A320 Neo gravity fuel feed ceiling
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Joined: Jun 2007
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From: Wanderlust
A320 Neo gravity fuel feed ceiling
A320 CEO gravity fuel feed ceiling if the aircraft was below 30000ft is 15000ft. But in same case the Neo ceiling is 20000ft. Can anyone provide authentic explanation please? Thank you
Thread Starter
Joined: Jun 2007
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From: Wanderlust
Following from a safety first article
This may give an idea that if an engine is handling higher volume of air may be it can handle more bubbling than the smaller one. But it is not authentic.
Limitations of fuel gravity feed. The altitude limitations linked to gravity feed are due to the application of Henry’s law. The law states that the concentration of a solute gas in a liquid is directly proportional to the partial pressure of that gas.Therefore, as the airplane climbs and as the atmospheric pressure decreases, so does the amount of air dissolved in the aircraft’s fuel. The excess air vents into the fuel tanks and engine fuel lines. At some point, the quantity of vapour present in the fuel, when it reaches the engine, may exceed the engine inlet maximum allowable vapour /liquid ratio and the operation of the engines is compromised.
Last edited by vilas; 14th June 2021 at 08:53.
Joined: Jan 2008
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From: Denver
I don't know if this counts as "authentic," but at least some of the NEO aircraft have different fuel tank configuations than their CEO cousins.
And possibly more to the point, the center tanks on NEOs use jet-ejector-venturi pumps rather than electric feed pumps.
And those pumps themselves can "suck out" dissolved or entrained vapor. Rather like a reverse version of using a hypobaric chamber to cure the "bends" in deep-divers. While at the same time sucking in more fuel though a side-port to replace the vapor.
It is also the case that the performance of the venturi pumps and resulting gravity-feed limitations/calculations may vary per airframe. Which may be enough to explain the 5000-foot difference.
https://hursts.org.uk/airbus-nonnormal/html/ch07.html
https://encyclopedia2.thefreedictionary.com/jet+pump
https://www.aviationsourcingsolution...s-made-simple/
And possibly more to the point, the center tanks on NEOs use jet-ejector-venturi pumps rather than electric feed pumps.
And those pumps themselves can "suck out" dissolved or entrained vapor. Rather like a reverse version of using a hypobaric chamber to cure the "bends" in deep-divers. While at the same time sucking in more fuel though a side-port to replace the vapor.
It is also the case that the performance of the venturi pumps and resulting gravity-feed limitations/calculations may vary per airframe. Which may be enough to explain the 5000-foot difference.
https://hursts.org.uk/airbus-nonnormal/html/ch07.html
https://encyclopedia2.thefreedictionary.com/jet+pump
Ejector Pumps are used to help ensure liquid fuel is always at the pump’s inlet, maintaining a constant flow of fuel from the pump to the tank. These make sure vapor pockets do not form, which could cause structural damage to the aircraft.
