Laminar zidlule lesiphithiphithi. izintlu zeenkqubo flow fluid

Ukufunda iimpawu ulwelo kunye neegesi flow kubaluleke kakhulu kwishishini kunye eziluncedo zoluntu. Le laminar nefuthe flow elinzima phezu izinga yothutho amanzi, i-oyile, imibhobho irhasi yendalo ngeenjongo ezahlukeneyo, ichaphazela nabanye parameters. Ezi ngxaki ukwenza hydrodynamics science.

ngezigaba

Ku imvelo neenkqubo flow fluid kunye neegesi zobunzululwazi yahlulwe iiklasi ezimbini abahlukene kakhulu:

• laminar (inkjet);
• ezinzima.

Kwakhona ukwahlula sigaba yenguqu. Kwenzeka ukuba, igama elithi "ulwelo" linentsingiselo ngokubanzi: oko kuba incompressible (engamanzi ngempela), a ngezinto (gas), conductive, etc ...

imbali icala

Enye Mendeleev ngo-1880 ingcamango ubukho kolawulo ezimbini flow malunga lwabonakaliswa. Ukuze ufumane iinkcukacha ezithe vetshe ngalo mba wabancina yamachiza British kunye injineli Osborne Reynolds abagqibe ukufunda ngo-1883. Okokuqala, ngokoqobo, yaye emva koko usebenzisa ifomula kufumaniseke ukuba ngexabiso eliphantsi ukuhamba kwezithuthi engamanzi ifomu laminar uba: maleko (yamasuntswana flow) phantse sukuxuba kunye nesihamba ecaleni umendo ngaxeshanye. Noko ke, emva kokuba ndiyoyisile ixabiso ethile kakhulu (kuba iimeko ezahlukeneyo ngayo yahlukile), iimeko flow ulwelo isihloko Inombolo Reynolds zitshintshiwe: ukuhamba jet uba omtsha umbhodamo - ngamanye amazwi, lesiphithiphithi. Kwathi kanti, ezi iparameters ukusa kumkhamo othile semvelo kunye neegesi.

Practical izibalo Isazinzulu IsiNgesi wabonisa ukuba yokuziphatha, umz, amanzi, kuxhomekeke kakhulu kwi imilo kunye nemilinganiselo itanki (imibhobho, imijelo, emithanjeni, njalo-njalo), apho ayajika. Xa imibhobho ukuba icandelo elijekelezayo umnqamlezo (ezifana esetyenziselwa for obandayo igiza uxinzelelo), inani Reynolds wayo - indlela karhulumente ezibalulekileyo ichazwa ngolu hlobo lulandelayo: Re = 2300. Ukuze ukuvula ukuhamba ijelo inani Reynolds yi ezahlukeneyo: Re = 900. Kuba amaxabiso ezincinane for Re lubekwa, ngokubanzi - ingalawuleki.

laminar flow

Ngokungafaniyo elinzima laminar flow uhlobo kunye nolwalathiso wamanzi (irhasi) yhuu. Zihamba zomaleko ngaphandle ukuxuba ngaphandle pulsations. Ngamanye amazwi, intshukumo kwenzeka ngokufanayo ngaphandle nokuxhuma guqukayo apha kwicala xi nesantya.

flow fluid Laminar ibunjiwe, umzekelo, xa kuxineneyo imithambo yegazi yezinto eziphilayo, izityalo emithanjeni phantsi kweemeko ezifanayo, kwi yangoku ulwelo viscous kakhulu (oil amafutha ngokusebenzisa yombhobho). Ukuba nomfanekiso ukuhamba jet lwanele ukutyhila itephu kancinane - kuya kumpompoza cwaka amanzi, ngokulinganayo, ngaphandle njengokuhlanganisa. Ukuba ukhulule spigot ade ase ekupheleni, uxinzelelo nkqubo iza kuvuka nomjikelo uya kuba ingalawuleki.

flow lesiphithiphithi

Ngokungafaniyo laminar, apho amasuntswana ezimelene siqhubeka iindlela kakhulu ngaxeshanye, eyayinethombo olungazolanga kolwelo ubuntu njengongekho. Ukuba usebenzisa indlela आयडेंटीफिकेशन iSazisi, le trajectories ye Amasuntswana nakanjani ziyangenana kwaye aziphathe ngendlela kusengaphambili. Movement of ulwelo kunye neegesi phantsi kwezi meko zisoloko zezomzuzwana, nezi parameters nonstationarities anokuba uluhlu olubanzi kakhulu.

Njengoko laminar igesi flow ibe ingeniso korhulumente anzima, ungenza kubekwa esweni umzekelo wisps of njengomsi umdiza ovuthayo nisamana emoyeni. Ekuqaleni, amasuntswana ukuhambisa iindlela phantse parallel zingatshintshi kwexesha. Umsi lubonakala kulungisiwe. Ke ekuhambeni kwexesha ngequbuliso kukho eddies esikhulu ukuhamba ngokuzenzekelayo ngokupheleleyo. Lo moya bayahlukana zibe ezincinane - zibe kakhulu njalo njalo. Ekugqibeleni, phantse batshaye ixutywa emoyeni engqongileyo.

imijikelo isiphithi-phithi

Umzekelo ngentla yesifundo, yaye izazinzulu ziye zenza izigqibo zilandelayo ukususela imibono yakhe:

1. Laminar kunye flow lesiphithiphithi ezi probabilistic ngokwendalo: inguqu ukusuka kwimo enye ukuya kwenye alikho ncam indawo elungileyo, yaye ngeranti ngendlela engaqondakaliyo, indawo ejikelezayo.
2. Okokuqala, kukho imisinga ezinkulu ezinkulu kuno ubungakanani wisps yomsi. Movement uba isiyezi kunye kakhulu anisotropic. nokuphuma ezinkulu zibe nkenenkene zizigungxule phezulu zibencinane kwaye ezincinane. Ngoko ke, kukho uluhlu eddies. I-eneji yeentshukumo ukhutshelwa ezinkulu amancinane, kwaye ekupheleni kwale nkqubo liyalahleka - eneji ukusasaza kwenzeka izikali ezincinane.
3. flow Uxhaphazelayo ingalunganga: a omtsha ethile kunokuba kwindawo random ngokupheleleyo, engalindelekanga.
4. Ukunxulumana umsi ngomoya okukufutshane akwenzeki phantsi flow laminar, kwaye anzima - ofuna kakhulu.
5. Nangona iimeko umda izinto zokubhala, esisiphithiphithi ngokwayo sele idlule ngokukhawuleza kwindalo - zonke iparameters igesi-olutshintshatshintshayo zingatshintsha ngokuhamba kwexesha.

Kukho nenye impahla ebalulekileyo sophazamiseko: kusoloko-ntathu. Nokuba siqwalasela flow-liyajikeleza kwi umbhobho okanye ezikumila kumacala mabini umda umaleko kusekho isindululo eddies ezenzekayo kwi imiyalelo ye nokulawula nezamazembe ezintathu.

Inombolo Reynolds: ifomula

Le nguqulelo laminar ukuba sophazamiseko luphawulwa ekuthiwa-ezibalulekileyo Inombolo Reynolds:

_{Re (/ μ ρuL) cr =} cr,

apho ρ - mninzi umlambo, u - isantya sokuqukuqela uphawu; L - flow ubukhulu iimpawu, μ - 'ngumlingani ka viscosity eliguqukayo, CR - ngokuba yi tube ne icandelo elijekelezayo emnqamlezweni.

Umzekelo, ukuba iqukuqele Velocity u kumbhobho L lisetyenziswa kwi umbhobho. Osborne Reynolds wabonisa ukuba kulo mzekelo, 2300 cr <20000. Sandile mkhulu kakhulu, phantse umyalelo yobukhulu.

A ofanayo ifunyenwe umaleko komda nomqathane. Ubukhulu uphawu ithathwa njengokuba umgama ukusuka ekupheleni phambi kwipleyiti, uze 3 × ¹⁰ Meyi cr <4 × ¹⁰ Apreli. Ukuba L uchazwa Ebubanzini umaleko kumda, i-2700 cr <9000. Kukho izifundo zovavanyo eziye lubonise ukuba ixabiso Re _CR ingaba nkulu.

Ingcamango Velocity perturbation

Le laminar neencindi flow anzima, kwaye ngokufanelekileyo, ixabiso ebalulekileyo kwinani Reynolds (Re) lixhomekeke inani elikhulu lezinto. Ukususela ithambeka uxinzelelo, ukuphakama inezigingqi uburhabaxa, turbulence ngamandla kwi flow yangaphandle, lobushushu umahluko, njl Ukunenzela lula, ezi zinto aggregate kuthiwa perturbation Velocity ekubeni babe nempembelelo ethile kwi bomyinge wamanzi. Ukuba le ukuphazamiseka nto incinane, oko yoconjululwa imikhosi viscous efuna ukulungelelanisa intsimi Velocity. Kuba perturbations ezinkulu kwemali kuba ukutshabalala, kunye lokungazinzi kwenzeka.

Sisazi ukuba intsingiselo ebonakalayo inani Reynolds - umlinganiselo imikhosi inertial kunye nemikhosi viscous, ingqumbo kokungcola ezibandakanywa ifomula:

Re = ρuL / μ = ρu ² / (μ × (u / L )).

Elingezantsi kabini intloko Velocity kunye nenani - ixabiso yi zomyalelo ntshikilelo frictional, ukuba L sithathwa Ebubanzini nwebu kumda. uxinzelelo Dynamic ithande ukuba atshabalalise imali kunye nemikhosi zochuku phikisa oku. Nakuba kunjalo, akucacanga ukuba kutheni imikhosi inertia (okanye uxinzelelo Velocity) kusenokukhokelela kwiinguqu kuphela xa amaxesha 1000 imikhosi viscous ngakumbi.

Ukubala amanqaku

Mhlawumbi, ngakumbi lula zisetyenziswe kwisantya uphawu Re _CR nto ingundoqo flow Velocity u, kunye perturbation Velocity. Kulo mzekelo, inani ezibalulekileyo Reynolds iya kuba malunga ne-10, ngamanye amazwi xa kunene izigigaba xi ukuphazamiseka neengxaki viscous phezu amaxesha 5 ukuhamba laminar ibe uhamba anzima ulwelo. Le nkcazo re ngokutsho kwezinye izazinzulu kuchazwe kakuhle izibakala ngokomfuniselo olungqiniweyo elandelayo.

Kuba yabucala Velocity efanayo ngokugqibeleleyo kumphezulu ngokugqibeleleyo ogudileyo ngokwemveli kumiselwa inani Re _cr luzobe Infinity, oko kukuthi, isigaba okunene kwenzeka isiphithi-phithi. Apha inani Reynolds ixhomekeke ubukhulu bezinto Velocity perturbation lingangaphantsi kwexabiso amanqam, leyo ilingana no-10.

Phambi sophazamiseko ngumntu, ibangela izinga chaphaza ufana rate esisiseko, ukuhamba iba kwi ehle kakhulu amanani nangxola Reynolds ngaphezu Re _CR, bamiliselwa ixabiso elililo lwe zesantya. Oku kuvumela ukusetyenziswa ngumlingani Re _cr = 10, apho uqina iimpawu ke ixabiso elililo perturbation Velocity ebangelwe zizathu ngasentla.

Stability wolawulo laminar flow olusezimbizeni

Le laminar kunye flow lesiphithiphithi kuqhelekileyo zonke iintlobo zokufuma kunye neegesi phantsi kweemeko ezahlukeneyo. Le laminar uhlobo ukuhamba azixhaphakanga kwaye luphawulwa, umzekelo, kuba limxinwa amathafa imilambo komhlaba. Kokukhona, le mpikiswano ezikhathaza izazinzulu kwimeko yesicelo esisebenzayo kwezothutho ngamanzi yombhobho, ioli, igesi kunye nezinye iziselo.

Q uzinzo laminar flow ihlobene ekufundweni kuphazanyiswa isindululo ezifika engundoqo. Kuye kwafunyaniswa ukuba bachatshazelwa perturbations ekuthiwa-amancinane. Kuxhomekeka ekubeni bakhule okanye kuphelelwa ngaphaya kwexesha, ukuhamba esisiseko ithathwa ezizinzileyo okanye ezingazinzanga.

Kuba ulwelo ngezinto kwaye ngezinto

Omnye wemiba ezichaphazela laminar neencindi flow lesiphithiphithi na compressibility wayo. Lo mhlaba fluid kubaluleke kakhulu ekufundeni Ukuzinza neenkqubo ezingezizo emileyo utshintsho olukhawulezayo kwi yangoku zaseprayimari.

Uhlolisiso lubonisa ukuba laminar ukuhamba i fluid incompressible kwi zohlobo lwe candelo zezindlu iyamelana axisymmetric and non-axisymmetric ukuphazamiseka omncinane ngexesha kunye nendawo.

Kutshanje, izibalo yenziwa phezu impembelelo yokuphazamiseka kwinkcaso axisymmetric-flow ugwebu isabelo ityhubhu zezindlu apho yangoku engundoqo kuxhomekeke uququzelelo ezimbini. I-axis Inanai elihambiselanayo lika umbhobho ithathwa njengokuba parameter ochaphazela iprofayile Velocity ecaleni kwirediyasi kombhobho flow engundoqo.

isiphelo

Nangona eminyaka zokufunda asinakho, bathi laminar kunye nangxola budget sifundwa ngokupheleleyo. Izifundo zovavanyo kwinqanaba micro, ukuphakamisa imiba emitsha efuna ukubala sesa ekugwetyelweni ebonisana. Uhlobo uphando isicelo kunye nokusetyenziswa: amawaka yehlabathi ngayo eekhilomitha amanzi, i-oyile, irhasi kunye nemveliso. Izisombululo elide kushicilelwa lobugcisa ukulungiselela ukuncitshiswa sophazamiseko ngexesha lothutho, olusebenzayo kokukhona kuya kuba.