Hydrogen is of growing interest in propulsion and energy generation due to its low carbon exhaust - when hydrogen burns in oxygen the only product is water. Previously S&C have run all of their experimental rigs using kerosene, which provides exhaust flows with pressures, temperatures and composition comparable to aerospace applications, but the ability to burn hydrogen opens up exciting R&D programmes including:

The development is already attracting interest from space and defence customers as an affordable means to trial low TRL hydrogen propulsion systems.

The hydrogen supply has been interfaced to S & C's existing combustor rig, which receives compressed air from a Gnome turboshaft. The ratio of hydrogen to air in the combustor is controllable as follows:

Hydrogen Supply System:

• Mass flow up to 0.03kg/s
• Pressure up to 20 bar

Combustor System:

• Mass flow 1 to 4 kg/s compressed air
• Pressure up to 5bar
• Exhaust temperatures up to 750ºC

The new rig was commissioned in July 2017, following an extensive refurbishment and development programme.

Development

Two studies have been undertaken to redesign the hydrogen supply for use at S & C since it was acquired in 2009, and in 2016 the rebuild commenced. A new control system has been built to perform the start up, ignition and emergency shut down features of the supply. All the hardware has been safety checked and replaced where necessary. The start up includes a purge of all lines with a nitrogen supply to ensure the hydrogen does not come into contact with air, and the nitrogen is also used to actuate the hydrogen supply valves. The system allows variable hydrogen flowrates to control the temperature of the burn.