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1、制冷空调专业英语,Unit Two,Lesson 5 Fluid Lesson 6 Level Measurement Lesson 7 Measuring Rate of Fluid Flow Lesson 8 What Is Humidity,New Words & Expressions Text Notes to the Text Exercise,Lesson 7 Measuring Rate of Fluid Flow,New Words & Expressions,Lesson 7,压力计,contraction n.,收缩, 缩写式, 紧缩, 断面收缩,upstream adv
2、.;adj.,溯流, 逆流地 溯流而上的,differential adj.,微分的，差动的, 差速的,proportional adj.,比例的, 成比例的, 相称的,flowmeter n.,流量计,orifice n.,孔, 口,orifice-plate meter,孔板流量计,insert vt.,插入, 嵌入,flange n.,轮缘, 凸缘, 法兰,manometer n.,Lesson 7,New Words & Expressions:,作为结果的, 随之发生的,calibrate v.,校准,calibration n.,标度, 刻度, 校准,in terms of,根据,
3、 按照, 在.方面,trapped adj.,捕集的, 收集的, 截留的,interfere with,乱动 干涉, 干扰,instead of,代替, 而不是.,gradually adv.,逐渐地,venturi tube,文丘里管,clog n.;v.,障碍 障碍, 阻塞,consequent adj.,Lesson 7,New Words & Expressions:,平稳的,安定的, 和谐的,abrupt adj.,突然的, 陡峭的, 生硬的,narrow vi.,变窄使变狭窄, 使缩小,parse vt.;vi.,解析 、分列,rotameter n.,旋转式流量计,转子流量计,t
4、apered tube,锥形管 渐缩管,plummet n.;vi.,铅锤, 重荷 垂直落下,ingenuity n.,机灵, 独创性, 精巧, 灵活性,balanced adj.,Text,The most common means of measuring rate of flow of a fluid is based on the principle that if there is a contraction (a section of reduced diameter)in a pipe, the pressure of fluid flowing downstream from
5、the contraction will be lower than that upstream from the contraction. This pressure differential is proportional to the rate of flow. The simplest form of such a flowmeter is known as an orifice-plate meter.,最常见的测量流体流速的方法是基于这样一个原理，即如果在管路上有断面收缩，则收缩断面下游流体压力比上游的要低。这种压力的变化与流体的速度成比例。最简单的流量计是孔板式流量计。,Less
6、on 7,Text:,It consists simply of a plate with a hole in it, inserted into the pipeline, usually between two flanges. 1 The hole in the plate is called an orifice and is smaller than the internal diameter of the pipe. Small openings, called taps, are made in the pipe on both sides of the orifice plat
7、e, and these are connected to some kind of pressure-measuring device most often a manometer.,Lesson 7,孔板式流量计只有一个带有孔的板，插入管路中，通常插在两个法兰之间。板孔的大小小于管子的内径。在孔板两侧的管路上开有小孔，与某种压力测量装置(通常是压力计)相连。,Text:,The manometer reads the differential in pressure on both sides of the orifice and may be calibrated to read in
8、terms of rate of flow. 2 Orifice plates cannot be used if the liquid being measured contains solids because they will be trapped by the plate. The trapped solids interfere with the calibration of the flowmeter and may even clog the pipe. 3 An orifice plate also causes pressure losses and a consequen
9、t increase orifice plates in pumping costs.,Lesson 7,压力计读出孔板流量计两侧的压力变化然后校正标定流量。孔板流量计不能用于带有固体物质的被测液体，因为孔板会将固体截止。被截止的固体会干涉流量计的读数，甚至会堵塞管路。孔板流量计也会导致压力损失从而增加成本。,Text:,Instead of an abrupt contraction in the pipe size, as is caused by an orifice plate, the contraction may be gradual. Special fittings (cal
10、led venturi tubes) are used, by which the pipe is gradually narrowed and gradually enlarged. The pressure taps are placed at the largest part of the venturi tube (before it narrows), and at the smallest diameter.,Lesson 7,为了改变由孔板引起的管子直径的突变，可采用渐缩管。应用的一种特殊的装置叫文丘里管，这种装置的管子直径大小是逐渐变化的。压力检测点安置在文丘里管直径最大和直径
11、最小的地方。,Text:,These tubes overcome most of the problems of the orifice plate meter, but the venturi tubes themselves are rather expensive, particularly when they must be made from corrosion resistant materials such as stainless steel. 4 Although there is a decrease in pressure at the narrowest pare o
12、f the venturi tube, the pressure is almost entirely recovered as the liquid parses through the gradual enlargement, so that added pumping costs are minimal.,Lesson 7,这种文丘里管克服了孔板流量计的大多数的问题，但文丘里管的价格太高，尤其是当文丘里管必须用耐腐蚀材料如不锈钢制造时。虽然在文丘里管的隘路段压力会有损失，但当液体通过渐扩管段时压力几乎会完全恢复，所以流体附加的泵送费用是小的。,Text:,Another type of
13、flowmeter is the rotameter, or variable-area meter (Fig7-2). The liquid to be measured passed upward through a tapered tube with the smallest part of the taper at the bottom. In the tube is a small metal plummet, or float. (Although usually called a float, it is made of metal and is denser than the
14、fluid to be measured.) As liquid flows up the tube, it lifts the float to a position where the weight of the float (a downward force) is exactly balanced by the lifting effect of the liquid in the space between the edge of the float and the inside of the tapered tube. 5,Lesson 7,另一种流量计是转子流量计。被测的流体通过
15、一个带有较小锥度的锥型管。在管内有一个小的金属铅锤，也就是浮子（虽然叫浮子，但它是由密度比液体大的金属制成）。当流体流过锥形管时，液体使浮子处于一个特定的位子，这时浮子和锥形管之间的液体产生的浮力等于浮子的重力。,Text:,The ingenuity of engineers is great, and many other types of flowmeters have been invented and are in use. The types described above are simply the most common.,Lesson 7,工程师的独创性是巨大的，发明了很多
16、种类的流量计并且得到应用。上面叙述的仅仅是最常用的。,Notes to the Text,Lesson 7,Notes to the Text,1.It consists simply of a plate with a hole in it, inserted into the pipeline, usually between two flanges.,Lesson 7,在句中It代表orifice-plate meter，其中with a hole in it, inserted into the pipeline, usually between two flanges都是补充说明plate的。,Notes to the Text,2.The manometer reads the differential in pressure on both sides of the orifice and may be calibrated to read in terms of rate of flow.,Lesson 7,differential的意思是 “微分的，微分”。如 a
