航空發(fā)動機系統(tǒng) 燃油系統(tǒng)

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1、航空發(fā)動機系統(tǒng)中國民航大學航空電氣系孫兆榮2 0 1 4 .4 5 燃 油 系 統(tǒng) 縮寫詞 ECU HMU FMV FRV VSV VBV BSV TBV 2 0 1 4 -4航空自動化學院航空電氣系2 HPTACC LPTACC HPSOV 2 0 1 4 -4航空自動化學院航空電氣系3 發(fā)動機燃油系統(tǒng)功用： 是在各個工作狀態(tài)下將清潔的、無蒸汽的、經(jīng)過增壓的、計量好的燃油供給發(fā)動機。 飛機的不同飛行階段（滑跑、起飛、爬升、巡航、下降、進近、復飛等）需要不同的推力（或功率），對應著發(fā)動機不同的工作狀態(tài)，也就是說需要供給發(fā)動機不同的燃油量。動力裝置在地面和空中有其安全工作范圍，燃油量的供給必須在

2、安全限制之內(nèi)。發(fā)動機控制應該避免發(fā)動機工作中出現(xiàn)超溫、超轉(zhuǎn)、喘振、貧油或富油熄火、超壓和超扭。 2 0 1 4 -4航空自動化學院航空電氣系4 CFM5 6 -7 B燃油系統(tǒng) 2 0 1 4 -4航空自動化學院航空電氣系5 CFM5 6 -7 B燃油系統(tǒng) 供給燃油供發(fā)動機燃燒和伺服系統(tǒng)操作。飛機燃油系統(tǒng)供油給發(fā)動機燃油分配系統(tǒng)。 發(fā)動機燃油分配系統(tǒng)的主要部件： 燃油泵組件從飛機燃油系統(tǒng)接受燃油供給增壓的燃油至液壓機械裝置的伺服和計量部分燃油濾清潔液壓機械裝置的燃油IDG滑油冷卻器在燃油流至液壓機械裝置之前，加熱燃油的裝置： IDG滑油冷卻器燃油滑油熱交換器伺服燃油加溫器發(fā)動機燃油分配系統(tǒng) 2

3、0 1 4 -4航空自動化學院航空電氣系6 CFM5 6 -7 B燃油系統(tǒng)燃油泵-負責供油和增壓，部件殼體內(nèi)常常包括增壓級和主級。發(fā)動機燃油分配系統(tǒng)部件燃油泵 2 0 1 4 -4航空自動化學院航空電氣系7 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油泵CFM56-7B燃油泵 2 0 1 4 -4航空自動化學院航空電氣系8 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油泵是依靠葉輪作旋轉(zhuǎn)運動，使流經(jīng)葉輪的液體增加動能和壓力能，在葉輪后的擴壓器中再將液體的動能部分滯止，轉(zhuǎn)化為壓力能。這類泵有離心泵、汽心泵、螺旋泵。容積式泵葉輪式泵是依靠泵的抽吸元件作相對運動，交替改變元

4、件間的自由容積進行吸油、排油的。供油量取決于元件一次循環(huán)運動中自由容積變化的大小。在一定的供油量下，泵根據(jù)出口處的液體流動阻力來建立壓力。如：柱塞泵、齒輪泵、旋板泵（葉片泵）。 2 0 1 4 -4航空自動化學院航空電氣系9 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油泵柱塞式燃油泵：變量泵，供油量不僅取決于轉(zhuǎn)速還取決于斜盤角度， 轉(zhuǎn)速不變時，供油量通過改變斜盤角度容易調(diào)節(jié)。 2 0 1 4 -4航空自動化學院航空電氣系1 0 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油泵齒輪式燃油泵：定量泵，當轉(zhuǎn)速不變時，供油量通過旁通回油調(diào)節(jié)。 即齒輪泵的供油量始終高于需油量，

5、超出需要的油量返回油泵進口。 2 0 1 4 -4航空自動化學院航空電氣系1 1 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油噴嘴功用：執(zhí)行燃油霧化或汽化的任務，以保證燃油快速燃燒。 2 0 1 4 -4航空自動化學院航空電氣系1 2 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油噴嘴燃油噴嘴及安裝 2 0 1 4 -4航空自動化學院航空電氣系1 3 CFM5 6 -7 B燃油噴嘴（ FUEL NOZZLE ） The fuel nozzles spray fuel into the combustion chamber and ensure good light-o

6、ff capability and efficient burning at all engine power settings. There are twenty fuel nozzles, which are installed all around the combustion case area, in the forward section. Basically, all fuel nozzle models are similar, provide the same operational performances, and are mounted and connected to

7、 the engine in an identical manner. However, four nozzles located on either side of the spark plugs, have a wider primary spray angle.CFM5 6 -7 B燃油系統(tǒng) 2 0 1 4 -4航空自動化學院航空電氣系1 4 CFM5 6 -7 B燃油噴嘴（ FUEL NOZZLE ） The wider spray angle is incorporated to improve altitude re-light capability. Blue color ban

8、d on the 1 6 regular fuel nozzles. Natural color band on the 4 wider spray fuel Nozzles.CFM5 6 -7 B燃油系統(tǒng) 2 0 1 4 -4航空自動化學院航空電氣系1 5 CFM5 6 -7 B燃油系統(tǒng) CFM5 6 -7 B燃油噴嘴（ FUEL NOZZLE ） At 1 5 psig, the fuel opens the check valve. It is sent to the central area of the metering set which calibrates the spray

9、pattern of the primary fuel flow (narrow angle). When the fuel pressure reaches 1 2 0 psig, it opens the flow divider metering valve and the fuel goes through the outer tube of the support to another port in the metering set. This ports calibrates the spray pattern of the secondary fuel flow (wider

10、angle of 1 2 5). 2 0 1 4 -4航空自動化學院航空電氣系1 6 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油噴嘴單油路噴嘴雙油路噴嘴它有一個內(nèi)腔，使燃油產(chǎn)生漩渦，還有一個固定面積的霧化孔。這種燃油噴嘴，在較高的燃油流量，即在較高的燃油壓力時，能提供良好的霧化質(zhì)量；但是，在低的發(fā)動機轉(zhuǎn)速和特別在高空要求的油壓較低，這種噴嘴就很不適合。雙油路噴嘴有中心孔和外圈孔。中心孔處理較低的燃油流量，較大的外圈孔隨著燃油壓力的增加供應較高的燃油流量。采用增壓活門將燃油分配到不同的油路。隨燃油流量和壓力增加，增壓活門移動，逐漸使燃油進入外圈油路和外圈油孔，給組合的兩個油 路供

11、油。雙油路噴嘴 2 0 1 4 -4航空自動化學院航空電氣系1 7 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油噴嘴霧化：燃油流被破碎成極細的油珠的過程，液滴越細，蒸發(fā)越快。 噴霧的形狀是霧化程度的重要指示。 漩渦的程度和噴嘴燃油的壓力是良好霧化的重要因素。 2 0 1 4 -4航空自動化學院航空電氣系1 8 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油噴嘴空氣霧化噴嘴使噴射的燃油攜帶一部分燃燒室的一股空氣。它用空氣的高速代替燃油的高速引起霧化。為防止發(fā)動機停車后噴嘴積碳，在燃油噴嘴中有單向活門。高壓切斷活門關閉后當燃油總管壓力降低，單向活門關閉，確保沒有燃油從總管

12、中因重力進入燃燒室。 2 0 1 4 -4航空自動化學院航空電氣系1 9 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-流量分配器（BSV）功用：保證所有噴嘴流過等量的燃油。補償在低燃油壓力下油路中的重力壓頭。某些燃燒系統(tǒng)使燃油在進入燃燒區(qū)時汽化。燃油流量分配器將燃油導入主、副燃油總管。 2 0 1 4 -4航空自動化學院航空電氣系2 0 CFM5 6 -7 B燃油系統(tǒng) CFM5 6 -7 B燃燒分級活門（ BSV） The burner staging valve enables the fuel delivery to 1 0 fuel nozzles to be shut off

13、. This increases the local richness and prevents the engine from flaming out during decelerations. Used in decel to keep the fuel flow above the lean flame-out limit. Cuts 1 0 of the 2 0 engine fuel nozzles. 2 0 1 4 -4航空自動化學院航空電氣系2 1 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-伺服燃油加熱器目的： 加溫燃油防止結冰，堵塞油路。加溫的方法可用發(fā)動機的熱滑油

14、以及壓氣機的引氣。燃油加熱有限制，在起飛、進近、復飛這些關鍵的飛行階段不能使用引氣加溫燃油，這是為了防止出現(xiàn)熄火的可能。 2 0 1 4 -4航空自動化學院航空電氣系2 2 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件IDG滑油冷卻器It cools the IDG oil. The IDG oil cooler is located on the fan case at the 7 oclock position. The interfaces are:The fuel supply and return lines.The oil supply and return lines.

15、2 0 1 4 -4航空自動化學院航空電氣系2 3 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件IDG滑油冷卻器 發(fā)動機燃油系統(tǒng) May, 2 0 1 2中國民航大學航空電氣系2 4 The purpose : to cool the scavenged oil with cold fuel, through conduction and convection, inside the exchanger where both fluids circulate. The servo fuel heater is another heat exchanger which uses engi

16、ne scavenge oil as the heat source to warm up fuel in the fuel control system. This prevents ice particles entering sensitive servo mechanisms.發(fā)動機燃油分配系統(tǒng)部件燃油/滑油熱交換器 發(fā)動機燃油系統(tǒng) May, 2 0 1 2中國民航大學航空電氣系2 5 發(fā)動機燃油分配系統(tǒng)部件燃油/滑油熱交換器 May, 2 0 1 2中國民航大學航空電氣系2 6 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-液壓機械裝置（HMU） May, 2 0 1 2中國

17、民航大學航空電氣系2 7 It transforms electrical signals sent from the ECU into hydraulic pressures in order to actuate various actuators used in engine control. The HMU has different functions： It provides internal calibration of fuel pressures. It meters the fuel flow for combustion. It provides the fuel shu

18、t-off and fuel manifold minimum pressurization levels. It by-passes the return of unused fuel. It provides mechanical N2 over speed protection. It delivers the correct hydraulic power source to various engine fuel equipment.CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-液壓機械裝置（HMU） May, 2 0 1 2中國民航大學航空電氣系2 8 To manage

19、and control the engine systems and equipment, the HMU houses two different internal subsystems, which are: The servo-mechanism area, including the pressure regulation system, the servo flow regulation system, solenoid valve and electro-hydraulic servo valves to supply fuel to the various valves and

20、actuators of the engine. The fuel metering system, including the fuel metering valve, the head sensor, the pressurizing and shut-off valve, the by-pass valve, and the over speed governor system.CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-液壓機械裝置（HMU） May, 2 0 1 2中國民航大學航空電氣系2 9 To achieve all the different engine func

21、tions, the HMU is fitted with : 6 Electro-Hydraulic Servo Valves (EHSV) for the control of: FMV, VSV, VBV, TBV, HPTACC, LPTACC. 1 solenoid (S) for airframe shut-off solenoid valve signal generation (this solenoid is not controlled by the EEC, but by the A/C Start lever & Fire switches). 1 resolver (

22、R), to track the FMV position. 1 switch for the over speed governor. 1 set of switches, connected to A/C, for position feedback of the pressurizing and shut-off valve.CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-液壓機械裝置（HMU） May, 2 0 1 2中國民航大學航空電氣系3 0 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-液壓機械裝置（HMU） May, 2 0 1 2中國民航大學航空電氣系3 1 C

23、FM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-液壓機械裝置（HMU） 2 0 1 4 -4航空自動化學院航空電氣系3 2 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油回油活門（FRV）The FRV（ FUEL RETURN VALVE ）returns part of the by-pass fuel, flowing through the IDG oil cooler, back to the A/C fuel tank. FRV部件 2 0 1 4 -4航空自動化學院航空電氣系3 3 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油回油活門（FRV） 2

24、0 1 4 -4航空自動化學院航空電氣系3 4 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油回油活門（FRV） 2 0 1 4 -4航空自動化學院航空電氣系3 5 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油回油活門（FRV） 2 0 1 4 -4航空自動化學院航空電氣系3 6 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油回油活門（FRV） 2 0 1 4 -4航空自動化學院航空電氣系3 7 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油回油活門（FRV） Inside the FRV, cold fuel from the fuel pu

25、mp LP stage outlet is mixed with the warm fuel returning from the IDG oil cooler. This is to limit the temperature of the fuel going back to the A/C tank. A shut-off system is provided to isolate the engine fuel circuit from the A/C fuel tank return circuit. The FRV is fuel operated and electrically

26、 controlled through the ECU control logic. The control logic of the FRV is dependent on the engine oil temperature (TEO). In case of failure of the TEO sensor, FRV positioning cannot be calculated based on the sensor. In this case, a default value for the oil is set ( 1 7 8C) and the FRV opens. 2 0

27、1 4 -4航空自動化學院航空電氣系3 8 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油回油活門（FRV） Above a certain engine oil temperature, the ECU commands a LOW return fuel flow to the A/C. If the engine oil temperature continues to increase, the ECU commands a HIGH return fuel flow to the A/C. The engine oil temperature thresholds dep

28、end on the fuel inner tank temperature, and A/C ground or flight conditions. On ground, if the engine oil temp reaches 9 0C, only the LOW return fuel flow is redirected to the A/C, until the oil temperature drops to 7 8C. In flight conditions, LOW return fuel flow may be selected at the same engine

29、oil temperature as on ground. Following LOW, HIGH return fuel flow is selected, if the engine oil temperature reaches 9 5C. It is deselected when the temperature drops below 8 5C. The FRV is opened to the second level (HIGH) during a FADEC ground motoring test. 2 0 1 4 -4航空自動化學院航空電氣系3 9 CFM5 6 -7 B燃

30、油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-燃油回油活門（FRV） FRV will be closed in any of the following cases :When N2 speed is below 5 0 % during engine start.When the metered fuel flow is greater than 5 5 2 0 pph. (T/O).With engine shut-down.When the aircraft management system sends an inhibit signal (fuel temp high + fuel tank fu

31、ll).When flight / ground status is not available. 2 0 1 4 -4航空自動化學院航空電氣系4 0 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-可變幾何尺寸控制系統(tǒng) To maintain satisfactory compressor performance over a wide range of operation conditions. Commanded by the ECU and operated through HMU hydraulic signals. Consists of : a VBV system, lo

32、cated downstream from the booster. a VSV system, located within the first stages of the HPC. To establish a more suitable air flow, VBVs are installed on the contour of the primary airflow stream, between the booster and the HPC. 2 0 1 4 -4航空自動化學院航空電氣系4 1 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-可變幾何尺寸控制系統(tǒng) At low

33、 speed, they are fully open and reject part of the booster discharge air into the secondary airflow, preventing the LPC from stalling. At high speed, the VBVs are closed. 2 0 1 4 -4航空自動化學院航空電氣系4 2 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-VBV 2 0 1 4 -4航空自動化學院航空電氣系4 3 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-VBVThe purpose of t

34、he Variable Bleed Valve (VBV) system is to regulate the amount of air discharged from the booster into the inlet of the HPC.To eliminate the risk of booster stall during low power conditions, the VBV system by-passes air from the primary airflow into the secondary.the ECU calculates the VBV position

35、 and the HMU provides the necessary fuel pressure to drive a fuel gear motor, through a dedicated servo valve.VBV 作動筒是一個活塞式作動筒。HMU 輸送伺服燃油壓力至活塞的筒側(cè)和桿側(cè)移動活塞至指令的位置。 2 0 1 4 -4航空自動化學院航空電氣系4 4 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-VBV 2 0 1 4 -4航空自動化學院航空電氣系4 5 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-VBV VBV SYSTEM OPERATION: Usin

36、g engine parameters, the ECU calculates the VBV position. The ECU commands the HMU to drive the gear motor with pressured fuel. The gear motor actuate the master bleed valve. The stop mechanism mechanically limits the opening and closing of the valve. The master bleed valve drives the 1 1 variable b

37、leed valves, through a series of flexible shafts, which ensure that the VBVs remain fully synchronized throughout their complete stroke. A feedback rod is attached between the master bleed valve and the feedback transducer, which transforms the angular position of the master bleed valve into an elec

38、trical signal for the ECU. 2 0 1 4 -4航空自動化學院航空電氣系4 6 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-VSV 2 0 1 4 -4航空自動化學院航空電氣系4 7 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-VSVThe VSV system positions the HPC stator vanes to the appropriate angle to optimize HPC efficiency. It also improves the stall margin during transient engine ope

39、rations.The VSV position is calculated by the ECU using various engine parameters, and the necessary fuel pressure is delivered by the HMU.The variable stator stages consist of: Inlet Guide Vanes (IGV), Variable Stator Vane (VSV) stages1 -2 -3 , 2 actuators and 2 feedback sensors (LVDT). 2 0 1 4 -4航

40、空自動化學院航空電氣系4 8 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-VSVThe VSV control law depends on altitude (high, low) and the status (steady state/transient). According to sensor signals, the EEC computes the appropriate VSV actuator position. The two actuators, located at the 2 and 8 oclock positions on the HPC case, m

41、ove the 4 actuation rings to change the angular position of the vanes. Two electrical feedback sensors (LVDT), one per actuator, transmit the VSV position to the EEC to close the control loop. The right hand side feedback sensor is connected to channel A and the left hand side feedback sensor to cha

42、nnel B.VSV control loop: 2 0 1 4 -4航空自動化學院航空電氣系4 9 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-VSVVSV control loop: 2 0 1 4 -4航空自動化學院航空電氣系5 0 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-TBV 2 0 1 4 -4航空自動化學院航空電氣系5 1 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-TBVThe Transient Bleed Valve (TBV) system improves the HPC stall margin during engine start

43、ing and rapid acceleration.Using engine input parameters, the ECU logic calculates when to open or close the TBV to duct HPC 9th stage bleed air, in order to give optimum stability for transient mode operations.The 9th stage bleed air is ducted to the LPT stage 1 nozzle, providing an efficient start

44、 stall margin.The ECU, working through the HMU, controls the TBV position. 2 0 1 4 -4航空自動化學院航空電氣系5 2 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-TBVThe TBV system consists of:uThe TBV, located on the HPC case, between the 7 and 8 oclock positions.uThe 9th stage air IN and OUT pipes. 2 0 1 4 -4航空自動化學院航空電氣系5 3 CFM5 6

45、-7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-TBV The TBV operational actuation is as follows: Start: open. Idle: closed. Accel from idle to 7 6 %-8 0 % N2 : open. Above 8 0 %: closed. The EEC monitors TBV system position through two LVDTs (channel A and channel B). 2 0 1 4 -4航空自動化學院航空電氣系5 4 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-TBV 2

46、0 1 4 -4航空自動化學院航空電氣系5 5 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-HPTACC 2 0 1 4 -4航空自動化學院航空電氣系5 6 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-HPTACC The HPTACC system optimizes HPT efficiency through active clearance control between the turbine rotor and shroud and reduces compressor load during starting and transient engine cond

47、itions. The HPTCC system uses bleed air from the 4 th and 9 th stages to cool down the HPT shroud support structure in order to: maximize turbine efficiency during cruise. minimize the peak EGT during throttle burst. 2 0 1 4 -4航空自動化學院航空電氣系5 7 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-HPTACC 2 0 1 4 -4航空自動化學院航空電氣系5

48、 8 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-HPTACC This is a closed loop system, using the valve position as feedback. The EEC uses various engine and aircraft sensor information to take into account the engine operating range and establish a schedule. A thermocouple, located on the right hand side of the HPT shr

49、oud support structure, provides the EEC with temperature information. To control the temperature of the shroud at the desired level, the EEC calculates a valve position schedule. This valve position is then sent by the EEC active channel to the HPTACC Electro-Hydraulic Servo Valve (EHSV), within the

50、 HMU. 2 0 1 4 -4航空自動化學院航空電氣系5 9 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-HPTACC The servo valve modulates the fuel pressure sent to command the HPTACC valve. Two sensors (LVDT), connected to the actuator, provide the EEC with position feedback signals and the EEC changes the valve position until the feedback matc

51、hes the schedule demand. The HPTACC control law depends on HP rotor temperature (hot/cold) and is calculated versus N2 . May, 2 0 1 2中國民航大學航空電氣系6 0 發(fā)動機燃油分配系統(tǒng)部件-LPTACC The LPTACC system uses fan discharge air to cool the LPT case during engine operation and controls the LPT rotor to stator clearances

52、. It also protects the turbine case from over-temperature by monitoring the EGT. This ensures the best performance of the LPT at all engine ratings. The LPTACC system is a closed loop system, which regulates the cooling airflow sent to the LPT case, through a valve and a manifold. The LPTACC valve i

53、s located on the engine core section at the 4 oclock position. CFM5 6 -7 B燃油系統(tǒng) May, 2 0 1 2中國民航大學航空電氣系6 1 The LPTACC system consists of: An air scoop. The LPTACC valve. An air duct and manifold. Six LPT case cooling tubes.CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-LPTACC May, 2 0 1 2中國民航大學航空電氣系6 2 The LPTACC valve

54、is a fuel-operated modulating valve that consists of the following: Two RVDTs. Fuel manifold mount flange. Actuator. Butterfly valve.CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-LPTACC May, 2 0 1 2中國民航大學航空電氣系6 3 The LPTACC controls the quantity of fan discharge air that goes through the LPTACC manifold to the LPT cas

55、e. The LPTACC valve has a fuel-operated piston valve and the HMU sends servo fuel to either the rod, or head side of the piston in the actuator. The actuator controls the position of the butterfly valve. The butterfly valve controls fan air flow to the LPTACC manifold. Two RVDTs send butterfly posit

56、ion signals to the EEC. The LPTACC has a drain port to drain fuel that leaks from the actuator shaft seal. The position of the valve can be checked through a visual indicator.CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-LPTACC May, 2 0 1 2中國民航大學航空電氣系6 4 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-LPTACC May, 2 0 1 2中國民航大學航空電氣系6 5 Acc

57、ording to a schedule from the EEC, an electrical order, proportional to a valve position demand, is first sent to the EHSV within the HMU. The servo valve changes the electrical information into fuel pressure and sends it to the LPTACC valve. Within the LPTACC valve, an actuator drives a butterfly,

58、installed in the airflow. The butterfly valve position determines the amount of fan discharge air entering the manifold and cooling tube assembly. RVDT sensors, built in the valve, send the valve position to the EEC as feedback, to be compared with the position demand. If the valve position does not

59、 match the demand, the EEC sends an order, through the HMU, to change the valve state until both terms are equal.CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-LPTACC May, 2 0 1 2中國民航大學航空電氣系6 6 The expansion or contraction of the case positions the LPT rotor shrouds in relationship to the LPT rotor. The tighter the cle

60、arances between shroud and rotor, the greater improvement in specific fuel consumption (SFC). At low altitude, Z 1 3 5 0 0 ft, the cooling airflow is inversely proportional to N1 K1 2 (N1 corrected versus T1 2 ), in order to optimize turbine clearances.CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-LPTACC May, 2 0 1 2中國民航大學航空電氣系6 7 CFM5 6 -7 B燃油系統(tǒng)發(fā)動機燃油分配系統(tǒng)部件-LPTACC May, 2 0 1 2中國民航大學航空電氣系6 8 CFM5 6 -7 B燃油系統(tǒng)CFM56-7B燃油分配