# Hydrodynamic calculation vertical lift gates

## Values for calculation

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

## 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

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

### Effective closing time factor

$$c_{ef}=0$$

### Under-pressure behind the gate

$$P_{u}=\max\left(-\cfrac{L\cdot v_{max}}{g\cdot t\cdot c_{ef}}, -10\right)$$

### Pressure parameter

$$p=\cfrac{Δ_h}{H}$$$$0 < p \le 1$$