Laminar uye kugadzikana chokubuda. Urume kuyerera neChikomonisiti

Kudzidza zvivako zviri mvura uye magasi kuerera kunokosha chaizvo kuti bhizimisi uye voruzhinji utilities. The laminar uye ichivhiringidza kuerera zvainoita mvura chokufambisa zvazvingava, mafuta, negasi mapaipi zvinangwa zvakasiyana-siyana, kunokanganisa mumwe parameters. matambudziko aya ita hydrodynamics sayenzi.

kupatsanura

In zvesayenzi hwaiitwa Urume kuyerera neChikomonisiti uye magasi vari huviri makirasi akasiyana chaizvo:

• laminar (inkjet);
• kugadzikana.

Uyewo kusiyanisa Transitional Danho. Sezvineiwo, shoko rokuti "mvura" rine zvarinoreva; zvingava incompressible (mvura chaizvoizvo riri), munhu compressible (gasi), conductive, etc ...

nyaya nhoroondo

Imwe Mendeleev muna 1880 pfungwa nokuvapo mbiri pakatarisana kuyerera neChikomonisiti dzakaratidzwa. Kuti uwane mamwe mashoko panyaya iyi vakaongorora British yefizikisi uye injiniya Osborne Reynolds uyo akapedza kudzidza muna 1883. Chokutanga, kushanda, uye kushandisa Masvomhu vakaona kuti yakaderera aibuda yevanhu emura chokufambisa anova laminar fomu: akaturikidzana (PARTICIPLE aibuda) iri zvinenge hazvipindiri uye zvinokambaira inofambirana migwagwa. Zvisinei, pashure kukunda mumwe ukoshi dzinonetsa (nokuti ezvinhu akasiyana kwakatosiyana), musoro Reynolds nhamba mvura iyerere mamiriro vanochinjwa: kuti ndege aibuda anova runobva vortex - i.e., inonetsa. Somugumisiro, parameters ava kusvika pamwero tinoberekwa uye magasi.

Practical Chirungu musayendisiti Masvomhu akaratidza kuti unhu, semuenzaniso, mvura, zviri zvikuru novimba chimiro uye kukura tangi (pombi, migero, capillaries, etc.), umo inoyerera. In pombi kuva raundi muchinjikwa chikamu (zvakadai kushandiswa kuwedzera kumanikidzwa muridzo unoridzirwa), Reynolds nhamba yacho - the nzira yokuoma wehurumende anorondedzerwa sezvinotevera: Re = 2300. Kuti kuzarura kuerera nzira ari Reynolds nhamba iri zvakasiyana: Re = 900. Nokuti maduku tsika kuti Re nomurayiro, takawanda - ita mhirizhonga.

laminar kuyerera

Kusiyana laminar aibuda inovhiringidza ndiwo hunhu uye kutungamirirwa mvura (negasi) inoyerera. Ivo kufambisa akaturikidzana pasina nokusanganisa uye pasina pulsations. Nemamwe mashoko, sangano kunoitika noruvara pasina sechisina musoro akasvetuka ari kufurirwa negwara uye nokukurumidza.

Urume kuyerera Laminar aumbwa Somuenzaniso, mune yakamanikana ropa midziyo zvinhu zvipenyu, zvinomera capillaries uye pasi akafanana ezvinhu, pane imwe kwazvino viscous chaizvo mvura (mafuta mafuta kuburikidza Mapaipi). Kuona ndege aibuda kwakakwanira kuzarura zvishoma pombi - mvura dzichayerera chinyararire, zvakaenzana, pasina nokusanganisa. Kana sunungura spigot kusvikira pakuguma, gadziriro kufurirwa vachamuka uye kuerera vachava runobva.

ichivhiringidza kuyerera

Kusiyana laminar, sezvamakaropafadzwa yakavakidzana nezvimedu zvinokambaira substantially dzakafanana makwara, inovhiringidza aibuda Urume ndiyo disordered hunhu. Kana tikashandisa Lagrange nzira, ivo trajectories ari nezvimedu anogona pamadiro bindepinde uye vazvibate zvikuru unpredictably. Movement kuti mvura uye magasi pasi izvi ezvinhu vanogara zvinopfuura, pamwe parameters izvi nonstationarities vanogona yakafarikana chaizvo-siyana.

Sezvo laminar gasi nokuyerera kupinda ichivhiringidza hurumende mberi, zvinogona kuongororwa nomuenzaniso wisps utsi ane uchipfuta mudzanga iri richiri mumhepo. Pakutanga, inoramba kufamba anenge rinofambirana nzira kuchinja nguva. Utsi anoita wakaiswa. Zvadaro pane imwe nguva pakarepo varipo guru eddies kuti kufamba zvachose randomly. vortices izvi kuputsa akakwira madiki vaduku - kupinda kunyange zviduku uye zvichingodaro. Pakupedzisira, raishanda vanosvuta mixes pamwe yakapoteredza mhepo.

mhirizhonga zvinogara

Muenzaniso kumusoro bhuku, uye kubva ake zvakawanika masayendisiti akaita zvinotevera ndezvipi:

1. Laminar uye ichivhiringidza kuerera zviri probabilistic zvakasikwa: kuchinja kubva nzira kune mumwe hakusi chaizvo nekodzero nzvimbo, uye ari zvakanaka zvemasanga, chero nzvimbo.
2. Chokutanga, pane vortices guru kuti akakura kupfuura ukuru wisps dzoutsi. Movement anova kusimba uye zvakasimba anisotropic. Rwako Large kuva kusagadzikana uye kuputsa akakwidzwa zviduku uye duku. Saka, pane akanyatsorongwa kuti eddies. The simba kufamba iri kubva makuru maduku, uye pakupera izvi nokupera - simba nounzenza ndepana chikero diki.
3. Ichivhiringidza kuyerera iri sechisina musoro: imwe vortex kunogona ari zvachose asingashumbi, nzvimbo nezvimwewo.
4. Vachisanganisa utsi pamwe ambient mhepo hakuiti kuitika pasi laminar kuyerera, uye inonetsa - iri nyanyisa chaizvo.
5. Pasinei nokuti mamiriro muganhu vari mira, kuti mhirizhonga pacharo rine raidudzwa zvinopfuura zvakasikwa - zvose gasi-simba parameters kusanduka nenguva.

Pane imwe pfuma inokosha mhirizhonga: nguva dzose-dimensional matatu. Kunyange kana isu funga mumwe-dimensional chokubuda iri nyere kana maviri-dimensional muganhu rukoko achiri inofamba pakati hwekutambudzika eddies dzinoitika mirayiridzo nhatu rinoronga namasanhu.

Reynolds nhamba: kuti nzira

Kuchinja kubva laminar kuti mhirizhonga dzinoratidzwa inonzi Reynolds nhamba dzinonetsa:

_{Re Kr = (ρuL / μ)} Kr,

apo ρ - arambe achirema rukova, u - kubuda zvazvingava mamirire; L - dzinoyerera maitiro saizi, μ - the coefficient simba viscosity, Kr - nokuti kumicheto ane raundi muchinjikwa chikamu.

Somuenzaniso, kuti inoyerera velocity nepfambi mu nenyere L inoshandiswa sezvo nomutopota dhayamita. Osborne Reynolds akaratidza kuti iyi nyaya, 2300 Kr <20000. Kupararira yakakura chaizvo, anenge ane hurongwa zvikuru.

A yakafanana mugumisiro inotengwa mune muganhu rukoko pamusoro chitete. The maitiro kwemavara chinobviswa sezvo chinhambo kubva pamberi pamucheto mundiro, uye ipapo 3 × ¹⁰ May Kr <4 × ¹⁰ April. Kana L kunotsanangurwa so pakukora muganhu layer kuti 2700 Kr <9000. Pane zvidzidzo zvokuongorora vakaratidza kuti kukosha Re _Kr kungava yakatokura.

Pfungwa velocity perturbation

The laminar uye inotambudza mvura kuyerera, uye maererano, dzinonetsa kukosha Reynolds nhamba (Re) kunotsamira zhinji zvinoverengeka. Kubva kwokudzvinyirira gradient, kukwirira anorovera roughness, mhirizhonga kuchinyanya munyika zvokunze aibuda, differential tembiricha, etc. For nyore, izvi uwandu hwezvinhu zvose zvabatanidzwa. zvikonzero dzinonzi perturbation velocity sezvo vaine imwe rokuchinja kuerera unodiwa. Kana kuvhiringidza iri diki, rinogona kugadziriswa viscous mauto achitsvaka swatanudza yacho velocity munda. For guru perturbations ari kuerera anogona kuva isina, uye mhirizhonga kunoitika.

Kwakapiwa kuti zvinoreva Reynolds nhamba panyama - nhamba inertial mauto uye viscous nemauto, kutsamwa runoyerera nokufukidzwa fomura:

Re = ρuL / μ = ρu ² / (μ × (nepfambi / L )).

The numerator iri kaviri velocity musoro uye dhinomineta - kukosha iri sezvakarayirwa frictional kunetseka kana L chinobviswa sezvo pakukora muganhu rukoko. Dynamic kumanikidzwa ruchigona kuparadza akazodzikama uye kukweshera nemauto vanoshora ichi. Zvisinei, hazvina kujeka sei masimba inertia (kana velocity nevezera) kutungamirira kuchinja chete kana ivo 1000 nguva yakawanda viscous mauto.

Masvomhu uye mashoko

Zvichida, kupfuura nyore kushandiswa senzvimbo maitiro nokukurumidza Re _Kr asina Mhedziso aibuda velocity nepfambi, uye velocity perturbation. Panyaya iyi, dzinonetsa Reynolds nhamba ichava pamusoro 10, i.e. apo runopfuura simba kumanikidzwa kuvhiringidza viscous atinosangana pamusoro 5 kakapetwa laminar aibuda mune inotambudza mvura ndokuyerera. Tsanangudzo iyi Re maererano mamwe masayendisiti ari kutsanangurwa zvakanaka nokuda zvinotevera experimentally nekusimba chokwadi.

Nokuti zvakakwana yakafanana velocity Profile pamusoro yakarurama pamusoro kare pakutsvaga nhamba Re _Kr ruchigona kusaverengeka, kureva kuchinja chaizvoizvo kunoitika kuti mhirizhonga. Pano Reynolds nhamba kunotemwa nokukura pamusoro perturbation velocity pazasi dzinonetsa mutengo, izvo zvakaenzana 10.

In pamberi chakagadzirwa mhirizhonga, zvichiita achitevedzera mwero akafanana mwero inokosha, kuerera anova kugadzikana panguva zvikuru kudzika Reynolds nhamba pane Re _Kr, kwakatemwa kubva Mhedziso kukosha pakukurumidza. Izvi zvinobvumira kushandisa coefficient Re _Kr = 10, umo maitiro velocity ndiko kukosha mhedziso yacho velocity perturbation anokonzerwa pamusoro zvikonzero.

Kutsiga laminar kuyerera hurumende iri Mapaipi

The laminar uye ichivhiringidza kuerera kunoitika mhando dzose mvura uye magasi pasi ezvinhu akasiyana-siyana. The laminar hunhu kuerera hadziwanzowaniki uye dzinoratidzwa Somuenzaniso, nokuti yakatetepa pevhu hova mumapani. Zvakawanda, nyaya iyi inonetsa masayendisiti ari akapoteredza kushanda kuti chokufambisa pedyo Mapaipi mvura, mafuta, gasi nezvimwe zvinwiwa.

Q laminar kuyerera Kugadzikana wakada kufanana adzidze anetseka inofamba huru chokubuda. It akawanikwa kukanganiswa vanonzi perturbations diki. Zvichienderana kana kukura kana uchabvuruvara pamusoro nguva, pfungwa kubuda anoonekwa igadzikane kana kusagadzikana.

For compressible uye kwete compressible zvinwiwa

Mumwe zvinhu kukanganisa laminar uye kugadzikana mvura iyerere chiri compressibility. Ichi Urume pfuma inokosha zvikuru kudzidza kutsiga non-mira pezvakaitwa pamwe nokukurumidza Kuchinja zvikuru riripo.

Ongororo dzinoratidza kuti laminar nokuyerera ane incompressible mvura iri sepombi ari cylindrical chikamu chiri husingakwanisi zviduku axisymmetric uye vasiri axisymmetric vachivavhiringidza munguva uye nzvimbo.

Munguva ichangopfuura, Masvomhu vakatakudzwa kubva pamusoro kufurirwa nenyonganiso pamusoro axisymmetric aibuda kuramba ari Inlet mugove cylindrical chubhu apo mukuru Kuyerera novimba Coordinates maviri. The batanidza akabatana kuti mutopota ichaongororwa sezvo parameter kunokanganisa velocity Profile achitevedza nharaunda huru chokubuda nenyere.

mhedziso

Pasinei emakore okudzidza, hatigoni kutaura kuti laminar uye ichivhiringidza kuerera iri kwazvo kudzidza. zvidzidzo zvokuongorora pamusoro micro chechetere, kutsvaga itsva yaida akakurukura kukarukureta kururamiswa. Mhando tsvakurudzo ndiko kushanda uye kushandiswa: zviuru enyika makiromita dzemvura, mafuta, gasi uye chigadzirwa. Kureba hwakatangwa hwokugadzira negadziriso rutapudzo kuti mhirizhonga munguva chokufambisa, zvinobatsira chaizvo zvichaita.