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AssigneeROLLS-ROYCE plc
InventorsCraig W Bemment, Benjamin J Keeler, Paul W Ferra, Alastair G Hobday, Kevin R McNally, Andrea Minelli, Martin K Yates
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A propulsion system for an aircraft includes a gas turbine engine and a fuel tank, wherein the fuel includes at least a proportion of a sustainable aviation fuel—SAF—having a density between 90% and 98% of the density, ρK, of kerosene and a calorific value between 101% and 105% the calorific value CVK, of kerosene. The engine includes a combustor; and a fuel pump arranged to supply a fuel thereto at an energy flow rate, C, the pump being arranged to output fuel at a volumetric flow rate, Q, the percentage of fuel passing through the pump not provided to the combustor being referred to as a spill percentage. The fuel include X % SAF, where X % is in the range from 5% to 100%, and has a density, ρF, and a calorific value CVF. The propulsion system is arranged so: the fuel-change spill ratio, Rs, of: R s = spill percentage at cruise using kerosene spill percentage at cruise using the fuel with X % S A F is equal to: Q - ( C / ( CV K × ρ K ) ) Q - ( C / ( CV F × ρ F ) ) .
A propulsion system for an aircraft comprising a gas turbine engine and at least one fuel tank arranged to store fuel to power the gas turbine engine, wherein the stored fuel comprises at least a proportion of a sustainable aviation fuel—SAF—having a density of between 90% and 98% of the density, ρK, of kerosene and a calorific value of between 101% and 105% the calorific value CVK, of kerosene,
A propulsion system for an aircraft comprising a gas turbine engine and at least one fuel tank arranged to store fuel to power the gas turbine engine, wherein the stored fuel comprises at least a proportion of a sustainable aviation fuel—SAF—having a density of between 90% and 98% of the density, ρK, of kerosene and a calorific value of between 101% and 105% the calorific value CVK, of kerosene,
A method of operating an aircraft comprising a propulsion system, the propulsion system comprising a gas turbine engine, and at least one fuel tank arranged to store fuel to power the gas turbine engine, wherein the stored fuel comprises at least a proportion of a sustainable aviation fuel—SAF—having a density of between 90% and 98% of the density, ρK, of kerosene and a calorific value of between 101% and 105% the calorific value CVK, of kerosene, the gas turbine engine comprising a fuel pump arranged to supply a fuel from at least one fuel tank to a combustor of the gas turbine engine at an energy flow rate, C, the fuel pump having an inlet arranged to receive fuel from the at least one fuel tank and an outlet arranged to output fuel at a pump output volumetric flow rate, Q, a proportion of the output fuel being provided to the combustor and a remaining portion of the fuel being recirculated, a percentage of the fuel passing through the pump which is not provided to the combustor being referred to as a spill percentage, the method comprising:
Dependencies are inferred from the claim text.