PAO Yakovlev has patented a new fuel tank inerting system in which neutral gas is supplied not only to the space above the fuel but also directly beneath the fuel layer. This approach should reduce oxygen concentration in two zones at once and increase tank explosion safety.
It is proposed to install special bubbling manifolds in the lower part of each wing and center-wing tanks. Through these, neutral gas is supplied from below and passes through the fuel, displacing dissolved oxygen from it.
Simultaneously, gas enters the ullage space and displaces the fuel-air mixture with an increased oxygen concentration from there.
According to the patent, the oxygen concentration in the tanks is proposed to be brought down to approximately 7.5%. At the same time, bubbling with dry neutral gas should remove dissolved water from the fuel and improve its operational properties.
Another feature of the development is a new piping scheme. In known systems, a large number of nozzles are placed in the upper part of the tanks, which makes the design heavier and more complex. Yakovlev proposes to move the main gas supply elements downwards and use special check valves.