(19) TZZ¥Z___T (11) EP 3 091 198 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.: 09.11.2016 Bulletin 2016/45 F01D 21/14 (2006.01) F02K 1/76 (2006.01) F02K 1/72 (2006.01) F02C 9/26 (2006.01) (21) Application number: 16168699.3 (22) Date of filing: 09.05.2016 (84) Designated Contracting States: (71) Applicant: United Technologies Corporation AL AT BE BG CH CY CZ DE DK EE ES FI FR GB Farmington, CT 06032 (US) GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR (72) Inventor: MARCOS, Juan A. Designated Extension States: Middletown, CT Connecticut 06457 (US) BA ME Designated Validation States: (74) Representative: Hull, James Edward MA MD Dehns St. Bride’s House (30) Priority: 08.05.2015 US 201514707500 10 Salisbury Square London EC4Y 8JD (GB) (54) THRUST REVERSAL FOR TURBOFAN GAS TURBINE ENGINE (57) A method of thrust reversal operation according is deployed, and denying the increase in engine power to an example of the present disclosure includes, among when the at least one criterion is met. A system for thrust other things, permitting an increase in engine power reversal is also disclosed. when at least one criterion is not met and a thrust reverser EP 3 091 198 A1 Printed by Jouve, 75001 PARIS (FR) 1 EP 3 091 198 A1 2 Description of a predefined limit when the at least one predetermined criterion is met. BACKGROUND [0010] A gas turbine engine according to an example of the present disclosure includes a fan section including [0001] The present disclosure relates to a thrust re- 5 a fan nacelle arranged at least partially about a fan, an verser, and more particular to thrust reversal operation. aft nacelle moveable relative to the fan nacelle, and a [0002] Gas turbine engines can include a fan nacelle core engine including a compressor section and a turbine defining a bypass duct. The fan also delivers air into a section arranged within a core cowling. The turbine sec- core engine where it is compressed. The compressed air tion is configured to drive the fan. The fan nacelle and is then delivered into a combustion section, where it is 10 the aft nacelle are arranged at least partially about the mixed with fuel and ignited. The combustion gas expands core cowling to define a bypass flow path. A thrust re- downstream over and drives turbine blades. verser is configured to selectively communicate a portion [0003] Some gas turbine engines include a thrust re- of fan bypass airflow from the bypass flow path when in verser in which a translatable nacelle forms an outer wall a thrust reversal mode. A controller is in communication portion of the bypass duct. The translatable nacelle is 15 with the core engine and the thrust reverser. The con- moved axially to communicate a portion of bypass airflow troller is configured to receive position information of the radially outward via a cascade to provide reverse thrust. thrust reverser and engine power information of the core engine, configured to cause the core engine to deny an SUMMARY engine power request during the thrust reversal mode 20 when at least one criterion is met, and configured to re- [0004] A system for thrust reversal according to an ex- spond to the engine power request when the at least one ample of the present disclosure includes a computing predetermined criterion is not met. device including memory and a processor. The comput- [0011] In a further embodiment of any of the forgoing ing device is configured to execute a data module and a embodiments, the at least one criterion is a predeter- comparison module. The data module is configured to 25 mined criterion and includes an engine reverse power access data corresponding to a thrust reversal mode, an threshold and a predefined time limit relating to the en- engine power condition and an engine power request. gine reverse power threshold. The comparison module is configured to cause an indi- [0012] In a further embodiment of any of the forgoing cator to be generated when the engine power request embodiments, the predefined time limit relates to a con- during the thrust reversal mode meets at least one crite- 30 figuration of at least one of the fan section and the thrust rion. reverser. [0005] In a further embodiment of any of the forgoing [0013] In a further embodiment of any of the forgoing embodiments, the at least one criterion is a predeter- embodiments, the controller is configured to permit mul- mined criterion and includes an engine reverse power tiple thrust reversal cycles during the thrust reversal threshold and a predetermined reversal time limit. 35 mode when aircraft velocity is below a predefined thresh- [0006] In a further embodiment of any of the forgoing old and a weight-on-wheel condition is met, and a mini- embodiments, the comparison module is configured to mum duration between each cycle of the multiple thrust permit multiple thrust reversal cycles during the thrust reversal cycles is according to the at least one predeter- reversal mode when aircraft velocity is below a prede- mined criterion. fined velocity threshold and a weight-on-wheel condition 40 [0014] In a further embodiment of any of the forgoing is met, and a duration between each cycle of the multiple embodiments, a maximum time period of each thrust re- thrust reversal cycles is according to the at least one versal cycle is less than the minimum duration. predetermined criterion. [0015] In a further embodiment of any of the forgoing [0007] In a further embodiment of any of the forgoing embodiments, the controller is configured to cause the embodiments, the comparison module is configured to 45 core engine to reduce engine power when the at least cause the present engine power to be reduced in re- one predetermined criterion is met, and is configured to sponse to the at least one criterion being met. permit the core engine to increase engine power when [0008] In a further embodiment of any of the forgoing the predetermined criterion is not met. embodiments, the comparison module is configured to [0016] A method of thrust reversal operation according cause the engine power request to be denied in response 50 to an example of the present disclosure includes permit- to the at least one criterion being met, the at least one ting an increase in engine power when at least one cri- criterion includes throttle position and an elapsed idle terion is not met and a thrust reverser is deployed, and time since a previous thrust reversal cycle, and the at denying the increase in engine power when the at least least one criterion relates to expiration of the elapsed idle one criterion is met. time. 55 [0017] A further embodiment of any of the foregoing [0009] In a further embodiment of any of the forgoing embodiments includes reducing engine power when the embodiments, the indicator is a maintenance indicator at least one criterion is met. The at least one criterion is relating to operation in the thrust reversal mode in excess a predetermined criterion and includes a predefined time 2 3 EP 3 091 198 A1 4 limit relating to an engine reverse power threshold. nacelle assembly with a thrust reverser and a vari- [0018] In a further embodiment of any of the forgoing able area fan nozzle (VAFN) in a closed position, embodiments, the steps of permitting the increase in en- according to an embodiment. gine power when the at least one criterion is not met and Figure 2B schematically shows the thrust reverser the thrust reverser is deployed, denying the increase in 5 of Figure 2A in the closed position and the VAFN in engine power when the at least one criterion is met, and an open position, according to an embodiment. reducing engine power when the at least one criterion is Figure 2C schematically shows the thrust reverser met are repeated when aircraft velocity is negative. of Figure 2A in an open position and the VAFN in [0019] In a further embodiment of any of the forgoing the closed position, according to an embodiment. embodiments, a minimum duration between a current 10 Figure 3 illustrates a controller for thrust reversal, iteration of the step of permitting the increase in engine according to an embodiment. power when the at least one criterion is not met and the Figure 4 illustrates a method for thrust reversal, ac- thrust reverser is deployed and a prior iteration of the cording to an embodiment. step of denying the increase in engine power when the Figure 5A illustrates an example of thrust reversal at least one criterion is met is greater than the predefined 15 during static operation. time limit. Figure 5B illustrates an example of thrust reversal [0020] In a further embodiment of any of the forgoing during a landing operation. embodiments, the step of denying the increase in engine power when the at least one predetermined criterion is DETAILED DESCRIPTION met includes comparing the minimum duration to an20 elapsed time since the predefined time limit was met. [0027] Figure 1 schematically illustrates a gas turbine [0021] In a further embodiment of any of the forgoing engine 20. The gas turbine engine 20 is disclosed herein embodiments, the at least one criterion includes throttle as a two-spool turbofan that generally incorporates a fan position and an elapsed idle time since a previous thrust section 22,a compressor section 24, acombustor section reversal cycle. 25 26 and a turbine section 28.