Viscosity othakazelisayo uketshezi. Lisho ukuthini ngokomzimba futhi mechanical?

Lolu ketshezi kuchazwa njengoba umzimba wenyama, ikhono ukushintsha ukuma kwayo nethonya ezinqumela ezincane. Ngokuvamile kunezinhlobo ezimbili eziyinhloko uketshezi kanye amagesi ukuvuza. Ukuvuza uketshezi - uketshezi ngomqondo evamile: amanzi, amafutha iziketekete uwoyela nokunye. Gaseous uketshezi - amagesi okuyinto ngaphansi kwezimo ezivamile, isibonelo, izinto gaseous ezifana emoyeni, i-nitrogen,-propane, umoya-mpilo.

Lezi zinto zehlela kuhluke ukwakheka kwama-molecule nohlobo nokuxhumana molecule nomunye. Nokho, kusukela iphuzu Ngenxa Mechanics, zingabantu abezindaba okuqhubekayo. Futhi ngenxa yalokho, ngoba ukubonakala ezinye izici ezivamile mechanical: ukuminyana futhi gravity ethize; futhi eziyisisekelo Izakhiwo: compressibility, ukunwetshwa ezishisayo, amandla eqine, amandla surface ukungezwani futhi viscosity.

Ngaphansi viscosity ukuqonda isakhiwo into ewuketshezi simelane beya noma shift Icwele komunye nomunye. Ingqikithi yalo mqondo okuvela ngomshikisho amabutho phakathi laphakathi ezahlukene ngaphakathi uketshezi phakathi ezinyakazayo zawo ezilinganiselwe. Hlukanisa emkhatsini welithi "viscosity othakazelisayo uketshezi" futhi "viscosity kinetic" zalo. Ngokulandelayo, sihlolisise, yini umehluko phakathi imiqondo le.

imiqondo Eyisisekelo kanye ubukhulu

amandla viscous F, okuyinto kuphakama kusukela ezihambayo isihlobo komunye nomunye izingqimba eduze we uketshezi generalized ngokuqondile wakhona Isivinini zezendlalelo futhi contact endaweni yabo S. Le mandla izenzo ohlangothini perpendicular ezinyakazayo futhi wazwakalisa e Newton ndaba kuyindlela analytically

F = μS (ΔV) / (Δn),

lapho (ΔV) / (Δn) = GV - le umyela Isivinini ohlangothini evamile nengxenye ezihambayo.

Coefficient proportionality μ - kuyinto viscosity ashukumisayo, noma umane viscosity generalized uketshezi. Kusukela zibalo Newton kuba

μ = F / (S ∙ GV).

Esikhathini ngokomzimba nesilinganiso uhlelo iyunithi viscosity lichazwa ngokuthi viscosity medium, lapho ngezinye iyunithi Isivinini umyela GV = 1 cm / umzuzwana ngamunye isentimitha skwele ungqimba kokukhuhlana amandla izenzo e 1 dyne. Ngakho, lo isici phiko kulesi simiso lubonakaliswa dynes ∙ s ∙ cm ^ (- 2) = r ∙ cm ^ (- 1) ∙ s ^ (- 1).

Lesi isilinganiso ibizwa ngokuthi ashukumisayo viscosity poise (P).

1 P = 0.1 Pas ∙ c = 0,0102 kgf ∙ nge ∙ m ^ (- 2).

Sebenzisa futhi ezincane, okuyilezi: P 1 = 100 centipoises (CPS) = 1000 mPas (millipuaz) = 1000000 INC (mikropuaz). Kuhlelo lobuchwepheshe ukuze iyunithi ukubaluleka viscosity ukuthatha kgf ∙ nge ∙ m ^ (- 2).

Esikhathini ngamazwe uhlelo iyunithi viscosity lichazwa ngokuthi viscosity medium, lapho ngezinye iyunithi Isivinini umyela GV = 1 m / s no-1 m per imitha square ketshezi ungqimba oyibamba ngomshikisho amandla 1 N (Newton). Amanani isici μ e le SI lubonakaliswa kg ∙ m ^ (- 1) ^ ∙ nge (- 1).

izici ephakeme ezifana umqondo viscosity ashukumisayo ketshezi yethulwa ngokuthi isilinganiso kinematic viscosity Coefficient μ ukuze kwabantu uketshezi. Inani viscosity kinematic ulinganiswa Stokes (Class 1st = 1 cm ^ (2) / c).

Coefficient viscosity kuyinto anda ilingane enanini traffic ezithwalwa igesi ezihambayo per unit isikhathi ohlangothini perpendicular ukunyakaza, per unit endaweni lapho isivinini ukunyakaza kuyahluka iyunithi Isivinini ngayinye ku izingqimba igesi ahlukaniswe per unit obuphelele. Viscosity Coefficient kuncike hlobo kanye isimo impahla (lokushisa nokucindezelwa).

viscosity Dynamic kanye viscosity kinematic uketshezi kanye amagesi ngokwezinga elikhulu incike izinga lokushisa. It kwaqashelwa ukuthi kokubili ukwehla Coefficient nge okwandisa izinga lokushisa zokuyeka isikole liquid, Ngakolunye uhlangothi, iyanda njengoba izinga lokushisa likhuphuka - I-amagesi. Ngokungafani lokhu kwencika zingachazwa ngezinqubo ubunjalo ezingokomzimba nokuxhumana-molecule e-uketshezi droplet futhi amagesi.

Okwakushiwo ngokomzimba

Ngokombono walaba nezinhlayiya theory kinetic yamagesi viscosity mkhuba itholakala lokuthi ukuthi medium ezihambayo ngenxa ezinyakazayo okungahleliwe zishintshe kwenzeka ukuqondanisa zamatshe aphenduka ngejubane elingafani. Ngakho, uma ungqimba lokuqala isiqondiso ezihambayo ngokushesha kunokuba eduze nalokho ungqimba yesibili, ungqimba lokuqala yesibili ezihambayo-molecule ngokushesha, futhi okuphambene nalokho.

Ngakho, ungqimba wokuqala ivame ukusheshisa ukuhamba ungqimba yesibili, kanti eyesibili - ukubambezela ukuhamba lokuqala. Ngakho, inani ukunyakazisa ungqimba wokuqala uzokwehla, kanti eyesibili - ukwandisa. Ushintsho okuholela kule ubuningi motion libhekene Coefficient viscosity ukuba amagesi.

I droplet ngokungafani amagesi ukungqubuzana sangaphakathi ngokwezinga elikhulu ngenxa yesenzo amabutho aphakathi. Futhi, ngoba ibanga eliphakathi amangqamuzana we droplet ketshezi incane uma iqhathaniswa ezindaweni gaseous, nezinhlayiya nokuxhumana amabutho ngesikhathi - abalulekile. La ma-molecule ketshezi, kanye molecule ukudla okuqinile, esukela eduze amaphuzu zilingana. Nokho, uketshezi, la malungiselelo akuzona umile. Ngemva kwenkathi ethile yesikhathi engqamuzaneni ketshezi evele sesimweni esisha. Ngesikhathi esifanayo, lapho isikhundla yezinhlayiya in the ketshezi ayishintshi, isikhathi walibiza ngokuthi "ukuphila okunethezekile".

amabutho aphakathi zincike kakhulu ngohlobo ketshezi. Uma viscosity ketshezi incane, ubizwa ngokuthi "flowable", njengoba ukugeleza Coefficient futhi viscosity othakazelisayo uketshezi - kuyinto inhlukanozigaba. Ngakolunye uhlangothi, i-material nge viscosity okusezingeni eliphezulu ungase ube ubulukhuni mechanical, njengoba, ngokwesibonelo, resin. Viscosity efana ngenkathi kakhulu incike yokwakheka ukungcola kanye namanani azo futhi izinga lokushisa. Nge lokushisa okwandisa ubukhulu "ukuphila ngaphandle kokuzivivinya" isikhathi kuyehla, ngaleyo ndlela kwande uketshezi viscosity liyancipha futhi ukuhamba kwento.

Lo mkhuba viscosity, kanye nezinye ezokuthutha imihlola yamangqamuzana (ukwanda okusheshayo kanye conductivity ezishisayo) kuyinto inqubo okungenakuhlehliswa okuholela ukuzuzwa esimweni yakhoibrium elihambisana entropy esiphezulu kanye khulula namandla ubuncane.