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Hydrodynamic calculation vertical lift gates

Vertical lift gate Q max H s 0 b B s s d' θ a 1 a 2 d r e L s Q air +W +P
Vertical lift gate

Values for calculation

$ s_0 $ $ \mathrm{mm} $
$ b $ $ \mathrm{mm} $
$ B $ $ \mathrm{mm} $
$ s_s $ $ \mathrm{mm} $
$ d^´ $ $ \mathrm{mm} $
$ θ $ $ \mathrm{°} $
$ e/d $
$ a_1 $ $ \mathrm{mm} $
$ a_2 $ $ \mathrm{mm} $
$ d $ $ \mathrm{mm} $
$ r $ $ \mathrm{mm} $
$ e $ $ \mathrm{mm} $
$ Q_{max} $ $ \mathrm{m^3/s} $
$ H $ $ \mathrm{m} $
$ ΔP $ $ \mathrm{m} $
$ g $ $ \mathrm{m/s^2} $
$ T $ $ \mathrm{°C} $
$ ρ $ $ \mathrm{kg/m^3} $
$ P_{SV} $ $ \mathrm{Pa} $
$ h $ $ \mathrm{m} $
$ ρ_{air} $ $ \mathrm{kg/m^3} $
$ p_{air} $ $ \mathrm{Pa} $
$ t $ $ \mathrm{s} $
$ L $ $ \mathrm{m} $

Calculation

Cross-sectional area of the conduit

$$A=\cfrac{s_0\cdot b}{10^6}$$

Area of the horizontal projection of the top seal

$$A_s=\cfrac{B\cdot a_2}{10^6}$$

Minimum cross-sectional area between upstream face of the gate and upstream wall of the gate chamber

$$A_1=a_1\cdot b$$

Cross-sectional area of the contracted jet issuing from the gap between the downstream face of the gate and the downstream wall of the gate chamber

$$A_2=a_2\cdot b$$

Coefficient $ K_T $

$$K_T=\cfrac{1}{1+\left(\cfrac{A_2}{A_1}\right)^2}$$

Velocity before the gate

$$v_{max}=\cfrac{10^6\cdot Q_{max}}{s_0\cdot b}$$

Theoretical pressure in the gate at full opening

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

Effective closing time factor

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

Under-pressure behind the gate

$$P_{u}=\max\left(-\cfrac{L\cdot v_{max}}{g\cdot t\cdot c_{ef}}, -\cfrac{p_{air}}{ρ\cdot g}\right)$$

Pressure parameter

$$p=\cfrac{Δ_h}{H}$$

$$0 < p \le 1$$
Gate position
Flow coefficient
Coefficient $ K_B $
Coefficient of contraction
Gate opening
$ s/s_0 $ $ K_Q $ $ K_B $ $ C_c $ $ s $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{mm} $
No data

$ K_Q\ [-] $
No data
$ s/s_0\ [-] $
Flow coefficient

$\text{if }\ s/s_0= 0$
$$K_Q=1E-100$$
$\text{else}$
$$K_Q=s/s_0\cdot C_c$$

$ K_B\ [-] $
No data
$ s/s_0\ [-] $
Coefficient $ K_B $

$ C_c\ [-] $
No data
$ s/s_0\ [-] $
Coefficient of contraction

$ s\ [\mathrm{mm}] $
No data
$ s/s_0\ [-] $
Gate opening

$$s=s/s_0\cdot s_0$$
Gate position
Loss coefficient
Reduced free flow area in the throttle control system
Relative flow
Flow of water before the gate
Water velocity before the gate
Velocity in the contracted jet issuing from underneath the gate
$ s/s_0 $ $ ζ $ $ f_r $ $ Q_p $ $ Q $ $ v $ $ v_j $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{m^3/s} $ $ \mathrm{m/s} $ $ \mathrm{m/s} $
No data

$ ζ\ [-] $
No data
$ s/s_0\ [-] $
Loss coefficient

$$ζ=\cfrac{1-K_Q^2}{K_Q^2}$$

$ f_r\ [-] $
$ Q_p\ [-] $
No data
$ s/s_0\ [-] $
Coefficients

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

$ Q\ [\mathrm{m^3/s}] $
No data
$ s/s_0\ [-] $
Flow of water before the gate

$\text{if }\ K_Q\cdot\sqrt{2\cdot g\cdot H} \le v_{max}$
$$Q=K_Q\cdot A\cdot\sqrt{2\cdot g\cdot H}$$
$\text{else}$
$$Q=Q_p\cdot Q_{max}$$

$ v\ [\mathrm{m/s}] $
No data
$ s/s_0\ [-] $
Water velocity before the gate

$$v=\cfrac{10^6\cdot Q}{s_0\cdot b}$$

$ v_j\ [\mathrm{m/s}] $
No data
$ s/s_0\ [-] $
Velocity in the contracted jet issuing from underneath the gate

$\text{if }\ s/s_0= 0$
$$v_j=0$$
$\text{else}$
$$v_j=\cfrac{Q}{K_Q\cdot A}$$
Gate position
Loss of pressure on the gate
Pressure on the gate
Cavitation number
Force on gate
$ s/s_0 $ $ H_L $ $ H_v $ $ σ $ $ W $
$ \mathrm{\ } $ $ \mathrm{m} $ $ \mathrm{m} $ $ \mathrm{\ } $ $ \mathrm{kN} $
No data

$ H_L\ [\mathrm{m}] $
$ H_v\ [\mathrm{m}] $
No data
$ s/s_0\ [-] $
Loss of height on gate and pressure height on gate

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

$ σ\ [-] $
No data
$ s/s_0\ [-] $
Cavitation number

$$σ=\cfrac{\cfrac{p_{air}-P_{SV}}{ρ\cdot g}+H-H_L}{H_v}$$

$ W\ [\mathrm{kN}] $
No data
$ s/s_0\ [-] $
Force on gate

$\text{if }\ s/s_0= 0$
$$W=\cfrac{ρ\cdot g\cdot H_v\cdot B\cdot s_s}{10^6}$$
$\text{else}$
$$W=\cfrac{ρ\cdot g\cdot H_v\cdot B\cdot\left(s_0-s\right)}{10^6}$$
Gate position
Downpull resulting from the difference between the pressures acting on the top and bottom surfaces of the gate
Downpull resulting from the pressure differential acting on the horizontal protrusions of the gate
Downpull resulting from the lip
Downpull force
$ s/s_0 $ $ P_1 $ $ P_2 $ $ P_3 $ $ P $
$ \mathrm{\ } $ $ \mathrm{kN} $ $ \mathrm{kN} $ $ \mathrm{kN} $ $ \mathrm{kN} $
No data

$ P_1\ [\mathrm{kN}] $
No data
$ s/s_0\ [-] $
Downpull resulting from the difference between the pressures acting on the top and bottom surfaces of the gate

$$P_1=\left(K_T-K_B\right)\cdot B\cdot d\cdot ρ\cdot\cfrac{v_j^2}{2\cdot10^9}$$

$ P_2\ [\mathrm{kN}] $
No data
$ s/s_0\ [-] $
Downpull resulting from the pressure differential acting on the horizontal protrusions of the gate

$$P_2=K_T\cdot A_s\cdot ρ\cdot\cfrac{v_j^2}{2\cdot10^3}$$

$ P_3\ [\mathrm{kN}] $
No data
$ s/s_0\ [-] $
Downpull resulting from the lip

$$P_3=K_T\cdot B\cdot d^´\cdot ρ\cdot\cfrac{v_j^2}{2\cdot10^9}$$

$ P\ [\mathrm{kN}] $
No data
$ s/s_0\ [-] $
Downpull force

$$P=P_1+P_2+P_3$$
Gate position
Depth of water at vena contracta
Froude number
Aerated coefficient
$ s/s_0 $ $ h_c $ $ F_c $ $ β $
$ \mathrm{\ } $ $ \mathrm{m} $ $ \mathrm{\ } $ $ \mathrm{\ } $
No data

$ h_c\ [\mathrm{m}] $
No data
$ s/s_0\ [-] $
Depth of water at vena contracta

$$h_c=\cfrac{K_Q\cdot s_0}{10^3}$$

$ F_c\ [-] $
No data
$ s/s_0\ [-] $
Froude number

$\text{if }\ s/s_0= 0$
$$F_c=0$$
$\text{else}$
$$F_c=\sqrt{\cfrac{2\cdot\left(H-h_c\right)}{h_c}}$$

$ β\ [-] $
No data
$ s/s_0\ [-] $
Aerated coefficient

$\text{if }\ s/s_0= 0$
$$β=0$$
$\text{else}$
$$β=0.03\cdot\left(F_c-1\right)^{1.06}$$
Gate position
Coefficient of under-pressure of aerated hole
Under-pressure in the aerated pipeline
Air flow
Air velocity
The flow area of the aerated hole
The flow area of the aerated pipeline
$ s/s_0 $ $ f_{air} $ $ p_{air} $ $ Q_{air} $ $ v_{air} $ $ A_{air} $ $ A_{air-pipe} $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{Pa} $ $ \mathrm{m^3/s} $ $ \mathrm{m/s} $ $ \mathrm{m^2} $ $ \mathrm{m^2} $
No data

$ f_{air}\ [-] $
No data
$ s/s_0\ [-] $
Coefficient of under-pressure of aerated hole

$ p_{air}\ [\mathrm{Pa}] $
No data
$ s/s_0\ [-] $
Under-pressure in the aerated pipeline

$$p_{air}=-\min\left(p_{air}, f_{air}\cdot\cfrac{v^2}{2\cdot g}\cdot ρ+\left(1-Q_p\right)\cdot\min\left(\cfrac{L\cdot v_{max}\cdot ρ}{t\cdot c_{ef}}, p_{air}\right)\right)$$

$ Q_{air}\ [\mathrm{m^3/s}] $
No data
$ s/s_0\ [-] $
Air flow

$\text{if }\ p_{air}< \cfrac{p_{air}}{2}$
$$Q_{air}=\min\left(Q_{max}-Q, β\cdot Q\right)$$
$\text{else}$
$$Q_{air}=\max\left(Q_{max}-Q, β\cdot Q\right)$$

$ v_{air}\ [\mathrm{m/s}] $
No data
$ s/s_0\ [-] $
Air velocity

$$v_{air}=\min\left(0.7\cdot\sqrt{-\cfrac{2\cdot p_{air}}{ρ_{air}}}, 250\right)$$

$ A_{air}\ [\mathrm{m^2}] $
No data
$ s/s_0\ [-] $
The flow area of the aerated hole

$\text{if }\ v_{air}= 0$
$$A_{air}=0$$
$\text{else}$
$$A_{air}=\cfrac{Q_{air}}{v_{air}}$$

$ A_{air-pipe}\ [\mathrm{m^2}] $
No data
$ s/s_0\ [-] $
The flow area of the aerated pipeline

$\text{if }\ v_{air}> 50$
$$A_{air-pipe}=\cfrac{Q_{air}}{50}$$
$\text{else}$
$$A_{air-pipe}=A_{air}$$
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