Viscosity. I Coefficient viscosity ashukumisayo. Okwakushiwo ezingokomzimba Coefficient viscosity

viscosity Inkomba - ipharamitha ayisihluthulelo uketshezi ukusebenza noma igesi. Ngamagama ngokomzimba, viscosity kungase kuchazwe ngokuthi ukungqubuzana yangaphakathi kubangelwa ukunyakaza izinhlayiya akha lesi mass ketshezi (gaseous) naphakathi, noma, ngaphezulu nje, ukumelana ukunyakaza.

Kuyini viscosity

A elula isipiliyoni enokwehla viscosity ukuzimisela: olubushelelezi ebusweni luthi ukutsheka kanyekanye batheleka isamba alinganayo amanzi namafutha. Amanzi agelezela uwoyela ngokushesha. Kuyinto uketshezi xaxa. Ukuhambisa ngokushesha sokukhipha amafutha uvikela ngomshikisho ephakeme phakathi molecule ayo (ukumelana yangaphakathi - viscosity). Ngakho, viscosity uketshezi inhlukanozigaba ukuze fluidity yayo.

viscosity Inkomba: ifomula

Ifomu lula inqubo uketshezi viscous iphayiphi kubhekwe njengento flat izingqimba parallel A no B efanayo surface area S, ibanga phakathi okuyinto ubukhulu h.

Lezi izingqimba ezimbili (A no B) ukuhambisa nge velocities ezahlukene (V V + ΔV). Isendlalelo kokuba ijubane eliphezulu kakhulu (V + ΔV), kuhilela ukuhamba B ungqimba, ezihambayo ngejubane kancane (V). Ngesikhathi esifanayo ungqimba B ivame ukubambezela ngesilinganiso A. ungqimba Okwakushiwo ezingokomzimba Coefficient viscosity wukuthi ukungqubuzana yezinhlayiya akha ukumelana ukugeleza izingqimba yakha amandla okuyinto Isaak Nyuton esachazwa fomula elandelayo:

F = μ × S × (ΔV / h)

lapha:

• ΔV - umahluko phakathi ukuthi lingakanani ijubane lokuya uketshezi ukugeleza izingqimba;
• h - ibanga phakathi ketshezi ekusakazeni izingqimba;
• S - ndawo ubuso uketshezi ukugeleza ungqimba;
• μ (i-mu) - isici kuncike izakhiwo uketshezi, ngokuthi viscosity ashukumisayo ngokuphelele.

Ngo SI amayunithi ifomula simiswe ngalendlela lelandzelako:

μ = (F × h) / (S × ΔV) = [Pa × s] (× Pascal yesibili)

Lapho F - amandla adonsela phansi (isisindo) iyunithi we wokubacindezela umthamo woketshezi.

ukubaluleka viscosity

Ezimweni eziningi, Coefficient ka viscosity ashukumisayo ulinganiswa centipoises (CP) ngokuhambisana cgs uhlelo (isentimitha, amalutshwana, kwesibili). Ekusebenteni, viscosity ketshezi isilinganiso mass ihlobene umthamo yayo, isb ketshezi kwabantu:

ρ = m / V

lapha:

• ρ - ukuminyana ketshezi;
• m - mass uketshezi;
• V - ivolumu okusamanzi.

Lihlela isilinganiso phakathi kwama viscosity ashukumisayo (μ) kanye kwabantu (ρ) ibizwa ngokuthi kinematic viscosity ν (ν - Greek - nu):

ν = μ / ρ = [m ² / s]

Phela, izindlela sokunquma Coefficient viscosity zihlukile. Ngokwesibonelo, viscosity kinematic namanje kulinganiswa ngokuhambisana uhlelo GHS e centistokes (cSt) kanye nenani submultiple - Stokes (St):

• 1st Class = 10 ^-4 m ² / s = 1 cm ² / s;
• 1sSt = 10 ^-6 m ² / s = 1 mm ² / s.

Ukunqunywa viscosity amanzi

Viscosity Coefficient amanzi latholakala ngokulinganisa indawo uketshezi ukugeleza isikhathi ngokusebenzisa ulinganiswe capillary tube. Le divayisi ayikwazi ukukala usebenzisa eyaziwa ejwayelekile liquid viscosity. Ukuze ubone ukuthi viscosity kinematic, kulinganiswa mm ² / s, uketshezi ukugeleza isikhathi, kulinganiswa ngemizuzwana, iyanda yi value njalo.

Njengoba iyunithi ukuqhathanisa isetshenziswa viscosity yamanzi distilled, ogama value cishe njalo ngisho nalapho nokushintshashintsha kwezinga lokushisa. Viscosity - isilinganiso isikhathi ngemizuzwana ukuthi kuyadingeka ivolumu esimisiwe amanzi distilled ukuze kokuphela umgodi ulinganiswe, nenani efanayo test ketshezi.

viscometers

Viscosity kukalwa ngokwamazinga osengowakwa-Engler (° E) Saybolt Universal Seconds ( "Jesu) noma ama-degree Redwood (° RJ) kuncike hlobo rheometer. Kunezinhlobo ezintathu viscometers kuhluke kuphela inani egeleza naphakathi ketshezi.

Viscometer yokulinganisa viscosity e-European iyunithi osengowakwa-Engler ngamadigrizi (° E), kubalwa ngayinye 200 cm ³ egeleza naphakathi ketshezi. Viscometer yokulinganisa viscosity e Saybolt Universal Seconds ( "Jesu noma" SSU), e-United States, equkethe 60 cm ³ lokuvivinywa ketshezi. ENgilandi, lapho kusetshenziswa ama-degree Redwood (° RJ), uqhuba viscometer yokulinganisa viscosity 50 cm ³ okusamanzi. Ngokwesibonelo, uma 200 cm ³ kusukela uwoyela ageleza ngaso kancane kuka esilinganayo amanzi izikhathi eziyishumi, viscosity 10 ° osengowakwa-Engler E.

Njengoba izinga lokushisa luyisici esiyinhloko ekushintsheni isilinganiso viscosity kwawo, izilinganiso zobukhulu ajwayele ekuqaleni izohlala ezingeni lokushisa elifanayo of 20 ° C no-ke ngesikhathi nezinombolo zayo. Umphumela, ngaleyo ndlela, lubonakaliswa ngokunezela lokushisa elifanele, isib 10 ° E / 50 ° C noma 2.8 ° E / 90 ° C. viscosity uketshezi at 20 ° C ephakeme kunaleyo viscosity yayo at okushisa ephakeme. amafutha umfutholuketshezi abe viscosity ngesikhathi okushisa ezilandelayo ngokulandelana:

190 cSt at 20 ° C = 45.4 cSt at 50 ° C = 11.3 cSt at 100 ° C.

amanani translation

Ukunqunywa viscosity kwenzeka izinhlelo ezahlukene (aseMelika, eBrithani, GHS) ngakhoke kaningi ziyadingeka ukuhumusha idatha kusukela kusistimu eyodwa wokulinganisa kwenye. Ukuguqula amagugu viscosity uketshezi obonakaliswe degrees osengowakwa-Engler e centistokes (mm ² / s) usebenzisa le ndlela elandelayo enokwehla:

ν (cst) = 7.6 × ° E × (1-1 / ° E3)

Ngokwesibonelo:

• 2 ° E = 7.6 × 2 × (1-1 / 23) = 15,2 × (0.875) = 13,3 cSt;
• 9 ° E = 7.6 × 9 × (1-1 / 93) = 68,4 × (0,9986) = 68,3 cSt.

Ukuze ngokushesha ukunquma viscosity esezingeni ifomula wokubacindezela kungenziwa lula uwoyela kanje:

ν (cst) = 7.6 × ° E (mm ² / s)

Ukuba ν viscosity kinematic mm ² / s noma cSt, kungaba iguqulwe ibe ashukumisayo viscosity Coefficient μ, usebenzisa ubuhlobo ezilandelayo:

μ = ν × ρ

Isibonelo. Kufinyeta ezihlukahlukene amafomula translation osengowakwa-Engler ngamadigrizi (° E) centistokes (cSt) kanye centipoises (CPS), ucabange ukuthi uwoyela wokubacindezela nge kwabantu ρ = 910 kg / m ³ has a viscosity kinematic 12 ° E, amayunithi centistokes:

ν = 7.6 × 12 × (1-1 / 123) = 91,2 × (0,99) = 90,3 mm ² / s.

Njengoba 1sSt = 10 ^-6 m ² / s 1br = N × 10 ^-3 s / m ^2, bese viscosity ashukumisayo kuyoba ulingana:

μ = ν × ρ = 90,3 × 10 ^-6 · 910 = 0.082 × N s / m ² = 82 CPS.

Viscosity Coefficient igesi

Okunqumayo indlela yokwakheka (chemical, mechanical) igesi lokushisa nokucindezelwa isicelo izibalo igesi-ashukumisayo elihlobene ne igesi ukunyakaza. Ekusebenteni, viscosity igesi is kubonelelwe ukuthuthukiswa Umklamo igesi Amasimu, lapho ukubala uqhutshwa izinguquko Coefficient kuncike izinguquko igesi Ukwakheka (ezibalulekile ikakhulukazi igesi condensate ezifakwa), izinga lokushisa nokucindezelwa.

Thina ukubala Coefficient viscosity emoyeni. Izinqubo kuyoba ezifana nalezo ezichazwe ngenhla notshwala amabili amanzi. Lokucabanga parallel ezihambayo ezimbili igesi ukusakaza U1 U2, kodwa ngamazinga angafani. Phakathi laphakathi kwehlamvu Ukubika Inkinga YeWindows kuzokwenzeka (interpenetration) ama-molecule. Ngenxa yalokho, umfutho ngokushesha ezihambayo komoya uzokwehla futhi ekuqaleni lihamba kancane - kuye embili ngesivinini.

I Coefficient viscosity emoyeni, ngokuvumelana nomthetho Newton, esashiwo fomula elandelayo:

F = × -H (du / DZ) × S

lapha:

• du / DZ iyona umyela Isivinini;
• S - indawo umthelela force;
• Factor h - viscosity ashukumisayo.

viscosity inkomba

Viscosity Inkomba (VI) - ipharamitha ngokuqhathanisa ushintsho viscosity futhi lokushisa. Ukuhlanganisa siwukuba nobuhlobo kwencika kwezibalo, kulokhu amanani amabili lapho ushintsho lokushisa kuhambisana ukushintshashintsha esihleliwe viscosity. Ayanda Inkomba viscosity, kancane ushintsho phakathi kwamanani amabili, okusho ukuthi, viscosity uketshezi ukusebenza sizinze kakhulu nge lokushisa.

Viscosity lamafutha

Ngesikhathi izisekelo yesimanje uwoyela viscosity Inkomba amayunithi esingaphansi 95-100. Ngakho imishini wokubacindezela futhi imishini ingasetshenziswa uketshezi ngokwanele esimile ukhawule ukushintshashintsha ububanzi e viscosity ngaphansi kwezimo okushisa ezibucayi.

"Evumayo" Coefficient viscosity kungenziwa enakekelwa wethula izithasiselo ekhethekile uwoyela (polymers) etholwe the ziphuzo zazihluzwa we-petroleum. Bona ukwandisa amafutha viscosity Inkomba ngokukhawulela izinguquko izici senhlobo kuvunyelwe. Ngo umkhuba ukwethulwa ubuningi kudingekile kwezithako aphansi viscosity Inkomba uwoyela base bangavuselwa amayunithi 100-105. Nokho, ingxube ngaleyo ndlela yayithi olimaza impahla yayo ngaphansi umfutho ophakeme futhi ukushisa umthwalo, ngaleyo ndlela kuncishiswe ukuphumelela okufakiwe.

Ngamandla izifunda kumele kusetshenziswe uketshezi enamandla wokubacindezela nge Inkomba viscosity amayunithi 100. Uketshezi equkethe izithasiselo ukwandisa Inkomba viscosity, asetshenziswa wokubacindezela ukulawula izifunda kanye nezinye izinhlelo zokusebenzisa ku ezahlukene ongaphakeme / ingcindezi esiphakathi, elinganiselwe lokushisa ububanzi izinguquko ukuvuza amancane batchwise. Njengoba ukwanda ingcindezi futhi viscosity ukwanda, kodwa inqubo eyenzeka kuwo izingcindezi ngenhla 30.0 MPA (300 ibha). In practice, lokhu isici ngokuvamile azinakwa.

Silinganiso kanye nekusebentisa indexation

Ngokuhambisana amazinga ISO ngamazwe, viscosity yamanzi (kanye nezinye iziphuzo) lubonakaliswa centistokes: cSt (mm ² / s). Izilinganiso yenqubo viscosity amafutha kufanele kwenziwe emazingeni okushisa abephakathi kuka-0 ° C, 40 ° C no-100 ° C. Kunoma ikuphi, ikhodi uphawu uwoyela viscosity kufanele kuboniswe kweyoku inani 40 ° C. Away viscosity inikezwa 50 ° C. Marks, avame ukusetshenziswa hydraulics ubunjiniyela, ububanzi kusukela ISO VG 22 ISO VG 68.

Umfutholuketshezi uwoyela VG 22 VG 32, VG 46, VG 68, VG 100 ezingeni lokushisa 40 ° C babe viscosities elihambisana kophawu yabo: 22, 32, 46, 68 kanye no 100 cSt. I elikhulu viscosity kinematic we uketshezi usebenza izinhlelo wokubacindezela itholakala uhla 16 kuya 36 cSt.

American Society of Izithuthi Engineers (Society of Izithuthi Onjiniyela - Sae) isungule amabanga of viscosities okushisa ethize namakhodi ezifanele eliyifa lawo. Inombolo kulandela W incwadi, - an ngokuphelele ashukumisayo viscosity Coefficient μ at 0 ° F (-17.7 ° C), futhi ν viscosity kinematic likalwa ezingeni 212 ° F (100 ° C). Lokhu nangenkomba mayelana amafutha multigrade esetshenziswa embonini yezimoto (ukudluliswa, motor, nokunye. D.).

Umthelela viscosity emsebenzini wokubacindezela

Ukunqunywa viscosity uketshezi akuyona isithakazelo yezesayensi nasezinzuzweni zokufundisa kuphela, kodwa futhi athwala ukubaluleka ezibalulekile esisebenzayo. Nokusaketshezi wokubacindezela hhayi kuphela uthumele amandla futha motor wokubacindezela, kodwa futhi gcoba zonke izingxenye futhi izingxenye kuhoxiswe kusukela ukushisa ngomshikisho ngazimbili. Ayihambisani umsebenzi we ukusebenza viscosity uketshezi kungaba sina ukuphazamisa ukusebenza hydraulics.

Viscosity eziphakeme ukusebenza uketshezi (uwoyela high density kakhulu) kuholela miphumela elandelayo ezimbi:

• I anda ukugeleza ukumelana uketshezi wokubacindezela kubangela ngokweqile ingcindezi yokwehla kwezinga uhlelo wokubacindezela.
• Deceleration ukulawula isivinini kanye iminyakazo mechanical of the actuators.
• Development of futha cavitation.
• Zero noma aphansi kakhulu emoyeni ukukhululwa ethangini wokubacindezela uwoyela.
• Ukulahlekelwa lubonakale kwamandla (ukusebenza kahle ukunciphisa) ka hydraulics ngenxa zibiza kakhulu amandla zokunqoba ngomshikisho sangaphakathi uketshezi.
• torque engu ekhulile yemiphumela oyinhloko walelo umshini kubangelwa okwandisa umthwalo evula umpompi.
• Amazinga ukuvelela uketshezi wokubacindezela eyenziwe ngomshikisho anda.

Ngakho, lokho okushiwo ezingokomzimba Coefficient viscosity ungaphakathi ukukhinyabezeka kwayo (emihle noma emibi) on the izingxenye futhi izindlela izimoto, imishini kanye nezinto zokusebenza.

Ukulahlekelwa amandla wokubacindezela

Viscosity eliphansi uketshezi ukusebenza (ongaphakeme uwoyela ukuminyana) kubangela imiphumela elandelayo ezimbi:

• Falling kahle volumetric we amaphampu ngenxa yokwanda ukuvuza yangaphakathi.
• Ukwanda ukuvuza sangaphakathi izingxenye wokubacindezela e lonke uhlelo wokubacindezela - amaphampu, ama-valve, valve, izinjini wokubacindezela.
• Ukwandiswa bafake amayunithi uzotshala kanye amaphampu wenza umcimbi ngenxa enganele uketshezi wokubacindezela viscosity ezidingekile Lubrication izingxenye bezihlikihla.

compressibility

Noma yiluphi uketshezi ngaphansi kwengcindezi onomfutho. Mayelana amafutha, coolants kanye zokugcoba elisetshenziswa hydraulics isiqoqi sama-softwe, empirically lwathola ukuthi inqubo kokucindezelwa kuyinto inhlukanozigaba mass unamanzi umthamo yayo. Inani ilungu kokucindezelwa ukuba amafutha amaminerali kukhona aphansi kakhulu kwabane amanzi aphansi kakhulu zokwenziwa eziwuketshezi.

Ngo elula ingcindezi ongaphakeme wokubacindezela uketshezi compressibility umphumela azinakwa ekunciphiseni ivolumu kokuqala. Kodwa imishini enamandla nge high-ingcindezi drive wokubacindezela amasilinda futhi ezinkulu, le nqubo kuzibonakalisa batshengise. Ngo wokubacindezela uwoyela amaminerali ngesikhathi ukucindezela 10.0 MPA (100 ibha), ivolumu incipha ngo 0.7%. Kulokhu, ushintsho ivolumu kokucindezelwa ngokwezinga elincane nomthelela viscosity kinematic nohlobo uwoyela.

isiphetho

Ukunqunywa viscosity ivumela ukubikezela ukusebenza kwe-imishini nemishini ngaphansi kwezimo ezihlukahlukene, ukuthatha bangeniswa izinguquko akhawunti uketshezi noma igesi Ukwakheka, ingcindezi, izinga lokushisa. Futhi, ukulawula izinkomba ahambisana uwoyela negesi umkhakha, Tinsita nezinye izimboni.