40.流體力學(xué)教程-introduction to aerospace engineering dte4321lecture

1、AE 2350Lecture #2April 5, 1999TOPICS ALREADY COVEREDWe reviewed the history of aeronautics and rocketry.(Read, if you have not done so already, Chapter I, pages 1-46)We discussed the parts of the airplane.(Read Chapter II of text, pages 47-50. Study figure 2.4 which shows possible layouts)We discuss

2、ed various ways an aircraft is graphically represented.TOPICS TO BE COVEREDRoadmap of Disciplines“English” to “S.I.” unitsCommon Aerospace TerminologyAirplane Axes and MotionPreliminary Thoughts on Aerospace DesignSpecifications (“Specs”) and StandardsSystem IntegrationVARIOUS DISCIPLINESAerodynamic

3、s &PerformanceStability & ControlPropulsionStructuresDesignAEROSPACE ENGINEERINGDISCIPLINESAerodynamics (First 3 weeks)Structures (1 week)Flight Mechanics, Stability & Control (2 weeks)Propulsion ( 1 Week)Performance (1 Week)Design - An integration of these disciplinesto come up with a new product o

4、r concept (Entire course)Astronautics (2 weeks)ENGLISH UNITSU. S. aerospace industries use this convention.mass : lbm or in slugsDistance : feetTime: secondsForce: lbf (pronounced pound force)Pressure: psi (pounds per square inch), or in atmenergy: Btu (British thermal units)Power: HPTemperature: Fa

5、hrenheit or degree Rankine ( R)S. I. UNITSSystme International dUnitesMost other European and Asian nations use this.mass - kgDistance - m (pronounced meters)Time - secondsForce - N (pronounced Newtons)Pressure - N/m2, or in atmenergy in JoulesPower in Watts (Joule/sec)Temperature in Celsius or degr

6、ee Kelvin ( K)English Units (Continued)Note:1 slug = 32.2 lbm1 atm = 14.7 psi (14.7 pounds per square inch)0 Degrees F = 460 Degrees RankineWe convert Fahrenheit to Rankine by adding 460 to F1 BTU = 778.15760 ft lb1 HP = 550 ft.lb/s CONVERSION FACTORS1 ft = 0.3048 m1 slug = 14.594 kg1 slug = 32.2 lb

7、m1 lbm = 0.4536 kg1 lb = 4.448 N1 atm = 114.7 psi = 2116 lb/ft2 = 1.01 x 105 N/m21degree K = 1.8 degree R Convert Celsius to Kelvin by adding 273 to Celsius 1HP = 745.69987 Wattsg = Acceleration due to gravity = 32.2 ft/s2 = 9.8 m/s2ExamplesWright Flyer weighed 340 kgIts weight in English Units: Its

8、 wing area was 46.5 m2The area in English units:Its speed = 56 km/h = 35mph (VFY: verify for yourself, please!)AEROSPACE TERMINOLOGYGW=Gross Weight= The nominal weight for a standard mission before the aircraft (or spacecraft) takes off.Crew Weight: Weight of crew and associated equipment (parachute

9、, oxygen, etc.)P/L= Payload Weight = Weight the aircraft was designed to carry. (passengers weight, baggage for aircraft;satellites, imaging equipment etc. for spacecraft)Fuel/Weight: That required to do the mission plus required reservesEmpty Weight = What the aircraft or spacecraft weighs when it

10、is nominally empty (may include trapped fuel )GW = Crew weight+ P/L + Fuel Weight + Empty WeightAEROSPACE TERMINOLOGYWing Loading = Aircraft Weight/Wing AreaPower Loading = Aircraft Weight/ Nominal Engine Power Aspect ratio, AR = (Wing Span)2 / Wing AreaTaper ratio = Root Chord/ Tip ChordSpecific Fu

11、el Consumption, sfc = (Fuel Weight)/ (Power x Hour)Empty Weight Fraction = Empty Weight/ Gross WeightPayload Fraction = Payload Weight/ Gross WeightTYPICAL WING LOADINGLight Civil Aircraft: 10 to 30 lb/ft2High Altitude Fighter 30 to 60 lb/ft2Interceptor Fighter 120 to 350 lb/ft2Long Range Transport

12、110 to 140 lb/ft2Axes of an AirplaneRoll of an AirplaneThe longitudinal axis extends lengthwise through the fuselage from the nose to the tail. Movement of the airplane around the longitudinal axis is known as roll and is controlled by movement of the ailerons. PITCHThe lateral axis extends crosswis

13、e from wingtip to wing tip. Movement of the airplane around the lateral axis is known as pitch.Pitch is controlled by movement of the elevators. YawThe vertical or normal axis passes vertically through the center of gravity. Movement of the airplane around the vertical axis is yaw. Yaw is controlled

14、 by movement of the rudder.AERODYNAMIC CONTROL SURFACESElevators control pitch angleAilerons control roll angleRudder controls yaw angleFlaps increase lift and dragLeading edge slats increase liftDrag brakes increase dragSpoilers reduce lift.Canard is a horizontal control surface placed near the nos

15、e.PRELIMINARY THOUGHTS ON DESIGNDesign is, in general,a team efforta large system integration activitydone in three stagesiterativecreative, knowledge based.The three stages are:Conceptual designPreliminary designDetailed designConceptual DesignWhat will it do?How will it do it?What is the general a

16、rrangement of parts?The end result of conceptual design is an artists or engineers conception of the vehicle/product.Example: Clay model of an automobile.Preliminary DesignHow big will it be?How much will it weigh?What engines will it use?How much fuel or propellent will it use?How much will it cost

17、?This is what you will do in this course.Detailed DesignHow many parts will it have?What shape will they be?What materials?How will it be made?How will the parts be joined?How will technology advancements (e.g. lightweight material, advanced airfoils, improved engines, etc.) impact the design?SPECIF

18、ICATION AND STANDARDSThe designer needs to satisfyCustomer who will buy and operate the vehicle (e.g. Delta, TWA)Government Regulators (U.S. , Military, European, Japanese)CUSTOMER SPECIFICATIONSPerformance: Payload weight and volume how far and how fast it is to be carried how long and at what alti

19、tudepassenger comfortflight instruments, ground and flight handling qualitiesCostPrince of system and spares, useful life, maintenance hours per flight hourFirm order of units, options, Delivery schedule, payment scheduleTYPICAL GOVERNMENT STANDARDSCivilFAA Civil Aviation Regulations define such thi

20、ngs as required strength, acoustics, effluents, reliability, take-off and landing performance, emergency egress time.MilitaryMay play a dual role as customer and regulatorMIL SPECS (Military specifications)May set minimum standards for Mission turn-around time, strength, stability, speed-altitude-maneuver capability, detectability, vulnerabilitySYSTEM INTEGRATIONAircraft/Spacecraft Design often involves integrating parts, large and small, made by other vendors, into an airframe or spaceframe (also called “the bus.”)Parts includeengines, land