Pokey. Ko te tau whakarea o te pokey hihiri. Ko te tikanga tinana o te tau whakarea o pokey

taupū pokey - he tawhā matua o te inu mahi hau ranei. I roto i ngā tinana, kia tautuhia te pokey rite te waku ā-meinga e te motini o te matūriki whakatu te papatipu o te wai (haurehu waihā) reo, ranei, atu noa, te resistance kaupapa.

He aha te mea te pokey

He faaotiraa wheako hōhonu pokey ohie: wā kotahi ringihia te mata tahifó maheni ki te nui rite o te wai, me te hinu. Water rere te hinu tere. Ko reira atu inu. Moving hohoro tatau te hinu ārai te waku teitei i waenganui i ona rāpoi ngota (parenga ā - pokey). Ko te kupu, pokey wai inversely hautanga ki tona fluidity.

taupū pokey: te tātai

I roto i te puka māmā o te tukanga o te inu Kaore i roto i te paipa e taea te whakaaro rite flat paparanga whakarara A me B ki te wāhi mata taua S, te tawhiti i waenganui i nei ko te nui o te h.

Ēnei paparanga rua (A me B) neke ki velocities rerekē (V ko V + ΔV). He apa he te tere teitei (V + ΔV), tā te kaupapa o te apa B, neke i te tere pōturi (V). I te wa ano e whangai ana i te apa B ki pōturi iho te auau o te A. papanga te tikanga tinana o te whakarea pokey ko e te waku o te rāpoi ngota e whakatu te ātete rere o te paparanga hanga he ope e Isaak Nyuton whakaahuatia e te tātai e whai ake nei:

F = μ × S × (ΔV / h)

konei:

• ΔV - rerekētanga i waenganui i te tere o te kaupapa o paparanga rere inu;
• h - tawhiti i waenganui i nga paparanga awa wai;
• S - horahanga mata o te apa rere inu;
• μ (mu) - take i runga i te āhua āhuatanga o te wai, ka karanga pūmau pokey hihiri.

I roto i te SI wae tātai ko e whai ake:

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

Hea F - te kaha o te mahara (taimaha) waeine o te rōrahi inu waipēhi.

uara o te pokey

I roto i te nuinga o te wā, te tau whakarea o pokey hihiri whanganga te i roto i centipoises (CP) i roto i runga i te cgs pūnaha (henemita, karamu, tuarua). I roto i te mahi, e pā ana te pokey o te ōwehenga papatipu wai te ki tona rōrahi, i.e. wai kiato:

ρ = m / V

konei:

• ρ - kiato o te wai;
• m - papatipu o te wai;
• V - rōrahi o te wai.

huaina te ōwehenga i waenganui i te pokey hihiri (μ) me te mātotoru (ρ) ko te pokey ν kinematic (ν - Kariki - nu):

ν = μ / ρ = [m ² / s]

Ratau, he rerekē ngā tikanga mō te whakatau i te tau whakarea pokey. Hei tauira, te pokey kinematic te whanganga tonu i roto i runga i te pūnaha GHS i roto i centistokes (Cst) me te rahinga submultiple - Stokes (St):

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

Whakatau i o te pokey o te wai

whakaritea pokey tau whakarea o te wai e ine te wā rere inu i roto i te ngongo weu tukuoro. tukuoro tēnei pūrere te whakamahi i te pokey wai paerewa mohiotia. Hei whakatau i pokey kinematic, whanganga i te mm ² / s, te wa rere inu, whanganga i roto i hēkona, e whakanuia e te uara tamau.

Ka rite ki te whakamahia he kōwae whakarite ko te pokey o te wai māturu, tona uara ko tata tonu noa, no te nga huringa pāmahana. Pokey - he ōwehenga o te wa i roto i hēkona hiahiatia e te rōrahi pūmau o te wai māturu ki te paunga o te poka tukuoro te, ki te uara taua mo te wai whakamātautau.

viscometers

whanganga pokey te i roto i nga nekehanga Engler (° E) Saybolt Universal Hēkona ( "sus) ranei nga nekehanga Redwood (° RJ) i runga i te momo o te rheometer rānei. toru momo o viscometers rerekē anake i roto i te nui o rerengia reo wai.

Viscometer whanganga te pokey i roto i wae Pākehā Engler nekehanga (° E), tatau ia 200 cm ³ o rerengia reo wai. Viscometer whanganga te pokey i roto i Hēkona Saybolt Universal ( "sus ranei" SSU), whakamahia i roto i te United States, kei roto 60 cm ³ o whakamātautau wai. I roto i Ingarangi, te wahi e whakamahia nekehanga Redwood (° RJ), whakahaere viscometer whanganga te pokey o 50 cm ³ o te wai. Hei tauira, ki te 200 cm ³ i te hinu rere i tekau nga wa pōturi atu te nui ano o te wai, te pokey ko 10 ° Engler E.

Mai te pāmahana Ko te take matua i roto i te huri i te ōwehenga pokey, te tikanga e nga inenga kawea i roto i te tīmatanga i te pāmahana taimau o te 20 ° C, me te ka i ona uara teitei. Te hua, ko te kupu, e whakahuatia mā te tāpiri i te pāmahana e tika ana, hei tauira 10 ° E / 50 ° C ranei 2.8 ° E / 90 ° C. pokey wai i 20 ° C ki runga ake i tona pokey i pāmahana teitei. hinu waipēhi i te pokey i te pāmahana tēnā e whai ake nei:

190 Cst i 20 ° C = 45.4 Cst i 50 ° C = 11.3 Cst i 100 ° C.

uara translation

Whakatau i o pokey puta i roto i ngā pūnaha rerekē (American, Ingarangi, GHS) me e maha reira hiahiatia ki te iriti raraunga i tetahi pūnaha ruri ki tetahi atu. Ki te tahuri nga uara o pokey o te inu whakahuatia i roto i nga nekehanga e Engler i centistokes (mm ² / s) te whakamahi i te ture tëtehi e whai ake nei:

ν (te CT) = 7,6 × ° E × (1-1 / ° E3)

Hei tauira:

• 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.

I roto i te tikanga ki te hohoro te whakatau i te pokey paerewa o te ture waipēhi taea te māmā hinu e whai ake:

ν (te CT) = 7,6 × ° E (mm ² / s)

He pokey kinematic ν i roto i mm ² / s Cst ranei, e taea te tahuri te reira ki te pokey whakarea hihiri μ, te whakamahi i te hononga e whai ake nei:

μ = ν × ρ

Tauira. Whakarāpopoto ngā tātai translation Engler nekehanga (° E) centistokes (Cst) me centipoises (CPS), amo e hinu waipēhi ki te kiato ρ = 910 kg / m ³ He he pokey kinematic o 12 ° E, i roto i ngā wae o centistokes:

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

Mai 1sSt = 10 ^-6 m ² / s me 1br = N × 10 ^-3 s / m ^2, katahi ka waiho i te pokey hihiri rite ki:

μ = ν × ρ = 90.3 × 10 ^-6 · 910 = 0.082 × N s / m ² = 82 CPS.

Pokey tau whakarea o te hau

Kei te whakaritea te reira e te hanganga (matū, pūkaha) hau ki te pāmahana me te pēhanga tono i roto i te tātai hau-hihiri e pā ana ki te kaupapa hau. I roto i te mahi, tangohia te pokey o te hau e ki pūkete i roto i te whanaketanga hoahoa o mara hau, te wahi whakahaere te tātaitanga kei te huringa tau whakarea i runga i te huringa hau hanganga (rawa nui mo putunga hau condensate) rānei, pāmahana me te pēhanga.

tātai tatou i te tau whakarea o pokey o rangi. ka kia rite ki te hunga whakaahuatia ana i runga i nga rerenga wai e rua nga tukanga. Kī whakarara neke e rua hau awa U1 me U2, engari i reiti rerekē. I waenganui i nga paparanga o te iakawe ka puta (interpenetration) rāpoi ngota. Ka rite ki te hua, ka iti haere torohaki rere o te hau tere pokarekarenga me te tīmatanga neke āta - whakatere.

Ko te tau whakarea o te pokey o rangi, kia rite ki te ture a Newton, whakahuatia e te tātai e whai ake nei:

F = -h × (du / DZ) × S

konei:

• du / DZ ko te rōnaki tere;
• S - rohe o kaha pānga;
• h Factor - te pokey hihiri.

taupū pokey

Index pokey (VI) - he tawhā tiraa i te huringa i roto i te pokey me te pāmahana. Ko te ine, ko te he hononga fakafalala tauanga, i roto i tenei take i te uara e rua i ai haere tahi te huringa pāmahana e rerekētanga nahanaha o pokey. Ko te teitei te taupū pokey, te iti te huringa i waenganui i nga uara e rua, i.e. te pokey o te inu mahi ko atu kainga ki te pāmahana.

Ko te pokey o te hinu

I nga turanga o te hou taupū hinu pokey o iti iho i te 95-100 wae. Na taea te whakamahi i roto i te mīhini waipēhi me te taputapu feunga fluids pūmau e te rāhui rerekētanga whānui i roto i te pokey i raro i ngā āhuatanga o pāmahana tino.

Ka taea te tonu "pai" tau whakarea o pokey i te whakauru i te tāpiritanga hinu motuhake (waerau) whiwhi e te Māturu o te hinu. whakanui i ratou i te hinu pokey taupū e whāiti huringa i roto i te āhuatanga o te whānuitanga whakaaetia. I roto i te mahi i te whakataki o te nui e tika ana o tāpiritanga taea te hinu turanga pokey taupū iti kia whakaarahia ki te 100-105 wae. Heoi, ko ranunga kupu whiwhi impairs ona āhuatanga i raro i te pēhanga teitei, me te kawenga wera, reira whakaiti te whai huatanga o te tāpiri.

I roto i te mana me te whakamahi iahiko fluids waipēhi kaha ki te taupū pokey o 100 wae. Fluids kei roto tāpiritanga e whakanui i te taupū pokey, e whakamahia i roto i iahiko mana waipēhi me ētahi atu pūnaha whakahaere i roto i te whānuitanga o te pēhanga iti / reo, i roto i te iti huringa ngā pāmahana ki ngā turuturu iti me te batchwise. Ka rite ki nga piki pēhanga me nga piki pokey, engari puta te tukanga i tenge i runga 30.0 MPa (300 pae). I roto i te mahi, kei te maha mahue tenei take.

Inenga me te indexation

I roto i runga ki te paerewa ISO ao, ua faaite te pokey o te wai (me ētahi atu wai) Kei roto i centistokes: Cst (mm ² / s). kia whakamana ngä inenga o tukanga pokey hinu i pāmahana i waenganui i te 0 ° C, 40 ° C, me te 100 ° C. I roto i tetahi take, i roto i te waehere tohu hinu pokey kia tohua i whika 40 ° C. Atu hoatu pokey te i 50 ° C. Tohu, tino maha whakamahia i roto i Hydraulics engineering, ngā i ISO VG 22 ki ISO VG 68.

Waipēhi hinu VG 22, VG 32, VG 46, VG 68, VG 100 i te pāmahana o te 40 ° C i viscosities e ōrite ana ki to ratou tapanga: 22, 32, 46, 68 me te 100 Cst. Ko te pokey kinematic tino arotau o te inu mahi i roto i ngā pūnaha waipēhi takoto i roto i te whānuitanga o 16 ki te 36 Cst.

kua whakapumautia awhe o viscosities i pāmahana motuhake me waehere tika whakaritea ki a ratou - American Society o Automotive Engineers (SAE Society o Automotive Engineers). Ko te tokomaha e whai ake nei i te W reta, - he hihiri μ pokey whakarea tino i 0 ° F (-17.7 ° C), me ν te pokey kinematic whakaritea i 212 ° F (100 ° C). Tenei whakaaro fakahokohoko hinu multigrade whakamahia i roto i te ahumahi automotive (tuku, motor, a na i runga i. D.).

Ko te pānga o te pokey i runga i te mahi waipēhi

e kore he moni pūtaiao, me te mātauranga anake faaotiraa o te pokey o te inu, engari te maua e hoki auraa mahi nui. Ko te fluids waipēhi whakawhiti kore anake pūngao i te papu ki te nekeneke waipēhi, engari ano ki te whakahinuhinu mawehe atu te wahi me wāhanga katoa i te wera hanga takirua waku. E kore Tuamata ki te mahi o te pokey inu mahi tino taea whakapōrearea i te whai huatanga o te Hydraulics.

Ko te pokey tiketike o te inu mahi (hinu kiato tiketike rawa) arata'i ki te pānga kino e whai ake nei:

• Ko te ātete rere nui haere o te inu waipēhi ai te maturuturunga iho pēhanga nui i roto i te pūnaha waipēhi.
• Whakapōturinga mana o te tere, e tuhi pūkaha o te actuators.
• Whanaketanga o papu cavitation.
• Kore ranei te tino iti tuku rangi i te tank hinu waipēhi.
• He mate kitea o te kaha (whakaiti tōtika) o Hydraulics tika ki te utu nui o te pūngao mō te upooti'araa i te waku ā o te inu.
• te taipana nui ake o te koroke pirimia o te mīhini meinga e te whakanui ake i te kawenga i runga i te papu.
• Ko te pāmahana ara o te inu waipēhi i hanga e nui haere te waku.

Ko te kupu, ko te tikanga tinana o te tau whakarea o pokey kei roto i tona pānga (pai kino ranei) i runga i te wāhanga me te tikanga mo waka, mīhini me te taputapu.

Mate o te mana waipēhi

Ko te pokey iti o te inu mahi (hinu kiato iti) ai te pānga kino e whai ake nei:

• Hinga kakama rōrahi o te papua rite ki te hua o te whakanui ake i leakage ā-.
• Ko te hua i roto i te leakage ā o wāhanga waipēhi i roto i te pūnaha waipēhi katoa - e papua, vaolo, piha, motors waipēhi.
• Nui ake kākahu o ngā waeine kutētē, me te papua jamming tika ki iti pokey inu waipēhi tika mō te whakahinuhinu o ngā wāhanga komukumuku.

compressibility

kōpeke Tetahi wai i raro i te pēhanga te. Ki te whakaute ki hinu, coolants me lubricants whakamahia i roto i Hydraulics engineering aunoa, empirically kitea taua mea e he inversely hautanga ki te papatipu inu i runga i tona rōrahi te tukanga kōpeketanga. Ko te nui o te mema kōpeketanga ki hinu kohuke e tino raro hoki te wai, me te nui raro mo nga fluids waihanga.

I roto i te pēhanga iti waipēhi inu compressibility pānga iti ohie i runga i te whakaiti i te rōrahi tuatahi. Ko mīhini kaha ki tiketike-pēhanga ipurau puku waipēhi me te nui, faaite tenei tukanga iho faahitihia. I roto i te waipēhi hinu kohuke i te pēhanga o 10.0 MPa (100 pae), te rōrahi heke i 0.7%. I roto i tenei take, he huringa i roto i te rōrahi kōpeketanga ki te whānuitanga iti whakaawe i te pokey kinematic me momo o te hinu.

mutunga

Whakatau i o pokey taea ki te matapae i te mahi o te taputapu me te mīhini i raro i ngā tikanga, tango ki huringa pūkete i roto i inu hau ranei hanganga, te pēhanga, te pāmahana. Hoki, mana o te tohu e hāngai ana ki te hinu, me te hau ahumahi, taputapu, me te tahi atu ahumahi.