航空发动机的种类与结构课件.ppt

航空发动机的种类与结构Aircraft Engine Types And Construction1PPT课件活塞式 燃气涡轮式 冲压式三大种类2PPT课件活塞式航空发动机活塞式航空发动机早期在飞机或直升机上应用的航空发动机，用于带动螺旋桨或旋翼。大型活塞航空发动机的功率可达 500千瓦。后来为功率大、高速性能好的燃气涡轮发动机所取代。但小功率的活塞式航空发动机仍广泛地用于轻型飞机、直升机及超轻型飞机。燃气涡轮发动机燃气涡轮发动机应用最广。包括涡轮喷气发动机、涡轮风扇发动机、涡轮螺旋桨发动机和涡轮轴发动机，都具有压气机、燃烧室和燃气涡轮。涡轮螺旋桨发动机主要用于时速小于800千米的飞机；涡轮轴发动机主要用作直升机的动力；涡轮风扇发动机主要用于速度更高的飞机；涡轮喷气发动机主要用于超声速飞机。冲压发动机冲压发动机冲压发动机特点是无压气机和燃气涡轮，进入燃烧室的空气利用高速飞行时的冲压作用增压。它构造简单、推力大，特别适用于高速高空飞行。由于不能自行起动和低速下性能欠佳，限制了应用范围，仅用在导弹和空中发射的靶弹上。3PPT课件The Heat EngineConverts chemical energy(fuel)into heat energy.Heat energy is then converted into mechanical energy.The heat energy is released at a point in the cycle where the pressure is high,relative to atmospheric.4PPT课件The Heat EngineDivided into groups or types depending upon:The working fluid used.The means of compression.The Propulsive working fluid.5PPT课件Types Of Heat Engines6PPT课件Types Of Heat EnginesTurbojetMeans of compression:Turbine-driven compressorEngine working fluid:Fuel/air mixturePropulsive working fluid:Fuel/air mixture7PPT课件Types Of Heat EnginesTurbopropMeans of compression:Turbine-driven compressorEngine working fluid:Fuel/air mixturePropulsive working fluid:Ambient Air8PPT课件Types Of Heat EnginesRamjetMeans of compression:Ram compression Engine working fluid:Fuel/air mixturePropulsive working fluid:Fuel/air mixture9PPT课件Types Of Heat EnginesPulse-JetMeans of compression:Compression due to combustionEngine working Fluid:Fuel/air mixturePropulsive working Fluid:Fuel/air mixture10PPT课件Types Of Heat EnginesRocketMeans of compression:Compression due to combustionEngine working fluid:Oxidizer/fuel mixturePropulsive working fluid:Oxidizer/fuel mixture11PPT课件Types Of Heat EnginesReciprocatingMeans of compression:Reciprocating action of pistonsEngine working fluid:Fuel/air mixturePropulsive working fluid:Ambient air12PPT课件Engine Requirements13PPT课件Engine RequirementsEfficiencyPower and Weight:If the specific weight of an engine is decreased,the performance of the aircraft will increase.Reciprocating engines produce approximately 1 HP for each pound of weight.14PPT课件Engine RequirementsFuel EconomyThe basic parameter for describing the fuel economy of aircraft engines is specific fuel consumption.Specific fuel consumption for reciprocating engines is the fuel flow(lbs/hr)divided by brake horsepower.15PPT课件Engine RequirementsDurability and ReliabilityDurability is the amount of engine life obtained while maintaining the desired reliability.Reliability and durability are built into the engine by the manufacture.Continued reliability is determined by the maintenance,overhaul,and operating personnel16PPT课件Engine RequirementsOperating FlexibilityThe ability of an engine to run smoothly and give desired performance at all speeds from idling to full-power.The engine must also function efficiently through all variations in atmospheric conditions.17PPT课件Engine RequirementsCompactnessTo effect proper streamlining and balancing of an aircraft,the shape and size of the engine must be compact.In a single engine aircraft,the shape and size of the engine will affect the view of the pilot.18PPT课件Engine RequirementsPowerplant Selection?19PPT课件Reciprocating EngineFor aircraft whose cruising speeds will not exceed 250 MPH the reciprocating engine is the usual choice.Chosen for its excellent efficiency.Turbocharged or supercharged for high altitude use.-Turbo-use exhaust-Super-use accessory drive20PPT课件Turboprop EngineFor cruising speeds from 180 to 350 MPH the turboprop engine performs better.Develops more power per pound then reciprocating.Operate most economicallyat high altitudes.21PPT课件Turbojet/Turbofan EnginesIntended to cruise from high subsonic speeds up to Mach 2.0.Operates most efficiently at high altitudes.Less instrumentation andcontrols required.22PPT课件Types Of Reciprocating Engines23PPT课件In-Line EnginesGenerally has even number of cylinders.Liquid or air cooled.Has only one crankshaft.24PPT课件In-Line EnginesSmall Frontal area,better adapted to streamlining.When mounted inverted,it offers the added advantages of a shorter landing gear.High weight to horsepower ratio.25PPT课件V-type EnginesCylinders are arranged in two in-line banks generally set 30-60 apart.Even number of cylinders and are liquid or air cooled.26PPT课件Radial EnginesConsists of a row,or rows,of cylinders arranged radially about a center crankcase.The number of cylinders composing a row may be either three,five,seven,or nine.27PPT课件Radial EnginesProven to be very rugged and dependable.High horsepower.28PPT课件Rotary-RadialUsed during World War I by all of the warring nations.Cylinders mounted radially around a small crankcase and rotate with the propeller.29PPT课件Rotary-RadialTorque and gyro effect made aircraft difficult to control.Problems with carburetion,lubrication,and exhaust.30PPT课件Opposed Or O-type EnginesTwo banks of cylinders opposite each other with crankshaft in the center.Liquid or air cooled,air cooled version used predominantly in aviation.31PPT课件Opposed Or O-type EnginesHas low weight-to-horsepower ratio.Its narrow silhouette makes it ideal for installation on wings.Little vibration.32PPT课件33PPT课件34PPT课件