Danko. A coefficient na tsauri danko. A zahirin ma'anar coefficient na danko

danko index - a key siga na aiki ruwa ko iskar gas. A zahirin sharuddan, da danko iya bayyana a matsayin ciki gogayya sa da motsi na da barbashi da ke cikin taro na ruwa (gaseous) matsakaici, ko, mafi kawai, da motsi juriya.

Mene ne danko

A sauki empirical kwarewa danko kafiya: da santsi sloped surface lokaci guda zuba a cikin wani daidai adadin ruwa da kuma man fetur. Ruwa gudana sauri man fetur. Shi ne mafi m. Motsi da sauri lambatu man hana hakan gogayya tsakanin ta da kwayoyin (ciki juriya - danko). Saboda haka, m danko inversely na gwargwado ga ta fluidity.

danko index: da dabara

A wani Sauki nau'i na aiwatar da danko sosai ruwa a cikin bututun za a iya gani a matsayin lebur layi daya yadudduka A da B da wannan surface yankin S, nĩsa a tsakãninsa da abin da yake da girma da h.

Wadannan biyu yadudduka (A da B) matsawa da daban-daban velocities (V kuma V + ΔV). A Layer da ciwon da mafi sauri (V + ΔV), shafi na motsi na Layer B, motsi a hankali gudun (V). A daidai wannan lokaci da B Layer o ƙarin tabbatar da rage gudu cikin kudi na Layer A. The jiki ma'anar danko coefficient ne cewa gogayya da kwayoyin da ke cikin kwarara juriya da yadudduka Forms karfi wanda Isaak Nyuton aka bayyana da wadannan dabara:

F = μ × S × (ΔV / h)

a nan:

• ΔV - bambanci tsakanin gudun motsi na ruwa ya kwarara yadudduka.
• h - nesa tsakanin ruwa rafi yadudduka.
• S - surface yankin na ruwa ya kwarara Layer.
• μ (Mu) - factor dangane da kaddarorin wani ruwa, kira cikakkar tsauri danko.

A SI raka'a dabara ne kamar haka:

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

Ina F - da karfi na nauyi (nauyi) naúrar na na'ura mai aiki da karfin ruwa ruwa girma.

darajar danko

A mafi yawan lokuta, da coefficient na tsauri danko aka auna a centipoises (Cp) daidai da tsarin cgs (santimita, gram, na biyu). A yi, da danko daga cikin ruwa taro rabo ne alaka ta girma, Ina nufin ruwa yawa:

ρ = m / V

a nan:

• ρ - yawa daga cikin ruwa.
• m - taro na ruwa.
• V - juz'i na ruwa.

A rabo tsakanin tsauri danko (μ) da yawa (ρ) aka kira wani kinematic danko ν (ν - Greek - nu):

ν = μ / ρ = [m ² / s]

Ba zato ba tsammani, hanyoyin domin kayyade danko coefficient ne daban-daban. Alal misali, da kinematic danko har yanzu auna daidai da GHS tsarin a centistokes (cSt) da kuma wani submultiple yawa - dana kunamar rura (St):

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

Tabbatar da dalilin da danko ruwa

Danko coefficient na ruwa ne m da aunawa da ruwa ya kwarara lokaci ta hanyar da calibrated capillary tube. Wannan na'urar da aka calibrated amfani sananne misali ruwa danko. Domin sanin kinematic danko, auna a mm ² / s, da ruwa ya kwarara lokaci, auna a seconds, aka tara da akai darajar.

Kamar yadda a kwatanta naúra tana amfani da danko distilled ruwa, wanda darajar ne kusan m koda lokacin da zafin jiki da canje-canje. Danko - wani rabo daga lokacin a seconds abin da ake bukata ajali girma na distilled ruwa zuwa ga ƙarewar a calibrated rami, to wannan darajar da gwajin ruwa.

viscometers

Danko aka auna da darajõji Engler (° E) Saybolt Universal Seconds ( "SUS) ko Redwood darajõji (° RJ) dangane da irin rheometer. Iri uku ne ake viscometers bambanta kawai a cikin adadin gudãna ruwa matsakaici.

Viscometer aunawa da danko a Turai naúrar Engler darajõji (° E), lasafta ta 200 cm ³ na gudãna ruwa matsakaici. Viscometer aunawa da danko a Saybolt Universal Seconds ( "SUS ko" SSU), amfani a Amurka, dauke da 60 cm ³ na gwajin ruwa. A Ingila, inda amfani da Redwood darajõji (° RJ), gudanar da viscometer aunawa da danko 50 cm ³ na ruwa. Alal misali, idan 200 cm ³ daga wani mai gudana a sau goma hankali fiye da guda adadin ruwa, da danko ne 10 ° Engler E.

Tun da yawan zafin jiki ne key factor a canza danko rabo, da ma'aunai yawanci za'ayi farko a akai da yawan zafin jiki na 20 ° C sa'an nan a ta mafi girma dabi'u. A sakamakon haka, ta haka ne, aka bayyana ta wurin kara dace zazzabi, msl 10 ° E / 50 ° C ko 2.8 ° E / 90 ° C. ruwa danko a 20 ° C fi ta danko a mafi girma yanayin zafi. Na'ura mai aiki da karfin ruwa mai da danko a wadannan Game da yanayin zafi:

190 cSt a 20 ° C = 45,4 cSt a 50 ° C = 11.3 cSt a 100 ° C.

translation dabi'u

Tabbatar da dalilin da danko ya auku a daban-daban tsarin (Amurka, Birtaniya, GHS) sabili da haka sukan ake bukata don fassara data daga daya ma'auni tsarin zuwa wani. Don maida da dabi'u na danko na ruwa da aka bayyana a darajõji Engler a centistokes (mm ² / s) ta amfani da wadannan empirical dabara:

ν (cst) = 7,6 × ° E × (1-1 / ° E3)

Ga misali:

• 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.

Domin sauri ƙayyade da misali danko na na'ura mai aiki da karfin ruwa dabara za a iya Sauki mai kamar haka:

ν (cst) = 7,6 × ° E (mm ² / s)

Samun ν kinematic danko a mm ² / s, ko cSt, shi za a iya tuba a cikin wani tsauri danko coefficient μ, ta amfani da wadannan dangantaka:

μ = ν × ρ

Misali. Rungumar daban-daban dabarbari translation Engler darajõji (° E) centistokes (cSt) da kuma centipoises (CPS), ɗauka cewa na'ura mai aiki da karfin ruwa mai da yawa ρ = 910 kg / m ³ yana mai kinematic danko 12 ° E, a raka'a centistokes:

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

Tun 1sSt = 10 ^-6 m ² / s da 1br = N × 10 ^-3 s / m ^2, sa'an nan da tsauri danko zai zama daidai:

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

Danko coefficient na gas

An ƙaddara da abun da ke ciki (sinadaran, inji) gas zuwa da zazzabi da kuma matsa lamba amfani a cikin gas-tsauri lissafin dangantawa da gas motsi. A yi, da danko da gas da aka ɗauke shi zuwa lissafi a cikin zane ci gaban gas filayen, inda lissafi an gudanar coefficient canje-canje dangane da gas abun da ke ciki canje-canje (da muhimmanci musamman ga gas condensate adibas), zazzabi da kuma matsa lamba.

Mun ƙididdige coefficient na danko iska. The matakai za su yi kama da waɗanda aka bayyana a sama da biyu ruwa gudana. Ya ɗauka a layi daya motsi biyu gas kõguna U1 da U2, amma a daban-daban rates. Tsakanin yadudduka na convection zai faru (interpenetration) kwayoyin. A sakamakon haka, lokacinta sauri dabba ba a kanta iska ya kwarara zai ragu da farko motsi sannu a hankali - kara.

A coefficient na danko iska, bisa ga Newton ta dokar, ya bayyana ta da wadannan dabara:

F = -H × (Du / dZ) × S

a nan:

• Du / dZ ne gudu dan tudu.
• S - yanki na tasiri da karfi;
• Factor h - tsauri danko.

danko index

Danko Index (VI) - a siga correlating da canji a cikin danko da kuma zazzabi. The hulda ne a ilimin kididdiga dogara dangantaka, a cikin wannan yanayin da biyu dabi'u a da zazzabi canji yana tare da tsanaki bambancin da danko. A mafi girma da danko index, da kasa da canji tsakanin biyu dabi'u, Ina nufin danko na aiki ruwa ne mafi barga tare da zazzabi.

A danko na mai

A tushe na zamani mai danko index of kasa da 95-100 raka'a. Saboda haka a cikin na'ura mai aiki da karfin ruwa da injuna da kuma kayan aiki za a iya amfani da isasshe barga ruwaye cewa takura m bambancin a danko a karkashin yanayi na m yanayin zafi.

"M" coefficient na danko za a iya kiyaye ta gabatar da wani musamman mai Additives (polymers) samu ta hanyar da barasan na man fetur. Sun kara da danko index man ta iyakance canje-canje a cikin halaye na halatta kewayo. A yi gabatarwar dole yawa na Additives da low danko index tushe mai iya za a tashe su 100-105 raka'a. Duk da haka, haka ta samu cakuda ya impairs da kaddarorin a karkashin babban matsin da zafi load, game da shi, rage tasiri na ƙari.

A ikon haihuwarka dole ne a yi amfani da na'ura mai aiki da karfin ruwa m ruwaye da danko index of 100 raka'a. Ruwaye dauke da Additives cewa kara da danko index, ana amfani da na'ura mai aiki da karfin ruwa iko haihuwarka da sauran tsarin aiki a cikin kewayon low / matsakaici matsa lamba, a cikin wata iyaka da zazzabi kewayon canje-canje da kananan leaks kuma batchwise. Kamar yadda matsa lamba ƙaruwa da kuma danko ƙaruwa, amma tsari ya auku a matsin lambar sama 30,0 MPa (300 mashaya). A aikace, wannan factor ne sau da yawa a bari.

Ji kuma indexation

A daidai da na kasa da kasa ISO matsayin, na danko na ruwa (da kuma sauran taya) da aka bayyana a cikin centistokes: cSt (mm ² / s). Ma'aunai na danko tsari mai ya kamata a yi a yanayin zafi tsakanin 0 ° C, 40 ° C da kuma 100 ° C. A cikin wani hali, a cikin code maki mai danko ya kamata a nuna a adadi 40 ° C. Away danko ne ba a 50 ° C. Marks, mafi sau da yawa amfani da aikin injiniya hydraulics, kewayon daga ISO VG 22 zuwa ISO VG 68.

Na'ura mai aiki da karfin ruwa mai VG 22, VG 32, VG 46, VG 68, VG 100 a zazzabi na 40 ° C da viscosities m zuwa ga lakabtawa: 22, 32, 46, 68 da kuma 100 cSt. A ganiya kinematic danko na aiki ruwa a na'ura mai aiki da karfin ruwa da tsarin da yake a cikin kewayon 16 to 36 cSt.

American Society of Engineers Automotive (Society of Engineers Automotive - Sae) ya kafa jeri na viscosities a takamaiman yanayin zafi da kuma dace lambobin sanya musu. Yawan wadannan da wasika W, - mai cikakkar tsauri danko coefficient μ a 0 ° F (-17.7 ° C), da kuma ν da kinematic danko m at 212 ° F (100 ° C). Wannan Indexing game multigrade mai amfani a cikin mota masana'antu (baza, motor, da sauransu. D.).

A sakamakon danko a kan na'ura mai aiki da karfin ruwa aikin

Tabbatar da dalilin da danko na ruwa ne ba kawai kimiyya da ilimi da amfani, amma kuma daukawa muhimmanci m muhimmanci. A na'ura mai aiki da karfin ruwa ruwaye ba kawai canza wurin samar da makamashi daga famfo da na'ura mai aiki da karfin ruwa mota, amma kuma ya sa mai da dukkan sassan da aka gyara an janye daga zafi gogayya da nau'i-nau'i. Ba ya dace da aikin da aiki m danko iya tsanani rushe da tasiri na hydraulics.

A high danko na aiki ruwa (mai sosai high yawa) take kaiwa zuwa da wadannan korau effects:

• A ƙãra kwarara juriya da na'ura mai aiki da karfin ruwa ruwa sa wuce kima matsa lamba digo a cikin na'ura mai aiki da karfin ruwa tsarin.
• Deceleration iko da gudun da kuma inji motsi na actuators.
• Development of famfo cavitation.
• Zero ko sosai low iska saki daga na'ura mai aiki da karfin ruwa mai tanki.
• A m asarar ikon (rage yadda ya dace) na hydraulics saboda babban kudin da makamashi domin shawo kan matsalar ciki gogayya da ruwa.
• Karuwan karfin juyi na Firayim mover na na'ura sa ta kara load a kan famfo.
• A zazzabi Yunƙurin na na'ura mai aiki da karfin ruwa ruwa generated da ya karu gogayya.

Saboda haka, jiki ma'anar coefficient na danko ne a da tasiri (tabbatacce ko korau) a kan gyara da kuma sunadaran don motocin, kayan aiki da kuma kayan aiki.

Asarar na'ura mai aiki da karfin ruwa ikon

A low danko na aiki ruwa (low yawa man) Yanã da wadannan korau effects:

• Fadowa volumetric yadda ya dace da farashinsa a sakamakon kara ciki yayyo.
• A karuwa a ciki yayyo na na'ura mai aiki da karfin ruwa da aka gyara a cikin dukan na'ura mai aiki da karfin ruwa tsarin - farashinsa, bawuloli, bawul, na'ura mai aiki da karfin ruwa Motors.
• Karuwan lalacewa daga famfo raka'a da farashinsa jamming saboda kasa na'ura mai aiki da karfin ruwa ruwa danko dole for lubrication na shafa sassa.

compressibility

Duk wani ruwa a karkashin matsin da aka matsa. Tare da girmamawa ga mai, coolants kuma lubricants amfani da aikin injiniyan inji hydraulics, empirically shi gano cewa, da matsawa tsari ne inversely na gwargwado ga m taro a kan ta girma. The adadin matsawa memba to ma'adinai mai suna muhimmanci ƙananan for ruwa da yawa m ga roba ruwaye.

A sauki low matsa lamba na'ura mai aiki da karfin ruwa ruwa compressibility negligible sakamako a kan rage farko girma. Amma iko inji tare da high-matsa lamba na'ura mai aiki da karfin ruwa drive cylinders da kuma manyan, wannan tsari bayyana kanta fili. A na'ura mai aiki da karfin ruwa ma'adinai da man fetur a matsa lamba na 10,0 MPa (100 mashaya), da girma raguwa da 0.7%. A wannan yanayin, wani canji a cikin matsawa girma zuwa kananan har tasiri cikin kinematic danko da kuma irin man fetur.

ƙarshe

Tabbatar da dalilin da danko damar hango ko hasashen da aiki na kayan aiki da kuma kayan aiki a karkashin daban-daban yanayi, shan la'akari canje-canje a cikin ruwa ko gas abun da ke ciki, matsa lamba, zazzabi. Har ila yau, iko da Manuniya dacewa da masana'antar mai da gas, utilities da sauran masana'antu.