# US 9,518,965 B2 · Fuel system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,965 B2 - Document ID: US9518965B2 - Status: Granted - Kind: B2 - Application number: 13/896,690 - Filed: 2013-05-17 - Published: 2013-12-26 - Granted: 2016-12-13 - Earliest claimed: 2012-06-22 - Assignees: ROLLS-ROYCE plc - Applicants: Rolls-Royce PLC - Inventors: Peter Swann - Web page: https://patentgrep.com/patent/US9518965B2 ## CPC - G01N 33/0004: {Gaseous mixtures, e.g. polluted air} - F02C 3/30: Adding water, steam or other fluids {for influencing combustion, e.g. to obtain cleaner exhaust gases (F02C7/141, F02C7/30, F01D21/00, F01K21/04, F23D11/10 take precedence)} - F02C 9/00: Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants (controlling air intakes F02C7/057; controlling turbines F01D; controlling compressors F04D27/00; controlling in general G05) - F02C 9/28: Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed (F02C9/30 - F02C9/38, F02C9/44 take precedence) - F02C 9/40: specially adapted to the use of a special fuel or a plurality of fuels - F05D 2270/08: to produce clean exhaust gases - F05D 2270/081: with as little smoke as possible - F05D 2270/0831: indirectly, at the exhaust - F05D 2270/804: Optical devices - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A fuel system (12) comprising a vapor trail detection sensor (20) configured to generate a first signal (28) which indicates the optical depth of a vapor trail (35). A control unit (40) is provided responsive to the first signal (28) and configured to generate a second signal (80) in dependence upon the first signal (28). The second signal (80) defines a percentage of at least one of a first fuel composition and second fuel composition required to produce a resultant fuel composition. At least one regulator (42) is provided configured to receive and be responsive to the second signal (80) and regulate the percentage of first and second fuel composition required to produce the resultant fuel composition. ## Claims ### Claim 1 A fuel system comprising: a vapor trail detection sensor configured to generate a first signal which indicates an optical depth of a vapor trail; a control unit responsive to the first signal and configured to generate a second signal in dependence upon the first signal which defines a percentage of at least one of a first fuel composition and a second fuel composition required to produce a resultant fuel composition; and at least one regulator configured to receive and be responsive to the second signal and regulate the percentage of the at least one of the first fuel composition and the second fuel composition required to produce the resultant fuel composition that controls the optical depth of the vapor trail, wherein the control unit comprises a blending ratio calculator configured to calculate the required resultant fuel composition as a function of desired soot emission index determined by a soot requirement generator which communicates a value of soot emission index to the blending ratio calculator. ### Claim 2 (depends on 1) A fuel system as claimed in claim 1 wherein the control unit is operable to determine a likelihood of persistence of the vapor trail and determine the resultant fuel composition in dependence upon the determined likelihood of persistence of the vapor trail. ### Claim 3 (depends on 1) A fuel system as claimed in claim 1 further comprising a fluid blender in fluid communication with a source of the first fuel composition and a source of the second fuel composition via the at least one regulator, the blender being configured to mix the at least one of the first fuel composition and the second fuel composition to produce the resultant fuel composition. ### Claim 4 (depends on 1) A fuel system as claimed in claim 1 wherein the vapor trail detection sensor is an optical device configured to deliver a signal indicative of a presence and/or properties of the vapor trail. ### Claim 5 (depends on 1) A fuel system as claimed in claim 1 comprising a source of illumination, the vapor trail detection sensor being configured to detect electromagnetic radiation of at least one wavelength emitted and/or reflected by the vapor trail in response to energy emitted from the source of illumination. ### Claim 6 (depends on 1) A fuel system as claimed in claim 1 wherein a source of the first fuel composition is a first tank for storage of the first fuel composition; a source of the second fuel composition is a second tank for storage of the second fuel composition; and the first tank and second tank are fluidly isolated from one another. ### Claim 7 (depends on 3) A fuel system as claimed in claim 3 wherein the fluid blender has at least one outlet for delivering the resultant fuel composition to an engine fuel injector. ### Claim 8 (depends on 1) A fuel system as claimed in claim 1 wherein the soot requirement generator is configured to calculate the desired soot emission index as a function of one or more of vapor trail optical depth and/or measured values of ambient temperature, ambient pressure and/or ambient humidity. ### Claim 9 (depends on 8) A fuel system as claimed in claim 8 wherein the soot requirement generator is in communication with the vapor trail detection sensor to receive vapor trail optical depth data and/or a sensor to receive the one or more measured values. ### Claim 10 (depends on 1) A fuel system as claimed in claim 1 wherein the soot requirement generator is in communication with a second sensor to receive a value for instantaneous measured actual values of soot emission index generated by an engine. ### Claim 11 (depends on 1) A fuel system as claimed in claim 1 wherein the soot emission index is derived from a look up table or database in dependence upon one or more of the first fuel composition and the second fuel composition, combustion characteristics of an engine and/or engine operating point. ### Claim 12 (depends on 1) A fuel system as claimed in claim 1 wherein the soot requirement generator determines a value of desired soot emission index which would generate optimal vapor trail optical depth for given ambient conditions and engine operating point. ### Claim 13 (depends on 1) A fuel system as claimed in claim 1 wherein the soot requirement generator comprises a model and/or algorithm for direct calculation of the desired soot emission index. ### Claim 14 (depends on 1) A fuel system as claimed claim 1 comprising a vapor trail modeling tool configured to first determine ambient air conditions in dependence upon actual measured values of ambient air conditions, and then to determine the likelihood of vapor trail formation and/or vapor trail persistence based upon engine operating point and the determined ambient air conditions. ### Claim 15 (depends on 14) A fuel system as claimed in claim 14 further comprising a comparator for comparing output from the vapor trail modeling tool with an instantaneous actual vapor trail observation to determine the effect of the resultant fuel composition on vapor trail formation and/or vapor trail persistence. ### Claim 16 (depends on 1) An aircraft comprising a fuel system as claimed in claim 1, wherein the vapor trail detection sensor is mounted towards a rear of an aircraft facing aft. ### Claim 17 (depends on 16) An aircraft as claimed in claim 16 comprising an engine, the vapor trail detection sensor mounted such that it has a field of view directed towards a vapor trail formation region. ### Claim 18 (depends on 17) An aircraft as claimed in claim 17 wherein a source of illumination is directed towards at least one region downstream of the engine.