Abstract: A fuel system for a hydrogen fuelled gas turbine engine includes a main hydrogen fuel storage unit, a hydrogen fuel pump configured to be supplied with hydrogen from the hydrogen storage unit, a hydrogen fuel preheater configured to be supplied with high pressure hydrogen from the hydrogen fuel pump, and configured to supply heated gaseous hydrogen to a combustor of the gas turbine engine, and a hydrogen priming tank configured to store compressed gaseous hydrogen and to deliver gaseous hydrogen to at least the hydrogen fuel pump and preheater. The fuel system comprises a high-pressure gaseous hydrogen fuel offtake downstream in hydrogen fuel flow of the fuel pump in fluid communication with the hydrogen priming tank, and configured to fill the hydrogen priming tank with high pressure gaseous hydrogen.

Abstract: A method of starting a liquid hydrogen fuelled gas turbine engine of an aircraft propulsion system, wherein the aircraft propulsion system includes a hydrogen storage tank configured to store liquid hydrogen, a liquid hydrogen pump configured to pump hydrogen in at least a liquid state, a core combustor configured to receive hydrogen fuel from the hydrogen fuel pump, and a hydrogen fuel vent provided downstream of the liquid hydrogen pump, and configured to selectively vent hydrogen fuel. The method includes, in a liquid priming step, flowing hydrogen from the hydrogen storage tank through the liquid hydrogen pump and venting hydrogen through the hydrogen fuel vent until the hydrogen pump is primed with liquid hydrogen, then, in a liquid pumping step, operating the liquid hydrogen pump to pump liquid hydrogen to the core combustor at a required flow rate and pressure for engine ignition in an engine ignition step.

Abstract: A sealing element for positioning radially outwardly of aerofoil blades of a gas turbine engine is provided. A radially inner surface region of the sealing element includes a seal structure having one or more inwardly projecting walls formed by additive layer, powder fed, laser weld deposition. The walls form a plurality of curved profile shapes which are arranged in a repeating pattern across the radially inner surface region. None of the walls intersects with any other wall. The curved profile shapes have no radii of curvature less than 0.5 mm.

Abstract: A sealing element for positioning radially outwardly of aerofoil blades of a gas turbine engine is provided. A radially inner surface region of the sealing element includes a seal structure having one or more inwardly projecting walls formed by additive layer, powder fed, laser weld deposition. The walls form a plurality of curved profile shapes which are arranged in a repeating pattern across the radially inner surface region. None of the walls intersects with any other wall. The curved profile shapes have no radii of curvature less than 0.5 mm.

Abstract: The invention relates to bone cement compositions comprising a calcium component and a liquid component in which the liquid component comprises pyrophosphate ions with either orthophosphate ions or water, or with both orthophosphate ions and water.

Abstract: A method for making a disposable garment with de-elasticed elastic members in the crotch area of the garment is disclosed using means for de-elasticing the elastic members such as macerators, chemicals, selective laser beams, heat, and freezing.