译文：
一、泵的汽蚀现象： 液体在一定温度下，降低压力至该温度下的汽化压力时，液体便产生汽泡。把这种产生汽泡的现象称为汽蚀。汽蚀时产生的汽泡，流动到高压处时，其体积减小以致破灭。这种由于压力上升汽泡消失在液体中的现象称为汽蚀溃灭。 泵在运转中，若其过流部分的局部区域（通常是叶轮叶片进口稍后的某处）因为某种原因，抽送液体的{jd1}压力降低到当时温度下的液体汽化压力时，液体便在此处汽化，产生大量蒸气，形成气泡，当含有大量气泡的液体向前经过叶轮内的高压区时，气泡周围的高压液体致使气泡急剧地缩小以致破裂。在气泡凝结破裂的同时，液体质点以很高的速度填充空穴，在此瞬间产生很强烈的水击作用，并以很高的冲压频率打击金属表面，冲击应力可达几百至几千个大气压，严重时会将壁厚击穿。 在水泵中产生气泡和气泡破裂使过流部分遭受到破坏的过程就是水泵中的汽蚀过程。水泵产生汽蚀后除了对过流部件产生破坏作用以外，还会产生振动和噪音，并导致泵原性能下降，严重时会使泵中液体中断，不能正常工作。 二、泵汽蚀基本关系式 泵发生汽蚀的条件是由泵本身和吸入装置两方面决定的。因此研究汽蚀发生的条件，应从泵本身和吸入装置双方来考虑，泵的基本关系式为： NPSHc≤NPSHr≤［NPSH］≤NPSHa NPSHa=NPSH（NPSHc）－－－－－－－－泵开始汽蚀 NPSHa＞NPSHr（NPSHc）－－－－－－泵无汽蚀 式中NPSHa－－-装置汽蚀余量又叫有效汽蚀余量，越大越不易汽蚀； NPSHr－－－－泵汽蚀余量，又叫必需汽蚀余量或泵进口压降，越小抗汽蚀性能越好； NPSHc－－－－-临界汽蚀余量，是指对应泵性能下降一定值的汽蚀余量； [NPSH]－－－－-许用汽蚀余量，是确定泵使用条件用汽蚀余量，通常取[NPSH]=（1.1～1.5）NPSHc. 三、防止汽蚀措施： 欲防止发生汽蚀必须提高NPSHa,使NPSHa＞NPSHr,可防止发生汽蚀的措施如下： 1、减小几何吸上高度hg（或增加几何倒灌高度）； 2、减小吸入损失hc，为此可设法增加管径，尽量减小管路长度、弯头和附件等； 3、防止长时间在大流量下工作； 4、在同样转速和流量下，采用双吸泵，因减小进口流速，泵不易发生汽蚀； 5、泵发生汽蚀时，应尽量把流量减小功降速运行； 6、泵吸水池的情况对泵汽蚀有重要影响； 7、对于在苛刻条件下运行的泵，为避免汽蚀破坏，可使用耐汽蚀材料。

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原文：
1, pump cavitation phenomenon: Liquid at a certain temperature, reduce the pressure to the pressure of vaporization temperature, the liquid will produce bubbles. This produces the phenomenon known as cavitation bubble. Cavitation bubbles generated when the mobile to the high-pressure office, the volume decrease resulting in burst. Such as increased pressure in the liquid bubble away the phenomenon known as cavitation bubble collapse. Pumps in operation, if the over-current part of the local area (usually the impeller blade inlet somewhere later) for some reason, the absolute pressure of pumping the liquid down to temperatures of liquid vaporization at the pressure, the liquid will in this Department of vaporization, resulting in a lot of steam, the formation of bubbles, the bubble when the liquid contains a lot of forward pressure through the impeller zone, bubble bubble around the high pressure liquid resulted in dramatically reduced and rupture. Condensation in the bubble burst at the same time, liquid filled particles at high speed holes, in this moment has a very strong effect of water hammer and punch to a very high frequency against the metal surface, the impact of stress up to several hundred to several thousand atmospheric pressure, a serious breakdown when will thickness. Generated in the pump and the bubble burst the bubble so that suffered some damage over the course of flow is the water pump cavitation in the process. Pump Cavitation after the addition to the over-current components other than disruptive, but also vibration and noise, and cause the pump to original performance degradation, severe disruption of liquid pump will not work properly. Second, the basic relationship pump cavitation Pump cavitation condition is inhaled by the pump itself and the decisions of both devices. Therefore, the conditions of cavitation, the pump itself and the inhalation device from both sides to consider the basic relation between the pump are: NPSHc ≤ NPSHr ≤ [NPSH] ≤ NPSHa NPSHa = NPSH (NPSHc )-------- start pump cavitation NPSHa> NPSHr (NPSHc )------ pump without cavitation Type in NPSHa --- device known as the effective NPSH NPSH, the more difficult the greater the cavitation; NPSHr ---- pump, NPSH, also known as the necessary NPSH or pump inlet pressure drop, the smaller the better resistance to cavitation; NPSHc ----- critical NPSH, is the decline in the corresponding certain value Pump NPSH; [NPSH ]----- permissible NPSH, is to determine the conditions of use with the pump NPSH is usually taken [NPSH] = (1.1 ~ 1.5) NPSHc. Third, measures to prevent cavitation: To prevent the occurrence of cavitation must improve NPSHa, so NPSHa> NPSHr, prevent the occurrence of cavitation as follows: 1, reduce the absorption on the high degree of geometric hg (or increase the geometric intrusion height); 2, reduce the inhalation of loss hc, this could be to increase the diameter, to minimize the pipe length, elbows and attachments; 3, to prevent prolonged work under high flow; 4, in the same rotational speed and flow rate, double suction pump, the flow rate due to reduced imports, less prone to pump cavitation; 5, pump cavitation, we should try to reduce the power flow of spin-down operation; 6, the situation of the pool pump cavitation on the pump have a major impact; 7, running under harsh conditions for the pump to avoid cavitation damage, cavitation-resistant materials can be used.