Nafwaayay. Wehliyaha ee ku nafwaayay firfircoon. Macnaha jirka ah ee Wehliyaha ee ku nafwaayay

nafwaayay index - dhimaya muhiim ah oo dheecaanka ka shaqeeya ama gas. In la eego jirka, ku nafwaayay ah waxaa lagu qeexi karaa khilaaf gudaha sababa mooshinka ka mid ah qayb ka ah dhismaha mass ee dareeraha ah (gas) dhexdhexaad ah, ama, ka badan si fudud, iska caabin ah dhaqdhaqaaqa.

Waa maxay nafwaayay ah

A go'an tahay waayo-aragnimo taaban karo ku nafwaayay fudud: dusha siman sloped isku mar ku shubtay galay tiro isla'eg oo biyo iyo saliid. Biyaha webigu saliid si dhakhso ah. Waa dheeraad ah dheecaan. Lyadoo si deg deg ah ka daadi saliidda ka hortagtaa khilaaf sare u dhexeeya taagoo ay (iska caabin gudaha - nafwaayay). Sayidka, nafwaayay dheecaan dhigmayn in ay is beddelid.

index nafwaayay: caanaha

In nooc ka mid ah fududeeyey of habka of dheecaan viscous in dhuumaha la oran karo waa layers sida guri isku midka ah A iyo B oo leh bedka isku S, ee masaafada u dhaxaysa taas oo ah baaxadda h.

Labadan layers (A iyo B) guurto la velocities kala duwan (V iyo V + ΔV). Lakabka A isagoo xawaaraha ugu sareeya (V + ΔV), oo ku lug leh dhaq-dhaqaaqa ee lakabka B ah, dhaqaaqin xawaare gaabis ah (V). Isla mar ahaantaana lakabka B waxay u egtahay in ay hoos u dhigi heerka of lakabka A. macnaha The jirka ah ee Wehliyaha nafwaayay waa in khilaaf ah ee u taagoo ee dhismaha iska caabin socodka of layers ah foomamka ciidan oo Isaak Nyuton tilmaamay by formula soo socda:

F = μ × S × (ΔV / h)

halkan:

• ΔV - farqiga u dhexeeya xawaaraha dhaqdhaqaaqa of layers socodka dareeraha;
• h - masaafada u dhaxaysa layers dareere il;
• S - bedka of lakabka dheecaanka socodka;
• μ (mu) - factor ku xiran tahay sifooyinka dareere ah, loo yaqaan nafwaayay firfircoon buuxda.

In SI unugyada formula waa sida soo socota:

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

Halkee F - ciidamada of cuf (miisaanka) unit ee mugga Haydarooliga dheecaanka.

qiimaha ku nafwaayay

Xaaladaha intooda badan, Wehliyaha ah ee ku nafwaayay firfircoon waxaa lagu cabiraa centipoises (cP) iyadoo la raacayo nidaamka cgs (sentimitir, garaam, labaad) ah. In dhaqanka, nafwaayay ee saamiga dareere mass la xiriira in ay mugga, i.e. cufnaanta dareere ah:

ρ = m / V

halkan:

• ρ - cufnaanta ee dareeraha ah,
• m - mass of dheecaan;
• V - mugga dareeraha ah.

ratio u dhexeeya nafwaayay ee firfircoon (μ) iyo mugga (ρ) waxaa lagu magacaabaa ν nafwaayay kinematic (ν - Greek - nu):

ν = μ / ρ = [m ² / s]

Waana mid ka, hababka lagu ogaanayo Wehliyaha ku nafwaayay ku kala duwan yihiin. Tusaale ahaan, ku nafwaayay ku kinematic weli qiyaasay iyadoo la raacayo nidaamka GHS in centistokes (CST) oo ah tiro submultiple - Stokes (St):

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

Determination of nafwaayay biyaha

Wehliyaha nafwaayay oo biyo ah waxaa lagu go'aamiyaa qiyaaso markii ugu socodka dheecaan tuubada gaddoonka dhexdiisa. qalab Tani waa dhexdiisa isticmaalaya nafwaayay dareere heer yaqaan. Si loo go'aamiyo nafwaayay kinematic, qiyaasay in mm ² / s, markii ugu socodka dheecaan, qiyaasay in ilbiriqsi, waxaa lagu dhuftay qiimaha joogto ah.

Sida unit barbar waxaa loo isticmaalaa nafwaayay biyaha debeda, kuwaas oo qiimo ku dhow joogto ah xitaa marka ay isbedel heerkulka. Nafwaayay - cabirku yahay waqtiga ee seconds in loo baahan yahay in mugga go'an oo biyo arimaha debeda in dhicitaanka of god dhexdiisa, si ay qiimaha isku mid ah dareere ah imtixaanka.

viscometers

Nafwaayay waxaa lagu cabiraa digrii Seconds Engler (° E) Saybolt Universal ( "Sus) ama darajo Redwood (° RJ) taas oo ku xidhan nooca rheometer. Saddex nooc oo kala duwan viscometers kaliya in xaddiga dal dhexdhexaad ah ee dareeraha ah.

Viscometer qiyaaso nafwaayay ee qaybta Yurub degrees Engler (° E), xisaabiyaa per 200 cm ³ of dal dhexdhexaad ah ee dareeraha ah. Viscometer qiyaaso nafwaayay ee Seconds Saybolt Universal ( "Sus ama" SSU), loo isticmaalo ee dalka Mareykanka, oo ay ku jiraan 60 cm ³ of dareeraha ah imtixaanka. In England, halkaas oo loo isticmaalo degrees Redwood (° RJ), wuxuu sameynayaa viscometer qiyaaso ku nafwaayay 50 cm ³ ee dareeraha ah. Tusaale ahaan, haddii 200 cm ³ ka saliid ah la barwaaqaysan at toban jeer ka badan gaabis ah tiro la mid ah oo biyo ah, ku nafwaayay waa 10 ° Engler E.

Tan iyo heerkulka waa arrin muhiim ah in la beddelo ratio nafwaayay ah, cabbiraadda waxaa sida caadiga ah ku qaadeen markii hore heerkulka joogta ah 20 ° C, ka dibna at qiimaha ay sare. Natiijadu waxay, sidaas, waxaa lagu qeexay by daray heerkulka ku habboon, tus 10 ° E / 50 ° C ama 2.8 ° E / 90 ° C. nafwaayay dareere at 20 ° C ka badan ay ku nafwaayay at heerkul ka sareeya. saliidaha Haydarooliga leedahay nafwaayay ah ee soo socda heerkulka kala:

190 CST at 20 ° C = 45,4 CST at 50 ° C = 11.3 CST at 100 ° C.

qiimaha turjumaad

Determination of nafwaayay dhacdaa nidaamyada kala duwan (American, British, GHS) oo sidaas daraaddeed waxaa inta badan loo baahan yahay inuu turjumo macluumaadka ka mid ah nidaamka lagu qiyaaso in kale. Si loogu badalo qiimaha ee ku nafwaayay dheecaanka ka muujiyay in degrees Engler in centistokes (mm ² / s) isticmaalaya formula taaban soo socda:

ν (CST) = 7,6 × ° E × (1-1 / ° E3)

Tusaale ahaan:

• 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.

In si ay u si dhakhso ah loo ogaado nafwaayay caadiga ah ee caanaha Haydarooliga fududeeyey karaa saliid sida soo socota:

ν (CST) = 7,6 × ° E (mm ² / s)

Isagoo ku nafwaayay kinematic ν in mm ² / s ama CST, waxaa loo roggi karaa nafwaayay Wehliyaha firfircoon μ, oo isticmaalaya xidhiidhka soo socda:

μ = ν × ρ

Tusaale. Koobaya turjumaad qaaciidooyinka kala duwan degrees Engler (° E) centistokes (CST) iyo centipoises (CPS), u qaadan saliid in Haydarooliga la cufnaanta ah ρ = 910 kg / m ³ ayaa ku nafwaayay ah kinematic of 12 ° E, in cutub oo centistokes:

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

Tan iyo 1sSt = 10 ^-6 m ² / s iyo 1br = N × 10 ^-3 s / m ^2, ka dibna ku nafwaayay ku firfircoon noqon doonaa siman yahay si:

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

Wehliyaha nafwaayay gaaska

Waxaa la go'aamiyey by kooban (kiimikada, farsamo) gaaska si heer kulka ah iyo cadaadis codsatay in xisaabinta gaas-firfircoon ee la xidhiidha dhaqdhaqaaqa gaaska. In dhaqanka, nafwaayay ee gaaska waa la tixgeliyaa in horumarka design of beeraha gaaska, halkaas oo xisaabinta la sameeyay isbedel Wehliyaha ku xiran tahay isbedelka ka kooban gaaska (gaar ahaan muhiim u ah kayd condensate gaaska), heerkulka iyo cadaadiska.

Waxaan xisaabiso Wehliyaha ee ku nafwaayay hawada. geeddi socodka wuxuu noqon doonaa mid ah kuwa kor ku xusan laba qulqulka biyaha ku tilmaamay. Qabtaan barbar dhaqaaqin laba gaaska durdurrada U1 iyo U2, laakiin heerar kala duwan. Inta u dhaxaysa layers of convection dhici doona (interpenetration) taagoo. Sidaas darteed, dardar socodka hawada dhakhso dhaqaaqaan yaraan doonaa waxana uu markii hore si tartiib ah u dhaqaaqin - degdegsiimada.

Wehliyaha ee ku nafwaayay hawada, sida uu qabo sharciga Newton ee, ninba formula soo socda:

F = × -h (Du / dZ) × S

halkan:

• du / dZ waa Wehliyaha xawaare ah;
• S - aagga xoog saameyn;
• Factor h - nafwaayay ku firfircoon.

index nafwaayay

Nafwaayay Index (VI) - dhimaya a xiriir isbedelka ku dhacay ku nafwaayay iyo heerkulka. xiriir waa xiriir ku tiirsanaanta tirakoobka ah, haddii ay taasi labada qiimaha at kaas oo isbedel heerkulka waxaa ku weheliyay kala duwanaansho nidaamsan oo ku nafwaayay. The sare index nafwaayay ah, ee ka yar isbedel u dhexeeya labada qiyamka, i.e. nafwaayay hoorka shaqeeya waa ka xasilloon leh heerkulka.

nafwaayay The of saliidaha ah

At aasaaskii index ku nafwaayay saliid casriga ah ee ka yar 95-100 unugyada. Sidaas mishiino Haydarooliga iyo qalab loo isticmaali karaa filan dheecaanka deggan in la xaddido kala duwanaansho ballaaran ku nafwaayay ku hoos jira xaalad of heerkulka muhiim ah.

"Habboon" Wehliyaha ee ku nafwaayay lagu ilaalin karaa iyadoo soo bandhigid lagu daro gaarka ah ee saliidda (polymers) helay muxaadaro ee batroolka. Waxay kordhin saliid index nafwaayay ah by xadidaysa isbeddel ah ee dabeecadaha kala duwan ee la ogolaan karo. In dhaqanka hordhaca ah ee tirada loo baahan yahay ee lagu daro saliidda lagu hooseeyo index nafwaayay saldhig waa in la 100-105 unugyada kiciyey karo. Si kastaba ha ahaatee, isku dar ah sidaas laga heli jiray daciifiyaa hantida cadaadis sare iyo load kulaylka, taasoo wax ku oolnimada daro ah.

In xoog wareeggeedii waa in la isticmaalaa dareere Haydarooliga awood leh nafwaayay index of 100 unugyo ah. Dareeraha ka kooban lagu daro in la kordhiyo index nafwaayay ah, waxaa loo isticmaalaa in wareeggeedii gacanta Haydarooliga iyo nidaamyada kale ee ka hawlgala kala duwan ee hooseeyo cadaadiska / dhexdhexaad ah, in qofka oo isbedesha kala duwan heerkulka kooban la darroor yar iyo batchwise. Sida uu kordho cadaadis iyo ku nafwaayay koror ah, laakiin habka dhacdaa at cadaadis ku xusan 30.0 MPA (300 bar). In dhaqanka, factor this waxaa inta badan la dayacay.

Cabbiraad iyo indexation

Iyadoo la tixraacayo heerka ISO caalamiga ah, ku nafwaayay ah oo biyo ah (oo cabitaanno kale) waxaa lagu qeexay in centistokes: CST (mm ² / s). Qiyaasaha saliidaha habka ku nafwaayay waa in la sameeyaa marka heerkulku u dhexeeya 0 ° C, 40 ° C iyo 100 ° C. Si kastaba ha ahaatee, in code calaamaddu ku nafwaayay saliidda waa in la tilmaamay at tireedyada 40 ° C. Away nafwaayay waxaa la siiyaa at 50 ° C. Marks, inta badan la isticmaalo ee hydraulics injineernimada, kala duwan oo ka ISO VG 22 in ISO VG 68.

Haydarooliga VG saliid 22, VG 32, VG 46, VG 68, VG 100 at heerkul ah 40 ° C leeyihiin viscosities u dhiganta ay dhidibada: 22, 32, 46, 68 iyo 100 CST. nafwaayay ayaa si mug leh kinematic dheecaanka ka shaqeeya nidaamka Haydarooliga been kala duwan ee 16 ilaa 36 CST.

American Society of Automotive Injineerro (Society of Automotive Injineerro - SAE) ayaa aasaasay safafka of viscosities at heerkulka gaar ah oo ku haboon codes u yeellay. Tirada soo socda W warqadda, - an μ buuxda Wehliyaha nafwaayay firfircoon at 0 ° F (-17.7 ° C), iyo ν ku nafwaayay ku kinematic goostay at 212 ° F (100 ° C). xiriira tusmaynta Tani saliidaha loo isticmaalo multigrade suuqa baabuurta (gudbinta, motor, iyo D. sidaas on.).

Raad ku nafwaayay shaqada Haydarooliga

Determination of nafwaayay ee dareeraha ma aha oo kaliya danta sayniska iyo waxbarashada, laakiin sidoo kale xanbaarsan muhiimadda wax ku ool ah oo muhiim ah. The dareere Haydarooliga ma aha oo kaliya tamarta ka bamka wareejiyo motor ka Haydarooliga, laakiin sidoo kale si ay u saliidayn dhammaan qaybaha iyo qaybaha waxaa laga saaray kulaylka ahbaa lammaanaha khilaaf. Ma u dhigma shaqada ee ku nafwaayay dheecaanka ka shaqeeya si dhab ah carqaladeeyo kartaa waxtarka hydraulics ah.

nafwaayay sare ee ka shaqeeya dheecaan (saliid cufnaanta aad u sarreeya) ku keenaysaa in saamaynta xun ee soo socda:

• The iska caabin socodka dheecaanka Haydarooliga kor u keena hoos u cadaadiska xad-dhaafka ah ee nidaamka Haydarooliga.
• Deceleration gacanta ku xawaaraha iyo damacyadii farsamo ee actuators ah.
• Horumarinta cavitation bamka.
• Zero ama aad u yar in la sii daayo hawada ka taangiga saliidda Haydarooliga.
• khasaare A dareemi awoodda (oolnimada yaraynta) ee hydraulics ay sabab u tahay qiimaha sare ee tamarta ka gudbo khilaaf gudaha ah ee dareeraha ah.
• Xuddunta soo korodha fidmad Ra'iisul mishiinka sababa kordhaya load ku on bamka.
• kaca heerkulka dareeraha Haydarooliga ee ay khilaaf kordhay.

Sayidka, macnaha jirka ah ee Wehliyaha ee ku nafwaayay waa in ay saamayn (wanaagsan ama xun) on qaybaha iyo habab ee baabuurta, mashiinada iyo qalabka.

Loss of xoog Haydarooliga

nafwaayay yar oo ah dheecaan oo ku shaqeeya (saliid cufnaanta low) waxay keentaa saamaynta taban ee soo socda:

• Hoos-oolnimada volumetric of bambooyin ah iyadoo ay sabab u kordhaya baxsiga gudaha.
• Kororka baxsiga gudaha ee qaybaha Haydarooliga in nidaamka oo dhan Haydarooliga - bambooyin, khaanadaha, waalka, matoorrada Haydarooliga.
• Kordhinta Duugga ah unugyada ku listo iyo bambooyin arrimha dibada sabab u nafwaayay dheecaan Haydarooliga ku filnayn lagama maarmaanka u ah sifaynta ah ee qaybaha ku xoqeen ayay.

compressibility

dareere kasta oo cadaadis la cadaadiyo. Marka la eego saliidaha, coolants iyo saliidaha loo isticmaalo hydraulics injineernimada farsamada, siman waxaa lagu ogaaday in habka riixo waa dhigmayn in mass ah dheecaan ay mugga. Inta ay xubin ka riixo in saliidaha macdanta si weyn u yihiin hoos u dhaca biyaha iyo aad uga hooseeya ee dareeraha dardaro.

In cadaadis hoose compressibility dheecaan Haydarooliga saamayn dayac fudud on yaraynta mugga hore. Laakiin mashiinada awood la-cadaadis sarreeya oo dhululubada drive Haydarooliga oo ballaadhan, habka this laftiisa muuqata teedu. In Haydarooliga saliid macdanta at cadaadis ah 10.0 MPA (100 bar), mugga hoos by 0.7%. Xaaladdan oo kale, isbeddel ku mugga riixo ilaa xad yar oo saameyn ku nafwaayay ku kinematic iyo nooca saliidda.

gunaanad

Determination of nafwaayay ogolaanaya in la saadaaliyo howlgalka ka mid ah qalab iyo mishiino xaaladaha kala duwan, iyada oo isbedel account in dheecaan ama gaaska ka kooban, cadaadis, heerkulka. Sidoo kale, control of tilmaamayaasha ee la xiriira warshadaha saliida iyo gaaska, korontada iyo warshadaha kale.