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《泵和压缩机》姬忠礼主编习题参考答案第一章离心泵1、解:)(66.1308.98001013332.03001471005.02)(32321221212mmNmNmgvvppZZH2、解:)7596.96(KW7.51368.91000gHQN%77986096.7596ahvmNN%9192.092.077048.0vmh3、解:1))(6.64.420mNPSHhgPPZTSAVAg,而该泵的安装高度为-8m,小于该泵的最大允许安装高度(-6.6m),所以该泵能正常吸入。2)下降1.4m,泵开始汽蚀。3)转速提高2900r/min后,由汽腐蚀相似定律可知:6.1724.422',nnNPSHNPSHTT。所以,泵不能正常吸入。4、解:smSQcs185.31.014.3413600902mgcdlhsSA553.38.92185.31.08.12.21682.322.0222吸mhgcHzSAsSg13.2553.38.92185.32.6222即河水最低液面距泵轴轴心距为2.13米。5、解:由相似公式:''nnQQ→min''21753514505.52mQnQn2'')(nnHH→mnnHH5.139217514506222''3'')(nnNN→KWnnNN65.25217514506.733''6、解:由切割定律,叶轮外径切割后:2'2'DDQQ,,)(22'2'DDHH,)(32'2'DDNNη’=η即:Q’=0.945Q;H’=0.893H;N’=0.844N;η’=η分别求得各参数为:Q’,m3/h014.1828.3647.2756.73H’,m60.7860.3458.1053.6349.16N’,kw——8.4510.9912.26η’033546260绘制曲线(略)。7、解:由单吸多级离心泵的比转数计算公式求得该离心泵的比转数为:1)该泵的比转数为;该泵属于低比转数泵;2)泵在1450r/min下运转时,由相似公式''nnQQ→hmnnQQ3322900145064''2'')(nnHH→mnnHH701450290028022''比转数:(此题不用计算,可直接判断。)8、解:由泵的管路特性方程分别计算出各相应流量下的h值:1)输水时:h=30+0.02Q2Q(L/s)4812162024283236h(m)30.3231.2832.8835.123841.5245.6850.4855.922)输油时:h=30+0.04Q2Q(L/s)4812162024283236h(m)30.6432.5635.7640.244653.0461.3870.9681.84将以上两种h各对应值绘制在图1-77中,两种曲线的交点即为工作点,其对应的纵、横坐标值即为相应的Q和H值。584280360064290065.3)(65.3434/3KHQnns58470360032145065.3)(65.3434/3KHQnns3)增大泵排出管的直径;缩短排出管的长度;9、解:根据泵的安装位置和三个流动阻力损失分别计算得:h1=-5+0.044Q2;h2=30+0.05Q2;h3=35+0.1Q2泵在不同流量时泵和管路特性参数Q,L/s061218243036H,m36.537.53837.53530.524h1,m-5-3.416-1.6649.25620.34434.652.024h2,m3031.837.246.258.87594.8h3,m3538.649.467.492.6125164.6绘制图,由图来确定杨程、流量。(参考教材P46-图1-32)10、解:由能量方程:)(2101955.05.200)3(4521221212mhgvvgppZZH)(68.25236005202108.9850KWgHQN
本文标题:离心泵习题答案
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