Iska

Iska, ko iskar iska, shine motsi na iska. Iska tana nunawa a cikin hanyar ruwa, ma'ana barbashi suna gudana daga yankunan da ke da matsin lamba zuwa waɗanda matsin lamba ya fi ƙasa. Matsin iska na sararin samaniya yana da alaƙa kai tsaye da tsawo, zafin jiki, da abun da ke ciki.

A cikin injiniya, iska mai gudana shine ma'auni na adadin iska a kowane ɗayan lokaci wanda ke gudana ta hanyar takamaiman na'urar. Ana iya bayyana shi azaman ƙimar gudana (ƙarar iska a kowane lokaci) ko ƙimar gudummawa (ƙarar iskar iska a kowane lokacin). Abin da ke danganta nau'ikan bayanin guda biyu shine yawan iska, wanda shine aikin matsin lamba da zafin jiki ta hanyar dokar gas mai kyau. Ana iya haifar da kwararar iska ta hanyar inji (kamar ta hanyar aiki da fan na lantarki ko na hannu) ko kuma yana iya faruwa ba tare da la'akari ba, a matsayin aikin bambancin matsin lamba da ke cikin muhalli.

 Nau'o'in iska 
Kamar kowane ruwa, iska na iya nuna alamun laminar da turbulent. Laminar yana faruwa ne lokacin da iska za ta iya gudana a hankali, kuma tana nuna Bayanan saurin parabolic; kwararar turbulent tana faruwa ne lokacin cewa akwai rashin daidaituwa (kamar rushewa a farfajiyar da ruwa ke gudana), wanda ke canza jagorancin motsi. Gudun turbulent yana nuna bayanin saurin gudu. Bayanan saurin motsi na ruwa suna bayyana rarraba sararin samaniya na saurin saurin sautin a fadin wani sashi na giciye. Girman da siffar tsarin lissafi wanda ruwa ke tafiya ta hanyar, kaddarorin ruwa (kamar viscosity), rushewar jiki ga kwarara, da kayan aikin injiniya (misali famfo) waɗanda ke ƙara makamashi ga kwarara sune abubuwan da ke ƙayyade yadda bayanin saurin yake. Gabaɗaya, a cikin kwararru, saurin saurin sautin ya fi girma a tsakiyar bayanin martaba saboda tasirin friction daga kayan bututu, bututu, ko bangon tashar a kan yadudduka na ruwa. A cikin kwararar yanayi na tropospheric, saurin yana ƙaruwa tare da tsawo daga matakin ƙasa saboda rikici daga cikas kamar itatuwa da tuddai suna rage iska kusa da farfajiya. Matsayin rikice-rikice an ƙayyade shi ta hanyar siginar da ake kira "tsawon tsayi. " Streamlines suna haɗa saurin kuma suna da alaƙa da jagorancin saurin sauri da yawa. Za a iya karkata su kuma ba koyaushe suna bin siffar akwati ba. Bugu da ƙari, suna wanzu ne kawai a cikin kwarara mai ɗorewa, watau kwarara wanda saurin saurin sa ba ya canzawa a tsawon lokaci. A cikin kwararar laminar, duk barbashi na ruwa suna tafiya a layi daya wanda ke haifar da layi daya. A cikin kwararar rikice-rikice, barbashi suna tafiya a cikin bazuwar da kuma rikice-rikicen da ke haifar da karkata, juyawa, kuma sau da yawa suna haɗuwa.

Lambar Reynolds, rabo da ke nuna alaƙar da ke tsakanin dakarun viscous da inertial a cikin ruwa, ana iya amfani da su don hango hasashen canjin daga laminar zuwa kwararar turbulent. Gudun Laminar yana faruwa a ƙananan lambobin Reynold inda karfi mai laushi ya mamaye, kuma gudana mai rikitarwa yana faruwa a manyan lambobin Reynol inda karfi mai ƙarfi ya mamaye. Yankin lambar Reynold wanda ke bayyana kowane nau'in kwarara ya dogara da ko iska tana motsawa ta hanyar bututu, bututun ruwa mai faɗi, tashar buɗewa, ko kusa da airfoils. Lambar Reynold na iya nuna wani abu (alal misali, wani abu a ƙarƙashin tasirin daidaitawa) yana motsawa ta hanyar ruwa. Ana iya amfani da wannan lambar da ra'ayoyin da suka danganci don nazarin kwarara a cikin tsarin dukkan ma'auni. Gudun canji shine cakuda turbulence a tsakiyar bayanin saurin da laminar a kusa da gefuna. Kowane ɗayan waɗannan kwararru uku suna da hanyoyi daban-daban na asarar makamashi wanda ke haifar da halaye daban-daban. A sakamakon haka, ana amfani da ma'auni daban-daban don yin hasashen da kuma ƙididdige halayyar kowane nau'in kwarara.

Saurin da ruwa ke wucewa ta hanyar wani abu ya bambanta da nesa daga farfajiyar abu. Yankin da ke kewaye da wani abu inda saurin iska ke kusa da sifili an san shi da Layer na iyaka. A nan ne rikice-rikice na ƙasa ya fi shafar gudana; rashin daidaito a saman na iya shafar kauri na iyaka, sabili da haka yana aiki don rushe gudana.

 Rukunin 
Kayan aiki na yau da kullun don bayyana iska sune: 

 Ta hanyar girma 

 m3/min (cubic mita a minti daya) 
 m3/h (cubic mita a kowace awa) 
 ft3/h (cubic feet per hour) 
 ft3/min (cubic feet per minute, a.k.a. CFM) 
 l/s (lita a kowace dakika) 

 Ta hanyar taro 

 kg/s (kilo a kowace dakika) 

Hakanan ana iya bayyana iska ta hanyar canje-canjin iska a kowace awa (ACH), yana nuna cikakken maye gurbin girman iska da ke cika sararin da ake tambaya. Ana amfani da wannan rukunin akai-akai a fagen kimiyyar gini, tare da ƙimar ACH mafi girma wanda ya dace da ambulaf ɗin leakier waɗanda ke da alaƙa da tsofaffin gine-gine waɗanda ba su da hatimi sosai.

 Aunawa 
Kayan aiki wanda ke auna iska ana kiransa mita iska. Ana kuma amfani da Anemometers don auna saurin iska da iska ta cikin gida.

Akwai nau'o'i daban-daban, gami da Annemometers masu bincike madaidaiciya, waɗanda aka tsara don auna saurin iska, matsin lamba, zafin jiki, da danshi; anemometers mai juyawa, wanda aka yi amfani da shi don auna gudun iska da gudana; da anemometters masu zafi.

Anemometers na iya amfani da ultrasound ko waya mai tsayayya don auna canja wurin makamashi tsakanin na'urar auna da barbashi masu wucewa. Misali, ana amfani da anemometer mai zafi, yana yin rajista yana raguwa a cikin zafin waya, wanda za'a iya fassara shi zuwa saurin iska ta hanyar nazarin canjin canji. Convective sanyaya aiki ne na iska, kuma juriya ta lantarki na mafi yawan karafa ya dogara da zafin jiki na ƙarfe, wanda sanyaya ta convective ta shafa. Injiniyoyi sun yi amfani da waɗannan abubuwan jiki a cikin ƙira da amfani da anemometers na waya mai zafi. Wasu kayan aiki suna iya lissafin iskar iska, zafin fitila mai laushi, raɓa, da turbulence.

 Manazarta 
Rukuni:Shafuka masu fassarorin da ba'a duba ba