Vent system
A vent system includes a vent stack for venting a tank fluid from a fuel tank that is external to the vent stack, during fuelling of the fuel tank. The vent stack includes a conduit including a conduit inlet and a conduit outlet, the conduit outlet opening to atmosphere external to the conduit. The vent stack also includes an opening into the conduit between the conduit inlet and the conduit outlet. The opening is fluidically connected, or connectable, to the fuel tank so the tank fluid from the fuel tank flows through the opening to the conduit outlet, in use. The vent stack also includes a fluid mover operable to cause a mixer fluid receivable in the conduit inlet to flow through the conduit towards the conduit outlet, thereby to mix the mixer fluid with the tank fluid in the conduit, upstream of the conduit outlet.
1 . A vent system comprising:
a vent stack for venting a tank fluid from a fuel tank that is external to the vent stack, during fueling of the fuel tank, the vent stack comprising:
a conduit comprising a conduit inlet and a conduit outlet, the conduit outlet opening to atmosphere external to the conduit;
an opening into the conduit between the conduit inlet and the conduit outlet, the opening fluidically connected, or connectable, to the fuel tank so that the tank fluid from the fuel tank flows through the opening to the conduit outlet, in use; and
a first fluid mover operable to cause a mixer fluid receivable in the conduit inlet to flow through the conduit towards the conduit outlet, thereby to mix the mixer fluid with the tank fluid in the conduit, upstream of the conduit outlet; and
one or more further fluid movers, each of which is operable to cause the mixer fluid receivable in the conduit inlet to flow through the conduit towards the conduit outlet, thereby mixing the mixer fluid with the tank fluid in the conduit, the mixing of the mixer fluid with the tank fluid occurring upstream of the conduit outlet.
2 . The vent system of claim 1 , wherein the vent stack comprises a vane system configured to impart turbulence into the mixer fluid upstream of the opening.
3 . The vent system of claim 1 , wherein at least a part of an inner wall of the conduit downstream of the opening comprises a thermally insulating material.
4 . The vent system of claim 1 , wherein:
the opening is defined at least in part by an aperture in a sidewall of a pipe in the conduit; and
the aperture is distanced from each part of an inner wall of the conduit by an amount that is greater than 20% of a minimum distance between opposing sides of the conduit.
5 . The vent system of claim 1 , wherein;
the opening is a first opening;
the vent stack comprises one or more further openings into the conduit;
each of the one or more further openings is between the conduit inlet and the conduit outlet; and
wherein each further opening is fluidically connected to the fuel tank so that, in use, the tank fluid from the fuel tank flows through each such further opening to the conduit outlet.
6 . The vent system of claim 5 , wherein each of the one or more further openings is defined at least in part by an aperture in a sidewall of a pipe in the conduit.
7 . The vent system of claim 1 , wherein:
the conduit comprises a diffuser section between the opening and the conduit outlet; and
the diffuser section increases in internal cross-sectional area as a function of distance from the opening, in a direction towards the conduit outlet.
8 . The vent system of claim 1 , comprising a controller configured to simultaneously:
cause a fuel supply valve to open to thereby cause the tank fuel to move through the opening towards the conduit outlet; and
cause operation of the first fluid mover and the one or more further fluid movers to cause the mixer fluid to move through the conduit and mix with the tank fuel upstream of the conduit outlet.
9 . The vent system of claim 1 , wherein:
the fuel tank is an aircraft fuel tank; and
the vent stack is a ground-based vent stack that is connectable to the aircraft fuel tank via the opening during fuelling of the aircraft fuel tank.
10 . A fuelling system comprising:
the vent system of claim 1 ; and
a fuel source connectable to the fuel tank to supply fuel to the fuel tank.
11 . The vent system of claim 1 , wherein:
the opening is a first opening;
the vent stack comprises one or more further openings into the conduit;
each of the one or more further openings is between the conduit inlet and the conduit outlet; and
wherein each further opening is fluidically connectable to the fuel tank so that, in use, the tank fluid from the fuel tank flows through each such further opening to the conduit outlet.
12 . The vent system of claim 11 , wherein each of the one or more further openings is defined at least in part by an aperture in a sidewall of a pipe in the conduit.
13 . The vent system of claim 1 , wherein at least one of the first fluid mover and the one or more further fluid movers is located in the conduit downstream of the conduit inlet.
14 . A method of venting a tank fluid from a fuel tank to atmosphere external to the fuel tank using a vent system, the vent system comprising:
a vent stack comprising:
a conduit comprising a conduit inlet and a conduit outlet, the conduit outlet opening to the atmosphere external to the conduit;
an opening into the conduit between the conduit inlet and the conduit outlet, the opening fluidically connected, or connectable, to the fuel tank; and
a first fluid mover; and
one or more further fluid movers;
the method comprising simultaneously:
causing the tank fluid to move from the fuel tank through the opening towards the conduit outlet; and
operating the one or more further fluid movers to cause a mixer fluid receivable in the conduit inlet to flow through the conduit towards the conduit outlet, thereby mixing the mixer fluid with the tank fluid in the conduit, the mixing of the mixer fluid with the tank fluid occurring upstream of the conduit outlet.
15 . The method of claim 14 , wherein the mixer fluid flows through the conduit at a mass flow rate that is at least 25 times greater than a mass flow rate of the tank fluid through the opening.
16 . A non-transitory computer-readable storage medium storing instructions that, when executed by a processor for operating a vent system, causes the processor to perform the method of claim 14 .
17 . The method of claim 14 , wherein the vent stack comprises a vane system, the method comprising using the vane system to impart turbulence into the mixer fluid upstream of the opening.
18 . The method of claim 14 , wherein:
the opening is defined at least in part by an aperture in a sidewall of a pipe in the conduit; and
the aperture is distanced from each part of an inner wall of the conduit by an amount that is greater than 20% of a minimum distance between opposing sides of the conduit.
19 . The method of claim 14 , wherein:
the opening is a first opening;
the vent stack comprises one or more further openings into the conduit;
each of the one or more further openings is between the conduit inlet and the conduit outlet; and
wherein each further opening is fluidically connected to the fuel tank so that, in use, the tank fluid from the fuel tank flows through each such further opening to the conduit outlet.
20 . The method of claim 14 , wherein:
the conduit comprises a diffuser section between the opening and the conduit outlet; and
the diffuser section increases in internal cross-sectional area as a function of distance from the opening, in a direction towards the conduit outlet.