Patent Application: US-53608905-A

Abstract:
fuel ignition system for jet engine starting contains pyrocartridges , connected by tubes to nozzles . the nozzles enter in a heat pipe so that the plumes hot pyrogases are in a zone of backflows of composite fuel . the pyrocartridges are connected to the electronic unit , control pyrocartridges and fuel supply .

Description:
ignition system comprises ignition cartridges set 1 wherein the number of ignition cartridges is not less than the number of engine starts during one operation cycle and where each ignition cartridge with powder mixture 2 and ignition torch 3 is connected by explosive gas outlet tube 4 through intermediate elements ( e . g . blow - out disk or internal nozzle ) to the engine ; the said tube 4 being connected to tube 5 leading to tubular circular collector 6 ; the latter being positioned before head 7 of fire tube 8 and is fitted with outlet pipes having nozzles 9 on the other end , each of these nozzles being positioned on head 7 of fire tube 8 and enters fire tube 8 . each nozzle 9 is oriented in the fire tube so that during starting operation they provide for the appearance of hot explosive gases flames in zone 10 of fuel mixture reverse flows . ( characteristics of explosive gases flames are given lower in the same division of the description ). the said tubular collector 6 can be made in the form of a closed or open ring . in this case ignition torches 3 of ignition cartridges 1 are switched in to electronic control block 11 calculating the moment of electric pulse delivery to ignition torch 3 and the moment of fuel 12 delivery to fuel collector 13 with injectors 14 at the outlet , each positioned in head 7 of fire tube 8 . jet engine ( e . g ., gas - turbine ) is , naturally , enclosed into casing 15 and besides fire tube ( tubes ) 8 is fitted with a shaft with compressor 16 and fuel collector 13 . this collector has tube 17 for fuel inlet and injectors 14 for fuel delivery into the head of fire tube . quantity and composition of powder mixture 2 in ignition cartridges 1 , ratio of lengths and diameters of tubes 4 , 5 and nozzles 9 are chosen for providing the determined values of powder mixture burning velocity , temperature of explosive gases and lengths of hot explosive gases flames formed , as well as the time of flames burning in zone 10 of fuel mixture reverse flows . ignition cartridges 1 and tubes 4 for explosive gas outlet are provided with thermal insulation sufficient for eliminating self - ignition of neighboring ignition cartridges . the number ignition cartridges 1 installed on the engine shouldn &# 39 ; t be less than the number of engine starts prognosed for one operation cycle ( one ignition cartridge is used per one starting ). engines with fire tubes pressure equal to tens or hundreds kg per sq . cm are provided with air - tight compartment 18 where all ignition cartridges 1 , tubes 4 and part of tube 5 are enclosed . compartment 18 is sealed by cover 19 . chamber of the said compartment is pneumatically connected with fire tube 8 chamber for equalizing pressure . cover 19 serves for changing a set of cartridges ( e . g . a magazine with cartridges ) before operation cycle ( in particular , before starting a flying vehicle ). in the process of engine starting , the starting electric pulse enters ignition torch 3 at the moment calculated by electronic control block 11 on the basis of current gas - dynamic parameters of the engine . a weak electric pulse is necessary for starting ignition torch 3 ( leading to simple technical solutions ): voltage of several volts , current less than 1 ampere , length — several milliseconds ( in contrast to the known electrical ignition systems where voltage supplied to the electric igniter plug is equal to several thousands of volts , current reaches several thousands amperes , ignition system consumes up to 100 w ( of electric energy per each igniter plug ) during 10 - 40 seconds ; for supplying such voltage and current to igniter plug positioned inside the engine , complex and cumbersome heat - and electricity - resistant equipment is necessary ). powder mixture 2 ignites , explosive gases from ignition cartridge 1 formed out of slowly burning powder mixture enter circular collector 6 through tubes 4 and 5 . further , explosive gases through nozzles 9 enter head 7 of fire tube 8 and form flames . quantity and composition of powder mixture 2 , ratio between lengths and diameters of tubes 4 and 5 and nozzles 9 as well as the pressure in fire tube 8 determine powder mixture burning velocity ( e . g ., 2 gr . per second ), length of flames ( several centimeters ), time of burning ( 3 seconds ) and explosive gases temperature in flames ( 1100 k ). flames appear in fire tube ahead of the fuel supply ( for 0 . 5 sec ) the figures given here correspond to a definite jet engine where the proposed ignition system was tested . length of hot explosive gas flames is longer than the distance between section of nozzle 9 and the zone of reverse flows 10 . explosive gases temperature in the flames mentioned is higher than the temperature of fuel mixture ignition . hot explosive gas flames occur in fire tube several seconds ahead of the fuel mixture delivery and up to obtaining stable burning along the whole zone of reverse flows in the fire tube . characteristics of explosive gas flames mentioned ( length of flames , explosive gas temperature , forestalling time and time of burning ) have definite values for each type of the engine . flames of hot explosive gases have the temperature of 1000 - 1300 k and the length longer than the distance between the nozzle 9 section ( situated on the fire tube wall ) and the zone of gas reverse flows even with the largest modern jet engine . spraying liquid components of the fuel touch the surface of hot explosive gases flames and evaporate , and the fuel vapors formed are heated to the temperature higher than the temperature of fuel mixture ignition . overheated fuel vapors ignite within the wide range of “ poor ” and “ rich ” mixtures ( propellant and oxidant ). extreme outer conditions for engine starting ( extremely low temperatures of the ambient air and fuel , bad fuel spraying , heavy kinds of fuel , high speeds of flying vehicles , low or high pressure in the fire tube ) cannot hinder fuel evaporation and ignition on the hot flame surface due to high heat energy of the flames . that &# 39 ; s why flames of hot explosive gases can ignite fuel mixture with all the ranges of heights , speeds and temperatures which preserve stable burning regime in the given fire tube . heat capacity of the system ( ignition cartridge 1 , tubes 4 , 5 collector 6 and nozzles 9 ) is small relative to thermal energy of hot explosive gases . that &# 39 ; s why all the system is heated to the temperature of hot gases within the period of time less than 1 sec ( e . g ., 0 . 1 sec ). thus , the gases leaving nozzles 9 are of stable temperature . when fuel ignites on the flame surface , flame front is being formed . the flame front moves along the circumference of the reverse flow zone at great speed ( e . g ., 5 - 15 m / sec ). time of attaining the regime of stable burning for ring and spherical fire tubes doesn &# 39 ; t exceed one second . for engines with several fire tubes this time depends on the method of flame transfer in between the tubes . number of nozzles 9 on fire tubes ( two or more ) depends on their characteristics determining the speed of flame front . it follows from the above said that the system of fuel ignition proposed when used as an auxiliary one for the main ignition system really increases safety of flights and stability of exploitation as this system is stable with fuel ignition under any extreme circumstances : with jet engine starting in winter conditions at extremely low temperatures of air and fuel ( including application of heavy kinds of fuel ) at passenger , transport and fighting aircrafts as well as in surface facility and armored vehicles , with emergency starting of jet engines at limiting heights of plane flight after flame - out due to unfavorable weather conditions or sharp evolutions of the plane , with anti - surge starting , when starting thrust augmenter . ignition system used as the only one in the engine widens the range of stable starting ( increases stability of exploitation ), considerably increases explosion safety when testing and in flight , decreases the weight of the ignition system set used for starting , in particular : small - size jet engine , jet engine at the single flight aircraft or drone , liquid rocket engine . the technical solution described herein ensures the accomplishment of the invention object , has all the features of the patentable invention ( in particularly it is nonobvious for the specialist in given field ) and therefore deserves a patent protection . 1 . j . r . marsden “ improvements in or relating to gas - turbine engines ”. gb patent no 627 , 722 dated 1949 , classes 75 ( iii ); 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