The water deluge system, which is activated at liftoff, was put to the test on the Ariane 6 launch pad at Europe’s Spaceport in May 2021. This is one of the qualification tests to prepare for the arrival of Ariane 6, Europe’s next generation heavy-lift launch vehicle.
Spraying huge volumes of water on the launch pad and beneath the launch table protects both the launch vehicle and its payloads by absorbing and deflecting the tremendous acoustic energy generated at liftoff. Shockwaves created as engine exhaust gasses exceed the speed sound and collide with ambient air cause noise levels to approach 200 decibels.
Three areas are deluged with water during launch, this is done in sequence.
At 20 seconds before liftoff, water sprays over the steel deflector 25 metres below the launch table. This deflector channels the engine exhaust into the two trenches,.
At 6 seconds before liftoff, the exhaust tunnel under the launch table is deluged. This channels the engine exhaust below the launch table and into the underground trenches leading away from the launch pad.
Finally, as Ariane 6 lifts off the ground four arrays of pipes around the sides of the launch table will flood the launch pad.
This water also serves to cool and protect the ground installations, mainly the steel launch table.
About 700 cubic metres of water will be released during launch. This comes from the nearby tower which holds 1200 cubic metres of water. After launch it is refilled with water from a nearby lake.
After launch, any remaining water below the launch table is pumped away.