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1、第四章4-1解：4Q4?0.004vd0.51?0.1v???0.51m/s，Re???5080322水?6?d3.14?0.1?1.003?10水Re?50803?2000為紊流。水0.51?0.1Re??340?2000，為層流。重油?41.5?104-2解：2AA?0.52m，??2.14m，R??0.243m。?Re?vR?5?10?2?0.243?12114?500??61.003?10?6500??500?1.003?10?6保持層流V???2064?10m/s?0.21cm/smaxR0.2434-3解：vd12?0.45Re???3.4?10?2000為紊流。
2、?5?1.41?10?5?Re1.41?10?2000v?e??0.282m/s對管流而言，此流速是很小的。cd0.14-4解：u?u1hmax?ln，斷面（寬矩形）平均流速vuky*1h?u*h?h?u*y??y?u*v??u?ln?dy?u?lnd???u?，?0?max??0??max??maxh?ky??kh??h?ku*hhhhu?u?ln要u?v則ln?1，得y???0.368hmaxkyye2.7184-5解：101T110?0.5（1）ux??uxdt??uxdt??ux?t/10?0.5T010?0.501?1.88?2.05?2.34?2.3?2.17?1
3、.74?1.62?1.93?1.98?2.19??0.5?10?0.5?2.02m/s101T110?0.5uy??uydt??uydt??uy?t/10?0.5T010?0.5011???0.1?0.06?0.21?0.19?0.12?0.18?0.21?0.06?0.04?0.1?10?0.007m/s?0'2ux（2）（A點(diǎn)在x方向相對紊動(dòng)強(qiáng)度）v26'2uy（A點(diǎn)在y方向相對紊動(dòng)強(qiáng)度）v'u?u?uxxx-0.140.030.320.280.15-0.28-0.4-0.09-0.040.17(m/s)相應(yīng)的'2ux0.01960.00090.10240.07840.0
4、2250.07840.160.00810.00160.028922（m/s）'2'2'2'2220.5008/10uxux將ux相加得：?ux?0.5008(m/s)????0.111(相對紊動(dòng)強(qiáng)度為無2.02vux量綱量)'u?u?uyyy0.093-0.067-0.217-0.1970.1130.1730.203-0.053-0.047-0.107(m/s)'2相應(yīng)的uy0.0086490.0044890.0470890.038810.0127690.0299290.0412090.0028090.0022090.01144922（m/s）'2'2'2'20.019941
5、uxux將uy相加平均得：?uy????0.0677(相對紊動(dòng)強(qiáng)度為無量綱量)2.02vux(3)A點(diǎn)的紊動(dòng)附加切應(yīng)力'''????uu??998.2?yxxy???0.14??0.093???0.03???0.067???0.32???0.217???0.28???0.197???0.15??0.113????0.28??0.173????0.4??0.203????0.09??0.053????0.04???0.047???0.17???0.107??/10??2??998.2?0.02738/10?27.33N/m。2''2??dux??22（4）?uu??l?27.3
6、3??l?0.26?xy??dy??27.33摻長：l??0.6364m??2998.2?0.26du2x??22???l?998.2?0.6364?0.26?105N?s/m(Pa?s)dydu2x??22??l?0.6364?0.26?0.1053m/sdy已知水溫，查得分子粘度?32??1.002?10N?s/m(Pa?s)?62??1.003?10m/s計(jì)算紊動(dòng)動(dòng)力粘性系數(shù)（又叫渦粘度）??105Pa?s計(jì)算得紊動(dòng)運(yùn)動(dòng)粘性系數(shù)（又叫渦運(yùn)動(dòng)粘度）??0.1053(Pa?s)?1055?0.10535兩種相比??1.05?10;??1.05?10?3?6?1.002?10
7、?1.003?10??可見紊動(dòng)粘性遠(yuǎn)大于分子粘度，在均質(zhì)流有???4-6解：27?5vd2?10?4Re?,斷面平均流速v??0.113m/s2?6?3.14?15?104℃時(shí)水的運(yùn)動(dòng)粘度?2?6???1.5722m/s?100.113?0.015Re??1078?2000為層流?61.5722?10222lv64lv6440.113h???????0.0103mfd2gRd2g10780.01519.6e2644v當(dāng)水流從紊流轉(zhuǎn)為層流時(shí)，Re?2000,h???f20000.0152g3這時(shí)流速及流量
