1、Ch.1 Low speed aerodynamicsDivision of Aerodynamic Subsonic aerodynamics 亞音速空氣動力學 M0.8 Transonic aerodynamics 跨音速空氣動力學 0.8M1.2 Supersonic aerodynamics 超音速空氣動力學 1.2M51.1 The atmosphere Composition of air （See tab.） Layer of atmosphere Troposphere 對流層 Stratosphere 同溫層 Mesosphere 散逸層 Thermosphere 熱電離層

2、Ionosphere 離子層，電離層 Ozone layer 臭氧層 專業(yè)名詞ISA International Standard Atmosphere 國際標準大氣 pressure 壓強 P temperature 溫度 Tdensity 密度 altitude 高度 H，hspeed，velocity 速度 vattitude 姿態(tài)viscosity 粘度 compressibility 壓縮性 compressible 可壓縮的，可壓的（density changes with pressure） incompressible 不可壓縮的，不可壓的（density does not c

3、hange with pressure）English system（英制）： Fundamental units 基本單位 force（力） pounds（lb） 磅 distance（距離） feet（ft） 英尺 time（時間） seconds（sec）秒Derived units 導出單位 速度： velocity（distance/time） V，ft/sec（fps），knots=1.69（fps）， 節(jié)=1海里/小時 面積： area（distance squared） S or A，squared ft（ft2） 壓強： pressure（force/unit area） P

4、，lb/ft2 加速度：acceleration（change in velocity） a，ft/sec/sec（fps2），ft/sec2質(zhì)量： mass（weight/ acceleration of gravity）m，lb-sec2/ft（slug） m=w/g=lb/ft/sec2 位能：potential energy（force height）p，ft-lb功： work（force distance）W，ft-lb海里：nautical miles，（nmi），浬 nmi=6076ft=1853.2m英里：statute miles，mile， （stmi），法定里， stm

5、i=5280ft=1609m 每分鐘轉速：revolution per minute，RPM，密度：density（mass/unit volume） ，slug/ft3，（lb-sec2/ft4）溫度：temperature 。F，F(xiàn)ahrenheit 。F=oC9/532 華氏溫度 。C，Centigrade，celsius，攝氏溫度 C=（F-32）5/9 （37。C=98.6。F） R，Rankine，。R=。F460 蘭氏溫度 K，Kelvin，。K=。C273 絕對溫度動壓：dynamic pressure q，lb/ft2，q=（1/2）v2靜壓：pressure p，lb/ft

6、2，lb/in2（psi），熱能：heat energy （joule）焦耳，（watt）瓦特International Standard Unit System （國際標準單制）temperature：溫度， cpressure： 壓強， p，（N/m2）pa，帕斯卡，帕，pa=N/m2， hpa，百帕斯卡，百帕，hpa=100padistance： 距離， m（米）force： 力， N（牛頓）time： 時間， t（秒）mass： 質(zhì)量， kg（公斤）density： 密度， （kg/m3） 1.2 Equation of continuityEquation of continuity

7、 連續(xù)方程Air mass flow is constant. AV=const.AV=const.（low speed = const.）1.3 Bernoullis theorem 伯努利定理kinetic energy 動能potential energy 位能，勢能pressure energy 壓力能heat energy 熱能static pressure 靜壓，pdynamic pressure 動壓，q，q=1/2v2total pressure 總壓，P0=p +q=p+1/2v2stagnation point 駐點，（v=0） In ideal fluid（理想流體）an

8、d incompressible fluid pressure energy + kinetic energy = constant total energy static pressure + dynamic pressure= total pressureP + 1/2V2 = Ptotal （in incompressible fluid）P V, or P V The airflow around an aerofoil may be likened to theairflow through a Venturi.（文氏管） When air has an angle of attac

9、k, the total reaction on the aerofoil has two components- one at right angles to the relative airflow known as lift and one parallel to the relative airflow and opposing the relative motion known as drag. Relative theory（相對性原理）relative flow 相對來流When a body is moving at a certain velocity and angle o

10、f attack, the force and flow pattern on the body are same as that of the relative flow at same velocity and angle of attack. This is called relative theory.1.4 Airspeed 空速IAS indicated airspeed 指示空速CAS calibrated airspeed 校正空速EAS equivalent airspeed 當量空速TAS true airspeed 真空速 PEC position error corre

11、ction 位置誤差修正IEC instrument error correction 儀表誤差修正CEC compressibility error correction 壓縮性誤差修The IAS is the value you read on the airspeed indicator（ASI）. IF there are any errors in the ASI itself, there may be instrument error correction and position error correction.CAS=IAS+PEC+IECUntil now we ass

12、ume that the air is incompressible, i.e. its density does not change with pressure. But at the speed above 300 knots the effect becomes significant and cannot be ignored. CAS must be corrected with compressibility error correction. EAS=CAS+CEC For a constant EAS, as air density decreases with increa

13、sing altitude, the true airspeed must increase. The relationship between EAS and TAS is function of the proportional change in density. TAS=EAS/ density ratio（relative density）=/h=0（KIAS knots of indicated airspeed）for example： FL350=35000 ft IAS=280 kt assume：IAS=CASfrom under fig.1-21compressibili

14、ty correction（Vc=-16 kt） EAS=CAS+CEC=CAS+VC=280-16=264 ktFrom ISA table=0.31 TAS=EAS/=264/0.31=474 kt1.5 Force and coefficientp 壓強p 耒流壓強Cp=（p-p）/q pressure coefficient 壓強系數(shù)，壓力系數(shù)lift ，升力，Ldrag， 阻力，D lift coefficient 升力系數(shù)，CL=L/qsdrag coefficient 阻力系數(shù)，CD=D/qsdimensional 有因次的，non- dimensional 無因次的VV，pp，

15、Cp0，suction 吸力，pressure direction from away surfaceVp，Cp0，pressure壓力，pressure direction pointed surfaceat stagnation point p=pstagnation point，V=0，1/2v2+p=1/2v2+p= pstagnation point，Cp=（p-p）/q=1（at v=0） Ch 2. High speed aerodynamics2.1 Compressibility theory 壓縮性理論 Aircrafts that are flying at speeds

16、 well below the speed of sound send out pressure waves in all direction. This creates the sound that we hear as an aircraft approaches and also gives warning to the air ahead. The amount of vibration depends on the amount of disturbance or pressure to which the air is subjected, in turn, depends on

17、the size and shape of the object and the rate at which it approaches. Because air is compressible, the change in pressure that goes with the disturbance also creates a change in density and temperature. 1, wave propagation 波的傳播 A stationary source of pressure waves gives off a pattern much like the

18、radiating ripples（微波）from a stone thrown into a pond.If the pressure source is moving the waves ahead of the source tend to compress, they can never catch up with one another since they all emanate from the same source that is traveling at a constant speed below the speed of propagation of the press

19、ure wave（the speed of sound）. When the aircraft is traveling at the speed of sound, all the pressure waves bunch up together to form a single compression wave（a Mach wave）.When the aircraft is traveling over the speed of sound, all the pressure waves form a single compression wave（a Mach cone）.Mach

20、cone 馬赫錐, Mach wave 馬赫波speed of sound in air 音速 a a2=RT =a rate of specific heats 比熱比 R=the gas constant 氣體常數(shù) T=absolute temperature 絕對溫度a=39T knots （in the air） Ta，HTa2, Mach number 馬赫數(shù) M=v/a MFS，M，M free stream Mach number 自由耒流馬赫數(shù) example：M=0.7, 0.7M, M0.7 Mlocal local Mach number 當?shù)伛R赫數(shù) Mlocal= Vl

21、ocal/ alocal Mcrit critical Mach number 臨界馬赫數(shù) When a local Mach number first reaches unity（Mlocal=1）, the aircrafts Mach number（free stream Mach number）at this point is called critical Mach number. MDR drag rise Mach number 阻力劇增馬赫數(shù) MDRMcrit there is a significant rise in drag due to the formation sh

22、ockwave（激波）. Mdet detachment Mach number 激波離體馬赫數(shù) This Mach number is the upper limit of the transonic region, all values of local Mach numberbecome supersonic, the free stream Mach number is called detachment Mach number.3, speed divisions Subsonic： The subsonic regime is from zero to Mcrit 0MMcrit . All local Mach number1.0 Transonic： The transonic regime is from Mcrit to Mdet McritMMdet . It has a