Viscosity. 'Ngumlingani ka viscosity olutshintshayo. Intsingiselo yesitalato 'ngumlingani ka viscosity

index viscosity - i parameter engundoqo ulwelo ukusebenza okanye igesi. Ngokwamanani emzimbeni, le viscosity ukuze ichazwa zochuku kwangaphakathi okwenziwa isindululo ze amasuntswana okumisele ubunzima ulwelo (sukube) eliphakathi, okanye, ngendlela elula, umlo intshukumo.

Yintoni viscosity

Umiselo amava reseach viscosity elula: kumphezulu kakuhle luthi ngaxeshanye agalelwa isixa esilingana amanzi neoli. Amanzi kwemali namafutha ngokukhawuleza. Kuyinto fluid ngakumbi. Ukuhambisa ngokukhawuleza asophise ioli luthintele zochuku eliphezulu phakathi iimolekyuli yayo (nokumelana lwangaphakathi - viscosity). Ngenxa yoko, viscosity ulwelo bomzimba ngokomlinganiselo fluidity yayo.

index viscosity: ifomula

Xa uhlobo lula inkqubo ulwelo viscous olusezimbizeni kunokuthathwa zomaleko nanjengokuba tyaba ezinxuseneyo A and B kunye kwindawo umphezulu enye S, umgama phakathi leyo ubukhulu h.

Ezi zoleko ezimbini (A no-B) ukuhambahamba sesiqhelo ezahlukeneyo (V kunye V + ΔV). A umaleko ukuba isantya liphezulu (V + ΔV), ibandakanya intshukumo umaleko B, ehamba ngesantya esisezantsi (V). Ngelo xesha linye umaleko B ithande ukuba isantya phantsi izinga lo maleko A. intsingiselo ebonakalayo kwezi lomlingani viscosity kukuba iimpikiswano zochuku ezo molekyuli okumisele kweelana ukuhamba kweemaleko enza amandla apho Isaak Nyuton echazwe kule ndlela ilandelayo:

F = μ × S × (ΔV / h)

here:

• ΔV - umahluko phakathi isantya intshukumo lamanqanaba flow fluid;
• h - umgama phakathi maleko umjelo wamanzi;
• S - umphezulu kwindawo ukuhamba maleko fluid;
• μ (mu) - factor ngokuxhomekeke iimpawu ulwelo, ebizwa ngokupheleleyo onamandla viscosity.

In SI units ifomyula ngolu hlobo lulandelayo:

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

Apho F - amandla womxhuzulane (ubunzima) unit umqulu hydraulic kulwelo.

ukubaluleka viscosity

Kwiimeko ezininzi, 'ngumlingani ka viscosity olutshintshayo ulinganiswa centipoises (CP) ngokungqinelana nenkqubo ye cgs (isentimitha, gram, okwesibini). Nto ithetha ukuba, viscosity le ratio ulwelo ubunzima kunxulumene ukuba umthamo wayo, ngamanye wamanzi ukuxinana:

ρ = m / V

here:

• ρ - mninzi yamanzi;
• m - ubunzima kolwelo;
• V - umthamo wamanzi.

Umlinganiselo phakathi viscosity olutshintshatshintshayo (μ) kunye nengxinano (ρ) ibizwa viscosity ν kinematic (ν - Greek - nu):

ν = μ / ρ = [m ² / s]

Phela, iindlela yokuqingqa inani viscosity zahlukile. Umzekelo, i-viscosity kinematic nangoku kulinganiswa ngokungqinelana nenkqubo GHS e centistokes (cSt) kunye 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.

Nokuzimisela viscosity amanzi

Viscosity ukungavumelani kwe amanzi bubonwa ngokulinganisa ixesha flow fluid ngokusebenzisa capillary tube ukukala. Esi sixhobo ulinganiswe usebenzisa i eyaziwa viscosity ulwelo eqhelekileyo. Ukuze ubone viscosity kinematic, kulinganiswa mm ² / s, ixesha flow fluid, kulinganiswa kwimizuzwana, yande yi ixabiso rhoqo.

Njengeyunithi uthelekiso kusetyenziswe viscosity amanzi Yek, ixabiso yayo phantse rhoqo naxa lobushushu utshintsho. Viscosity - umlinganiselo ixesha kwimizuzwana okufunekayo umthamo esisigxina wamanzi Yek kokuphela emngxunyeni lihlelwe, ukuya ixabiso efanayo engamanzi test.

viscometers

Viscosity ulinganiswa ngamaqondo Seconds Engler (° E) Saybolt Universal ( "hakona) okanye izidanga Redwood (° RJ) ngokuxhomekeke kuhlobo rheometer. Iintlobo ezintathu viscometers ziyahluka kuphela kwisixa ugeleza wamanzi medium.

Viscometer ukulinganisa viscosity kwi kwiyunithi European Engler (° E), ibalwe ngamnye 200 cm ³ ugeleza wamanzi medium. ukulinganisa viscosity kwi Saybolt Universal Seconds ( "uJesu okanye" SSU), esetyenziswa eUnited States, equlethe 60 cm ³ bolwelo test Viscometer. ENgilani, apho kusetyenziswa amaqondo Redwood (° RJ), uqhuba yokulinganisa viscosity-50 cm ³ bolwelo viscometer. Umzekelo, ukuba 200 cm ³ ukusuka ioli aphume kalishumi esisezantsi ngaphezu umlinganiselo ofanayo wamanzi, le viscosity yi-10 ° Engler E.

Ekubeni lobushushu ingundoqo ekutshintsheni umlinganiselo viscosity, imilinganiselo ezo ngokuqhelekileyo luqhutywa ekuqaleni kubushushu rhoqo 20 ° C kwaye ngoko imilinganiselo yayo ephezulu. Isiphumo, ngoko, kubonakaliswa ukungeza lobushushu efanelekileyo, umz 10 ° E / 50 ° C okanye 2.8 ° E / 90 ° C. viscosity ulwelo kwi-20 ° C ngaphezu viscosity layo kwiqondo lobushushu eliphezulu. oyile hydraulic kufuneka viscosity kwi obushushu abakuzo zilandelayo:

190 cSt kwi-20 ° C = 45.4 cSt kwi-50 ° C = 11.3 cSt kwi-100 ° C.

amanani translation

Ukubekwa viscosity lwenzeka kwiinkqubo ezahlukeneyo (American, British, GHS) kwaye ke ngoko kudla kufuneka ukuba aguqulele data evela kwinkqubo enye zokukala komnye. Ukuguqula amaxabiso viscosity ye kulwelo ichazwe ngamaqondo Engler e centistokes (mm ² / s) usebenzisa ifomula olwenziwe ilandelayo:

ν (cst) = 7,6 × ° E × (1-1 / ° E3)

Umzekelo:

• 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 kumiselwe ngokukhawuleza viscosity ibhanile formula ngesanti kubunzulu baphantsi zinakho lula ioli ngolu hlobo lulandelayo:

ν (cst) = 7,6 × ° E (mm ² / s)

Ukuba viscosity ν kinematic mm ² / s okanye cSt, oko inokujikwa ibe viscosity lomlingani eliguqukayo μ, ngokusebenzisa ubudlelwane ilandelayo:

μ = ν × ρ

Umzekelo. Ukushwankathela ezahlukeneyo ifomula inguqulelo Engler (° E) centistokes (cSt) kunye centipoises (CPS) cingela ukuba ioli ngamanzi kunye ezixineneyo ρ = 910 kg / m ³ uye viscosity kinematic we 12 ° E, ngeeyunithi of centistokes:

ν = 7,6 × 12 × (1-1 / 123) = 91,2 × (0,99) = 90,3 mm ² / s.

Ekubeni 1sSt = 10 ^-6 m ² / s kunye 1br = N × 10 ^-3 s / m ^2, ngoko ke viscosity enamandla iya kulingana:

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

Viscosity ukungavumelani kwe igesi

Oku kumiselwa ubume (imichiza, mechanical) irhasi lobushushu kunye noxinzelelo isicelo kwi izibalo igesi-olutshintshatshintshayo ezinxulumene intshukumo igesi. Nto ithetha ukuba, viscosity yalerhasi kuthathelwa ingqalelo kuphuhliso kuyilo lwencwadi amasimi gesi, apho ubalo lwenziwa utshintsho lomlingani kuxhomekeke utshintsho ukwakheka igesi (kubaluleke ngakumbi khona imali condensate igesi), lobushushu kunye noxinzelelo.

Thina ubale ukungavumelani kwe viscosity komoya. Le nkqubo iya kufana naleyo echazwe ngaphezu kwemali ezimbini amanzi. Zicingele parallel ihamba irhasi ezimbini imilambo U1 kunye U2, kodwa ngamazinga ahlukeneyo. Phakathi esicwangciswe පිළිතුරු iimpendulo kuya kwenzeka (interpenetration) iimolekyuli. Ngenxa yoko, amandla ngokukhawuleza ihambe ukungena komoya kuya kuncipha kwaye ekuqaleni uthe chu - olungongezwanga.

'Ngumlingani ka viscosity lomoya, ngokuvumelana nomthetho Newton, oluvakaliswe ndlela ilandelayo:

F = -h × (du / DZ) × S

here:

• du / DZ ke ithambeka Velocity;
• S - indawo amandla;
• Factor h - le viscosity olutshintshayo.

index viscosity

Viscosity Index (VI) - i parameter correlating notshintsho viscosity kunye obushushu. Kungqinelwano lunxulumano nokuxhomekeka statistical, kule meko amaxabiso ezimbini apho utshintsho ubushushu ihamba ukwahluka eyondeleleneyo viscosity. Uphakamile isalathiso viscosity, kokukhona utshintsho phakathi amaxabiso amabini, ngamanye amazwi ke viscosity ye kulwelo ukusebenza uzinzile kakhulu lobushushu.

Le viscosity kwe-oyile

Xa iziseko mihla index oyile viscosity kweeyunithi ngaphantsi kwe 95-100. Ngoko koomatshini kubunzulu baphantsi komhlaba kunye nezixhobo zingasetyenziswa ngokwaneleyo ulwelo ezizinzileyo ezithintela zahlukile iimeko viscosity phantsi kweemeko amaqondo ezibalulekileyo.

"Elilungileyo" ukungavumelani kwe viscosity zigcinwe ngokusungula ongeziweyo ioli ekhethekileyo (iipholima) ezifunyenwe yi na ulwelo lwe petroleum. ioli index viscosity Bona anyuswe ngokunciphisa utshintsho iimpawu kuluhlu obuvumelekileyo. Ekusebenzeni ukuqaliswa ubungakanani eyimfuneko kwezithako ioli isiseko Isalathisi viscosity eliphantsi banokuvuselwa neeyunithi 100-105. Noko ke, umxube ngaloo yayithi ngokonakalisa iimpawu zayo phantsi koxinzelelo oluphezulu kunye nomthwalo nobushushu, ngokwenjenjalo kuncitshiswe ifuthe additive.

Ngamandla iziphaluka kufuneka zisetyenziswe iziselo ezinamandla hydraulic index viscosity leeyunithi 100. Ulwelo equlathe kwezithako ezandisa isalathiso viscosity, ezisetyenziswa kwiisekethe ulawulo kubunzulu baphantsi komhlaba kunye nezinye iinkqubo ezisebenzayo uluhlu ephantsi / uxinzelelo ephakathi, xa kukho utshintsho ubushushu uluhlu encinane kunye ezivuzayo ezincinane kunye batchwise. Njengoko landisa kunye nokunyuka viscosity, kodwa inkqubo kwenzeka iingcinezelo ngentla 30,0 MPA (ibha 300). Ukuziqhelisa, le isici zingahoywa.

Zemilinganiselo indexation

Ngokungqinelana nemigangatho ISO yamazwe ngamazwe, ukuba viscosity kwamanzi (kunye nezinye izinto) lubonakaliswa centistokes: cSt (mm ² / s). Imilinganiselo inkqubo viscosity oyile kufuneka yenziwe kwiqondo lobushushu liphakathi kuka-0 ° C, 40 ° C ne-100 ° C. Enoba kwenzeka ntoni na, kwi khowudi viscosity oyile uphawu kufuneka kuboniswe kwi Inani u-40 ° C. Away viscosity inikwa kwi-50 ° C. Marks, amaninzi asetyenziswa hydraulics zobunjineli, uluhlu evela ISO VG 22 ukuya ISO VG 68.

Ngesanti kubunzulu baphantsi oyile VG 22, VG 32, VG 46, VG 68, VG 100 kubushushu kwe-40 ° C kufuneka viscosities ohambelana zokuphawula wabo: 22, 32, 46, 68 no-100 cSt. Le viscosity kangangoko kinematic ye kulwelo ukusebenza kwiinkqubo hydraulic ilele kuluhlu ka-16 ukuya ku-36 cSt.

American Society of Automotive Iinjineli (Society of Automotive Iinjineli - æ) iseke zibe viscosities kwiqondo lobushushu ezithile kunye neekhowudi ezifanelekileyo ubuwasekele yona. Inani elandelayo ileta W, - eliphelele olutshintshatshintshayo viscosity lomlingani μ ku 0 ° F (-17.7 ° C), kwaye ν le viscosity kinematic eliqingqwe 212 ° F (100 ° C). Le nezikhokelo noku oyile multigrade ezisetyenziswa kushishino lweemoto (transmission, injini, njalo njalo. D.).

Isiphumo viscosity umsebenzi hydraulic

Nokuzimisela viscosity ye kulwelo nje kuphela umdla yenzululwazi kunye zemfundo, kodwa uthwele ukubaluleka esebenzayo kubalulekile. Ulwelo hydraulic Ukudlulisa nje amandla ukusuka kwimpompo ukuya injini yiHydraulic, kodwa kuthambisa zonke iindawo kunye namacandelo uyarhoxiswa ukusuka kubushushu eyenziwe ngezibini kunobunye. Ngaba abufani umsebenzi yokusebenza viscosity fluid angafaka ukuphazamisa ukusebenza ngempumelelo hydraulics.

Le viscosity aphezulu kulwelo yokusebenza (oyile ezixineneyo kakhulu) nezikhokelela imiphumela emibi zilandelayo:

• Luvukelo flow eyandisiweyo kulwelo ngesanti kubunzulu baphantsi ebangela uxinzelelo nokuhla kakhulu kwinkqubo ngamanzi.
• Deceleration ulawulo isantya kwiziphakamiso mechanical le actuators.
• Uphuhliso sokumpompa cavitation.
• Igunkcu okanye asezantsi kakhulu release umoya itanki oyile hydraulic.
• A ilahleko olubonakalayo amandla (ucikizeko nokunciphisa) of hydraulics ngenxa yeendleko eziphezulu amandla kuphele usukuzwano yangaphakathi kulwelo.
• torque Ukwanda ohambisa yinkulumbuso matshini wabangela ngokwandisa umthwalo kwi impompo.
• Iqondo lobushushu nokuvela ulwelo ngesanti kubunzulu baphantsi eveliswa ngokwanda kunobunye.

Ngenxa yoko, intsingiselo ebonakalayo 'ngumlingani ka viscosity na impembelelo yayo (kakuhle okanye kakubi) kwi amacandelo kunye neendlela izithuthi, oomatshini kunye nezixhobo.

Ukulahleka kwamandla hydraulic

Le viscosity phantsi kulwelo yokusebenza (oyile loxinano libya) ebangela imiphumela emibi zilandelayo:

• Ukuwa ukusebenza ngokomthamo le iimpompo ngenxa yokwanda ukuvuza ngaphakathi.
• Ukwanda ukuvuza ngaphakathi kumacandelo hydraulic in yonke inkqubo ngamanzi - iimpompo, izivingco, vana, Iimoto hydraulic.
• Ukwanda ukuguga iiyunithi zokumpompa kwaye iimpompo jamming ngenxa zaneleyo fluid ngesanti kubunzulu baphantsi viscosity eziyimfuneko ukuthambisa ajikeleze ungamalungu ngokukhuhla.

compressibility

Nawuphi ulwelo phantsi xi zixinaniswe. Ngokubhekiselele neeoyile, coolants kunye zokuthambisa ezisetyenziswa hydraulics ngezobunjineli, empirically ziphuma ukuba inkqubo ucinezelo yi bomzimba ngokomlinganiselo ubunzima unamanzi umthamo wayo. Isixa Ilungu ucinezelo ukuya oyile kwezimbiwa kakhulu asezantsi amanzi asezantsi kakhulu ulwelo zokwenziwa.

Uxinzelelo eliphantsi hydraulic incindi compressibility isiphumo elula ayinamsebenzi ekunciphiseni umthamo sokuqala. Kodwa oomatshini ezinamandla abanama-uxinzelelo iisilinda hydraulic drive becala, le nkqubo kubonakala ngokubonakalayo. In hydraulic oyile izimbiwa noxinzelelo ka 10.0 MPA (100 bar), umthamo lehla nge-0.7%. Kulo mzekelo, kukho utshintsho umthamo ucinezelo ubukhulu encinane nefuthe viscosity kinematic kunye nohlobo ioli.

isiphelo

Ukubekwa viscosity ivumela ukuqikelela ukusebenza kwezixhobo noomatshini phantsi kweemeko ezahlukeneyo, kuthathelwa ingqalelo utshintsho akhawunti ulwelo okanye igesi ukubunjwa, uxinzelelo, lobushushu. Kwakhona, ulawulo yeempawu efanelekileyo kushishino oyile negesi, eziluncedo kunye namanye amashishini.