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Hydrodynamic calculation Howell-Bunger valve

Howell-Bunger valve D 90° 48° R 72° S 25° 40° a b c e f g +F x
Howell-Bunger valve

Values for calculation

$ D $ $ \mathrm{mm} $
$ S $ $ \mathrm{mm} $
$ R $ $ \mathrm{mm} $
$ a $ $ \mathrm{mm} $
$ b $ $ \mathrm{mm} $
$ c $ $ \mathrm{mm} $
$ e $ $ \mathrm{mm} $
$ f $ $ \mathrm{mm} $
$ g $ $ \mathrm{mm} $
$ H $ $ \mathrm{m} $
$ g $ $ \mathrm{m/s^2} $
$ T $ $ \mathrm{°C} $
$ ρ $ $ \mathrm{kg/m^3} $
$ P_{SV} $ $ \mathrm{Pa} $
$ n $
$ ΔP $ $ \mathrm{m} $
$ Σζ $
$ h $ $ \mathrm{m} $
$ ρ_{air} $ $ \mathrm{kg/m^3} $
$ p_{air} $ $ \mathrm{Pa} $
$ h_j $ $ \mathrm{m} $
Hydraulic jump behind the valve - model no.1 D 2.5 D L 1 L 2 h l h j
Hydraulic jump behind the valve - model no.1
Dimensional sketch - model no.1 x D 1.25 D 1 D 45° 2.5 D 2.5 D 30° 3 D 6 D 0.4D 2.76D 0.39D 0.86D 1.36D 1.39D 2.77 D 3.08 D 45° P u P u P 1 u-air P 2 u-air P 1 u-air P 2 u-air
Dimensional sketch - model no.1
Hydraulic jump behind the valve - model no.2 D 2.5 D L 1 L 2 h l h j
Hydraulic jump behind the valve - model no.2
Dimensional sketch - model no.2 D 2.82 D 3.33 D 45° 1.36D 3 D 6 D 30° 0.39D 2.56D 1.94D 0.39D 0.58D 45° 0.64D 2.5 D 1.11D 0.6D 0.44 D 0.1 D 4.36D 1.5 D 1.5 D P u P u P 1 u-air P 1 u-air P 2 u-air P 2 u-air
Dimensional sketch - model no.2
Hydraulic jump behind the valve - model no.3 h l h j D 1.2 D L 1 L 2
Hydraulic jump behind the valve - model no.3
Dimensional sketch - model no.3 D 1.82 D 2.33 D 45° 1.36D 3 D 6 D 30° 0.39D 2.56D 1.94D 45° 1.2 D 1.11D 0.6D 0.1 D 4.36D 1.5 D 1.5 D P u P u P 1 u-air P 1 u-air P 2 u-air P 2 u-air
Dimensional sketch - model no.3

Calculation

Flow

$$Q_{max}=\cfrac{1}{\sqrt{1+Σζ+\min\left(ζ\right)}}\cdot\cfrac{π\cdot D^2}{4\cdot 10^6}\cdot\sqrt{2\cdot g\cdot H}$$

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

$$p=\cfrac{Δ_h}{H}$$

$$0 < p \le 1$$
Valve position
Flow coefficient
Coefficient of hydraulic force on body in the axis x
Loss coefficient
Reduced free flow area in the throttle control system
Relative flow
$ S/D $ $ K_Q $ $ K_{bx} $ $ ζ $ $ f_r $ $ Q_p $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $
No data

$ K_Q\ [-] $
No data
$ S/D\ [-] $
Flow coefficient

$ K_{bx}\ [-] $
No data
$ S/D\ [-] $
Coefficient of hydraulic force on body in the axis x

$ ζ\ [-] $
No data
$ S/D\ [-] $
Loss coefficient

$$ζ=\cfrac{1-K_Q^2}{K_Q^2}$$

$ f_r\ [-] $
$ Q_p\ [-] $
No data
$ S/D\ [-] $
Coefficients

$$f_r=\cfrac{K_Q}{K_{Qmax}}$$
$$Q_p=\cfrac{f_r}{\sqrt{p+f_r^2\cdot \left(1-p\right)}}$$
Valve position
Flow of water in the pipeline
Water velocity in pipeline
Energy before the valve
$ S/D $ $ Q $ $ v $ $ T_x $
$ \mathrm{\ } $ $ \mathrm{m^3/s} $ $ \mathrm{m/s} $ $ \mathrm{m} $
No data

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

$$Q=Q_p\cdot Q_{max}$$
$$v=Q_p\cdot v_{max}$$

$ T_x\ [\mathrm{m}] $
No data
$ S/D\ [-] $
Energy before the valve

$\text{if }\ \text{model }$$\text{number }$$\text{for }$$\text{Howell-Bunger }$$\text{valve}= 3$
$$T_x=H+\cfrac{v^2}{2\cdot g}+1.5\cdot \cfrac{D}{1000}-\cfrac{v^2}{2\cdot g}\cdot Σζ$$
$\text{else}$
$$T_x=H+\cfrac{v^2}{2\cdot g}+2.5\cdot \cfrac{D}{1000}-\cfrac{v^2}{2\cdot g}\cdot Σζ$$
Valve position
Coefficient of water level for $ \cfrac{T_x}{D}=10 $
Coefficient of water level for $ \cfrac{T_x}{D}=20 $
Coefficient of water level for $ \cfrac{T_x}{D}=30 $
Coefficient of water level for $ \cfrac{T_x}{D}=40 $
Coefficient of water level for $ \cfrac{T_x}{D}=50 $
Water level
$ S/D $ $ h_{l-10} $ $ h_{l-20} $ $ h_{l-30} $ $ h_{l-40} $ $ h_{l-50} $ $ h_l $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{m} $
No data

$ h_{l-10}\ [-] $
$ h_{l-20}\ [-] $
$ h_{l-30}\ [-] $
$ h_{l-40}\ [-] $
$ h_{l-50}\ [-] $
No data
$ S/D\ [-] $
Coefficient of water level

$ h_l\ [\mathrm{m}] $
No data
$ S/D\ [-] $
Water level

$\text{if }\ \cfrac{T_x\cdot 10^3}{D}< 10$
$$h_l=h_{l-10}\cdot\cfrac{D}{1000}$$
$\text{else if }\ \cfrac{T_x\cdot 10^3}{D}< 20$
$$h_l=h_{l-20}\cdot\cfrac{D}{1000}$$
$\text{else if }\ \cfrac{T_x\cdot 10^3}{D}< 30$
$$h_l=h_{l-30}\cdot\cfrac{D}{1000}$$
$\text{else if }\ \cfrac{T_x\cdot 10^3}{D}< 40$
$$h_l=h_{l-40}\cdot\cfrac{D}{1000}$$
$\text{else}$
$$h_l=h_{l-50}\cdot\cfrac{D}{1000}$$
Valve position
Coefficient of under-pressure for $ \cfrac{h_l}{D}=0 $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=2 $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=2.5 $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=3 $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=3.5 $
$ S/D $ $ K_{Pu-0} $ $ K_{Pu-2} $ $ K_{Pu-2.5} $ $ K_{Pu-3} $ $ K_{Pu-3.5} $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $
No data

$ K_{Pu-0}\ [-] $
$ K_{Pu-2}\ [-] $
$ K_{Pu-2.5}\ [-] $
$ K_{Pu-3}\ [-] $
$ K_{Pu-3.5}\ [-] $
No data
$ S/D\ [-] $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=0\ \text{to}\ 3.5 $

Valve position
Coefficient of under-pressure for $ \cfrac{h_l}{D}=3.6 $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=3.9 $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=4 $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=4.2 $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=4.5 $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=5 $
$ S/D $ $ K_{Pu-3.6} $ $ K_{Pu-3.9} $ $ K_{Pu-4} $ $ K_{Pu-4.2} $ $ K_{Pu-4.5} $ $ K_{Pu-5} $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $
No data

$ K_{Pu-3.6}\ [-] $
$ K_{Pu-3.9}\ [-] $
$ K_{Pu-4}\ [-] $
$ K_{Pu-4.2}\ [-] $
$ K_{Pu-4.5}\ [-] $
$ K_{Pu-5}\ [-] $
No data
$ S/D\ [-] $
Coefficient of under-pressure for $ \cfrac{h_l}{D}=3.6\ \text{to}\ 5 $

Valve position
Coefficient of under-pressure
Under-pressure behind the valve
Loss of pressure on the valve
Pressure on the valve
Cavitation number
$ S/D $ $ K_{Pu} $ $ P_{u} $ $ H_L $ $ H_v $ $ σ $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{m} $ $ \mathrm{m} $ $ \mathrm{m} $ $ \mathrm{\ } $
No data

$ K_{Pu}\ [-] $
No data
$ S/D\ [-] $
Coefficient of under-pressure

$\text{if }\ \cfrac{h_l\cdot 10^3}{D}\le 0$
$$K_{Pu}=K_{Pu-0}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 2$
$$K_{Pu}=K_{Pu-2}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 2.5$
$$K_{Pu}=K_{Pu-2.5}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3$
$$K_{Pu}=K_{Pu-3}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3.5$
$$K_{Pu}=K_{Pu-3.5}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3.6$
$$K_{Pu}=K_{Pu-3.6}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3.9$
$$K_{Pu}=K_{Pu-3.9}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 4$
$$K_{Pu}=K_{Pu-4}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 4.2$
$$K_{Pu}=K_{Pu-4.2}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 4.5$
$$K_{Pu}=K_{Pu-4.5}$$
$\text{else}$
$$K_{Pu}=K_{Pu-5}$$

$ P_{u}\ [\mathrm{m}] $
No data
$ S/D\ [-] $
Under-pressure behind the valve

$$P_{u}=\max\left(K_{Pu}\cdot H_v, -\cfrac{p_{air}}{ρ\cdot g}\right)$$

$ H_L\ [\mathrm{m}] $
$ H_v\ [\mathrm{m}] $
No data
$ S/D\ [-] $
Loss of height on valve and pressure height on Howell-Bunger valve

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

$ σ\ [-] $
No data
$ S/D\ [-] $
Cavitation number

$$σ=\cfrac{\cfrac{p_{air}-P_{SV}}{ρ\cdot g}+H-H_L}{H_v}$$
Valve position
Coefficient of lenght $ L_1 $ for $ \cfrac{T_x}{D}=10 $
Coefficient of lenght $ L_1 $ for $ \cfrac{T_x}{D}=20 $
Coefficient of lenght $ L_1 $ for $ \cfrac{T_x}{D}=30 $
Coefficient of lenght $ L_1 $ for $ \cfrac{T_x}{D}=40 $
Lenght $ L_1 $
$ S/D $ $ L_{1-10} $ $ L_{1-20} $ $ L_{1-30} $ $ L_{1-40} $ $ L_1 $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{m} $
No data

$ L_{1-10}\ [-] $
$ L_{1-20}\ [-] $
$ L_{1-30}\ [-] $
$ L_{1-40}\ [-] $
No data
$ S/D\ [-] $
Coefficient of lenght $ L_1 $

$ L_1\ [\mathrm{m}] $
No data
$ S/D\ [-] $
Lenght $ L_1 $

$\text{if }\ \cfrac{T_x\cdot 10^3}{D}< 10$
$$L_1=L_{1-10}\cdot\cfrac{D}{1000}$$
$\text{else if }\ \cfrac{T_x\cdot 10^3}{D}< 20$
$$L_1=L_{1-20}\cdot\cfrac{D}{1000}$$
$\text{else if }\ \cfrac{T_x\cdot 10^3}{D}< 30$
$$L_1=L_{1-30}\cdot\cfrac{D}{1000}$$
$\text{else}$
$$L_1=L_{1-40}\cdot\cfrac{D}{1000}$$
Valve position
Coefficient of lenght $ L_2 $ for $ \cfrac{T_x}{D}=10 $
Coefficient of lenght $ L_2 $ for $ \cfrac{T_x}{D}=20 $
Coefficient of lenght $ L_2 $ for $ \cfrac{T_x}{D}=30 $
Coefficient of lenght $ L_2 $ for $ \cfrac{T_x}{D}=40 $
Coefficient of lenght $ L_2 $ for $ \cfrac{T_x}{D}=50 $
Lenght $ L_2 $
$ S/D $ $ L_{2-10} $ $ L_{2-20} $ $ L_{2-30} $ $ L_{2-40} $ $ L_{2-50} $ $ L_2 $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{m} $
No data

$ L_{2-10}\ [-] $
$ L_{2-20}\ [-] $
$ L_{2-30}\ [-] $
$ L_{2-40}\ [-] $
$ L_{2-50}\ [-] $
No data
$ S/D\ [-] $
Coefficient of lenght $ L_2 $

$ L_2\ [\mathrm{m}] $
No data
$ S/D\ [-] $
Lenght $ L_2 $

$\text{if }\ \cfrac{T_x\cdot 10^3}{D}< 10$
$$L_2=L_{2-10}\cdot\cfrac{D}{1000}$$
$\text{else if }\ \cfrac{T_x\cdot 10^3}{D}< 20$
$$L_2=L_{2-20}\cdot\cfrac{D}{1000}$$
$\text{else if }\ \cfrac{T_x\cdot 10^3}{D}< 30$
$$L_2=L_{2-30}\cdot\cfrac{D}{1000}$$
$\text{else if }\ \cfrac{T_x\cdot 10^3}{D}< 40$
$$L_2=L_{2-40}\cdot\cfrac{D}{1000}$$
$\text{else}$
$$L_2=L_{2-50}\cdot\cfrac{D}{1000}$$
Valve position
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=0 $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=2 $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=2.5 $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=3 $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=3.5 $
$ S/D $ $ K_{Pu-air1-0} $ $ K_{Pu-air1-2} $ $ K_{Pu-air1-2.5} $ $ K_{Pu-air1-3} $ $ K_{Pu-air1-3.5} $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $
No data

$ K_{Pu-air1-0}\ [-] $
$ K_{Pu-air1-2}\ [-] $
$ K_{Pu-air1-2.5}\ [-] $
$ K_{Pu-air1-3}\ [-] $
$ K_{Pu-air1-3.5}\ [-] $
No data
$ S/D\ [-] $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=0\ \text{to}\ 3.5 $

Valve position
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=3.6 $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=3.9 $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=4 $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=4.2 $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=4.5 $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=5 $
$ S/D $ $ K_{Pu-air1-3.6} $ $ K_{Pu-air1-3.9} $ $ K_{Pu-air1-4} $ $ K_{Pu-air1-4.2} $ $ K_{Pu-air1-4.5} $ $ K_{Pu-air1-5} $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $
No data

$ K_{Pu-air1-3.6}\ [-] $
$ K_{Pu-air1-3.9}\ [-] $
$ K_{Pu-air1-4}\ [-] $
$ K_{Pu-air1-4.2}\ [-] $
$ K_{Pu-air1-4.5}\ [-] $
$ K_{Pu-air1-5}\ [-] $
No data
$ S/D\ [-] $
Under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=3.6\ \text{to}\ 5 $

Valve position
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=0 $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=2 $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=2.5 $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=3 $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=3.5 $
$ S/D $ $ K_{Pu-air2-0} $ $ K_{Pu-air2-2} $ $ K_{Pu-air2-2.5} $ $ K_{Pu-air2-3} $ $ K_{Pu-air2-3.5} $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $
No data

$ K_{Pu-air2-0}\ [-] $
$ K_{Pu-air2-2}\ [-] $
$ K_{Pu-air2-2.5}\ [-] $
$ K_{Pu-air2-3}\ [-] $
$ K_{Pu-air2-3.5}\ [-] $
No data
$ S/D\ [-] $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=0\ \text{to}\ 3.5 $

Valve position
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=3.6 $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=3.9 $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=4 $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=4.2 $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=4.5 $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=5 $
$ S/D $ $ K_{Pu-air2-3.6} $ $ K_{Pu-air2-3.9} $ $ K_{Pu-air2-4} $ $ K_{Pu-air2-4.2} $ $ K_{Pu-air2-4.5} $ $ K_{Pu-air2-5} $
$ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{\ } $
No data

$ K_{Pu-air2-3.6}\ [-] $
$ K_{Pu-air2-3.9}\ [-] $
$ K_{Pu-air2-4}\ [-] $
$ K_{Pu-air2-4.2}\ [-] $
$ K_{Pu-air2-4.5}\ [-] $
$ K_{Pu-air2-5}\ [-] $
No data
$ S/D\ [-] $
Under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=3.6\ \text{to}\ 5 $

Valve position
The force at the valve axis x
Under-pressure coefficient in hole 1
Under-pressure coefficient in hole 2
Under-pressure in hole 1
Under-pressure in hole 2
$ S/D $ $ F_{bx} $ $ K_{Pu-air1} $ $ K_{Pu-air2} $ $ P_{u-air1} $ $ P_{u-air2} $
$ \mathrm{\ } $ $ \mathrm{kN} $ $ \mathrm{\ } $ $ \mathrm{\ } $ $ \mathrm{m} $ $ \mathrm{m} $
No data

$ F_{bx}\ [\mathrm{kN}] $
No data
$ S/D\ [-] $
The force at the valve axis x

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

$ K_{Pu-air1}\ [-] $
No data
$ S/D\ [-] $
Under-pressure coefficient in hole 1

$\text{if }\ \cfrac{h_l\cdot 10^3}{D}\le 0$
$$K_{Pu-air1}=K_{Pu-air1-0}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 2$
$$K_{Pu-air1}=K_{Pu-air1-2}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 2.5$
$$K_{Pu-air1}=K_{Pu-air1-2.5}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3$
$$K_{Pu-air1}=K_{Pu-air1-3}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3.5$
$$K_{Pu-air1}=K_{Pu-air1-3.5}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3.6$
$$K_{Pu-air1}=K_{Pu-air1-3.6}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3.9$
$$K_{Pu-air1}=K_{Pu-air1-3.9}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 4$
$$K_{Pu-air1}=K_{Pu-air1-4}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 4.2$
$$K_{Pu-air1}=K_{Pu-air1-4.2}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 4.5$
$$K_{Pu-air1}=K_{Pu-air1-4.5}$$
$\text{else}$
$$K_{Pu-air1}=K_{Pu-air1-5}$$

$ K_{Pu-air2}\ [-] $
No data
$ S/D\ [-] $
Under-pressure coefficient in hole 2

$\text{if }\ \cfrac{h_l\cdot 10^3}{D}\le 0$
$$K_{Pu-air2}=K_{Pu-air2-0}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 2$
$$K_{Pu-air2}=K_{Pu-air2-2}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 2.5$
$$K_{Pu-air2}=K_{Pu-air2-2.5}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3$
$$K_{Pu-air2}=K_{Pu-air2-3}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3.5$
$$K_{Pu-air2}=K_{Pu-air2-3.5}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3.6$
$$K_{Pu-air2}=K_{Pu-air2-3.6}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 3.9$
$$K_{Pu-air2}=K_{Pu-air2-3.9}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 4$
$$K_{Pu-air2}=K_{Pu-air2-4}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 4.2$
$$K_{Pu-air2}=K_{Pu-air2-4.2}$$
$\text{else if }\ \cfrac{h_l\cdot 10^3}{D}\le 4.5$
$$K_{Pu-air2}=K_{Pu-air2-4.5}$$
$\text{else}$
$$K_{Pu-air2}=K_{Pu-air2-5}$$

$ P_{u-air1}\ [\mathrm{m}] $
No data
$ S/D\ [-] $
Under-pressure in hole 1

$$P_{u-air1}=\max\left(K_{Pu-air1}\cdot H_v, -\cfrac{p_{air}}{ρ\cdot g}\right)$$

$ P_{u-air2}\ [\mathrm{m}] $
No data
$ S/D\ [-] $
Under-pressure in hole 2

$$P_{u-air2}=\max\left(K_{Pu-air2}\cdot H_v, -\cfrac{p_{air}}{ρ\cdot g}\right)$$
Valve position
Air flow
Air velocity in hole 1
Air velocity in hole 2
The flow area of the aerated hole
$ S/D $ $ Q_{air} $ $ v_{air1} $ $ v_{air2} $ $ A_{air} $
$ \mathrm{\ } $ $ \mathrm{m^3/s} $ $ \mathrm{m/s} $ $ \mathrm{m/s} $ $ \mathrm{m^2} $
No data

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

$\text{if }\ \text{n}= \text{no}$
$$Q_{air}=NAN$$
$\text{else}$
$$Q_{air}=0.04\cdot Q$$

$ v_{air1}\ [\mathrm{m/s}] $
$ v_{air2}\ [\mathrm{m/s}] $
No data
$ S/D\ [-] $
Air velocity

$\text{if }\ \text{n}= \text{no}$
$$v_{air1}=NAN$$
$\text{else}$
$$v_{air1}=\min\left(0.7\cdot\sqrt{-\cfrac{2\cdot P_{u-air1}\cdot g\cdot ρ}{ρ_{air}}}, 250\right)$$
$\text{if }\ \text{n}= \text{no}$
$$v_{air2}=NAN$$
$\text{else}$
$$v_{air2}=\min\left(0.7\cdot\sqrt{-\cfrac{2\cdot P_{u-air2}\cdot g\cdot ρ}{ρ_{air}}}, 250\right)$$

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

$\text{if }\ \text{n}= \text{no}$
$$A_{air}=NAN$$
$\text{else}$
$$A_{air}=\cfrac{Q_{air}}{v_{air1}+v_{air2}}$$
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