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1.AF泡沫泵輸送密度為800kg/m3的油品，實(shí)測(cè)到泵出口壓力表讀數(shù)為147100Pa，入口真空表讀數(shù)為300 mmHg,兩表測(cè)點(diǎn)的垂直距離(表位差)為0.5m.吸入管與排出管直徑相同。試求泵的實(shí)際揚(yáng)程。
2.有一臺(tái)離心水泵用來(lái)輸送清水，轉(zhuǎn)速π= 480r/min總揚(yáng)程H= 136m，流量Q=5.7m3/s,軸功率P= 9860kW,設(shè)ηv= ηm=0.92,求水力效率ηh為多少?
3.某離心油泵裝置如圖1-115所示。已知管內(nèi)油面壓力PA與油品飽和蒸氣壓pv相等，該泵轉(zhuǎn)速n=1450r/min.最小汽蝕余量Sh. =k,Q .取安全余量為0.4.則[OM]=0.4+ sh,=0.4+k,Q2，吸入管內(nèi)流動(dòng)阻力損失hu=k,Q: ,試分別計(jì)算:
(1)當(dāng)zg=8m,Q=0.5m3/min時(shí),泵的[NPSH.]=4. 4m,吸入管路阻力損失h:= 2m,此時(shí)泵能否正常吸入?
(2)保持Q=0.5m3/min時(shí),液面下降到什么位置泵開(kāi)始發(fā)生汽蝕?
(3)當(dāng)Zg =8m,Q= 0.5m2 /min時(shí)，若將泵的轉(zhuǎn)速提高到n' = 2900/min,泵還能否正常吸入?
4.某油庫(kù)消防泵位于河岸上，泵房?jī)?nèi)安裝一臺(tái)離心水泵， 如圖1- 116所示，使用時(shí)水流，吸水管直徑為100mm，底閥當(dāng)量長(zhǎng)度為160d(d為直徑)，彎頭當(dāng)量長(zhǎng)度為22d，閥門當(dāng)量長(zhǎng)度為18d，阻力系數(shù)為0.022.試求保證正常吸入時(shí)，河底最低頁(yè)面距泵軸心距離為多少？
5.某臺(tái)離心泵，在轉(zhuǎn)速1450r/min條件下，當(dāng)流量Q=30m3/h是，揚(yáng)程H=60m，軸功率p=7.6kW。 求當(dāng)轉(zhuǎn)速變?yōu)?/span>2900 r/min時(shí)， 流量、揚(yáng)程和軸功率各為多少?
6.已知1#泵的特性方程為H=40-0.01Q2 ,2#泵的特性方程為H=60-0.02Q2，根據(jù)串聯(lián)水力特點(diǎn),寫出1#泵和2#泵申聯(lián)后泵機(jī)組的總的特性方程。若兩臺(tái)泵串聯(lián)后與管路組成一水力系統(tǒng)，管路特性方程為h= 30+0.04Q ,試用解析法確定串聯(lián)后管路及每臺(tái)泵的工作點(diǎn)。(方程中Q單位為m/s.H.h單位為m)
The 1.AF foam pump has a density of 800kg/m3 oil, and the reading of the pump outlet pressure gauge is 147100Pa. The entrance vacuum gauge reading is 300 mmHg, and the vertical distance of the two measuring points is the same as the diameter of the suction pipe and the discharge pipe of the 0.5m.. Try to find the actual head of the pump.
2. A centrifugal pump is used to transport clean water. The speed is π = 480r / min, the total head H = 136m, the flow rate q = 5.7m3/s, and the shaft power P = 9860kw. Suppose η v = η M = 0.92, what is the hydraulic efficiency η H?
3. A centrifugal oil pump is shown in Fig. 1-115. The minimum NPSH sh sh. = k, Q. if the safety margin is 0.4, then [om] = 0.4 + sh, = 0.4 + K, Q2, the flow resistance loss in the suction pipe Hu = k, Q: respectively
(1) When ZG = 8m, q = 0.5m3/min, the pump's [NPSH.] = 4.4m, suction pipe resistance loss H: = 2m, can the pump normally inhale?
(2) When q = 0.5m3/min, where does the liquid level drop to and the pump begins to cavitation?
(3) When ZG = 8m, q = 0.5m2/min, if the pump speed is increased to n '= 2900 / min, can the pump still inhale normally?
4. The fire pump of an oil depot is located on the Bank of the river. A centrifugal pump is installed in the pump room, as shown in Fig. 1-116. When using, the diameter of the suction pipe is 100 mm, the equivalent length of the bottom valve is 160 D (D is the diameter), the equivalent length of the elbow is 22 D, the equivalent length of the valve is 18 D, and the resistance coefficient is 0.022?
5. A centrifugal pump, at the speed of 1450r / min, when the flow rate q = 30m3 / h, the head H = 60m, the shaft power P = 7.6kw. When the speed changes to 2900 R / min, what are the flow rate, head and shaft power?
6. It is known that the characteristic equation of 1 × pump is h = 40-0.01q2, and that of 2 × pump is h = 60-0.02q2. According to the hydraulic characteristics of series connection, the general characteristic equation of 1 × pump and 2 × pump unit after application is written. If two pumps are connected in series with pipelines to form a hydraulic system, and the pipeline characteristic equation is h = 30 + 0.04q, the working point of pipelines and each pump after series connection is determined by analytical method. (the unit of Q in the equation is m / s.h.h, the unit is m)
