What does water injection do in a jet engine?
In jet engines it increases engine thrust at low speeds and at takeoff. Water injection was used historically to increase the power output of military aviation engines for short durations, such as dogfights or takeoff. However it has also been used in motor sports and notably in drag racing.
How is the performance of a gas turbine engine increased by water injection?
The injection of coolant into the combustion chamber inlet increases the mass flow rate through the turbine. This cools the air passing into the combustion zone. The fuel control system senses the water pressure, which will automatically reset the engine speed governer to give a higher maximum engine speed.
Why does water injection increase horsepower?
Injecting water into your engine sounds crazy, but it’s a turbo tuner trick for big horsepower. The water immediately evaporates into the air in the manifold, reducing intake air temperature and increasing the air density.
How does water injection in the exhaust work?
Water injection in the exhaust could work if: The water is fully evaporated before it exits the engine exhaust. The injected steam counteracts the effect of the exhaust jet contracting due to extraction of heat to vaporise the water (it does not seem to, see edit below).
What is water injection used for in jet engines?
Water injection is used on the Rolls-Royce Pegasus engine on the Harrier jump jet, but it has nothing to do with combustion. Instead, water is injected to cool the turbine blades to temperatures that allow the engine to operate at full rated power.
What is the effect of temperature on a jet engine?
The pressure and temperature drop across the turbine results in an increase in pressure in the jet pipe, giving additional thrust. Also, the consequent reduction in turbine inlet temperature allows the fuel system to increase the fuel flow to a valve giving an increase in rotational speed of the engine. This provides even more additional thrust.
What happened to the water-injection system?
The water-injection system to cool the engines during takeoff was inadvertently filled with kerosene instead of water. More recent work on water injection focused on the reduction of nitrogen oxides which form in lean combustion and high temperature.