Viscosity. The coefficient simba viscosity. Zvinoreva coefficient pakati viscosity chaiko

viscosity indekisi - huru parameter pakati kushanda Urume kana gasi. In mumuviri nemashoko, kuti viscosity kungarondedzerwa se dzomunyika kukweshera anokonzerwa inofamba pakati nezvimedu vanoumba mukanyiwa nemvura (gaseous) unosvikirwa, kana, kupfuura kungoti, sangano kuramba.

Chii viscosity

A nyore empirical ruzivo viscosity kutsunga: kumeso sloped pamusoro panguva kudirwa zvakaenzana mvura uye mafuta. Mvura inoyerera mafuta nokukurumidza. Inonyanya mvura mvura. Kutamira nokukurumidza ubvise mafuta kunodzivisa wakakwirira kukweshera pakati mamorekuru ayo (womukati nemishonga - viscosity). Saka, Urume viscosity inversely Proportional wayo fluidity.

viscosity indekisi: kuti nzira

Mune nyore chimiro nedanho viscous mvura iri Mapaipi anogona kunzi sezvo sandara inofambirana akaturikidzana A uye B pamwe chete pamusoro nzvimbo S, daro pakati inova kwakakura h.

Izvi akaturikidzana maviri (A uye B) kufamba velocities siyana (V uye V ΔV +). A rukoko ane inonyanya nokukurumidza (V + ΔV), kunosanganisira kufamba zvakaturikidzaniswa B, kutamira pamusangano nomumugwagwa kwaitora nguva kumhanya (V). Panguva iyo B rukoko ruchigona sipidhi mwero zvakaturikidzaniswa A. The zvinoreva viscosity coefficient muviri kuti kukweshera pakati mamorekuru vanoumba kuerera kuramba ari akaturikidzana anoumba munhu simba iro Isaka Nyuton inotsanangurwa mutoo:

F = μ × S × (ΔV / h)

pano:

• ΔV - musiyano pakati kumhanya kufamba Urume kuyerera akaturikidzana;
• H - mufambo pakati nemvura yorwizi akaturikidzana;
• S - pose nzvimbo Urume kuyerera rukoko;
• μ (mü) - chinoita zvichienderana ehupfumi ane mvura, inonzi Mhedziso vakagwinya viscosity.

In SI zvidzidzo payakavakirwa iri sezvinotevera:

μ = (F × h) / (S × ΔV) = [Pa × va] (× Pascal wechipiri)

Where F - simba regiravhiti (uremu) Unit hydraulic uwandu hwemvura.

kukosha viscosity

Kazhinji, ari coefficient simba viscosity unotaurwa centipoises (CP) maererano maitiro cgs (sendimita, giremu, wechipiri). In tsika, iyo viscosity nemvura vakawanda reshiyo wakabatana inzwi rayo, i.e. mvura arambe achirema:

ρ = m / V

pano:

• ρ - arambe achirema nemvura;
• M - guru Urume;
• V - Vhoriyamu mvura.

The reshiyo pakati simba viscosity (μ) uye arambe achirema (ρ) inonzi kinematic viscosity ν (ν - Greek - nå):

ν = μ / ρ = [mamita ² / s]

Sezvineiwo, nzira nokuti Pakusarudza viscosity coefficient zvakasiyana. Somuenzaniso, mashoko kinematic viscosity ichiri akayera zvinoenderana GHS wemuTesitamende centistokes (cSt) uye submultiple zvakawanda - Stokes (St):

• 1st Kirasi = 10 ^-4 mamita ² / s = 1 masendimita ² / s;
• 1sSt = 10 ^-6 mamita ² / s = 1 mm ² / s.

Kutsunga of viscosity mvura

Viscosity coefficient kwemvura kunotemwa nokuyera Urume chokubuda nguva kuburikidza calibrated rirambe richibvira chubhu. mudziyo Izvi calibrated vachishandisa anozivikanwa mwero mvura viscosity. Kuti uone kinematic viscosity, akayera muna mm ² / s, iyo mvura nguva aibuda, akayera seconds, zvikawanda ne kugara ukoshi.

Somunhu kuenzanisa hadzisisina vakashandisa viscosity pamusoro kwakadonhera mvura, ane mutengo iri rinenge kuramba kunyange apo tembiricha kuchinja. Viscosity - mumwe reshiyo nguva masekonzi kuti zvinodiwa yakamisirwa Vhoriyamu kwakadonhera mvura kuti expiry munhu calibrated mugomba, kuti chete ukoshi nokuda bvunzo mvura.

viscometers

Viscosity kunoyerwa pamwero mumasekonzi Engler (° E) Saybolt Universal ( "su) kana Redwood madhigirii (° RJ) zvichienderana norudzi rheometer. Three mhando viscometers akasiyana chete uwandu inoyerera mvura svikiro.

Viscometer kuyera viscosity mu European chikwata Engler madhigirii (° E), akaverenga yokudengenyeka 200 masendimita ³ inoyerera mvura svikiro. Viscometer kuyera viscosity mumasekonzi Saybolt Universal ( "su kana" SSU), rinoshandiswa muUnited States, ane 60 masendimita ³ yomuedzo mvura. MuEngland, apo akashandisa Redwood madhigirii (° RJ), anoitisa viscometer kuyera viscosity 50 masendimita ³ emura. Somuenzaniso, kana 200 masendimita ³ kubva mafuta runoyerera nguva gumi nomumugwagwa kwaitora nguva pane zvakafanana mvura, kuti viscosity iri 10 ° Engler E.

Sezvo tembiricha iri chinhu chinokosha kuchinja viscosity reshiyo, kuyerwa kazhinji pavaiita pakutanga pane kuramba tembiricha 20 ° C uye panguva dzakakwirira tsika dzayo. Mugumisiro, saka, runoratidzwa nokuwedzera tembiricha yakakodzera, semuenzaniso 10 ° E / 50 ° C kana 2.8 ° E / 90 ° C. mvura viscosity pa 20 ° C kupfuura viscosity zvaro tembiricha yakakwirira. Hydraulic anonhuwirira vane viscosity panguva dzinotevera tembiricha dzakasiyana:

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

shanduro tsika

Kutsunga viscosity kunoitika akasiyana hurongwa (American, British, GHS) uye saka kazhinji zvinoda kushandura mashoko kubva tambo anyatsoita mumwe. Kutendeutsa zvinokosheswa viscosity of Urume chinoratidzwa madhigirii Engler mu centistokes (mm ² / s) kushandisa zvinotevera empirical payakavakirwa:

ν (cst) = 7,6 × ° E × (1-1 / ° E3)

Somuenzaniso:

• 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 nokukurumidza kuona mureza viscosity ari hydraulic payakavakirwa inogona nyore mafuta sezvinotevera:

ν (cst) = 7,6 × ° E (mm ² / s)

Kuva ν kinematic viscosity muna mm ² / s kana cSt, rinogona kushandiswa simba viscosity coefficient μ, uchishandisa zvinotevera ukama:

μ = ν × ρ

Example. Nokupfupikisa siyana Masvomhu shanduro Engler madhigirii (° E) centistokes (cSt) uye centipoises (cps), kufunga kuti mafuta hydraulic aine arambe achirema ρ = 910 makirogiramu / m ³ ane kinematic viscosity 12 ° E, riri vamapoka centistokes:

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

Sezvo 1sSt = 10 ^-6 mamita ² / s uye 1br = N × 10 ^-3 S / m ^2, ipapo guru viscosity achava akaenzana:

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

Viscosity coefficient of gasi

Zvinonzi pakutsvaga nziyo (namakemikari, zvemaziso) gasi kuti tembiricha uye kumanikidzwa kushandiswa gasi-simba Masvomhu chokuita gasi racho. In tsika, zviri viscosity pamusoro gasi inocherechedzwa nhoroondo pamasikiro kukura gasi minda, apo dzemaitirwe nevamwe coefficient kuchinja zvichienderana gasi nziyo kuchinja (kunyanya kukosha kuti gasi condensate deposits), tembiricha uye kumanikidzwa.

We ngaaverenge coefficient kuti viscosity mhepo. The pezvakaitwa vachava zvakafanana avo pamusoro apa maviri mvura ndokuyerera. Tambira zvinofambirana kutamira maviri gasi Hova U1 uye U2, asi pamwero yakasiyana. Pakati akaturikidzana ose convection chichaitika (interpenetration) mamorekuru. Somugumisiro, tichimhanya nokukurumidza kubvongodzwa mhepo kuyerera kuchaita kuderera uye pakutanga kunonoka - nokukurumidza.

The coefficient pamusoro viscosity mhepo, maererano nomutemo Newton raMwari, yakataurwa mutoo:

F = -h × (Du / dZ) × S

pano:

• Du / dZ ndiye velocity gradient;
• S - nzvimbo aaiitawo simba;
• Factor H - kukumikidza viscosity.

viscosity indekisi

Viscosity Index (VI) - iri parameter correlating kuchinja viscosity uye tembiricha. The kuwirirana chinhu Statistical nedoro ukama, muchiitiko ichi tsika maviri panguva iyo tembiricha shanduko achabatsirwa enderana kusiyana viscosity. The kumusoro ari viscosity indekisi, kashoma kuchinja pakati mbiri tsika, i.e. ari viscosity ari kushanda Urume akatsiga zvikuru pamwe tembiricha.

The viscosity of kwemafuta

At nheyo ano mafuta viscosity indekisi kuti asingasviki 95-100 dzakabatana. Saka hydraulic michina uye midziyo inogona kushandiswa zvakakwana kugadzikana zvinwiwa kuti ndikusungei nechishwe paupamhi kusiyana viscosity pasi ezvinhu ose dzakaoma tembiricha.

"Mumwaka Wakakodzera" coefficient kuti viscosity hunogona kuchengetedzwa nokusuma yokuvirisa rinokosha mafuta (Polymers) yaunganidzwa ari DISTILLATION epetroleum. Ivo kuwedzera mafuta viscosity indekisi nokusanyanya kuchinja zvechadenga bvumidzwa kwaasingasvikiri. In Tsika pakatanga zvakakodzera kwazvo yokuvirisa neyamapani viscosity indekisi chawo mafuta vanogona kumutsirwa 100-105 dzakabatana. Zvisinei, saka akawana muvhenganiswa akanga emunhu ehupfumi ayo pasi kumusoro kumanikidzwa nokupisa mutoro, nokudaro achidzikisa kubudirira chirungiso.

In simba nematunhu inofanira kushandiswa simba hydraulic zvinwiwa ane viscosity indekisi 100 dzakabatana. Zvinwiwa ane yokuvirisa kuti vawedzere viscosity indekisi, zvinoshandiswa hydraulic kuzvidzora mumatunhu uye dzimwe gadziriro kushanda kuwanda pasi / svikiro kumanikidzwa, zvishoma tembiricha siyana kuchinja idonhe diki uye batchwise. Sezvo kuita kunowedzera uye viscosity kunowedzera, asi muitiro ndepana nematambudziko kupfuura 30,0 MPa (300 kamwechete). In tsika, chinhu ichi rinowanzoshandiswa kuregeredzwa.

Chipimo uye indexation

Maererano dzakawanda ISO mitemo, mashoko viscosity mvura (uye vamwe mvura) runoratidzwa centistokes: cSt (mm ² / s). Kuyerwa viscosity kwacho kwemafuta zvinofanira kuitwa panguva kutonhora pakati 0 ° C, 40 ° C uye 100 ° C. Chero zvazvingava, zviri bumbiro chiratidzo mafuta viscosity zvinofanira pana nhamba 40 ° C. Away viscosity anopiwa pa 50 ° C. Marks, kazhinji kushandiswa injiniya hydraulics, zvinobva ISO VG 22 kuna ISO VG 68.

Hydraulic mafuta VG 22, VG 32, VG 46, VG 68, VG 100 panguva tembiricha 40 ° C vane viscosities zvakafanana Kunyora dzavo: 22, 32, 46, 68 uye 100 cSt. The optimum kinematic viscosity zviri kushanda Urume mu hydraulic gadziriro iri kuwanda 16 kusvika 36 cSt.

American Society of Automotive Engineers (Society of Automotive Engineers - SAE) wakadzikwa neeSultan pamusoro viscosities yazvakaitikira tembiricha Codes akakodzera basa navo. Nhamba inotevera tsamba W, - nemhedziso simba viscosity coefficient μ pa 0 ° F (-17.7 ° C), uye ν ari kinematic viscosity pakuguma 212 ° F (100 ° C). Izvi Indexing Panyaya multigrade anonhuwirira aishandiswa motokari indasitiri (yedzimudzangara, injini, uye zvichingodaro. D.).

The mugumisiro viscosity pamusoro hydraulic basa

Kutsunga of viscosity ari Urume hakusi chete zvesayenzi uye dzidzo kufarira, asi kunewo zvakakosha inoshanda kukosha. The hydraulic zvinwiwa kwete chete uchatamisa simba kubva pombi kusvika hydraulic injini, asi kuti tsvedzesa kumativi ose uye zvinoriumba oga kubva pakupisa kunotangira kukweshera yezvinoita. Asingadi dzinoenderana nebasa kushanda Urume viscosity anogona zvakakomba kuvhiringidza kubudirira hydraulics.

Yakakwirira viscosity ari kushanda Urume (mafuta mukuru chaizvo arambe achirema) zvinotungamirira zvinotevera Migumisiro:

• The zvakawedzera kuyerera kuramba ari hydraulic mvura kunokonzera kunyanya kumanikidzwa donhwe hydraulic ino.
• Deceleration kudzora nokukurumidza uye zvemaziso kuchiva pakati actuators.
• Development kuti pombi cavitation.
• Zero kana yakaderera chaizvo mhepo kusunungurwa kubva hydraulic mafuta mutangi.
• A kuoneka kurasikirwa nesimba (kuderedza kunyatsoshanda) pakati hydraulics nokuda kudhura simba kuti vakunde womukati kukweshera pamusoro mvura mvura.
• Inosimudzira torque kunonyanya unomutsa muchina kwakakonzerwa kuwedzera mutoro pamusoro pombi.
• The tembiricha richisimuka kubva hydraulic mvura kunotangira kwakawedzera kukweshera.

Saka, zvinorehwa coefficient ose viscosity mumuviri uri kukanganisa kwayo (akanaka kana akaipa) pamusoro zvinoriumba uye zvigadziriswe motokari, michina uye midziyo.

Kurasikirwa hydraulic simba

The pasi viscosity ari kushanda Urume (yakaderera arambe achirema mafuta) kunokonzera zvinotevera Migumisiro:

• Achiwa volumetric kunyatsoshanda pamusoro pombi semubairo kuwedzera womukati leakage.
• Kuwedzera munyika leakage pamusoro hydraulic zvinoriumba munyika yose hydraulic hurongwa - pombi, mavharuvhu, vharafu, hydraulic Motors.
• Inosimudzira kusakara kuti kupomba dzakabatana uye Pumps jamming nokuda kukwana hydraulic mvura viscosity zvakakodzera kuti lubrication kuti vachidzipukuta zvikamu.

compressibility

Chero mvura pasi kumanikidzwa kuri compressed. Noruremekedzo kuti mafuta, coolants uye lubricants inoshandiswa zvokuimba youinjiniya hydraulics, empirically yakawana kuti compression zvichiitika inversely Proportional kune Urume guru iri vhoriyamu yacho. Huwandu compression nhengo kuti chicherwa anonhuwirira vari yekudyidzana yakaderera mvura uye dzakaderera zvikuru nokuda chakaita zvokugadzirwa zvinwiwa.

In nyore pasi kumanikidzwa hydraulic mvura compressibility kunyora nezvavo sei mukuderedza kwokutanga vhoriyamu. Asi michina simba dzakakwirira-kumanikidzwa hydraulic nemotokari sepombi uye yakakura, izvi kunoratidza pacharo zvinooneka. In hydraulic chicherwa mafuta ari kumanikidzwa 10.0 MPa (100 kamwechete) Bhuku zvinoderedza pedyo 0,7%. Muchiitiko chino, kuchinja mune compression vhoriyamu imwe duku kumwero kupesvedzera kinematic viscosity uye mhando mafuta.

mhedziso

Kutsunga viscosity inobvumira kuti kufanotaura kushanda midziyo uye michina pasi ezvinhu akasiyana-siyana, dzimwe nyaya kuchinja Urume kana gasi sezvamunoita, kumanikidzwa, tembiricha. Uyewo, kudzora zviratidzi kuhupenyu mafuta uye gasi maindasitiri, utilities nezvimwe maindasitiri.