【正文】 區(qū)別？為何它們的交點(diǎn)是工作點(diǎn)？?6．簡述離心式水泵串聯(lián)、并聯(lián)工作的特點(diǎn)。?7．在什么情況下需進(jìn)行泵的調(diào)節(jié)？其調(diào)節(jié)方法有哪幾種？?8．離心式水泵主要有哪幾部分組成？D型和B型離心式水泵在結(jié)構(gòu)和應(yīng)用上有何特點(diǎn)？?9．離心式水泵的軸向推力是如何產(chǎn)生的？說明其平衡方法和原理。復(fù)習(xí)思考題（續(xù)）?10．設(shè)某水泵在n＝2950r/min時(shí)，流量Q－45m3/h，揚(yáng)程H＝ 70m，軸功率N＝15kW，若將轉(zhuǎn)速改為n ‘＝1480r/min，該水泵的流量Q、揚(yáng)程H和軸功率N各為多少？?11．水泵吸水管直徑d=150mm，管內(nèi)流量Q=，水泵吸入口真空度為H’s =300mmHg，管長L=8m，沿程阻力損失系數(shù)λ＝，局部阻力損失系數(shù)之和Σξ＝3。求水泵的吸入高度Hx。?12．根據(jù)以下條件選擇排水設(shè)備：井深600 m，正常涌水量qz =760m3/h，正常涌水期320天，最大涌水量qmax =1500m3/h，最大涌水期45天，礦水中性，密度ρ＝ 1020kg/m3；礦井電壓6000V；泵房設(shè)在井底車場附近，軌距600mm；礦井年生產(chǎn)量4106t。休息一會兒……________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________