| $ $
| model number for Howell-Bunger valve | $\mathrm{ }$
|
| $ $
| flow characteristic | $\mathrm{ }$
|
| $ $
| data | $\mathrm{ }$
|
| $A$
| the flow area | $\mathrm{m^2}$
|
| $A$
| function $ A $ | $\mathrm{ }$
|
| $A_{air-pipe}$
| the flow area of the aerated pipeline | $\mathrm{m^2}$
|
| $A_{air}$
| the flow area of the aerated hole | $\mathrm{m^2}$
|
| $B$
| function $ B $ | $\mathrm{ }$
|
| $C$
| function $ C $ | $\mathrm{ }$
|
| $D$
| valve diameter | $\mathrm{mm}$
|
| $D_c$
| inner diameter of the cage | $\mathrm{mm}$
|
| $D_p$
| internal pipe diameter | $\mathrm{mm}$
|
| $D_s$
| max diameter of the disc seal | $\mathrm{mm}$
|
| $D_s$
| max diameter seal on the rotating body | $\mathrm{mm}$
|
| $D_{HC}$
| diameter of piston in the hydraulic cylinder | $\mathrm{mm}$
|
| $D_{needle}$
| diameter needle | $\mathrm{mm}$
|
| $E$
| Young's modulus for pipe | $\mathrm{Pa}$
|
| $F$
| forces on disc | $\mathrm{kN}$
|
| $F$
| forces on rotating body | $\mathrm{kN}$
|
| $F_x$
| forces on disc in axis x | $\mathrm{kN}$
|
| $F_x$
| forces on rotating body in axis x | $\mathrm{kN}$
|
| $F_x$
| forces on the needle | $\mathrm{kN}$
|
| $F_x$
| forces on sliding plate in axis x | $\mathrm{kN}$
|
| $F_y$
| forces on disc in axis y | $\mathrm{kN}$
|
| $F_y$
| forces on rotating body in axis y | $\mathrm{kN}$
|
| $F_y$
| forces on sliding plate in axis y | $\mathrm{kN}$
|
| $F_{HC-flow-with-frictional}$
| force to the hydraulic cylinder during the closing at flow rate with frictional resistances | $\mathrm{kN}$
|
| $F_{HC-flow}$
| force to the hydraulic cylinder during the closing at flow rate without frictional resistances | $\mathrm{kN}$
|
| $F_{HC-with-frictional}$
| force to the hydraulic cylinder during the closing without flow rate with frictional resistances | $\mathrm{kN}$
|
| $F_{HC}$
| force to the hydraulic cylinder during the closing without flow rate without frictional resistances | $\mathrm{kN}$
|
| $F_{bx}$
| the force at the valve axis x | $\mathrm{kN}$
|
| $F_{by}$
| the force at the valve axis y | $\mathrm{kN}$
|
| $F_{e1}$
| force parallel to the axis of the disc | $\mathrm{kN}$
|
| $F_{e1}$
| force parallel to the axis of the rotating body | $\mathrm{kN}$
|
| $F_{e2}$
| force perpendicular to the axis of the disc | $\mathrm{kN}$
|
| $F_{e2}$
| force perpendicular to the axis of the rotating body | $\mathrm{kN}$
|
| $H$
| static head | $\mathrm{m}$
|
| $H$
| geopotential altitude | $\mathrm{m}$
|
| $H_L$
| loss of pressure on the valve | $\mathrm{m}$
|
| $H_b$
| lower limit geopotential altitude | $\mathrm{m}$
|
| $H_p$
| pressure scale height | $\mathrm{m}$
|
| $H_v$
| pressure on the valve | $\mathrm{m}$
|
| $I$
| number of holes | $\mathrm{ }$
|
| $I_{total}$
| total number of holes | $\mathrm{ }$
|
| $K$
| volume elastic modulus | $\mathrm{Pa}$
|
| $K_Q$
| flow coefficient | $\mathrm{ }$
|
| $K_m$
| hydraulic torque coefficient | $\mathrm{ }$
|
| $K_x$
| coefficient of hydraulic force on a disc in the axis x | $\mathrm{ }$
|
| $K_x$
| coefficient of hydraulic force on a rotating body in the axis x | $\mathrm{ }$
|
| $K_x$
| coefficient of hydraulic force on a needle in the axis x | $\mathrm{ }$
|
| $K_x$
| coefficient of hydraulic force on a sliding plate in the axis x | $\mathrm{ }$
|
| $K_y$
| coefficient of hydraulic force on a disc in the axis y | $\mathrm{ }$
|
| $K_y$
| coefficient of hydraulic force on a rotating body in the axis y | $\mathrm{ }$
|
| $K_y$
| coefficient of hydraulic force on a sliding plate in the axis y | $\mathrm{ }$
|
| $K_{Pu-0}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=0 $ | $\mathrm{ }$
|
| $K_{Pu-2.5}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=2.5 $ | $\mathrm{ }$
|
| $K_{Pu-2}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=2 $ | $\mathrm{ }$
|
| $K_{Pu-3.5}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=3.5 $ | $\mathrm{ }$
|
| $K_{Pu-3.6}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=3.6 $ | $\mathrm{ }$
|
| $K_{Pu-3.9}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=3.9 $ | $\mathrm{ }$
|
| $K_{Pu-3}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=3 $ | $\mathrm{ }$
|
| $K_{Pu-4.2}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=4.2 $ | $\mathrm{ }$
|
| $K_{Pu-4.5}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=4.5 $ | $\mathrm{ }$
|
| $K_{Pu-4}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=4 $ | $\mathrm{ }$
|
| $K_{Pu-5}$
| coefficient of under-pressure for $ \cfrac{h_l}{D}=5 $ | $\mathrm{ }$
|
| $K_{Pu-air1-0}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=0 $ | $\mathrm{ }$
|
| $K_{Pu-air1-2.5}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=2.5 $ | $\mathrm{ }$
|
| $K_{Pu-air1-2}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=2 $ | $\mathrm{ }$
|
| $K_{Pu-air1-3.5}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=3.5 $ | $\mathrm{ }$
|
| $K_{Pu-air1-3.6}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=3.6 $ | $\mathrm{ }$
|
| $K_{Pu-air1-3.9}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=3.9 $ | $\mathrm{ }$
|
| $K_{Pu-air1-3}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=3 $ | $\mathrm{ }$
|
| $K_{Pu-air1-4.2}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=4.2 $ | $\mathrm{ }$
|
| $K_{Pu-air1-4.5}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=4.5 $ | $\mathrm{ }$
|
| $K_{Pu-air1-4}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=4 $ | $\mathrm{ }$
|
| $K_{Pu-air1-5}$
| under-pressure coefficient in hole 1 for $ \cfrac{h_l}{D}=5 $ | $\mathrm{ }$
|
| $K_{Pu-air1}$
| under-pressure coefficient in hole 1 | $\mathrm{ }$
|
| $K_{Pu-air2-0}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=0 $ | $\mathrm{ }$
|
| $K_{Pu-air2-2.5}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=2.5 $ | $\mathrm{ }$
|
| $K_{Pu-air2-2}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=2 $ | $\mathrm{ }$
|
| $K_{Pu-air2-3.5}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=3.5 $ | $\mathrm{ }$
|
| $K_{Pu-air2-3.6}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=3.6 $ | $\mathrm{ }$
|
| $K_{Pu-air2-3.9}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=3.9 $ | $\mathrm{ }$
|
| $K_{Pu-air2-3}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=3 $ | $\mathrm{ }$
|
| $K_{Pu-air2-4.2}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=4.2 $ | $\mathrm{ }$
|
| $K_{Pu-air2-4.5}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=4.5 $ | $\mathrm{ }$
|
| $K_{Pu-air2-4}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=4 $ | $\mathrm{ }$
|
| $K_{Pu-air2-5}$
| under-pressure coefficient in hole 2 for $ \cfrac{h_l}{D}=5 $ | $\mathrm{ }$
|
| $K_{Pu-air2}$
| under-pressure coefficient in hole 2 | $\mathrm{ }$
|
| $K_{Pu}$
| coefficient of under-pressure | $\mathrm{ }$
|
| $K_{Q-hydraulic-cylinder}$
| flow coefficient $ K_{Q-hydraulic-cylinder} $ | $\mathrm{ }$
|
| $K_{Q-valve[s+10]}$
| flow coefficient $ K_{Q-valve[s+10]} $ | $\mathrm{ }$
|
| $K_{Q-valve[s-10]}$
| flow coefficient $ K_{Q-valve[s-10]} $ | $\mathrm{ }$
|
| $K_{Q-valve}$
| flow coefficient $ K_{Q-valve} $ | $\mathrm{ }$
|
| $K_{Q-valve}[10]$
| flow coefficient $ K_{Q-valve}[10] $ | $\mathrm{ }$
|
| $K_{Q-valve}[1]$
| flow coefficient $ K_{Q-valve}[1] $ | $\mathrm{ }$
|
| $K_{Q-valve}[2]$
| flow coefficient $ K_{Q-valve}[2] $ | $\mathrm{ }$
|
| $K_{Q-valve}[3]$
| flow coefficient $ K_{Q-valve}[3] $ | $\mathrm{ }$
|
| $K_{Q-valve}[4]$
| flow coefficient $ K_{Q-valve}[4] $ | $\mathrm{ }$
|
| $K_{Q-valve}[5]$
| flow coefficient $ K_{Q-valve}[5] $ | $\mathrm{ }$
|
| $K_{Q-valve}[6]$
| flow coefficient $ K_{Q-valve}[6] $ | $\mathrm{ }$
|
| $K_{Q-valve}[7]$
| flow coefficient $ K_{Q-valve}[7] $ | $\mathrm{ }$
|
| $K_{Q-valve}[8]$
| flow coefficient $ K_{Q-valve}[8] $ | $\mathrm{ }$
|
| $K_{Q-valve}[9]$
| flow coefficient $ K_{Q-valve}[9] $ | $\mathrm{ }$
|
| $K_{Q-σ_1}$
| flow coefficient for $ σ_1 $ | $\mathrm{ }$
|
| $K_{Q-σ_2}$
| flow coefficient for $ σ_2 $ | $\mathrm{ }$
|
| $K_{Q-σ_{min}}$
| flow coefficient for $ σ_{min} $ | $\mathrm{ }$
|
| $K_{Qmax}$
| max flow coefficient | $\mathrm{ }$
|
| $K_{bx}$
| coefficient of hydraulic force on body in the axis x | $\mathrm{ }$
|
| $K_{by}$
| coefficient of hydraulic force on body in the axis y | $\mathrm{ }$
|
| $K_{x-upstream}$
| coefficient of hydraulic force on a needle upstream in the axis x | $\mathrm{ }$
|
| $K_{x-σ_1}$
| coefficient of hydraulic force on a needle in the axis x for $ σ_1 $ | $\mathrm{ }$
|
| $K_{x-σ_2}$
| coefficient of hydraulic force on a needle in the axis x for $ σ_2 $ | $\mathrm{ }$
|
| $K_{x-σ_{min}}$
| coefficient of hydraulic force on a needle in the axis x for $ σ_{min} $ | $\mathrm{ }$
|
| $L$
| pipe length | $\mathrm{m}$
|
| $L$
| cage length | $\mathrm{mm}$
|
| $L$
| distance between the axis of rotation of the valve and the axis of the hydraulic cylinder | $\mathrm{mm}$
|
| $L$
| pipe length behind valve | $\mathrm{m}$
|
| $L_1$
| lenght $ L_1 $ | $\mathrm{m}$
|
| $L_2$
| lenght $ L_2 $ | $\mathrm{m}$
|
| $L_D$
| length from the axis of rotation to the outer edge of the disc | $\mathrm{mm}$
|
| $L_c$
| distance between the centre of gravity of the weight (weight + disc + lever) and the axis of pivot rotation | $\mathrm{mm}$
|
| $L_c$
| distance between the centre of gravity of the weight (weight + rotating body + lever) and the axis of pivot rotation | $\mathrm{mm}$
|
| $L_d$
| damping phase | $\mathrm{\%}$
|
| $L_{1-10}$
| coefficient of lenght $ L_1 $ for $ \cfrac{T_x}{D}=10 $ | $\mathrm{ }$
|
| $L_{1-20}$
| coefficient of lenght $ L_1 $ for $ \cfrac{T_x}{D}=20 $ | $\mathrm{ }$
|
| $L_{1-30}$
| coefficient of lenght $ L_1 $ for $ \cfrac{T_x}{D}=30 $ | $\mathrm{ }$
|
| $L_{1-40}$
| coefficient of lenght $ L_1 $ for $ \cfrac{T_x}{D}=40 $ | $\mathrm{ }$
|
| $L_{2-10}$
| coefficient of lenght $ L_2 $ for $ \cfrac{T_x}{D}=10 $ | $\mathrm{ }$
|
| $L_{2-20}$
| coefficient of lenght $ L_2 $ for $ \cfrac{T_x}{D}=20 $ | $\mathrm{ }$
|
| $L_{2-30}$
| coefficient of lenght $ L_2 $ for $ \cfrac{T_x}{D}=30 $ | $\mathrm{ }$
|
| $L_{2-40}$
| coefficient of lenght $ L_2 $ for $ \cfrac{T_x}{D}=40 $ | $\mathrm{ }$
|
| $L_{2-50}$
| coefficient of lenght $ L_2 $ for $ \cfrac{T_x}{D}=50 $ | $\mathrm{ }$
|
| $L_{HC}$
| distance between the axis of hydraulic cylinder and the axis of valve rotation | $\mathrm{mm}$
|
| $M$
| hydraulic torque without eccentricity | $\mathrm{kNm}$
|
| $M$
| air molar mass at sea level | $\mathrm{kg\cdot kmol^{-1}}$
|
| $M_B$
| friction torque bearing during the closing without flow rate | $\mathrm{kNm}$
|
| $M_H$
| hydraulic torque | $\mathrm{kNm}$
|
| $M_S$
| friction torque in main sealing | $\mathrm{kNm}$
|
| $M_W$
| static torque | $\mathrm{kNm}$
|
| $M_e$
| moment from eccentricity | $\mathrm{kNm}$
|
| $M_{B-flow}$
| friction torque bearing during the closing at flow rate | $\mathrm{kNm}$
|
| $M_{F-HC}$
| friction torque from the hydraulic cylinder | $\mathrm{kNm}$
|
| $M_{LD}$
| moment from the axis of the trunnion to the axis of the disc | $\mathrm{kNm}$
|
| $N_A$
| Avogadro constant | $\mathrm{kmol^{-1}}$
|
| $P_1$
| inlet absolute static pressure | $\mathrm{Pa}$
|
| $P_2$
| output absolute static pressure | $\mathrm{Pa}$
|
| $P_S$
| contact pressure of the main sealing | $\mathrm{MPa}$
|
| $P_{HC-flow-with-frictional}$
| pressure of oil under the hydraulic cylinder piston during the closing at flow rate with frictional resistances | $\mathrm{MPa}$
|
| $P_{HC-flow}$
| pressure of oil under the hydraulic cylinder piston during the closing at flow rate without frictional resistances | $\mathrm{MPa}$
|
| $P_{HC-with-frictional}$
| pressure of oil under the hydraulic cylinder piston during the closing without flow rate with frictional resistances | $\mathrm{MPa}$
|
| $P_{HC}$
| pressure of oil under the hydraulic cylinder piston during the closing without flow rate without frictional resistances | $\mathrm{MPa}$
|
| $P_{L-HC}$
| pressure loss in the hydraulic cylinder | $\mathrm{MPa}$
|
| $P_{SV}$
| saturated vapor pressure | $\mathrm{Pa}$
|
| $P_{u-air1}$
| under-pressure in hole 1 | $\mathrm{m}$
|
| $P_{u-air2}$
| under-pressure in hole 2 | $\mathrm{m}$
|
| $P_{u}$
| under-pressure behind the valve | $\mathrm{m}$
|
| $Q$
| flow of water in the pipeline | $\mathrm{m^3/s}$
|
| $Q_p$
| relative flow | $\mathrm{ }$
|
| $Q_{air}$
| air flow | $\mathrm{m^3/s}$
|
| $Q_{max}$
| flow | $\mathrm{m^3/s}$
|
| $R$
| dimension $ R $ | $\mathrm{mm}$
|
| $R$
| specific gas constant | $\mathrm{J\cdot K^{-1}\cdot kg^{-1}}$
|
| $R^*$
| universal gas constant | $\mathrm{J\cdot K^{-1}\cdot kmol^{-1}}$
|
| $S$
| dimension $ S $ | $\mathrm{mm}$
|
| $S$
| Sutherland's empirical coefficients $ S $ | $\mathrm{K}$
|
| $S/D$
| valve position | $\mathrm{ }$
|
| $S_S$
| stroke in the pivot position | $\mathrm{mm}$
|
| $S_S$
| the distance between the axis of the hydraulic cylinder and the axis of the eye of the hydraulic cylinder | $\mathrm{mm}$
|
| $S_T$
| percentage of hydraulic cylinder stroke at a given time | $\mathrm{\%}$
|
| $S_f$
| safety factor during the closing without flow rate | $\mathrm{ }$
|
| $S_{S\%}$
| stroke percentage | $\mathrm{\%}$
|
| $S_{f-flow}$
| safety factor during the closing at flow rate | $\mathrm{ }$
|
| $S_{max}$
| stroke | $\mathrm{mm}$
|
| $T$
| height $ T $ | $\mathrm{mm}$
|
| $T$
| temperature $ T $ | $\mathrm{K}$
|
| $T$
| the water temperature | $\mathrm{°C}$
|
| $T_b$
| lower limit temperature | $\mathrm{K}$
|
| $T_c$
| total closing time | $\mathrm{s}$
|
| $T_d$
| damping time | $\mathrm{s}$
|
| $T_s$
| time value | $\mathrm{s}$
|
| $T_x$
| energy before the valve | $\mathrm{m}$
|
| $W_D$
| weight of the disc | $\mathrm{kg}$
|
| $W_L$
| weight of the lever | $\mathrm{kg}$
|
| $W_R$
| weight of the rotating body | $\mathrm{kg}$
|
| $W_W$
| weight of the weight | $\mathrm{kg}$
|
| $a$
| dimension $ a $ | $\mathrm{mm}$
|
| $a$
| speed pressure waves in the pipe | $\mathrm{m/s}$
|
| $a$
| distance to hydraulic cylinder $ a $ | $\mathrm{mm}$
|
| $a$
| speed of Sound | $\mathrm{m/s}$
|
| $a_1$
| length $ a_1 $ | $\mathrm{mm}$
|
| $a_2$
| length $ a_2 $ | $\mathrm{mm}$
|
| $b$
| dimension $ b $ | $\mathrm{mm}$
|
| $b$
| distance to hydraulic cylinder $ b $ | $\mathrm{mm}$
|
| $c$
| dimension $ c $ | $\mathrm{mm}$
|
| $c_{ef}$
| effective closing time factor | $\mathrm{ }$
|
| $d$
| diameter of the hole | $\mathrm{mm}$
|
| $d$
| inner diameter | $\mathrm{mm}$
|
| $d_1$
| dimension $ d_1 $ | $\mathrm{mm}$
|
| $e$
| thickness of the pipe wall | $\mathrm{mm}$
|
| $e$
| dimension $ e $ | $\mathrm{mm}$
|
| $e$
| eccentricity | $\mathrm{mm}$
|
| $e_S$
| width of main seal in contact | $\mathrm{mm}$
|
| $f$
| dimension $ f $ | $\mathrm{mm}$
|
| $f_B$
| the bearing factor of the bushings, defined as the sum of the forces in the bushings divided by the load force | $\mathrm{ }$
|
| $f_r$
| reduced free flow area in the throttle control system | $\mathrm{ }$
|
| $f_{air}$
| coefficient of under-pressure of aerated hole | $\mathrm{ }$
|
| $g$
| dimension $ g $ | $\mathrm{mm}$
|
| $g$
| gravitational acceleration | $\mathrm{m/s^2}$
|
| $h$
| dimension $ h $ | $\mathrm{mm}$
|
| $h$
| height above sea level | $\mathrm{m}$
|
| $h_j$
| water depth behind the hydraulic jump | $\mathrm{m}$
|
| $h_l$
| water level | $\mathrm{m}$
|
| $h_{l-10}$
| coefficient of water level for $ \cfrac{T_x}{D}=10 $ | $\mathrm{ }$
|
| $h_{l-20}$
| coefficient of water level for $ \cfrac{T_x}{D}=20 $ | $\mathrm{ }$
|
| $h_{l-30}$
| coefficient of water level for $ \cfrac{T_x}{D}=30 $ | $\mathrm{ }$
|
| $h_{l-40}$
| coefficient of water level for $ \cfrac{T_x}{D}=40 $ | $\mathrm{ }$
|
| $h_{l-50}$
| coefficient of water level for $ \cfrac{T_x}{D}=50 $ | $\mathrm{ }$
|
| $i$
| dimension $ i $ | $\mathrm{mm}$
|
| $i$
| number of rows | $\mathrm{ }$
|
| $j$
| dimension $ j $ | $\mathrm{mm}$
|
| $k$
| dimension $ k $ | $\mathrm{mm}$
|
| $l$
| dimension $ l $ | $\mathrm{mm}$
|
| $l$
| rod length | $\mathrm{mm}$
|
| $l$
| mean free path of air particles | $\mathrm{m}$
|
| $m$
| dimension $ m $ | $\mathrm{mm}$
|
| $n$
| aeration | $\mathrm{ }$
|
| $n$
| dimension $ n $ | $\mathrm{mm}$
|
| $n$
| air number density | $\mathrm{m^{-3}}$
|
| $n_{max}$
| allowable maximum number of holes in one row | $\mathrm{ }$
|
| $o$
| dimension $ o $ | $\mathrm{mm}$
|
| $p$
| pressure parameter | $\mathrm{ }$
|
| $p$
| dimension $ p $ | $\mathrm{mm}$
|
| $p_b$
| lower limit pressure | $\mathrm{Pa}$
|
| $p_{air}$
| under-pressure in the aerated pipeline | $\mathrm{Pa}$
|
| $p_{air}$
| atmospheric pressure air | $\mathrm{Pa}$
|
| $q$
| dimension $ q $ | $\mathrm{mm}$
|
| $r$
| dimension $ r $ | $\mathrm{mm}$
|
| $r$
| lever arm length | $\mathrm{mm}$
|
| $r$
| nominal earth's radius | $\mathrm{m}$
|
| $r_T$
| radius of trunnions for bearings | $\mathrm{mm}$
|
| $s$
| stroke from open position | $\mathrm{\%}$
|
| $s$
| dimension $ s $ | $\mathrm{mm}$
|
| $t$
| closing time | $\mathrm{s}$
|
| $t$
| dimension $ t $ | $\mathrm{mm}$
|
| $t_{ef}$
| effective closing time | $\mathrm{s}$
|
| $u$
| dimension $ u $ | $\mathrm{mm}$
|
| $v$
| water velocity in pipeline | $\mathrm{m/s}$
|
| $v$
| dimension $ v $ | $\mathrm{mm}$
|
| $v_p$
| speed in the pipe | $\mathrm{m/s}$
|
| $v_{air1}$
| air velocity in hole 1 | $\mathrm{m/s}$
|
| $v_{air2}$
| air velocity in hole 2 | $\mathrm{m/s}$
|
| $v_{air}$
| air velocity | $\mathrm{m/s}$
|
| $v_{max}$
| velocity in valve | $\mathrm{m/s}$
|
| $v̄$
| mean air-particle speed | $\mathrm{m/s}$
|
| $w$
| speed of sound | $\mathrm{m/s}$
|
| $w$
| dimension $ w $ | $\mathrm{mm}$
|
| $x$
| dimension $ x $ | $\mathrm{mm}$
|
| $y$
| dimension $ y $ | $\mathrm{mm}$
|
| $z$
| dimension $ z $ | $\mathrm{mm}$
|
| $ΔP$
| water hammer | $\mathrm{m}$
|
| $Δ_h$
| theoretical pressure in the valve at full opening | $\mathrm{m}$
|
| $Σζ$
| loss before valve | $\mathrm{ }$
|
| $α$
| angle from open position | $\mathrm{°}$
|
| $α$
| lever angle in closed position | $\mathrm{°}$
|
| $α_c$
| angle of rotation centre of gravity in open position | $\mathrm{°}$
|
| $β$
| aerated coefficient | $\mathrm{ }$
|
| $β$
| swing angle | $\mathrm{°}$
|
| $β$
| temperature gradient $ β $ | $\mathrm{K\cdot m^{-1}}$
|
| $β_S$
| angle rotation of the rocking motion | $\mathrm{°}$
|
| $β_s$
| Sutherland's empirical coefficients $ β_s $ | $\mathrm{kg\cdot m^{-1}\cdot s^{-1}\cdot K^{-1/2}}$
|
| $β_{S[s-10]}$
| angle rotation of the rocking motion | $\mathrm{°}$
|
| $γ$
| the angle between the axis of the hydraulic cylinder and the imaginary line between the axis of the closure and the pivot axis of the hydraulic cylinder | $\mathrm{°}$
|
| $γ_{air}$
| specific weight air | $\mathrm{kg\cdot m^{-2}\cdot s^{-2}}$
|
| $δ$
| the angle between the lever axis and the imaginary line between the valve axis and the pivot axis of the hydraulic cylinder | $\mathrm{°}$
|
| $δ_{[0]}$
| the angle between the axis of the lever and the imaginary line between the axis of the valve and the pivot axis of the hydraulic cylinder in the open position | $\mathrm{°}$
|
| $ζ$
| loss coefficient | $\mathrm{ }$
|
| $ζ$
| valve loss coefficient | $\mathrm{ }$
|
| $θ$
| transformed temperature | $\mathrm{ }$
|
| $κ$
| adiabatic index | $\mathrm{ }$
|
| $λ$
| thermal conductivity | $\mathrm{W\cdot m^{-1}\cdot K^{-1}}$
|
| $μ$
| output coefficient | $\mathrm{ }$
|
| $μ$
| dynamic viscosity | $\mathrm{kg\cdot m^{-1}\cdot s^{-1}}$
|
| $μ_B$
| coefficient of friction for bearings | $\mathrm{ }$
|
| $μ_S$
| coefficient of friction for main sealing | $\mathrm{ }$
|
| $ν$
| kinematic viscosity | $\mathrm{m^2\cdot s^{-1}}$
|
| $ρ$
| density | $\mathrm{kg/m^3}$
|
| $ρ_{air}$
| density air | $\mathrm{kg/m^3}$
|
| $σ$
| cavitation number | $\mathrm{ }$
|
| $σ$
| effective collision diameter of an air molecule | $\mathrm{m}$
|
| $σ_1$
| first stage of cavitation | $\mathrm{ }$
|
| $σ_2$
| second stage of cavitation | $\mathrm{ }$
|
| $σ_{min}$
| fully developed cavitation | $\mathrm{ }$
|
| $φ$
| angle between pipe axis and hydraulic force | $\mathrm{°}$
|
| $φ$
| lever angle in open position | $\mathrm{°}$
|
| $ω$
| air-particle collision frequency | $\mathrm{Hz}$
|
