated hole

$ p_{air}\ [\mathrm{Pa}] $
No data
$ s\ [\mathrm{\%}] $
Under-pressure in the aerated pipeline

$\text{if }\ \text{n}= \text{no}$
$$p_{air}=NAN$$
$\text{else}$
$$p_{air}=-\min\left(p_{air}, f_{air}\cdot\cfrac{v^2}{2\cdot g}\cdot ρ+\left(1-Q_p\right)\cdot\min\left(\cfrac{L\cdot v_{max}\cdot ρ}{t\cdot c_{ef}}, p_{air}\right)\right)$$

$ Q_{air}\ [\mathrm{m^3/s}] $
No data
$ s\ [\mathrm{\%}] $
Air flow

$\text{if }\ \text{n}= \text{no}$
$$Q_{air}=NAN$$
$\text{else if }\ p_{air}<\cfrac{p_{air}}{2}$
$$Q_{air}=\min\left(Q_{max}-Q, 0.2\cdot Q\right)$$
$\text{else}$
$$Q_{air}=\max\left(Q_{max}-Q, 0.2\cdot Q\right)$$
Stroke from open position
Air velocity
The flow area of the aerated hole
The flow area of the aerated pipeline
$ s $ $ v_{air} $ $ A_{air} $ $ A_{air-pipe} $
$ \mathrm{\%} $ $ \mathrm{m/s} $ $ \mathrm{m^2} $ $ \mathrm{m^2} $
No data

$ v_{air}\ [\mathrm{m/s}] $
No data
$ s\ [\mathrm{\%}] $
Air velocity

$\text{if }\ \text{n}= \text{no}$
$$v_{air}=NAN$$
$\text{else}$
$$v_{air}=\min\left(0.7\cdot\sqrt{-\cfrac{2\cdot p_{air}}{ρ_{air}}}, 250\right)$$

$ A_{air}\ [\mathrm{m^2}] $
No data
$ s\ [\mathrm{\%}] $
The flow area of the aerated hole

$\text{if }\ \text{n}= \text{no}$
$$A_{air}=NAN$$
$\text{else if }\ v_{air}=0$
$$A_{air}=0$$
$\text{else}$
$$A_{air}=\cfrac{Q_{air}}{v_{air}}$$

$ A_{air-pipe}\ [\mathrm{m^2}] $
No data
$ s\ [\mathrm{\%}] $
The flow area of the aerated pipeline

$\text{if }\ \text{n}= \text{no}$
$$A_{air-pipe}=NAN$$
$\text{else if }\ v_{air}>50$
$$A_{air-pipe}=\cfrac{Q_{air}}{50}$$
$\text{else}$
$$A_{air-pipe}=A_{air}$$