Yana auna juriyar ciki ga damuwar yanka

Viscosity na dinamik (wanda ake kira viscosity cikakke) yana auna yawan karfin da ake bukata don motsa wani shimfiɗa na ruwa kan wani. Shi ne asalin halin ruwan da kansa, ba tare da la'akari da yawansa ba. Mafi girman daraja na nufin juriya mafi yawa.

Tsari: τ = μ × (du/dy) inda τ = damuwar yanka, du/dy = gangarawar gudu

Raka'o'i: Pa·s (SI), poise (P), centipoise (cP). Ruwa @ 20°C = 1.002 cP

Viscosity na dinamik da aka raba da yawa

Viscosity na kinematik yana auna yadda ruwa ke kwarara da sauri a ƙarƙashin jan hankali. Yana la'akari da duka juriyar ciki (viscosity na dinamik) da taro a kowane girma (yawa). Ana amfani da shi lokacin da kwarara da jan hankali ke da mahimmanci, kamar magudanar mai ko zubar da ruwa.

Tsari: ν = μ / ρ inda μ = viscosity na dinamik, ρ = yawa

Raka'o'i: m²/s (SI), stokes (St), centistokes (cSt). Ruwa @ 20°C = 1.004 cSt

• μ (dinamik) = 1.002 cP = 0.001002 Pa·s
• ρ (yawa) = 998.2 kg/m³
• ν (kinematik) = μ/ρ = 1.004 cSt = 1.004 mm²/s
• Rabo: ν/μ ≈ 1.0 (ruwa ne ma'auni)

• μ (dinamik) = 62 cP = 0.062 Pa·s
• ρ (yawa) = 850 kg/m³
• ν (kinematik) = μ/ρ = 73 cSt = 73 mm²/s
• Lura: Kinematik ya fi dinamik da 18% (saboda ƙarancin yawa)

• μ (dinamik) = 1,412 cP = 1.412 Pa·s
• ρ (yawa) = 1,261 kg/m³
• ν (kinematik) = μ/ρ = 1,120 cSt = 1,120 mm²/s
• Lura: Mai danko sosai—sau 1,400 ya fi kaurin ruwa

• μ (dinamik) = 0.0181 cP = 1.81×10⁻⁵ Pa·s
• ρ (yawa) = 1.204 kg/m³
• ν (kinematik) = μ/ρ = 15.1 cSt = 15.1 mm²/s
• Lura: Ƙarancin dinamik, babban kinematik (gas suna da ƙarancin yawa)

Ma'aunin ASTM D88, ana amfani da shi sosai a Arewacin Amurka don samfuran man fetur

ν(cSt) = 0.226 × SUS - 195/SUS (yana aiki ga SUS > 32)

• Ana auna shi a takamaiman yanayin zafi: 100°F (37.8°C) ko 210°F (98.9°C)
• Matsakaicin kewayon: 31-1000+ SUS
• Misali: Man SAE 30 ≈ 300 SUS @ 100°F
• Bambancin Saybolt Furol (SFS) don ruwa masu danko sosai: buɗaɗɗen rami sau ×10 ya fi girma

Ma'aunin Birtaniya IP 70, wanda aka saba amfani da shi a Burtaniya da tsoffin ƙasashen Commonwealth

ν(cSt) = 0.26 × RW1 - 179/RW1 (yana aiki ga RW1 > 34)

• Ana auna shi a 70°F (21.1°C), 100°F, ko 140°F
• Bambancin Redwood No. 2 don ruwa masu kauri
• Canji: RW1 ≈ SUS × 1.15 (kimanin)
• An maye gurbinsa da ma'aunin ISO amma har yanzu ana yin ishara da shi a tsofaffin ƙayyadaddun bayanai

Ma'aunin Jamus DIN 51560, ana amfani da shi a Turai da masana'antar man fetur

ν(cSt) = 7.6 × °E - 6.0/°E (yana aiki ga °E > 1.2)

• Ana auna shi a 20°C, 50°C, ko 100°C
• °E = 1.0 ga ruwa @ 20°C (ta hanyar ma'ana)
• Matsakaicin kewayon: 1.0-20°E
• Misali: Man dizal ≈ 3-5°E @ 20°C

Gwajin dakin gwaje-gwaje mafi tsawo a duniya (tun 1927) a Jami'ar Queensland yana nuna kwalta (tar) yana kwarara ta cikin mazurari. Yana kama da daskararre amma a zahiri ruwa ne mai danko sosai—sau biliyan 100 ya fi dankon ruwa! Diguna 9 ne kawai suka faɗi a cikin shekaru 94.

Lava na basaltic (mai ƙarancin danko, 10-100 Pa·s) yana haifar da fashewa mai sauƙi irin na Hawaii tare da koguna masu gudana. Lava na rhyolitic (mai danko sosai, 100,000+ Pa·s) yana haifar da fashewa mai ƙarfi irin na Dutsen St. Helens saboda iskar gas ba za ta iya tserewa ba. Danko yana siffanta duwatsun wuta a zahiri.

Jini yana da danko sau 3-4 fiye da ruwa (3-4 cP @ 37°C) saboda jajayen ƙwayoyin jini. Yawan dankon jini yana ƙara haɗarin bugun jini/ciwon zuciya. Aspirin mai ƙarancin kashi yana rage danko ta hanyar hana taruwar platelet. Gwajin dankon jini zai iya yin hasashen cututtukan zuciya.

Sabanin tatsuniya da aka saba, tsofaffin tagogi ba su da kauri a ƙasa saboda kwarara. Dankon gilashi a yanayin zafi na ɗaki shine 10²⁰ Pa·s (tiriliyan tiriliyan sau fiye da na ruwa). Zai ɗauki tsawon lokaci fiye da shekarun sararin samaniya don ya kwarara 1mm. Abu ne mai ƙarfi na gaske, ba ruwa mai tafiya a hankali ba.

SAE 10W-30 yana nufin: 10W = dankon hunturu @ 0°F (kwarara a yanayin sanyi), 30 = danko @ 212°F (kariya a yanayin zafi na aiki). 'W' na nufin hunturu (winter), ba nauyi (weight) ba. Man fetur masu daraja da yawa suna amfani da polima waɗanda ke nannade lokacin sanyi (ƙarancin danko) kuma suna faɗaɗa lokacin zafi (kiyaye danko).

Masu tsalle-tsalle na ruwa suna amfani da tashin hankali na sama, amma kuma suna amfani da dankon ruwa. Motsin ƙafafunsu yana haifar da karkatacciyar iska wacce ke turawa a kan juriyar danko, tana tura su gaba. A cikin ruwa maras danko (na ka'ida), ba za su iya motsawa ba—za su zame ba tare da riƙewa ba.

Isaac Newton ya bayyana viscosity a cikin Principia Mathematica. Ya gabatar da ra'ayin 'gogayyar ciki' a cikin ruwa.

Jean Poiseuille ya yi nazarin kwararar jini a cikin manyan jijiyoyi. Ya samo Dokar Poiseuille da ke danganta saurin kwarara da danko.

George Stokes ya samo lissafin kwarara mai danko. Ya tabbatar da dangantakar da ke tsakanin dankon dinamik da na kinematik.

Osborne Reynolds ya gabatar da lambar Reynolds. Yana danganta danko da yanayin kwarara (mai santsi vs. mai rikici).

An daidaita viscometer na Saybolt a Amurka. Hanyar kofin kwarara ta zama ma'auni a masana'antar man fetur.

An sanya sunan Poise da stokes a matsayin raka'o'in CGS. 1 P = 0.1 Pa·s, 1 St = 1 cm²/s sun zama ma'auni.

An fara gwajin digo na kwalta a Jami'ar Queensland. Har yanzu yana gudana—gwajin dakin gwaje-gwaje mafi tsawo a tarihi.

SI ya karɓi Pa·s da m²/s a matsayin raka'o'in ma'auni. Centipoise (cP) da centistokes (cSt) sun kasance na kowa.

ASTM D445 ya daidaita auna dankon kinematik. Viscometer na capillary ya zama ma'auni na masana'antu.

Viscometers na juyawa sun ba da damar auna ruwa marasa Newtonian. Yana da mahimmanci ga fenti, polima, abinci.

Viscometers na dijital sun sarrafa auna ta atomatik. Wuraren wanka masu sarrafa zafin jiki suna tabbatar da daidaito zuwa ±0.01 cSt.

Zaɓin man mota, ruwan haidrolik, da man shafawa na bera:

• Matsayin SAE: 10W-30 yana nufin 10W @ 0°F, 30 @ 212°F (kewayon dankon kinematik)
• Matsayin ISO VG: VG 32, VG 46, VG 68 (dankon kinematik @ 40°C a cSt)
• Zaɓin bera: Mai ruwa sosai = lalacewa, mai kauri sosai = gogayya/zafi
• Ma'aunin danko (VI): Yana auna jin zafi (mafi girma = mafi kyau)
• Man fetur masu daraja da yawa: Abubuwan da aka ƙara suna kiyaye danko a yanayin zafi daban-daban
• Tsarin haidrolik: Yawanci 32-68 cSt @ 40°C don ingantaccen aiki

Ƙayyadaddun bayanai na dankon man fetur, danyen mai, da tacewa:

• Man fetur mai nauyi: Ana auna shi a cSt @ 50°C (dole ne a dumama shi don a famfo shi)
• Dizal: 2-4.5 cSt @ 40°C (ƙayyadaddun bayanai na EN 590)
• Rabe-raben danyen mai: Mai sauƙi (<10 cSt), matsakaici, mai nauyi (>50 cSt)
• Gudun bututu: Danko yana ƙayyade buƙatun ikon famfo
• Matsayin man jirgi: IFO 180, IFO 380 (cSt @ 50°C)
• Tsarin tacewa: Ragewar danko yana rage sassan masu nauyi

Sarrafa inganci da inganta tsari:

• Rabe-raben zuma: 2,000-10,000 cP @ 20°C (ya danganta da danshi)
• Daidaiton sharbati: Sharabatin Maple 150-200 cP, sharabatin masara 2,000+ cP
• Kayayyakin kiwo: Dankon kirim yana shafar laushi da jin daɗi a baki
• Cakulan: 10,000-20,000 cP @ 40°C (tsarin sanyaya)
• Ƙara iskar gas a cikin abin sha: Danko yana shafar samuwar kumfa
• Man girki: 50-100 cP @ 20°C (wurin hayaki yana da alaƙa da danko)

Fenti, manne, polima, da sarrafa tsari:

• Dankon fenti: 70-100 KU (raka'o'in Krebs) don daidaiton amfani
• Rufin fesa: Yawanci 20-50 cP (mai kauri sosai yana toshewa, mai ruwa sosai yana gudana)
• Manne: 500-50,000 cP ya danganta da hanyar amfani
• Narkakken polima: 100-100,000 Pa·s (fitarwa/gyare-gyare)
• Tawadar bugu: 50-150 cP don bugun flexo, 1-5 P don bugun offset
• Sarrafa inganci: Danko yana nuna daidaiton tsari da tsawon rai

Viscosity na dinamik (Pa·s, poise) yana auna juriyar ciki na ruwa ga yanka—'kaurinsa' cikakke. Viscosity na kinematik (m²/s, stokes) shine viscosity na dinamik da aka raba da yawa—yadda yake kwarara da sauri a ƙarƙashin jan hankali. Kuna buƙatar yawa don canzawa tsakaninsu: ν = μ/ρ. Ka yi tunani kamar haka: zuma tana da danko mai yawa (tana da kauri), amma mercury ma yana da danko mai yawa na kinematik duk da cewa 'mai ruwa' ne (saboda yana da yawa sosai).

Ba tare da sanin yawan ruwan a lokacin auna zafin jiki ba. Ga ruwa kusa da 20°C, 1 cP ≈ 1 cSt (saboda yawan ruwa ≈ 1 g/cm³). Amma ga man mota (yawa ≈ 0.9), 90 cP = 100 cSt. Mai canjinmu yana toshe canje-canje tsakanin nau'ikan don hana kurakurai. Yi amfani da wannan dabarar: cSt = cP / (yawa a g/cm³).

Matsayin danko na SAE yana ƙayyade kewayon dankon kinematik. '10W' yana nufin yana biyan buƙatun kwarara a yanayin sanyi (W = hunturu, an gwada shi a 0°F). '30' yana nufin yana biyan buƙatun danko a yanayin zafi mai yawa (an gwada shi a 212°F). Man fetur masu daraja da yawa (kamar 10W-30) suna amfani da abubuwan da aka ƙara don kiyaye danko a yanayin zafi daban-daban, sabanin man fetur mai daraja ɗaya (SAE 30) wanda ke zama mai ruwa sosai lokacin da yake zafi.

Dakikoki na Saybolt Universal (SUS) suna auna tsawon lokacin da 60mL na ruwa ke ɗauka don kwarara ta cikin buɗaɗɗen rami. Dabarar gogewa ita ce: cSt = 0.226×SUS - 195/SUS (don SUS > 32). Misali, 100 SUS ≈ 21 cSt. Har yanzu ana amfani da SUS a cikin ƙayyadaddun bayanai na man fetur duk da cewa hanya ce ta da. Dakunan gwaje-gwaje na zamani suna amfani da viscometers na kinematik waɗanda ke auna cSt kai tsaye a kowane ASTM D445.

Yawan zafin jiki yana ba ƙwayoyin halitta ƙarin kuzarin motsi, yana ba su damar wucewa juna cikin sauƙi. Ga ruwa, danko yawanci yana raguwa da 2-10% a kowace °C. Man mota a 20°C na iya zama 200 cP amma 15 cP ne kawai a 100°C (raguwar sau 13!). Ma'aunin danko (VI) yana auna wannan jin zafin jiki: man fetur masu VI mai yawa (100+) suna kiyaye danko da kyau, man fetur masu VI mai ƙarancin (<50) suna zama masu ruwa sosai lokacin da aka dumama su.

Yawancin tsarin haidrolik suna aiki mafi kyau a 25-50 cSt @ 40°C. Mai ƙarancin (<10 cSt) yana haifar da zubar ciki da lalacewa. Mai yawa (>100 cSt) yana haifar da jinkirin amsawa, yawan amfani da wuta, da tarin zafi. Duba ƙayyadaddun bayanai na masana'antar famfonka—famfun fuka-fuki sun fi son 25-35 cSt, famfun piston suna jure 35-70 cSt. ISO VG 46 (46 cSt @ 40°C) shine man haidrolik na gama gari.

Babu matsakaicin ka'ida, amma auna a aikace yana da wahala sama da miliyan 1 cP (1000 Pa·s). Bitumen/kwalta na iya kaiwa biliyan 100 Pa·s. Wasu narkakken polima sun wuce miliyan 1 Pa·s. A cikin matsanancin danko, iyakar da ke tsakanin ruwa da daskararre ta zama ba a bayyane ba—waɗannan abubuwan suna nuna duka kwarara mai danko (kamar ruwa) da dawo da roba (kamar daskararru), wanda ake kira viscoelasticity.

Poise yana girmama Jean Léonard Marie Poiseuille (1840s), wanda ya yi nazarin kwararar jini a cikin manyan jijiyoyi. Stokes yana girmama George Gabriel Stokes (1850s), wanda ya samo lissafin kwarara mai danko kuma ya tabbatar da dangantakar da ke tsakanin dankon dinamik da na kinematik. An sanya sunan reyn (fam-karfin dakika a kowane inci murabba'i) da sunan Osbourne Reynolds (1880s), wanda ya shahara da lambar Reynolds a cikin ilimin injiniyan ruwa.