Laminar ndi chipwirikiti otaya. otaya ankhanza madzimadzi

Kuphunzira katundu zakumwa ndi mpweya otaya ndi wofunika kwambiri ku makampani ndi zofunikira anthu. The laminar ndi nthenda yotaya zotsatira chipwirikiti pa madzi mlingo zoyendera mafuta, gasi mapaipi zolinga zosiyanasiyana, zimakhudza magawo ena. Mavuto awa kuchita sayansi hydrodynamics.

Gawo

Mu chilengedwe sayansi ankhanza madzimadzi otaya ndi mpweya ndi magulu awiri osiyana kwambiri:

• laminar (inkjet);
• chipwirikiti.

Komanso kusiyanitsa siteji Transitional. Zodabwitsa ndizakuti, mawu akuti "madzi" ali ndi tanthauzo lonse: zingakhale incompressible (madzi kwenikweni), ndi compressible (mpweya), conductive, etc ...

mbiri nkhani

Wina Mendeleev mu 1880 lingaliro kuli awiri ankhanza zosiyana otaya wafotokozazo. Kuti mudziwe zambiri pa nkhani imeneyi kuphunzira sayansi British ndi injiniya Osborne Reynolds amene anamaliza kuphunzira mu 1883. Choyamba, pafupifupi, ndiyeno ntchito mitunduyi ndi anapeza kuti pa mtengo wotsika otaya zoyendera madzi amakhala laminar form: zigawo (tinthu otaya) pafupifupi kusakaniza ndi kusuntha m'njira yomweyi. Komabe, pambuyo polimbana ndi zina mtengo yovuta (zinthu zosiyana ndi osiyana), mutu Reynolds chiwerengero zinthu zamadzimadzi otaya tisandulika: otaya ndege amakhala wachisokonezo mmene kanyamaka - i.e., chipwirikiti. Mwamwayi, magawo awa kumlingo chibadidwe ndi mpweya.

Othandiza English wasayansi kuwerengetsera anasonyeza kuti khalidwe la, mwachitsanzo, madzi, amadalira kwambiri pa mawonekedwe ndi miyeso ya thanki (mipope, mitsinje, capillaries, etc.), umene umayenda. Mu mipope kukhala zozungulira mtanda gawo (monga ntchito chokakamizidwa piping), Reynolds nambala yake - chilinganizo cha boma ovuta akufotokozedwa motere: Re = 2300. Kuti kutsegula otaya njira ya nambala Reynolds ndi osiyana: Re = 900. Kuti mfundo zing'onozing'ono kwa Re amatsogozedwa, pa lalikulu - wachisokonezo.

laminar otaya

Mosiyana ndi laminar otaya chipwirikiti ndi chikhalidwe ndi malangizo a madzi (mpweya) umayenda. Iwo amasunthira zigawo popanda kuyanjana ndi wopanda pulsations. M'mawu ena, gululi chikuchitika uniformly popanda kudumpha zosathandiza motsogozedwa kuthamanga ndi liwiro.

Laminar madzimadzi otaya aumbike Mwachitsanzo, mu yopapatiza mitsempha ya zamoyo, zomera capillaries ndi m'mikhalidwe mofanana, pa panopa zakumwa viscous kwambiri (mafuta mafuta kudzera payipi ya). Udzakhalire otaya ndege ndi chokwanila akusonyeza kachizindikiro kakang'ono - madzi idzayenda mwakachetechete, wogawana, popanda kuyanjana. Ngati unscrew ndi spigot mapeto, dongosolo kuthamanga adzayamba otaya adzakhala wachisokonezo.

chipwirikiti otaya

Mosiyana laminar ndi m'mene oyandikana particles kusuntha m'njira zayamba kufanana, otaya chipwirikiti cha madzimadzi ndi disordered chikhalidwe. Ngati tigwiritsa ntchito njira Lagrange, ndi trajectories particles akhoza amangosankha alipo ndipo zinthu ndithu unpredictably. Movement zakumwa ndi mpweya pansi pa zikhalidwe izi nthawi zonse chosakhalitsa, ndi magawo awa nonstationarities akhoza kukhala osiyanasiyana kwambiri.

Monga laminar mpweya otaya mu chipwirikiti boma chimaposa, akhoza kuunikira chitsanzo wisps utsi wa ndudu akupsya akadali mpweya. Poyamba, particles kusuntha njira pafupifupi kufanana zikutsatiridwa nthawi. Utsi akuoneka lokhazikika. Ndiye nthawi ina, zonse mwadzidzidzi, pali eddies lalikulu kusuntha kwathunthu mosintha. vortices izi aswe mu ang'onoang'ono - mu ngakhale ang'onoang'ono ndi zina zotero. Pomaliza, pafupifupi kusuta kasakaniza ndi mpweya ozungulira.

m'zinthu kugwedezekagwedezeka

Chitsanzo chapamwambachi ndi buku, ndi ku kuzipenya asayansi apanga mfundo zotsatirazi:

1. Laminar ndi chipwirikiti otaya ndi probabilistic m'chilengedwe: kusintha kwa mode wina ndi mzake si mwa chimodzimodzi pa malo oyenera, ndi mwachilungamo lachabechabe, malo mwachisawawa.
2. Choyamba, pali vortices lalikulu ndi lalikulu kwambiri kuposa kukula kwa wisps utsi. Movement amakhala osakhazikika ndipo mwamphamvu anisotropic. utuluke Large kukhala osakhazikika ndi kuphwanya mu ang'onoang'ono ndi zing'onozing'ono. Choncho, pali utsogoleri wolowezana wa eddies. The mphamvu kuyenda ndi inasamutsidwa kuchoka lalikulu ang'ono, ndi kumapeto kwa ndondomekoyi Mwamsanga - mphamvu madyaidya ndikuledzera limapezeka pa mamba ang'onoang'ono.
3. Chipwirikiti otaya ndi zosathandiza: a mmene kanyamaka makamaka akhoza kukhala mu mwachisawawa kwathunthu, malo sizimadziwika.
4. Kusakaniza utsi ndi mpweya yozungulira sichichitika pansi laminar otaya, ndi chipwirikiti - ndi tima kwambiri.
5. Ngakhale kuti zikhalidwe malire ndi yosasuntha, ndi kugwedezekagwedezeka iyoyomwe ndi kufupika kutchulidwa mu chikhalidwe - magawo onse gasi zazikulu kusintha pa nthawi.

Pali katundu ina yofunika ya kugwedezekagwedezeka: nthawi zonse atatu azithunzi omwe tikunena. Ngakhale ngati ife tiganizirane azithunzi omwe tikunena otaya mu chitoliro kapena ziwiri ooneka enieni wosanjikiza malire akadali zoyenda wa eddies chipwirikiti chidzachitika malangizo atatu ntchito nkhwangwa.

Reynolds chiwerengero: chilinganizo

The kusintha kwa laminar kuti kugwedezekagwedezeka yodziwika ndi otchedwa yovuta Reynolds nambala:

_{Re Kr = (ρuL / μ)} Kr,

kumene ρ - kachulukidwe mtsinje, u - otaya mlingo khalidwe; L - ikuyenda khalidwe kukula, μ - ndi koyefishienti wa kukhuthala zazikulu, Kr - chifukwa ndi chubu ndi gawo zozungulira mtanda.

Mwachitsanzo, chifukwa otaya ndi mathamangidwe u mu chitoliro L ntchito monga m'mimba mwake chitoliro. Osborne Reynolds anasonyeza kuti mu nkhani iyi, 2300 Kr <20000. Kufala ioneka pafupifupi dongosolo la udzakwaniritsidwa.

Chifukwa ofanana ndi zopezera wosanjikiza malire pa kokulumunya lapansi. Kukula khalidwe walandiridwa monga mtunda kuchokera m'mphepete kutsogolo kwa mbale, ndiyeno: 3 × 10 ⁵ Kr <4 × 10 ^4. Ngati L limanenedwa ngati makulidwe a wosanjikiza malire, ndi 2700 Kr <9000. Pali maphunziro komanso kuti asonyeza kuti mtengo wa Re _Kr kungakhale kwambiri.

Lingaliro la mathamangidwe perturbation

The laminar ndi chipwirikiti madzimadzi otaya, ndi moyenera, phindu yapadera ya Reynolds chiwerengero (Re) zimadalira ambiri zinthu Kuchokera masinthidwe amtundu kuthamanga, kutalika tokhala roughness, kugwedezekagwedezeka mwamphamvu mu otaya zakunja masiyanidwe kutentha, etc. Pakuti mayiko, mfundozi akaphatikiza amatchedwa perturbation mathamangidwe. kuyambira ali ndi chikoka ena pa mlingo otaya. Ngati chisokonezo ichi ndi laling'ono, angathe kuthetsedwa mphamvu viscous kufunafuna agwirizane munda mathamangidwe. Pakuti perturbations lalikulu otaya akhoza kukhala osakhazikika, ndi kugwedezekagwedezeka amapezeka.

Popeza kuti tanthauzo thupi la Reynolds chiwerengero - chiŵerengero cha mphamvu inertial ndi magulu viscous, chakukhosi Umayenda ataphimbidwa ndi njira:

Re = ρuL / μ = ρu ² / (μ × (u / L )).

The numerator ndi kawiri mathamangidwe mutu ndi chimene chachititsa - mtengo ndi a dongosolo la maganizo frictional, ngati L amatengedwa ngati makulidwe a wosanjikiza malire. kuthamanga Mphamvu amamuchititsa kuwononga bwino ndi mikangano mphamvu amatsutsa zimenezi. Komabe, sizikumveka chifukwa mphamvu za inertia (kapena chipsyinjo mathamangidwe) kuyambitsa kusintha akakhala nthawi 1000 mphamvu kwambiri viscous.

Asayansi ndi mfundo

Mwina, conveniently zambiri ntchito ngati liwiro khalidwe Re _Kr malire otaya mathamangidwe u, ndi mathamangidwe ndi perturbation. Pankhaniyi, yovutayi Reynolds nambala 10, i.e. pamene choposa mphamvu kuthamanga chisokonezo viscous nkhawa pa nthawi 5 otaya laminar mu chipwirikiti utuluke madzimadzi. Ndipotu izi kukonzanso malinga ndi asayansi ndi bwino anafotokoza zotsatirazi mfundo experimentally kutsimikiziridwa.

Kuti mwangwiro yunifolomu mathamangidwe mbiri pa pamwamba mwangwiro yosalala ndi kale anatsimikiza ndi nambala Re _Kr amamuchititsa osawerengeka, ndiyo kusintha kwenikweni kumachitika kwa kugwedezekagwedezeka. Apa nambala Reynolds anatsimikiza ndi ukulu wa perturbation mathamangidwe pansipa phindu yovuta, yomwe ndi wofanana 10.

Pamaso pa kugwedezekagwedezeka yokumba, kuchititsa mlingo kuwaza ofanana ndi mlingo mwachidule, otaya amakhala chipwirikiti pa kwambiri m'munsi manambala Reynolds kuposa Re _Kr, anatsimikiza pa mtengo mtheradi wa liwiro la. Ichi chizathandiza ntchito koyefishienti Re _Kr = 10, pamene mathamangidwe khalidwe ndi phindu Mtheradi wa perturbation mathamangidwe chifukwa cha zifukwa pamwambapa.

Bata ulamuliro wa laminar otaya mu payipi ya

The laminar ndi chipwirikiti otaya si zachilendo mitundu yonse ya zakumwa ndi mpweya m'mikhalidwe yosiyanasiyana. The laminar chikhalidwe cha otaya ali osowa ndi yodziwika Mwachitsanzo, chifukwa yopapatiza mobisa mitsinje zigwa. Zambiri, nkhani imeneyi ndi nkhawa asayansi pa nkhani ya tiligwiritse ntchito zoyendera ndi madzi payipi, mafuta, mafuta ndi madzi ena.

Q laminar otaya bata ndi umafananirako cha phunziro kusokonezedwa zoyenda wa otaya chachikulu. Anapeza kuti anakhudzidwa ndi otchedwa perturbations yaing'ono. Malingana ngati iwo kukula kapena adzafota pa nthawi otaya ikupezeka ankaona kuti khola kapena kusokonekera.

Pakuti madzi compressible osati compressible

Chimodzi mwa zinthu okhudza laminar ndi chipwirikiti madzimadzi otaya ndi compressibility ake. Mundawu madzimadzi kwambiri makamaka kuphunzira mtendere wa njira sanali n'kupuma ndi kusintha mofulumira panopa chachikulu.

Kafukufuku amasonyeza kuti laminar otaya ndi madzimadzi incompressible mu machubu a chigawo cylindrical kugonjetsedwa axisymmetric ndipo sanali axisymmetric chisokonezo ochepa nthawi ndi malo.

Posachedwapa anapezazo zimagwiridwa pa chikoka cha chisokonezo pa axisymmetric otaya kukana mu polowera gawo la cylindrical chubu komwe panopa waukulu amadalira ndondomeko awiri. The ntchito yaikulu ya chitoliro ndi imatengedwa ngati chizindikiro imagwira mathamangidwe mbiri pamodzi ndi utali wozungulira otaya chitoliro chachikulu.

Pomaliza

Ngakhale zaka akuphunzira, sitingathe kunena kuti laminar ndi chipwirikiti otaya bwino kuphunzira. maphunziro Experimental pa mlingo yaying'ono, kwezani magazini atsopano zofuna ndi anakambirana mawerengedwe kulungamitsidwa. Chikhalidwe cha kafukufuku ndi ntchito ndi ntchito: zikwi dziko la makilomita wa madzi, mafuta, mafuta ndi mankhwala. The yaitali anakhazikitsa njira luso chifukwa kuchepetsa kugwedezekagwedezeka pa zoyendera ndi aluso amenewa.