Kukhuthala. The koyefishienti wa kukhuthala zazikulu. Tanthauzo thupi la koyefishienti wa kukhuthala

kukhuthala index - ndi chizindikiro kiyi wa madzimadzi ntchito kapena gasi. Kumbali thupi, kukhuthala mwina amatanthauziridwa kuti mikangano mkati chifukwa zoyenda particles amapanga misa ya madzi (gaseous) sing'anga, kapena, koposa chabe, kayendedwe kukana.

ndi kukhuthala Kodi

A yosavuta zinachitikira wazotsatira kukhuthala mtima: yosalala sloped pamwamba imodzi anazitsanulira mwa ofanana kuchuluka kwa madzi ndi mafuta. Madzi amalowa mofulumira mafuta. Ndi madzimadzi kwambiri. Kupita mwamsanga kukhetsa mafuta chindiletsa ndi mikangano apamwamba pakati mamolekyulu ake (mkati kukana - kukhuthala). Choncho, madzimadzi kukhuthala inversely njila kwa fluidity ake.

kukhuthala index: chilinganizo

Mu wosalira mawonekedwe a ndondomeko ya madzimadzi viscous mu payipi akhoza ankaona zomveka kufanana zigawo A ndi B ndi chimodzimodzi padziko dera S, mtunda wa pakati ndilo ukulu wa h.

zigawo ziwirizi (A ndi B) kusuntha ndi velocities osiyana (V ndipo V + ΔV). wosanjikiza A ndi liwiro apamwamba (V + ΔV), kumakhala kayendedwe ka wosanjikiza B, kusunthira pa liwiro pang'onopang'ono (V). Pa nthawi yomweyo B wosanjikiza amamuchititsa m'mbuyo mlingo wa wosanjikiza A. Tanthauzo thupi la kukhuthala koyefishienti ndi kuti mikangano ya mamolekyulu amapanga otaya kulimbikira zigawo ndipamene mphamvu zomwe Isaak Nyuton anafotokozedwa ndi chilinganizo zotsatirazi:

F = μ × S × (ΔV / h)

apa:

• ΔV - kusiyana pakati pa liwiro la kayendedwe ka zigawo madzimadzi otaya;
• H - mtunda pakati pa zigawo madzi mtsinje;
• S - padziko dera la wosanjikiza madzimadzi otaya;
• μ (Mu) - Chinthu malingana katundu wa madzi, wotchedwa mtheradi zazikulu kukhuthala.

Mu SI mayunitsi ndiyo njira motere:

μ = (F × h) / (S × ΔV) = [Pa × m] (× Pascal wachiwiri)

Kodi F - mphamvu yake yokoka (kulemera) unit wa buku hayidiroliki madzimadzi.

mtengo wa kukhuthala

Nthawi zambiri, koyefishienti wa kukhuthala zazikulu amayezedwa centipoises (cp) mogwirizana ndi dongosolo cgs (centimeter, gram, wachiwiri). Zochita za kukhuthala kwa madzi misa chiŵerengero likugwirizana buku lake, i.e. madzi kachulukidwe:

ρ = m / V

apa:

• ρ - osalimba a madzi;
• mamita - Unyinji wa madzimadzi;
• V - buku la madzi.

Chiŵerengero pakati pa kukhuthala zazikulu (μ) ndi kachulukidwe (ρ) amatchedwa kinematic kukhuthala ν (ν - Greek - Num):

ν = μ / ρ = [mamita ² / s]

Zodabwitsa ndizakuti, njira kudziŵa kukhuthala koyefishienti zosiyana. Mwachitsanzo, ndi kukhuthala kinematic akadali anayeza malinga ndi dongosolo GHS mu centistokes (cSt) ndi zedi ndi submultiple - Stokes (St):

• 1 Maphunziro = 10 ^-4 mamita ² / s = 1 cm ² / s;
• 1sSt = 10 ^-6 mamita ² / s = 1 mamilimita ² / s.

Khama la kukhuthala madzi

Kukhuthala koyefishienti wa madzi anatsimikiza ndi kuyeza madzimadzi otaya nthawi mwa calibrated capillary chubu. chipangizo Izi calibrated ntchito kudziwika muyezo madzi kukhuthala. Kudziwa kinematic kukhuthala, amayezedwa mamilimita ² / s, madzimadzi otaya nthawi, anayeza masekondi, ndi kuchulukitsa ndi mtengo nthawi zonse.

Monga fanizo wagawo ntchito ndi kukhuthala madzi otchezedwa, amene ubwino ndi pafupifupi nthawi zonse ngakhale pamene kusintha kutentha. Kukhuthala - chiŵerengero cha nthawi masekondi zofunika amodzi buku la madzi otchezedwa kwa lotha wa dzenje calibrated, kufunika chomwecho pa kuyesa madzi.

viscometers

Kukhuthala amayezedwa madigiri Engler (° E) Saybolt Universal Masekondi ( "Efeso) kapena madigiri Redwood (° RJ) malingana ndi mtundu wa rheometer. Mitundu itatu viscometers amasiyana yekha kuchuluka kwa loyenda sing'anga madzi.

Viscometer kuyeza kukhuthala ku European wagawo Engler madigiri (° E), masamu pa 200 masentimita ³ loyenda sing'anga madzi. Viscometer kuyeza kukhuthala mu Saybolt Universal Masekondi ( "Efeso kapena" SSU), ntchito mu United States, munali 60 masentimita ³ mayeso madzi. Mu England, komwe ntchito madigiri Redwood (° RJ), amachititsa viscometer kuyeza kukhuthala 50 cm ³ madzi. Mwachitsanzo, ngati 200 masentimita ³ kwa mafuta umayenda pa nthawi khumi pang'onopang'ono kuposa yofanana madzi, kukhuthala ndi 10 ° Engler E.

Popeza kutentha ndi chofunika kusintha kukhuthala chiŵerengero, miyezo ndi zambiri ikuchitika poyamba pa kutentha zonse 20 ° C ndiyeno pa mfundo zake zapamwamba. Zotsatira, chotero, chimaoneka powonjezera ndi kutentha koyenera, mwachitsanzo 10 ° E / 50 ° C kapena 2.8 ° E / 90 ° C. madzi kukhuthala pa 20 ° C kuposa kukhuthala ake pa apamwamba kutentha. Hayidiroliki mafuta ndi kukhuthala zotsatirazi kutentha analemba:

190 cSt pa 20 ° C = 45,4 cSt pa 50 ° C = 11,3 cSt pa 100 ° C.

mfundo yomasulira

Khama la kukhuthala amapezeka mu machitidwe osiyana (American Britain, GHS) choncho nthawi zambiri chofunika kuti amasulire deta ku kachitidwe kamodzi chingwe ndi mzake. Kutembenuza makhalidwe a kukhuthala madzimadzi m'kukoma madigiri Engler mu centistokes (mamilimita ² / s) pogwiritsa ntchito zotsatirazi chilinganizo wazotsatira:

ν (cst) = 7,6 × ° E × (1-1 / ° E3)

Mwachitsanzo:

• 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.

Kuti mofulumira kudziwa muyezo kukhuthala njira hayidiroliki akhoza wosalira mafuta motere:

ν (cst) = 7,6 × ° E (mamilimita ² / s)

Kukhala ν kinematic kukhuthala mu mamilimita ² / s kapena cSt, izo zikhoza kusinthidwa mu zazikulu kukhuthala koyefishienti μ, ntchito ubale zotsatirazi:

μ = ν × ρ

Chitsanzo. Kufotokoza mitunduyi zosiyanasiyana kumasulira Engler madigiri (° E) centistokes (cSt) ndi centipoises (cps), amaganiza kuti mafuta hayidiroliki ndi osalimba ndi ρ = 910 makilogalamu / mamita ³ ali ndi kukhuthala kinematic 12 ° E, mu mayunitsi a centistokes:

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

Popeza 1sSt = 10 ^-6 mamita ² / s ndipo 1br = N × 10 ^-3 s / mamita ^2, ndiye kukhuthala wamphamvu adzakhala wofanana:

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

Kukhuthala koyefishienti wa mpweya

Amaonekera ndi zikuchokera (mankhwala, mawotchi) mpweya ndi kutentha ndi kuthamanga ntchito kuwerengetsera mpweya-wamphamvu kugwirizana ndi gulu mpweya. Zochita za kukhuthala mpweya kupita naye nkhani za kamangidwe chitukuko cha minda mpweya, kumene mawerengedwe a wochititsidwa kusintha koyefishienti malingana ndi kusintha mafuta zikuchokera (lofunika kwambiri kwa madipoziti mpweya condensate), kutentha ndi mavuto.

Ife kuwerengera koyefishienti wa kukhuthala mpweya. njira adzakhala ofanana ndi tafotokozazi ndi utuluke madzi ziwiri. Kuganiza kufanana kusuntha awiri mpweya mitsinje U1 ndi U2, koma pamlingo wosiyanasiyana. Pakati pa zigawo wa convection zidzachitika (interpenetration) mamolekyulu. Chifukwa cha zimenezi, patsogolo mofulumira avundulidwe mpweya otaya adzakhala ndichepe ndi poyamba kusuntha pang'onopang'ono - zolimira.

The koyefishienti wa kukhuthala mpweya, malinga ndi lamulo Newton, anasonyeza mwa chilinganizo zotsatirazi:

F = -h × (Du / dZ) × S

apa:

• Du / dZ ndi mathamangidwe ndi masinthidwe amtundu;
• S - malo a mphamvu amadza;
• Factor H - mphamvu kukhuthala.

kukhuthala index

Kukhuthala Index (VI) - ndi chizindikiro mosagwirizana ndi kusintha kukhuthala ndi kutentha. The malumikizanidwe ndi zowerengera kudalira ubale, mu nkhani iyi mfundo ziwiri zomwe kusintha kutentha limodzi ndi kusintha mwadongosolo kukhuthala. The apamwamba a kukhuthala index, chindichepere kusintha pakati pa mfundo ziwiri, i.e. ndi kukhuthala madzimadzi ntchito ndi wolimba kwambiri ndi kutentha.

The kukhuthala mafuta

Pa maziko a makono mafuta kukhuthala index mayunitsi zosakwana 95-100. Choncho makina hayidiroliki ndi zipangizo angagwiritsidwe ntchito mokwanira madzi khola kuti asagwiritse kusintha lonse mu kukhuthala pansi zikhalidwe za kutentha yovuta.

"Yabwino" koyefishienti wa kukhuthala akhoza kuwonjezeredwa ndi kuyambitsa zina mafuta wapadera (ma polima) akamagwira pa distillation wa mafuta. Iwo kuonjezera kukhuthala index mafuta NADZIWA kusintha makhalidwe a osiyanasiyana chovomerezeka. Zochita kumayambiriro kuchuluka koyenera zina otsika kukhuthala index mafuta m'munsi angaukitsidwe kukhala mayunitsi 100-105. Komabe, Choncho analandira osakaniza anali impairs katundu wake pansi kuthamanga ndi kutentha katundu, potero kuchepetsa mphamvu ya zowonjezera ya.

Mu mphamvu madera ayenera kugwiritsidwa ntchito madzi amphamvu hayidiroliki ndi kukhuthala index mayunitsi 100. Madzi okhala zina zimene zingachititse kukhuthala index, ntchito m'madera kulamulira hayidiroliki ndi machitidwe ina imene imachitika osiyanasiyana / mochedwerako sing'anga yochepa kusintha kutentha osiyanasiyana ndi kuchucha ang'ono ndi batchwise. Monga ukuwonjezeka kuthamanga ndipo ukuwonjezeka kukhuthala, koma ndondomeko kumachitika pa mavuto pamwamba 30,0 MPa (300 kamodzi). Zochita chinthu ichi kawirikawiri kuwasamalira.

Muyeso ndi indexation

Malinga ndi mfundo mayiko ISO, ndi kukhuthala madzi (ndi zakumwa zina) yafotokozedwera centistokes: cSt (mamilimita ² / s). Miyezo ya kukhuthala ndondomeko mafuta ayenera kuchitidwa pa kutentha pakati pa 0 ° C, 40 ° C ndi 100 ° C. Mulimonsemo, Mpambo chizindikiro mafuta kukhuthala ayenera lemba la numeral 40 ° C. Away kukhuthala wapatsidwa pa 50 ° C. Marks, nthawi zambiri amagwiritsidwa ntchito hydraulics zomangamanga, osiyanasiyana kuchokera ISO VG 22 ISO VG 68.

Hayidiroliki mafuta VG 22, VG 32, VG 46, VG 68, VG 100 pa kutentha 40 ° C ndi viscosities lolingana olemba awo: 22, 32, 46, 68 ndi 100 cSt. The momwe akadakwanitsira kinematic kukhuthala kwa madzimadzi ntchito mu kachitidwe hayidiroliki lagona mu osiyanasiyana 16 36 cSt.

American Society of Automotive Akatswiri (Society of Automotive Akatswiri - SAE) wakhazikitsa ranges wa viscosities pa kutentha yeniyeni ndi zizindikiro zoyenera wawapatsa. chiwerengero zotsatirazi kalata W, - mtheradi zazikulu kukhuthala koyefishienti μ pa 0 ° F (-17.7 ° C), ndipo ν ndi kukhuthala kinematic anatsimikiza pa 212 ° F (100 ° C). Izi indexing nkhani multigrade mafuta ntchito makampani magalimoto (HIV, galimoto, ndi zina zotero. D.).

Zotsatira za kukhuthala pa ntchito hayidiroliki

Khama la kukhuthala madzimadzi si sayansi ndi maphunziro chidwi, koma lilinso zofunika zothandiza tanthauzo. madzi The hayidiroliki osati amatentha ku mpope injini hayidiroliki, komanso mafuta mbali zonse ndi zigawo ndi kudzipatula kwa kutentha kwaiye awiriawiri kukhululukirana. Kodi si zogwirizana ndi ntchito za ntchito madzimadzi kukhuthala akhoza kwambiri kusokoneza mphamvu ya hydraulics lapansi.

The kukhuthala mkulu wa ntchito madzimadzi (mafuta kwambiri kachulukidwe) zimabweretsa zotsatira mavuto:

• Chinawonjezeka otaya kulimbikira madzimadzi hayidiroliki amachititsa kuthamanga dontho kwambiri ndi dongosolo la hayidiroliki.
• Deceleration ulamuliro wa liwiro ndi mwaulesi makina a actuators lapansi.
• Development ya mpope cavitation.
• Zero kapena otsika kwambiri mpweya amasuke ku thanki hayidiroliki mafuta.
• A imfa noticeable mphamvu (kuchepetsa Mwachangu) wa hydraulics chifukwa cha kukwera mtengo kwa mphamvu kugonjetsa mikangano mkati mwa madzimadzi.
• Kuchuluka makokedwe a wotsogolera pachimake pa makina chifukwa cha kuwonjezeka katundu pa mpope.
• Kukwera kutentha kwa madzimadzi hayidiroliki kwaiye kuchuluka kukhululukirana.

Choncho, tanthauzo thupi la koyefishienti wa kukhuthala ndi zo ake (zabwino kapena zoipa) pa zigawo ndi njira galimoto, makina ndi zipangizo.

Achepe mphamvu hayidiroliki

The otsika kukhuthala kwa madzimadzi ntchito (otsika kachulukidwe mafuta) zimapangitsa zotsatirazi mavuto:

• Kugwa Mwachangu volumetric mwa mapampu monga chifukwa cha kuchuluka kutayikira mkati.
• Kuwonjezeka kutayikira mkati mwa zigawo hayidiroliki mu dongosolo lonse hayidiroliki - mapampu, mavavu, valavu, Motors hayidiroliki.
• Kuchuluka avale wa ikukoka mayunitsi ndi mapampu jamming chifukwa osakwanira hayidiroliki madzimadzi kukhuthala zofunika kondomu mbali akusisita.

compressibility

madzi aliyense ali pamavuto wothinikizidwa. Mokhudzana ndi mafuta, coolants ndi lubricants ntchito hydraulics luso lopanga, empirically inapeza kuti psinjika zimachitika inversely njila kwa misa madzimadzi pa buku ake. Kuchuluka kwa membala psinjika mafuta mchere ndi kwambiri kuchepetsa madzi ndi ochepa kwambiri kuti madzi a kupanga.

Mu losavuta otsika kuthamanga hayidiroliki madzimadzi compressibility negligible mphamvu pa kuchepetsa voliyumu koyamba. Koma makina amphamvu ndi paipi zonenepa hayidiroliki galimoto yaikulu, ndondomeko imeneyi kumaonekera mowonekera. Mu hayidiroliki mafuta mchere pa mavuto 10,0 MPa (100 bala), voliyumu amachepetsa ndi 0,7%. Pankhaniyi, kusintha buku psinjika Pamlingo yaing'ono zimakhudza kukhuthala kinematic ndi mtundu wa mafuta.

Pomaliza

Khama la kukhuthala amalola kuneneratu ntchito zida ndiponso makina m'mikhalidwe yosiyanasiyana, kutenga kusintha Nkhani madzimadzi kapena mafuta zikuchokera, kuthamanga, kutentha. Komanso, ulamuliro wa zizindikiro zogwirizana ndi mafuta ndi gasi makampani, zofunikira ndi mafakitale ena.