µÚÒ»ÕÂ
1-1 0.898 kg?m?3 1-2 633mmHg 1-3 ?z?1.78m 1-4 H =8.53m 1-5 ?pAB?1720mmHg 1-6 318.2Pa ; Îó²î11.2¨G
1-7 ÔÚ´ó¹ÜÖУºm1?4.575kg?s?1,u1?0.689m?s?1,G1?1261kg?m?2?s?1 ÔÚС¹ÜÖУº m2?4.575kg?s?1,u2?1.274m?s?1,G2?2331kg?m?2?s?1 1-8 6.68m
½â È¡¸ßλ²ÛÒºÃæÎª1-1£¬ÅçÍ·Èë¿Ú´¦½ØÃæÎª2-2Ãæ¡£¸ù¾Ý»úеÄܺáËã·½³Ì£¬ÓÐ gz1 + u12/2 + p1/¦Ñ=gz2+u22/2+p2/¦Ñ+wf
ʽÖУ¬u1 =0£¬p2 =0£¬u2 =2.2 m .s-1£¬p2 = 40*103 Pa£¬wf =25J.kg-1£¬´úÈëÉÏʽµÃ ¦¤z =u22/2g+p2¨Cp1/¦Ñg+wf/g
=2.22/2*9.81+40*103-0/1050*9.81+25/9.81 =6.68m 1-9 43.2kW
½â ¶ÔÈÝÆ÷AÒºÃæ1-1ÖÁËþÄڹܳö¿Ú½ØÃæ2-2´¦ÁлúеÄܺâËãʽ
22upup112 g z1 + + +we=gz2++2+wf 2?2?ÒÑÖª z1=2.1m£¬z2 =36m , u1 =0, u2µÄËÙ¶ÈÍ·ÒѼÆÈëËðʧÖУ¬p1=0, p2=2.16*106 Pa,
-1
wf =122J.kg, ½«ÕâЩÊý¾Ý´úÈëÉÏʽµÃ
we = (z2-z1)g+p2/¦Ñ+ wf
=(36-2.1)*9.81+2.16*106/890+122
=333+2417+122=2882J.kg-1
±ÃµÄÓÐЧ¹¦ÂÊNe=wems=2882*15/1000=43.2kw 1-10 (1) 4.36Kw£»(2) 0.227MPa
1-11 B´¦²âѹ¹Üˮλ¸ß£¬Ë®Î»Ïà²î172mm 1-12 H=5.4m£¬pa=36.2kPa
½â ÔÚ½ØÃæ1-1ºÍ2-2¼äÁв®Å¬Àû·½³Ì£¬µÃ
22u1p1u2p g z1 + + =gz2++2
2?2?22p?pu?u1221¼´ (a) ?g(z1?z2)??2 z1¡¢z2 ¿É´ÓÈÎÒ»¸ö»ù×¼ÃæËãÆð£¨ÏÂÃæ½«µÖÏû£©£¬È¡µÈÑ¹Ãæa-a £¬Óɾ²Á¦Ñ§·½³ÌµÃ
p1+¦Ñg(z1-z2)+ ¦ÑgR=p2+?HggR ¼´
P1?P2??Hg???g(z1?z2)??gR (b)
?ÓÉʽ(a)ºÍʽ(b)¿ÉµÃ
2u2?u12?Hg??13600?1000 ??gR??9.81?80?10?3?9.89J.kg?1 £¨c£©
2?1000ÓÖÓÉÁ¬ÐøÐÔ·½³ÌÖª u2= u1(d1/d2)2= u1? (125/100)2=1.252 u1 ´úÈëʽ£¨c£©µÃ £¨1.252 u1£©2 - u12=2?9.89 u1=3.70m.s-1 ÓÚÊÇ u2=1.25? 3.70=5.78
2
2
m.s?1
2
?1m.sÅç×ì´¦ u3= u1£¨d1/d3£©=3.70?125/75£©=10.28
ÔÚ½ØÃæ0-0Óë3-3¼äÁлúеÄܺâËãʽ
H= u32/2g=10.282/2?9.81=5.39m ÔÚ½ØÃæ0-0Óëa-a¼äÁв®Å¬Àû·½³Ì H=u22/2g+ pA/¦Ñg
2u2¹ÊÓÐ pA=¦ÑgH-?¦Ñ=1000*9.81*5.39-5.782/2 *1000 2 =36.2? 103Pa 1-13 d¡Ü39mm
1-14 Ë®0.0326m¡¤s-1£¬¿ÕÆø2.21m¡¤s-1 1-15 (1) 38.3kPa£» (2) 42.3% 1-16 ²»Ã¬¶Ü 1-17 ´ð°¸ÂÔ
1-18 (1) µÚÒ»ÖÖ·½°¸µÄÉ豸·ÑÓÃÊǵڶþÖÖµÄ1.24±¶£»
(2) ²ãÁ÷ʱ£¬µÚÒ»ÖÖ·½°¸ËùÐ蹦ÂÊÊǵڶþÖÖµÄ2±¶£»ÍÄÁ÷ʱ£¬µÚÒ»ÖÖ·½°¸ËùÐ蹦ÂÊÊǵڶþÖÖµÄ1.54±¶ 1-19 0.37kW 1-20 2.08kW
1-21 0.197m£»²»ÄÜʹÓà ½â £¨1£©ÇóÖýÌú¹ÜÖ±¾¶
?1kg.m È¡10¡æšìµÄÃܶȦÑ=1000,²é¸½Â¼ÎåÖª?=1.305 ? 10?3Pa.s
È¡ºþÃæÎª1-1Ãæ£¬³ØÃæÎª2-2Ãæ£¬ÔÚÃæ1-1ÓëÃæ2-2¼äÁлúеÄܺâËã·½³Ì
22u2?u1p?p2 g?z??1?wf
2?
Òòu1¡¢u2¡¢p1¡¢p2½ÔΪÁ㣬¹Êg?z= wf £¨a£©
2lu8??10003002??()?5.629ʽÖУ¬?z?45m , wf??´úÈëʽ£¨a£©µÃ d2?2d23600d5? 9.81 ? 45=5.6295
d d5=0.01275? (b)
?µÄ·¶Î§Ô¼Îª0.02-0.03£¬ÏÖÖªVSºÜ´ó£¬ReÒ²´ó£¬¹Ê?µÄ³õÖµ¿ÉȡСЩ¡£Éè?=0.02£¬´úÈëʽ£¨b£©½âµÃ
d =(0.01275?0.02)0.2=0.191m ¼ìÑé?Öµ£º
ÐÂÖýÌú¹ÜµÄ¾ø¶Ô´Ö‘V¶È Re=
?=0.03mm£¬Ôò
?/d=0.3/191=0.00157
0.231000?300/3600?Vs?ud5
=4.2610 ????3?(?/4)d?(?/4)?0.191?1.305?100.23?68???=0.100?????dRe?68??=0.100?0.00157??4.26?105??=0.02316
¿É¼û³õÉèµÄ?ƫС£¬¹ÊÐè½øÐеü´ú¼ÆËã¡£ÔÙÉè?=0.02316£¬´úÈ루b£©µÃ d=0.1968m
?0.3ÓÚÊÇ ?=0.00152
d196.8 Re=
1000?300/3600?4.13?105 ?5(?/4)?0.1968?1.305?1068?????0.100????dRe???0.23?0.100?(0.00152?680.23)?0.02302 54.13?10??Óë???Êý¾ÝÏà½ü£¬¹Êµü´úÒ»´Î¼´¿É½áÊø¡£¶ÔdÈ¡ÕûΪ0.2m¼´200mm (2) ?=1mmʱ£¬ºËËãÊÇ·ñÄÜÂú×ãÒýË®Á¿Îª300m3?h?1µÄÒªÇó
?=1/200=0.005 d1000?300/36005?4.067?10Re= ?3(?/4)?0.2?1.305?10
??0.100?(0.005?´úÈëʽ£¨b£©µÃ d=0.207m
68)0.23?0.0298 54.067?10¿É¼û£¬d=0.2mµÄ¹Ü×Ó²»ÄÜÂú×ãÔÚ?=1mmʱÒýË®Á¿²»±äµÄÒªÇó£¬Îª´ËÓ¦½«¹Ü¾¶È¡Îª210mm²ÅÐС£ 1-22 66.5L¡¤min-1
1-23 (1) 0.54m¡¤s-1 £»(2) R1=10.65cm£¬R2=17.65cm 1-24 ÊäËÍÄÜÁ¦±äС£¬·§ÃÅǰѹÁ¦±ä´ó
1-25 u1=7.25 m¡¤s-1£¬u2=10.52 m¡¤s-1£»·ç»ú³ö¿ÚѹÁ¦p=65.2mmH2O ½â £¨1£©Çóu1,u2
¸ù¾Ý²¢Áª¹Ü·µÄÌØµã£¬Öªwf1?wf2
2l1u12l2u2 ¼´ ?1 ??2d12d22ÏÖl1?2l2,d1?d2£¬¹ÊÉÏʽ»¯¼òΪ
2 2?1u12??2u2 £¨a£©
ÓÖ¸ù¾ÝÖÊÁ¿ºâËã¿ÉµÃ
2(?/4)d12u1?(?/4)d2u2?2(?/4)du2 u1d21?ud2?2ud22
0.152u1?0.152u2?10?0.2u1?u2?17.78 £¨b£©
ÓÉ£¨a£©£¨b£©Çóu1£¬u2ÐèÊԲ ³õÉè?1??2£¬ÔòÓÉ£¨a£©µÃ u2?2u1 ´úÈ루b£©µÃ
u1=7.36 m?s?1
ÓÚÊÇ u2=17.78- u1=17.78-7.36=10.42m?s?1 ¼ìÑéÒÔÉÏÊýÖµµÄ׼ȷÐÔ£º
²é¸½Â¼ÁùÖª30¡æ¿ÕÆø?=1.165kg..m-3, ??1.86?10?5Pa.s£¬Ôò
Re1?Re2??u1d11.165?7.36?0.154??6.915?10 ?5?1.86?10?u2d21.165?10.42?0.15??9.790?104 ?5?1.86?10?0.05?0.000333d1d2150?680.23680.23?1?0.100(?)?0.100?(0.000333?)?0.0217 4d1Re16.915?10????2?0.100(?d2?680.2368)?0.100?(0.000333?)0.23?0.0205 4Re29.790?10Óë³õÉèÖµÉÔÓÐÆ«²î£¬ÔÙ½«?1=0.0217£¬?2=0.0205µü´úÈ루a£©£¨b£©µÃ u1?7.24m?s?1,u2?10.54m?s?1