航空發(fā)動(dòng)機(jī)綜合課程設(shè)計(jì)-cfm56-5c發(fā)動(dòng)機(jī)啟動(dòng)不點(diǎn)火.

1、航空工程學(xué)院航空發(fā)動(dòng)機(jī)綜合課程設(shè)計(jì)題 目No Light Up During StartCFM56-5C發(fā)動(dòng)機(jī)啟動(dòng)不點(diǎn)火作者姓名賈嵩松專業(yè)名稱熱能與動(dòng)力工程指導(dǎo)教師尚永鋒提交日期 答辯日期 CONTENTS TOC o 1-3 h z u HYPERLINK l _Toc312249928 CHAPTER 1 GENERAL PAGEREF _Toc312249928 h 1 HYPERLINK l _Toc312249929 1.1 Overview of the CFM56-5C Turbofan Engine PAGEREF _Toc312249929 h 1 HYPERLINK l _

2、Toc312249930 1.2 The Technology behind the CFM56-5C Turbofan Engine PAGEREF _Toc312249930 h 2 HYPERLINK l _Toc312249931 1.3 The Subject of this Article PAGEREF _Toc312249931 h 2 HYPERLINK l _Toc312249932 CHAPTER 2 FADEC CONTROL SYSTEM PAGEREF _Toc312249932 h 4 HYPERLINK l _Toc312249933 2.1 FADEC Sys

3、tem Introduction PAGEREF _Toc312249933 h 4 HYPERLINK l _Toc312249934 PAGEREF _Toc312249934 h 4 HYPERLINK l _Toc312249935 PAGEREF _Toc312249935 h 4 HYPERLINK l _Toc312249936 2.2 Electronic Control Unit PAGEREF _Toc312249936 h 4 HYPERLINK l _Toc312249937 PAGEREF _Toc312249937 h 4 HYPERLINK l _Toc31224

4、9938 PAGEREF _Toc312249938 h 4 HYPERLINK l _Toc312249939 2.3 Hydro-mechanical Unit (HMU) PAGEREF _Toc312249939 h 5 HYPERLINK l _Toc312249940 PAGEREF _Toc312249940 h 5 HYPERLINK l _Toc312249941 PAGEREF _Toc312249941 h 5 HYPERLINK l _Toc312249942 PAGEREF _Toc312249942 h 6 HYPERLINK l _Toc312249943 2.4

5、 Process of FADEC Control PAGEREF _Toc312249943 h 7 HYPERLINK l _Toc312249944 PAGEREF _Toc312249944 h 7 HYPERLINK l _Toc312249945 PAGEREF _Toc312249945 h 8 HYPERLINK l _Toc312249946 PAGEREF _Toc312249946 h 8 HYPERLINK l _Toc312249947 CHAPTER 3 IGNITION SYSTEM PAGEREF _Toc312249947 h 10 HYPERLINK l _

6、Toc312249948 3.1 General Description PAGEREF _Toc312249948 h 10 HYPERLINK l _Toc312249949 3.2 Ignition System Distribution PAGEREF _Toc312249949 h 10 HYPERLINK l _Toc312249950 PAGEREF _Toc312249950 h 10 HYPERLINK l _Toc312249951 PAGEREF _Toc312249951 h 11 HYPERLINK l _Toc312249952 PAGEREF _Toc312249

7、952 h 12 HYPERLINK l _Toc312249953 PAGEREF _Toc312249953 h 12 HYPERLINK l _Toc312249954 3.3 Ignition System Control PAGEREF _Toc312249954 h 13 HYPERLINK l _Toc312249955 PAGEREF _Toc312249955 h 13 HYPERLINK l _Toc312249956 PAGEREF _Toc312249956 h 14 HYPERLINK l _Toc312249957 3.4 Principle Diagram of

8、the Ignition PAGEREF _Toc312249957 h 15 HYPERLINK l _Toc312249958 PAGEREF _Toc312249958 h 15 HYPERLINK l _Toc312249959 PAGEREF _Toc312249959 h 15 HYPERLINK l _Toc312249960 PAGEREF _Toc312249960 h 16 HYPERLINK l _Toc312249961 3.4 Fuel Nozzle PAGEREF _Toc312249961 h 16 HYPERLINK l _Toc312249962 CHAPTE

9、R 4 FAULT ANALYSIS PAGEREF _Toc312249962 h 18 HYPERLINK l _Toc312249963 4.1 Fault Analysis PAGEREF _Toc312249963 h 18 HYPERLINK l _Toc312249964 PAGEREF _Toc312249964 h 18 HYPERLINK l _Toc312249965 PAGEREF _Toc312249965 h 18 HYPERLINK l _Toc312249966 PAGEREF _Toc312249966 h 18 HYPERLINK l _Toc3122499

10、67 4.2 Process of Trouble Shooting PAGEREF _Toc312249967 h 19 HYPERLINK l _Toc312249968 Reference PAGEREF _Toc312249968 h 21 HYPERLINK l _Toc312249969 Appendix PAGEREF _Toc312249969 h 22AbbreviationsEGT: exhaust gas temperature ECU: Electronic Control Unit HMU: Hydro-mechanical Unit FADEC: Full Auth

11、ority Digital Engine Control PMC: Power Management Control ACC: Active Clearance Control ADIRU: Air Data/Inertial Reference Unit EIVMU: Engine Interface and Vibration Monitoring Unit VSV: Variable Stator Vane VBV: Variable Bleed Valve HPT: High Pressure Turbine LPT: Low Pressure Turbine LPTCC: Low P

12、ressure Turbine Case Cooling HPTCC: High Pressure Turbine Case Cooling RACSB: Rotor Active Clearance Start Bleed CHAPTER 1 GENERAL1.1 Overview of the CFM56-5C Turbofan EngineThe CFM56-5C, the most powerful engine in the CFM56 family, is the sole cost-effective propulsion system perfectly tailored fo

13、r the long-range Airbus A340-200 and A340-300 aircraft (Fig.1-1). Fig.1-1 CFM56-5CIn its class, the Airbus A340/CFM56-5C offers the lowest noise signature in commercial service. Supported at its entry into service in 1993 by the CFM56 familys more than 40 million engine flight hours of experience, t

14、he CFM56-5C has an excellent reliability ratea hallmark of the CFM56 family. Other versions of the CFM56 are also in service on the A320, providing airlines that operate A320/A340 mixed fleets a valuable commonality benefit due to reduced inventories and spare parts levels. To maximize overall perfo

15、rmance and profitability for airlines, CFM offers the CFM56-5C as a total propulsion system: engine, nacelle, and exhaust systems.Continuing the CFM56 engines excellent worldwide reputation, the CFM56-5C features innovative technologies, low fuel consumption, and the ability to meet all existing env

16、ironmental requirements with significant margins.1.2 The Technology behind the CFM56-5C Turbofan EngineTab.1-1 Related parameter of the CFM56-5CEngine model：CFM56-5C2-5C3-5C4Max. Thrust312003250034000Bypass ratio6.56.56.4So we can obtain some related general data of the CFM-5C:Max. Thrust (lb): 31,2

17、00 - 34,000 Max climb thrust (lb):73707580Max. Cruise thrust (lb):69107100Bypass ratio: 6.5Overall pressure ratio at max Climb: 37.438.3Length (in):103Fan diameter (in):72.3Basic dry weight (lb):87961.3 The Subject of this ArticleIn the process of using the engine, generally, many troubles may be ha

18、ppened. In this article, we focus on discussing the one of the deviant starting: No light up of Starting. This failure often occurs, when the starting of the engine. Namely, after the starter start, within the specified time (10 seconds after the supplying of the fuel), if the EGT or the indication

19、of N2 not increase, it show that the engine is no light up. Now we should close the switch of starting.By analyzing the information, we can obtain the main related component about this trouble:ECU, HMU, IGNITER-SPARK A and B.In this article, we will first introduce these components of this trouble,

20、including their operating principle, some subsystem and their parts that may cause misfiring. Then through these, we can obtain the fault tree of this trouble, and process or method of trouble shooting.CHAPTER 2 FADEC CONTROL SYSTEM2.1 FADEC System IntroductionThe Full Authority Digital Engine Contr

21、ol (FADEC) provides full range engine control to achieve steady state and transient engine performances when operated in combination with aircraft subsystems.FADEC can take complete control of engine systems in response to command inputs from the aircraft. It also provides information to the aircraf

22、t for flight deck indications, engine condition monitoring, maintenance reporting and trouble-shooting.The purposes of FADEC follow:(a) Power management control (PMC)(b) Starting/shutdown ignition control(c) Fuel control(d) Active clearance control (ACC)(e) Variable geometry control(f) Thrust revers

23、er The FADEC system consists of:-an Electronic Control Unit (ECU) containing two identical computers, designated channel A and channel B. The ECU electrically performs engine control calculation and monitors the engines condition.-a Hydro-Mechanical Unit (HMU), which converts electrical signals from

24、 the ECU into hydraulic pressures to drive the engines valves and actuators.-peripheral components such as valves, actuators and sensors used for control and monitoring.Refer to Fig.2-1.FADEC ComponentFig.2-1.FADEC Component2.2 Electronic Control UnitThe electronic control unit (ECU) is a dual chann

25、el digital electronic control with each channel utilizing a microprocessor for main control functions, a microcontroller for pressure transducer interface functions and a microcontroller for ARINC communication function. The ECU is a vibration-isolated single unit mounted on the fan case. Refer to F

26、ig.2-2. Electronic Control UnitThe functions of ECU follow:Each ECU channel receives data buses from two Air Data and Inertial Reference Units (ADIRU) and operational commands from the Engine Interface Vibration Monitoring Unit (EIVMU) in the aircraft on ARINC 429 data busses.It also receives operat

27、ing condition data from the various dedicated engine sensors such as T12, PS12, P0, N1, N2, PS3, T/P25, T3 and TC, and computes the necessary fuel flow, VSV, VBV, HPT clearance control, LPT clearance control, rotor active clearance control valve (only applicable for CFM56-5C) and transient bleed val

28、ve (only applicable for CFM56-5C/P) positions.Fig.2-2 Electronic Control UnitThe ECU provides the necessary current to the torque motors in the hydro-mechanical unit to control the various modulating valves and actuators.The ECU performs an On/Off control of the Ignition Relays, Starter Air Valve So

29、lenoid, the Aircraft Thrust Reverser Directional Valve and the Thrust Reverser Pressurizing Valve.The ECU provides digital data output in ARINC 429 format to the aircraft for engine parameter display, aircraft flight management system and the aircraft maintenance data system. So the ECU is powered b

30、y a three-phase engine alternator. Two independent coils from the alternator provide the power to the two separate ECU channels. A logic circuit within the ECU, automatically selects the correct power source：-A/C power supply. The power sources are the 115V-400HZ AC transfer busses 1and 2 -Control A

31、lternator. The control alternator provides two separate power sources from two independent windings. One is hardwired to channel A, the other to channel B. The alternator is capable of supplying the necessary power above an engine speed of approximately 15% N2.Refer to Fig.2-3 ECU power supplyFig.2-

32、3 ECU power supply2.3 Hydro-mechanical Unit (HMU)The Hydro-mechanical Unit (HMU) is attached to the aft section of the fuel pump unit housing. The two units make a bigger unit, or package. This package is installed on the aft side of the AGB, at the left side of the horizontal drive shaft housing. R

33、efer to Fig.2-4.Hydro-mechanical Unit. Fig.2-4.Hydro-mechanical UnitThe HMU has different functions:It provides internal calibration of fuel pressures.It meters the fuel flow for combustion.It provides the fuel shut-off and fuel manifold minimum pressurization levels.It bypasses unused fuel.It provi

34、des mechanical N2 over-speed protection.It delivers the correct hydraulic power source to various engine fuel equipments.Refer to Fig.2-5.HMU PURPOSES.Fig.2-5.HMU PURPOSESA general schematic of the HMU is shown in the referenced illustration. Fig.2-6. Schematic Diagram of HMU1. Fuel meteringThe fuel

35、 metering valve is hydraulically driven through a torque motor/servo valve by the ECU. The torque motor contains two electrically isolated, independent coils, one dedicated to channel A, the other to channel B of the ECU. A differential pressure regulating valve maintains a constant pressure drop ac

36、ross the metering valve. As a result, fuel flow varies proportionally with metering valve position. Two fuel metering valve position resolvers, one dedicated to each channel in the ECU, produce an electrical feedback signal in proportion to fuel metering valve position. The ECU uses this signal to c

37、ompute the current required at the fuel metering valve torque motor for achieving closed loop electrical control. Fig.2-6. Schematic Diagram of HMU2. Motive flow modulationThe HMU contains 5 additional torque motors/pilot valves that modulate hydraulic signals to the following: -low pressure turbine

38、 clearance control valve (LPTCC) -high pressure turbine clearance control valve (HPTCC) -rotor active clearance control system (RACSB) -transient bleed system -variable stator vane actuators (VSV) -variable bleed valve actuators (VBV)Each torque motor contains two electrically isolated, independent

39、coils. One is dedicated to channel A, the other to channel B, of the ECU. They provide flow and pressure at an HMU pressure port in response to electrical commands from the ECU.3. Fuel shut-off valve The fuel shut-off valve shuts off fuel flow to the engine in response to an aircraft supplied electr

40、ical signal (28VDC) commanded by the ENG/MASTER switch. It has to be noted that the shut-off signal of the HP fuel shut-off valve also closes the LP fuel valve. 2.4 Process of FADEC ControlWorking ProcessAccording to normal start programs, when the pilot press start switch, ECU through torque motor/

41、servo valve drive hydraulically the fuel metering valve, including CHAN A and CHAN B. At the same time, a differential pressure regulating valve maintains a constant pressure drop across the metering valve, so that fuel flow varies proportionally with metering valve position. There are two resolvers

42、 that produce an electrical feedback signal in proportion to fuel metering valve position. Then The ECU uses this signal to compute the current required at the fuel metering valve torque motor for achieving closed loop electrical control. Refer to Fig.2-7.Working process.Fig.2-7. Working processFunc

43、tion diagram of the FADECAccording to the subsystem and working process of the FADEC, we can obtain the function diagram of the FADEC. Refer to Fig.2-8. From it we can understand the function of FADEC. Fig.2-8. Function diagram of the FADECAbnormal workWhen light up during start, if EGT and N2 displ

44、ay does not increase, and the same time the flow indication also not increase, the engine will be ignition failure. This failure is called no light up during start.The process of ignition is controlled by ECU and HMU in FADEC. So we can find possible causes in them. The ECU controls mainly the power

45、 supply in ignition. If no light up occurs, we can guess that the ignition voltage may be below 24KV. Or the fuel nozzle emerges poor fuel or rich fuel conditions.Fig.2-9.Possible Failure PartsIn Fig.2-9 Possible Failure Parts, we show the some components that may cause the ECUs and HMUs abnormal wo

46、rking based on the reasons of the possible. From it the Maintenance personnel can find the related components to shoot the trouble.CHAPTER 3 IGNITION SYSTEM3.1 General DescriptionThe ignition system consists of two independent systems A and B. Each system is equipped with: -One ignition exciter, the

47、 exercitation of which is controlled by the ECU, either channel A or B of the ECU. -One spark igniter -One coaxial shielded ignition lead. A. Ignition Exciters The 2 ignition exciters are installed on shock dampened brackets on the outer surface of the fan case. Each exciter has an input connector a

48、nd an output connector. B. Spark Igniters The 2 spark igniters are installed into bosses at the 4 and 8 oclock positions on the outer surface of the combustion case. The inner tip extends, through ferrules, into the outer liner of the combustion chamber. C. Ignition Leads The ignition leads are cons

49、tructed of insulated wire in a sealed flexible conduit having a copper inner braid and a nickel outer braid. The leads connect the spark igniters to the ignition exciters. The aft ends of the leads, from the tube bundle junction box to the spark igniters, are cooled by fan discharge air passing thro

50、ugh the lead conduit.Fig.3-1.Ignition system LocationThe ignition system requires 115V, 400Hz from the electrical system via the ECU. The ECU controls the operation of ignition exciters A and B. The ignition for each engine is performed by one or both exciter(s) which transform(s) the 115V-400Hz pow

51、er supply into high voltage pulsating current. The high voltage flows through the ignition lead (shielded and ventilated) and delivers to the spark igniter the power required to ignite the fuel/air mixture by a series of sparks. The purpose of the system is: -to produce an electrical spark to ignite

52、 the fuel/air mixture in the engine combustion chamber during the starting cycle on ground and in flight -to provide continuous ignition in the following cases: (A) when manually selected.(B) auto-matically when engine flame out is detected.3.2 Ignition System DistributionThe ignition system enables

53、 three functions: -the electrical power supply -the distribution -the switchingThe ignition system requires 115V, 400Hz from the electrical system via the ECU. The ECU controls the operation of ignition exciters A and B. The ignition exciters transform the 115V, 400Hz into 20KV high voltage pulsatin

54、g current. Fig.3-2. Electrical Power Fig.3-2. Electrical PowerThe two ignition exciters are installed on the inlet fan case with resilient shock mounts at the 3 oclock position. A tin plated aluminum housing encloses each exciter. The components are secured to the housing mechanically or with silico

55、ne cement to protect them from vibration damage. The housing is sealed to ensure proper operation under varying environmental conditions.Each ignition exciter has: -One ignition lead connector -One electrical input connector. Fig.3-2. Ignition Exciter Fig.3-2. Ignition ExciterAn ignition lead transm

56、its electrical energy from an ignition exciter to a spark igniter. Each lead consists of a 0.28 in. (7 mm) diameter silicone insulated cable containing a No. 14 AWG nickel plated copper stranded conductor. The 0.28 in. (7 mm) cable is housed within a flexible conduit which features a nickel plated c

57、opper inner braid, a nickel-iron convoluted conduit, and a nickel outer braid. Fan discharge air is introduced into an enlarged diameter portion of each ignition lead conduit for cooling of the silicone insulated cable and igniter connection. Refer to Fig.3-3. Ignition LeadFig.3-3. Ignition LeadTher

58、e are 2 spark igniters in bosses at the 4 and 8 oclock positions, looking forward, on the combustion case assembly. The tip of the spark igniters extends, through ferrules, into the outer liner into the combustion chamber. Each spark igniter is connected by a lead to an ignition exciter. The ignitio

59、n exciter sends electrical energy to the spark igniter. The spark igniter supplies the spark necessary for ignition of the fuel/air mixture in the combustor. Fig.3-4. Ignition Leads and Left/Right Spark - IgnitionFig.3-4. Ignition Leads and Left/Right Spark Ignition3.3 Ignition System ControlThe eng

60、ine is fitted with a dual ignition system. Each system has an ignition exciter unit connected to its own spark igniter. Depending on the operating mode, one or both circuit(s) is (are) selected by the ECU. The ignition exciter is of the capacitor discharge type. It requires an 115VAC, 400Hz input cu