译文：
减压阀是通过启闭件的节流，将进口压力降至某一个需要的出口压力，并能在进口压力及流量变动时，利用本身介质能量保持出口压力基本不变的阀门。流体流经减压阀时，会产生压力损失，即能量损失，这部分损失的能量是造成振动和噪声的根源，减压阀在工作时产生振动和噪声是不可避免的现象。若减压阀的工作噪声过高，则不仅会影响操作者的身体健康，而且还会威胁到整个设备系统的安全运行，这种噪声已被列为公害之一。根据有关环保法规，若减压阀的噪声经测定超过了标准规定允许值，就必须采取降噪措施。因此，管路系统中减压阀的降噪问题，引起了人们越来越多的xx。笔者讨论了减压阀噪声允许值的确定方法，分析了减压阀工作时产生噪声的机理，提出了有效的降噪措施。实践证明，其降噪效果明显，令人满意。 1、减压阀的允许噪声等级 　　在实践中，减压阀噪声控制的合理范围一直是人们xx的问题。参照有关部门的环保标准、劳动安全标准以及减压阀的制造标准，减压阀的允许噪声如表1所示［1］。 表1　减压阀的允许噪声等级 持续时间/h 允许噪声/dB 8 85 4 88 2 91 1 94 　* 允许噪声{zg}值不得超过115 dB 　　实际上，在确定减压阀的噪声允许值时，还应该综合考虑下列各种因素，减压阀的安装位置及其工作环境；噪声源功率大小；操作者的位置等。 　　例如，当减压阀运行时，若操作者并不在其附近，此时，可以适当放宽减压阀的允许噪声等级，这是因为噪声在空气中传播时，其传播距离每增加一倍，噪声声强将衰减6 dB。但是，在离噪声源(即减压阀处)1 m处，{zd0}噪声声强不得大于85 dB，否则属于超标。 　　在采取防止噪声的措施时，首先应该确定噪声的允许值，然后进行噪声预测计算。若计算值超过允许值，则必须采取降噪措施。 2、减压阀的噪声源及噪声产生的机理 　　减压阀在降压过程中，消耗的流体介质内能转化为热能、机械能以及产生噪音的声能。要降低噪声，首先就要把减压过程中的能量尽量多地转化为热能。 　　减压阀的噪声源大体上可以分为如下3大类： ① 减压阀的零部件由于机械振动而产生噪声； ② 流体动力学噪声； ③ 空气动力学噪声。 2.1　机械振动产生的噪声 　　减压阀的零部件在流体流动时的激励作用下会产生机械振动，机械振动可分为两种形式： ① 低频振动，其频率约为50～500 Hz，其声压级约为90 dB。这种振动是由介质的射流和脉动造成的，其产生原因在于阀出口处的流速太快，管路布置不合理以及阀活动零件的刚性不足等。② 高频振动，其频率约为1 000～8 000 Hz，其声压级在90 dB以上。这种振动在阀的自然频率和介质流动所造成的激励频率一致时，将引起某种共振，它是减压阀在一定减压范围内产生的，而且一旦条件稍有变化，其噪声变化就很大。这种机械振动噪声与介质流动速度无关，且这种振动噪声事先无法预测。 　　减小机械振动噪声的措施是，改变减压阀阀腔形状和减压面积的形状，合理地设计衬套和阀杆的间隙、机械加工精度、阀的自然频率以及活动零件的刚性，正确地选用材料等。 2.2　流体动力学噪声 　　流体动力学噪声是由流体通过减压阀的减压口之后的紊流及涡流所产生的，其产生的过程可以分为两个阶段： ① 紊流噪声，即由紊流流体和减压阀或管路内表面相互作用而产生的噪声，其频率和噪声级都比较低，一般并不构成噪声问题。 ② 汽蚀噪声，即减压阀在减压过程中，当流体流速达到一定值时，流体(液体)就开始汽化，当液体中的气泡所受到的压力达到一定值时，就会爆炸。气泡在爆炸时，要在局部产生很高的压力和冲击波，这个冲击压力可达196 MPa，但是稍离爆炸中心的地方，压力急剧衰减。这个冲击波是造成减压阀汽蚀和噪声的一个主要因素，其噪声级可以达到100 dB以上。产生汽蚀的压力差可由式(1)表示［2］。 Δp初始=kc(p1-pv)　　　　　　　　　　　　　　(1) 　　安全汽蚀所需压力差值由式(2)表示： Δp临界=c2r(p1-pv)　　　　　　　　　　　　　　(2) 式中,p1为阀入口的压力；pv为液体在工作温度下的饱和蒸汽压力；kc为初始汽蚀系数；cr为临界流量系数。 　　由式(1)和式(2)可以看出，减压阀的实际减压值达到Δp初始值时，液体就开始产生汽蚀，而且噪声将急剧增大。所以，在设计减压阀时，必须把减压阀的减压值控制在Δp临界值以下，而且，{zh0}是在Δp初始以下。此外，还要注意相对于阀瓣的流体介质的流动方向。 2.3　空气动力学噪声 　　当蒸汽等可压缩性流体通过减压阀内的减压部位时，流体的机械能转换为声能而产生的噪声称为空气动力学噪声。这种噪声是一种在减压阀噪声中占大多数而且处理起来最为麻烦的噪声。该噪声的频率约为1 000～8 000 Hz，但它一般没有特别陡尖的峰值频率。这种噪声产生的原因分为两种情况，一是由于流体紊流所产生，二是由于流体达到临界流速引起的激波而产生的。空气动力学噪声不能xx被xx，因为减压阀在减压时引起流体紊流是不可避免的［3］。 3、降低减压阀噪声的方法 　　减压阀在运行时要消耗大量的介质内能，这些能量一部分通过摩擦、涡流等转换为热能，其余的则引起机械振动和碰撞等，从而产生噪声。也就是说，这些被损失的内能应尽可能多地转换为热能，这样才能达到降低噪声的目的。 　　图1是某种气动减压阀的结构原理图，减压孔是一细长的光孔，其阻力按式(3)计算［4］，即 R=k1×Q　　　　　　　　　　　　　　　(3) 式中，R为阻力值；Q为通过减压阀的流体流量；k1为阻力系数，k1与孔的长度、孔口形式和粗糙度等因素有关，孔越长、粗糙度越大，阻力系数也越大。 1—ZMB-5气动薄膜执行机构　　2—ZPS型傍式手轮机构 　　从以上分析可以看出，要想降低噪声，就必须尽量增大R值，从而使减压时消耗的内能尽可能多地转化为热能而不是机械能和声能。然而，对大口径大流量提升式减压阀来说，其减压孔的长度和粗糙度不可能太大。经过多年探索，笔者运用螺纹孔具有更大阻力并能产生涡流的原理，把减压孔设计成螺纹孔的形式。一方面，通过改变流体的流动方向并减小介质的喷射速度，让介质从阀体内四周经过螺纹孔后在套筒内混合，形成涡流而产生热能；另一方面，螺纹孔的孔径大小和两个螺纹孔间的距离也是影响降噪效果的两个重要因素，螺纹孔的孔径太大，不仅减压效果不理想，而且降噪效果差；螺纹孔太小又易被堵塞。螺纹孔间的距离太大，将在射流束之间产生干扰作用之前产生激波；而螺纹孔间距太小，两个相邻的射流将成为一个大射流，并在相互干扰作用之后产生激波。所以，必须恰当设计螺纹孔的孔径和间距。螺纹孔的孔径在M4～M8之间，两螺纹孔的间距在0.77～0.80倍的螺纹孔孔径时所产生的降噪效果比较理想。现在，这种结构的减压阀在国内几个大型化工企业使用的效果非常好。 4、结束语 　　关于噪声问题，目前已经能够进行预测计算，而且能采取有效的防止和降低噪声的措施。在确定了允许噪声级之后，可以从各种措施中选择xxx而且最经济的方法。实践表明，对大口径大流量提升套筒式减压阀这种特殊减压的减压孔，采取用螺纹孔代替光孔的办法，工艺可行，可以使减压阀的噪声控制在允许噪声之内，降噪效果较为理想，是行之有效的降噪措施。

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原文：
Valve by opening and closing parts of the throttle, the pressure will be reduced to a certain need to import the export pressure, and can change in pressure and flow of imports, the use of their media power to maintain the basic constant outlet pressure valve. Fluid through the valve, it will create pressure loss, that is, energy loss, this loss of energy is the root cause of vibration and noise, vibration at work valve and noise is inevitable phenomenon. If the valve's operating noise is too high, you will not only affect the health of the operator, but also threaten the safe operation of the equipment system, such as noise pollution has been one. According to the environmental regulations, if the valve's noise exceeds the standard requirements by the determination of allowable values, noise reduction measures must be taken. Therefore, the pipeline system, pressure reducing valve noise problems, has aroused more and more attention. The author discusses the valve noise method for determining the allowed values, analysis of the valve mechanism of the noise generated when the work is proposed effective noise reduction measures. Practice shows that the noise reduction effect is obvious and satisfactory. 1, pressure reducing valve to allow noise levels In practice, the reasonable range of noise control valve has been the people's concern. Reference to relevant environmental standards, labor safety standards, and valve manufacturing standards, pressure reducing valve to allow the noise as shown in Table 1 [1]. Table 1 pressure reducing valve to allow noise levels Duration / h to allow the noise / dB 885 488 291 194 * The maximum permitted noise not to exceed 115 dB In fact, the noise in the Que Ding valve to allow the value of time, Huan should be taken into account the following factors, pressure reducing valve of the installation location and work environment; noise source power level; the operator's location. For example, when the valve is running, if the operator is not in its vicinity, this time, you can relax the pressure reducing valve to allow the appropriate noise level, which is spread in the air because of the noise, its transmission distance for each doubling of noise acoustic forcing decay 6 dB. However, away from the noise source (ie valve Office) 1 m, the maximum sound intensity noise may not exceed 85 dB, or are excessive. In taking measures to prevent the noise, the noise should first determine the allowable value, then the noise prediction calculation. If the calculated values exceed the allowable value, noise reduction measures must be taken. 2, reducing valve noise sources and noise generation mechanism Valve in the step-down process, the consumption of energy within the fluid medium into heat energy, mechanical energy and the noise of the sound energy. To reduce noise, first on the decompression process should be as much energy into heat energy. Valve noise sources can be divided into the following three categories: ① valve parts due to mechanical vibrations caused by noise; ② noise fluid dynamics; ③ aerodynamic noise. 2.1 The noise generated by mechanical vibration Components in the fluid flow valve when the excitation will produce mechanical vibrations, mechanical vibrations can be divided into two types: ① low frequency vibration, its frequency is about 50 ~ 500 Hz, the sound pressure level of about 90 dB. This vibration is caused by the medium jet and pulse, and its causes is the valve outlet velocity is too fast, pipe and valve arrangement unreasonable lack of moving parts of the rigidity. ② high-frequency vibration, the frequency of approximately 1 000 ~ 8 000 Hz, the sound pressure level in more than 90 dB. That the natural frequency of vibration in the valve and medium flow caused by the same excitation frequency, it will cause some kind of resonance, which is a certain vacuum in the range of pressure reducing valve produced, and once the conditions change slightly, the noise changes in the great. This mechanical vibration has nothing to do with the medium flow rate, and this vibration and noise can not be predicted in advance. Measures to reduce the mechanical vibration is to change the regulator valve chamber shape and size of the shape of decompression, the rational design of bushing and valve stem clearance, precision machining, valve natural frequency and the moving parts of the rigid, properly selected materials. 2.2 fluid dynamics noise Hydrodynamic noise is from the mouth of fluid through the valve in the vacuum after the turbulence and eddy current generated by its production process can be divided into two stages: ① turbulence noise from turbulent fluid and the valve or the interaction of the inner surface of piping noise, its frequency and noise levels are relatively low, generally does not constitute a noise problem. ② cavitation noise, that valve in the decompression process, when the fluid velocity reaches a certain value, the fluid (liquid) to begin vaporization, when the liquid in the bubble the pressure reaches a certain value, it will explode. Bubbles in the explosion, local produce in a high pressure and shock, the shock pressure up to 196 MPa, but a little place away from the explosion center, the pressure rapidly decay. The shock wave is caused by cavitation valve and a major factor in the noise, the noise level can reach 100 dB or more. Cavitation pressure difference by type (1) that [2]. Δp initial = kc (p1-pv) (1) Cavitation pressure safety margin required by the type (2), said: Δp critical = c2r (p1-pv) (2) The formula, p1 pressure for the valve entrance; pv working temperature for the liquid saturation vapor pressure; kc initial cavitation coefficient; cr is the critical flow coefficient. From (1) and type (2) can be seen that the actual decompression valve Δp value to the initial value, the liquid will begin to cavitation, and noise will increase dramatically. Therefore, when designing pressure reducing valve, pressure relief valve must be the value of control threshold in Δp the following, and, preferably in the following initial Δp. In addition, we note that relative to the valve flap in the direction of the fluid flow. 2.3 The aerodynamic noise When the steam and other compressible fluid through the decompression valve position, the fluid mechanical energy into sound energy and noise generated by aerodynamic noise is called. This noise is a noise in the valve up the majority and the most trouble dealing with the noise. The frequency of the noise is about 1 000 ~ 8 000 Hz, but it is generally not particularly sharp and steep peak frequency. The cause of this noise is divided into two cases, one arising due to fluid turbulence, and second, to achieve critical velocity due to fluid shock caused arising. Aerodynamic noise can not be eliminated, because when the pressure reducing valve in the vacuum caused by fluid turbulence is inevitable [3]. 3, the method reduces valve noise Valve in the run-time to consume a large amount of media within the energy, part of that energy through friction, eddy current is converted to heat, etc., the rest are caused by mechanical vibration and impact, etc., resulting in noise. In other words, these are the loss of internal energy should be converted to heat as much as possible, in order to lower noise. Figure 1 is a schematic structure of pneumatic valve, vacuum hole is a thin light hole, and its resistance according to equation (3) calculation [4], that is, R = k1 × Q (3) The formula, R is the resistance value; Q fluid flow through the valve; k1 for the drag coefficient, k1 and the length of the hole, holes form and roughness and other factors, the longer the hole, the greater the roughness, drag coefficient also greater. 1-ZMB-5 pneumatic membrane actuator 2-ZPS-based Pong-style hand wheel body As can be seen from the above analysis, in order to reduce the noise, we must try to increase the R value, so that decompression can consume as much as possible within the heat energy into mechanical energy rather than sound energy. However, large-diameter raise-type valve for high flow, the vacuum holes and roughness length can not too. After years of exploration, I have a greater resistance to the use of screw holes and can produce eddy current principle, the vacuum holes designed in the form of threaded holes. On the one hand, by changing the direction of fluid flow and reduce the media's jet speed, so that media around the body from the valve through threaded holes in the sleeve after the mixing, the formation of eddy current generated heat; the other hand, the pore size of the screw hole and the two a screw hole is the distance between the impact of the noise reduction effect of the two important factors, threaded hole diameter is too large not only decompression result is not satisfactory, and poor noise reduction; threaded plug hole is too small it easily. The distance between screw holes too large will produce interference between the jet beam produced before the shock wave; the screw hole spacing is too small, the two adjacent jet will be a big jet, and interference in each other after the shock wave generated . Therefore, the design must be appropriate threaded hole diameter and spacing. Threaded hole diameter between the M4 ~ M8, the distance between the two threaded holes in the 0.77 to 0.80 times the diameter screw holes created when the ideal noise reduction. Now, the structure of the valve several large chemical companies in the country to use effect is very good. 4 Conclusion On the noise issue, has been able to predict the current calculation, but also to take effective measures to prevent and reduce noise. In determining the allowable noise level, you can choose from a variety of measures to the most effective and most economical way. Practice shows that the large flow of large diameter sleeve-type valve to enhance this special decompression of the decompression hole, to take place with a threaded hole aperture approach, technology is feasible, can make the noise control valve to allow the noise of , the noise reduction is more ideal, is an effective noise reduction measures.