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粘度 |
发布时间:2016-07-08 11:42:22 |
粘度
定义
由于液体的粘性将此力层层传递,各层液体也相应运动,形成一速度梯度du/dr,称剪切速率,以r′表示。F/A称为剪切应力,以τ表示。剪切速率与剪切应力间具有如下关系: NIUDUNLIUTI:FUHENIUDUNGONGSHIDELIUTI。 ZHANDUZHIYUWENDUYOUGUAN,YUQIEBIANSULVWUGUAN, τYUDWEIZHENGBIGUANXI。 FEINIUDUNLIUTI:BUFUHENIUDUNGONGSHIτ/D=f(D),YIηaBIAOSHIYIDING(τ/D)XIADEZHANDU,CHENGBIAOGUANZHANDU。 ZHANDUSUIWENDUDEBUTONGERYOUXIANZHUBIANHUA,DANTONGCHANGSUIYALIDEBUTONGFASHENGDEBIANHUAJIAOXIAO。YETIZHANDUSUIZHEWENDUSHENGGAOERJIANXIAO,QITIZHANDUZESUIWENDUSHENGGAOERZENGDA。DUIYURONGYE,CHANGYONGXIANGDUIZHANDUμrBIAOSHIRONGYEZHANDUμHERONGJIZHANDUμZHIBI,JI: BUTONGLIUTIDEZHANDUCHABIEHENDA。ZAIYAQIANGWEI101.325kPa、WENDUWEI20℃DETIAOJIANXIA,KONGQI、SHUIHEGANYOUDEDONGLIZHANDUHEYUNDONGZHANDUWEI: KONGQI μ=17.9×10^-6Pa·s, v=14.8×10^-6m²/s SHUI μ=1.01×10^-3Pa·s, v=1.01×10^-6m²/s GANYOU μ=1.499Pa·s, v=1.19×10^-3m²/s YOUYUZHANDUDEZUOYONG,SHIWUTIZAILIUTIZHONGYUNDONGSHISHOUDAOMOCAZULIHEYACHAZULI,ZAOCHENGJIXIENENGDESUNHAO(JIANLIUDONGZULI)。 GEZHONGLIUTIDEZHANDUSHUJU,ZHUYAOYOUSHIYANCEDE。CHANGYONGDEZHANDUJIYOUMAOXIGUANSHI、LUOQIUSHI、ZHUIBANSHI、ZHUANTONGSHIDENG。ZAIGONGYESHANGYOUSHIYONGTEDINGXINGSHIDEZHANDUJILAICEDINGTEDINGDETIAOJIANZHANDU。RULIANYOUGONGYEZHONGCHANGYONGENSHIZHANDU(HUOENGELAZHANDU)ZUOWEISHIYOUCHANPINDEYIGEZHIBIAO,TABIAOSHIMOUYIWENDUXIA200cm3YOUPINYUTONGTIJI20℃CHUNSHUI,CONGENSHIZHANDUJIZHONGLIUCHUSUOXUSHIJIANZHIBI。ENSHIZHANDUYUDONGLIZHANDUDEGUANXIKEANJINGYANGONGSHIHUANSUAN。YOURUXIANGJIAOGONGYEZHONGCHANGYONGMENNIZHANDUWEIHENGLIANGXIANGJIAOPINGJUNFENZILIANGJIKESUXINGDEYIGEZHIBIAO。 ZAIQUESHAOZHANDUSHIYANSHUJUSHI,KEANLILUNGONGSHIHUOJINGYANGONGSHIGUSUANZHANDU。DUIYUYALIBUTAIGAODEQITI,GUSUANJIEGUOJIAOZHUN;DUIYUYETIZEJIAOCHA。DUIFEIJUNXIANGLIUTI(RUDINONGDUXUANFUYE)DEZHANDU,KEYIYONGAIYINSITANGONGSHIGUSUAN: SHIZHONGμmWEIXUANFUYEDEZHANDU;μWEILIANXUXIANGYETIDEZHANDU;φWEIXUANFUYEZHONGFENSANXIANGDETIJIFENSHU;μdWEIFENSANXIANGZHANDU。DANGFENSANXIANGWEIGUTIKELISHI,μd→∞,;DANGFENSANXIANGWEIQIPAOSHI,μd→0,μm=(1+φ)μ。 DANWEIHUANSUANBIAOBIANJI DONGLIZHANDUDANWEIHUANSUAN 1BO (1P)=100LIBO(100cP) 1LIBO(1cP)=1HAOPASIKA·MIAO (1mPa·s) 1HAOPASIKA·MIAO (1mPa·s)=1000WEI PASIKA·MIAO(1000μ Pa.s) DONGLIZHANDUYUYUNDONGZHANDUDEHUANSUAN η=ν·ρ GONGSHIZHONGη--- SHIYANGDONGLIZHANDU(mPa·s) ν--- SHIYANGYUNDONGZHANDU(mm²/s) ρ--- YUCELIANGYUNDONGZHANDUXIANGTONGWENDUXIASHIYANGDEMIDU(g/cm³) CEDINGBIANJIDONGLI ηtSHIERYETICENGXIANGJU1cm,QIMIANJIGEWEI1(cm²)XIANGDUIYIDONGSUDUWEI1cm/sSHISUOCHANSHENGDEZULI,DANWEIWEIg/cm·s。1g/cm·s=0.1pa·s。YIBANGONGYESHANGDONGLIZHANDUDANWEIYONGpaLAIBIAOSHI。 YUNDONG ZAIWENDUt (℃)SHI,YUNDONGZHANDUYONGFUHAOγBIAOSHI,ZAIGUOJIDANWEIZHIZHONG,YUNDONGZHANDUDANWEIWEISI,JIMEIMIAOPINGFANGMI(m²/s),SHIJICEDINGZHONGCHANGYONGLISI,(cst)BIAOSHILISIDEDANWEIWEIMEIMIAOPINGFANGHAOMI(JI 1cst=1mm²/s)。YUNDONGZHANDUGUANGFANYONGYUCEDINGPENQIRANLIAOYOU、CHAIYOU、RUNHUAYOUDENGYETISHIYOUCHANPINSHENSESHIYOUCHANPIN、SHIYONGHOUDERUNHUAYOU、YUANYOUDENGDEZHANDU,YUNDONGZHANDUDECEDINGCAIYONGNILIUFA。 TIAOJIANZHICAIYONGBUTONGDETEDINGZHANDUJISUOCEDEDEYITIAOJIANDANWEIBIAOSHIDEZHANDU,GEGUOTONGCHANGYONGDETIAOJIANZHANDUYOUYIXIASANZHONG: ① 恩氏粘度又叫恩格勒(Engler)粘度。是一定量的试样,在规定温度(如:50℃、 80℃、100℃)下,从恩氏粘度计流出200毫升试样所需的时间与蒸馏水在20℃流出相同体积所需要的时间(秒)之比。温度tº时,恩氏粘度用符号Et表示,恩氏粘度的单位为条件度。 ② 赛氏粘度,即赛波特(sagbolt)粘度。是一定量的试样,在规定温度(如 100ºF、F210ºF或122ºF等)下从赛氏粘度计流出200毫升所需的秒数,以“秒”单位。赛氏粘度又分为赛氏通用粘度和赛氏重油粘度(或赛氏弗罗(Furol)粘度)两种。
③ 雷氏粘度即雷德乌德(Redwood)粘度。是一定量的试样,在规定温度下,从雷氏度计流出50毫升所需的秒数,以“秒”为单位。雷氏粘度又分为雷氏1号(Rt表示)和雷氏2号(用RAt表示)两种。 ZHANDUDECEDINGYOUXUDUOFANGFA,RUZHUANTONGFA、LUOQIUFA、ZUNIZHENDONGFA、BEISHIZHANDUJIFA、MAOXIGUANFADENGDENG。DUIYUZHANDUJIAOXIAODELIUTI,RUSHUI、YICHUN、SILVHUATANDENG,CHANGYONGMAOXIGUANZHANDUJICELIANG;ERDUIZHANDUJIAODALIUTI,RUBIMAYOU、BIANYAQIYOU、JIYOU、GANYOUDENGTOUMING(HUOBANTOUMING)YETI,CHANGYONGLUOQIUFACEDING;DUIYUZHANDUWEI0.1~100Pa?sFANWEIDEYETI,YEKEYONGZHUANTONGFAJINXINGCEDING。
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