闫贝翻译 脉动缓冲器工作原理.docx

1、闫贝翻译 脉动缓冲器工作原理UNDERSTANDING HOW PULSATION ACCUMULATORS WORKJ. C. Wachel and S. M. PriceEngineering Dynamics IncorporatedSan Antonio, Texas脉动缓冲器工作原理J. C. Wachel and S. M. Price工程动力公司San Antonio, TexasABSTRACTPulsation accumulators are used in reciprocating pump installations to reduce pump manifold p

2、ulsations and to attenuate pulsations transmitted into the piping. The pump and piping system form a complex acoustical system which has many acoustical and mechanical frequencies and the potential for high vibration and component failure problems .Many times the pulsation characteristics of the sys

3、tem are not calculated prior to installationand an accumulator is selected based on pressure and flow rate criteriaIn some cases ,this is acceptable as can be attested by the numerous installations that are installed and have operated successfully without problemsHowever，many installations do experi

4、ence high vibrations ,piping and component failures，cavitations in the suction manifold，and generally poor reliabilityThese problems are often the result of the failure to consider the systems acoustical characteristics when selecting an accumulator.摘要在往复泵中使用缓冲器旨在消减泵的主管线脉动并减缓脉动在管道内的传播。泵及其附属管道形成一个复杂的

5、声学系统，该系统具有多阶声学及机械固有频率，且该系统潜存剧烈振动和管件失效等问题。多数情况下，管路内的脉动特性在系统安装完成之前是不能计算出的。缓冲器是依据管道内的压力和液流的评价准则来选取的。在某些情况下，通过安装很多装置使系统运行平稳，安装得以认可。然而，这些安装在管路中的装置确承受着剧烈的振动，管道和附件的失效及吸气主管内的气穴现象等使管路的可靠性较低。这些问题的产生是由于在选择缓冲器的时候没有考虑到系统的声学特性所造成的。 The effects of several different types of accumulators in a three pump parallel sy

6、stem were studied using a digital computer program which models the pulsation characteristics of pump and compressor systemsDetailed computer analyses were performed on bladder gas charges appendage and flow-through accumulators，the non-bladder，flow-through，gas-charges accumulators，and all-liquid He

7、lmholtz filtersThese results indicate that the off-the-shelf accumulators can be effective in some cases，but can combine with the particular acoustical characteristics of the system to amplify pulsations in other cases，In addition，the interaction between the individual pumps in a parallel installati

8、on can cause severe amplification of the pulsationsGuidelines are presented for the selection of pulsation filters for pump systems and the type of analyses that should be performed in the design stage.本文研究了三台柱塞泵并机系统中几种不同规格的缓冲器的效果，研究工作是由对泵和压缩机系统的脉动特性进行建模的计算机程序完成的。计算机详细地分析了充满气泡、有流体通过的缓冲器，没有气泡、有气体通过的缓

9、冲器，和全液体的亥姆赫兹滤波器。这些结果表明在某些情况下现成的缓冲器是有效的，但是在另外一些情况下与特殊的系统的声学特性结合起来会放大脉动。此外，在并机运行的系统中单台泵之间的相互作用会很大程度上增强脉动。这些结果可以指导泵系统的脉动过滤器的选择，并且在设计阶段得以应用。INTRODUCTION Many reciprocating pump installations suffer problems that cause increased maintenance and unreliable operationTypical problems encountered are high vi

10、brations of the piping and pump and/or failures in the piping，valves，crossheads，connecting rods，crankshafts，and working barrelsMany of these problems can be caused by high pulsation levels.引言 许多往复泵装置出现的问题是由于不可靠地维护和运行所造成的。所遇到的典型的问题是泵和管道的剧烈振动，以及管道、阀门、十字结联轴、活塞连杆、曲轴、工作缸的故障。其中许多是由高的脉动水平引起的。 High pulsatio

11、ns are caused by the interaction of the excitation energy from the pump with the acoustical natural frequencies of the systemThe pump and its suction and discharge piping system form a complex acoustical system and will have numerous acoustical natural frequenciesA reciprocating pump generates pulsa

12、tions at integer multiples of the pump speedHowever，outside of the pump manifold the harmonics with significant energy content will generally be at the plunger frequency and its multiples. 高水平的脉动值是由于泵的激发能量与系统的固有声学频率相互作用引起的。泵和吸液、排液管道构成一个具有众多固有声学频率的复杂系统。一个往复泵产生脉动量的频率是其转速及整数倍，然而，在泵的主管线以外，包含大量能量的谐波一般是活塞

13、运动频率的整数倍。 Vibration of the piping and pump is caused by pulsation-induced shaking forces which are a function of the pulsation amplitude and the flow area of the pipingWhenever there is a coincidence of the excitation harmonics with the acoustical natural frequencies of the system，amplification of t

14、he pulsations occur and excessive vibrations can be inducedAmplification factors are typically 10-40 for pulsation resonances and 10-20 for mechanical resonancesIf the mechanical resonance coincides with an acoustical resonance, a combined amplification factor of 800 could occur. 管道和泵振动是由脉动诱发的激振力引起的

15、，该力为脉动幅度和管道的通流面积的函数。每当激励谐波与该系统的声学固有频率相重合时，脉动值将增大并诱发剧烈管路振动。脉动产生共振时放大系数通常是10-40，而机械共振的放大倍数通常10-20。如果机械共振和声共振重合，它们联合的放大系数可能达到800. Many pump systems are designed without consideration of the system acoustical pulsation characteristics and no accumulators or acoustical filters are installed. These system

16、s can encounter severe vibrations and failure problems immediately after startup. When excessive vibrations and failures occur, the piping system is typically modified by the addition of accumulators to reduce the pulsations. The accumulator is generally chosen on the basis of the system pressure an

17、d the flow rate; however, this may not be sufficientHence，the accumulator is sometimes successful in reducing the pulsations and other times it is not. When the selected accumulator does not reduce the pulsations, another brand or type is selected and it may or may not work properly. 许多泵的系统在设计时并未考虑系

18、统的声学脉动特性，也没有安装缓冲器或声学滤波器。这些系统在启动后立刻就会遇到强烈的振动和出现故障。当有过度的振动和出现失效时，典型的整改方式是在管道系统中增加缓冲器来减少脉动。缓冲器一般是基于系统的压力和流量来选取的，但这还不够。所以，缓冲器有时能够减少脉动，而有时则不能。当所选的缓冲器不能减少脉动时，将选择另一类型的缓冲器这有可能起到作用也许无效。It is possible to calculate the effectiveness of any given accumulator in the design stage or for a modification to an exist

19、ing installation 1,2. Using a digital computer model which has this capability, the pulsations at any point in a piping system can be predicted. This allows the engineer to design the piping system to minimize the pulsations and the shaking forces.在设计阶段对任何给定缓冲器及装置中已有缓冲器的修改的有效性进行计算是可行的1,2。使用数字化计算机模型能

20、够预测出管道系统中任意一点的脉动。这使得工程师可以设计管道系统使脉动和振动力减至最低。It is difficult to predict the exact effects of accumulators on the pulsation response of systems without a means of analysis, such as the computer program mentioned above. A parametric analysis of a typical system showing the effects of different types of

21、accumulators can provide insight into the system characteristics. This paper will discuss the results of an acoustic analysis of a reciprocating triplex pump system with various accumulators. The pump system studied has three pumps operating in parallel. The effects of the accumulators on the discha

22、rge system will be discussed; however, the understanding of the acoustical effects will also be applicable to the suction system.在没有如上述计算机程序的分析方法时，系统的脉动响应的精确效果是难以预测的。一个能显示出不同种类的缓冲器的效果的典型系统的参数分析使我们对系统特性有所了解。本文将讨论含有各种缓冲器的三柱塞往复泵的声学分析。所研究的泵系统有三台泵并机运行。我们将对在排出管系中缓冲器的效果进行讨论; 然而，对声学效果的认识也适用于吸入管系。In order to

23、 understand how the accumulator affects the acoustical characteristics of the system, it is necessary to understand how an acoustical wave is propagated. Acoustic pulsations travel at speed of sound in the fluid which, for most liquids, is from 3000 to 5000 feet per second. For the normal frequency

24、range of pump pulsations, it is possible to use plane wave acoustic theory to describe the acoustical standing wave patterns since the pipe diameters are small compared to the wave length of the acoustic wave. The wave length of an acoustical wave is the speed of sound divided by the frequency. The

25、frequencies of interest in pump installations are generally less than 300 Hz. Therefore, the wave lengths are greater than 10 feet. Low frequency harmonics which have the highest energy have wave lengths of 100 feet or more. The acoustical properties of systems having piping with diameters of less t

26、han 10 feet can therefore be accurately calculated using plane wave theory.为了理解缓冲器对系统声学特性的影响，就必须了解声波是如何传播的。声学脉动在大多数液体内的传播速度可以达到3000-5000英尺每秒(914-1524m/s)。因为管径和声波波长相比很小，所以对于泵的正常脉动频率，可以使用声学平面波动理论来描述声学驻波的模型。声波的波长等于声速除以频率。和泵装置有关的频率一般不超过300Hz。因此波长大于10英尺(3.048m)。具有高能量的低频谐波的波长大于100英尺(30.48m)。因此利用平面波理论可以精确的

27、计算出管径不到10英尺(3.048m)的管道系统的声学特性。One important facet of the problem is the relationship between the acoustic speed of sound and the flow velocity of the fluid. The pulsations (acoustic waves) generated from the pump travel with a velocity of 3000-5000 feet per second and typical flow velocities are les

28、s than 50 feet per second. Thus the flow velocity will have little or no effect on the acoustical characteristics of the system. The flow velocity can be neglected and the understanding of the effects of the accumulator based on the acoustic wave alone.问题的一个重要方面是声速和液体流速之间的关系。泵运行产生速度为3000-5000英尺每秒的脉动

29、（声波）和小于50英尺每秒(15.24m/s)的液流。因此流速很少或不会对系统的声学特性产生影响。流速可以忽略，可以单独基于声波来了解缓冲器的效果。TYPES OF ACCUMULATORSThere are several different types of accumulators and acoustical filters which are used to control pulsations in pump systems. Miller 3 described over 30 different kinds, although from an acoustic standpoi

30、nt, the devices can be divided into the following categories:1. Appendage accumulator with gas-filed bladder or diaphragm2. Appendage accumulator with diverter and gas-filed bladder or diaphragm3. Flow-through accumulator with gas-filed bladder/ diaphragm or gas blanket4. Resistive accumulator (pres

31、sure drop) devices5. Acoustical filters (Helmholtz type)The acoustical characteristics and the effects of the various types of accumulator on pulsations will be discussed.缓冲器的种类在泵系统中用来控制脉动的缓冲器和声学滤波器有若干种不同类型。Miller3描述了30多种不同的类型，但是从声学角度来看，这些设备可以划分为以下类型：1. 带有气囊或者隔膜的依附型缓冲器2. 带有分流器和气囊或者隔膜的依附型缓冲器3. 带有气囊/隔

32、膜或者气层的有液流通过的缓冲器4. 阻式缓冲器（降压）5. 声学滤波器（亥姆赫兹型）下面将讨论不同种类缓冲器的声学特性和对脉动的影响。Appendage with Gas-Filled BladderAccumulators that are mounted on the piping through a tee type installation are called appendage or side branch accumulators. Figure I show sketches of the different accumulators. The gas-filled bladder or diaphragm is separated from the flow by a throat or neck from the pipe flow and a volume of liquid beneath the elastic member （Figure 1a and 1b).带有气囊的依附型缓冲器安装在管道上通过T字形装置的缓冲器被称为附属或旁路缓冲器。图1显示了不同种类的缓冲器。气囊或隔膜由颈管或接管与管中液流及弹性部分之下的液体分开（图1a和1b）。（a） （b） （c）