British industrial engineering company Rolls-Royce has developed new fuel nozzles and other components that can successfully burn hydrogen to the specifications required for aircraft to take off. The test object was the combustor of the Pearl 700 turbofan engine that powers Gulfstream. The engine powers Gulfstream's G700 jets, with standard models capable of producing more than 18,000 pounds of thrust.
Rolls-Royce conducted a hydrogen combustion test of the Pearl 700 engine's burner in Germany, and the company reported that the test was very successful as the burner operated and the emissions produced by the test were as expected.
Like rocket engines, the engines that power aircraft come in a variety of thrust and flight profiles. Engine power is usually at its maximum during takeoff, as they must generate enough power to ensure there is enough airflow under the aircraft's wings to enable flight. After takeoff, the engine's thrust is adjusted based on fuel consumption and aircraft speed. Then, on landing, the engines are boosted again to maintain the correct descent speed, keeping the aircraft in line with the runway and giving the pilot enough leeway to ensure a maneuver around if necessary.
Naturally, this means that the engine's internal components are put under significant stress during takeoff and landing. One of those components is the combustor, the heart of an aircraft engine that produces thousands of pounds of thrust. As the name suggests, the aircraft's fuel is burned in the combustor, and the energy generated is responsible for driving the engine's turbine to ensure sufficient airflow to maintain thrust and lift.
A key component within the burner is the nozzle. The nozzle, also found in rocket engines, is responsible for delivering fuel to the combustor and must be designed to withstand the extreme forces within the combustor. Therefore, the nozzle is designed with the fuel that powers the engine in mind. For the hydrogen tests, Rolls-Royce designed new nozzles specifically for hydrogen.
Hydrogen is one of the most difficult fuels to process, as NASA discovered during its Artemis 1 flight earlier this year. However, burning hydrogen does not release greenhouse gases into the atmosphere, and the fuel also provides engines with a greater power advantage. According to Rolls-Royce, because hydrogen burns at a higher temperature than kerosene, the advanced hydrogen fuel nozzles used for testing must withstand higher combustion temperatures than kerosene nozzles. They can also control the flame within the burner by mixing hydrogen with air, thereby controlling how the former burns.
The hydrogen nozzle was also tested at Loughborough University in the UK and the German Aerospace Center in Cologne before full-pressure testing simulating take-off conditions. The latest tests were also carried out at the aerospace centre, and Rolls-Royce said they allowed it to collect data on the flammability of hydrogen and its suitability for jet flight.