58m三用工作船动力装置设计外文翻译资料

Design of an acoustic enclosure with duct silencers for the heavy duty diesel engine generator set

重型柴油发动机发电机组的具有管道消声器的声学壳体的设计

Hyeon-Don Jua,*, Shi-Bok Leeb, Weui-Bong Jeongb, Byung-Hoon Leeb

a Department of Computer Industrial Application, Chinju College, Chinju, 660-759, South Korea bSchool of Mechanical Engineering, Pusan National University, Pusan, 609-735, South Korea Received 15 October 2002; received in revised form 1 May 2003; accepted 21 October 2003

Hyeon-Don Jua,*, Shi-Bok Leeb, Weui-Bong Jeongb, Byung-Hoon Leeb

a Department of Computer Industrial Application, Chinju College, Chinju, 660-759, South Korea bSchool of Mechanical Engineering, Pusan National University, Pusan, 609-735, South Korea Received 15 October 2002; received in revised form 1 May 2003; accepted 21 October 2003

Abstract

Diesel engine generator sets in heavy industry plants and residential/official buildings can cause serious noise problems. In this paper, a low noise diesel engine generator set is developed through constructing an acoustic enclosure with ventilation duct silencers that effectively block the acoustic flow but guarantee good thermal flow. Acoustic design of the enclosure, which is initially layout by rule of thumb, is evolved systematically through numerical reanalysis procedure, based on indirect boundary element method (IBFM) with a commercial acoustic analysis code. The cooling performance of the acoustically determined enclosing structure is checked and confirmed through numerical heat flow analysis. The acoustic and cooling performances of the developed low noise diesel engine generator set are confirmed by the experiment.

摘要

放置在在重工业厂房和住宅以及官方建筑中的柴油发动机发电机组可能导致严重的噪音问题。在本文中，一个低噪声柴油发动机发电机组被开发出来，其通过构造具有通风管道消声器的声学壳体，能有效地阻挡声流，与此同时保证良好的热流动。这种外壳声学方面的设计，最初是凭经验法则，然后在数值再分析过程的系统化发展的基础上，与商业声学分析代码间接边界元法相接轨（IBFM）。这种具有消声功能的封闭结构的冷却性能通过数值热流分析检查和确认是可行的。这种新型柴油发动机发电机组的消声和冷却性能被实验所证实。

2.Measurement of noise characteristics and sound power

Noise characteristics of the generator set should be identified to produce effective and concrete measures to control the noise. The sound powers of the noise sources need to be used in the numerical analysis.The sound powers of the main noise sources, the diesel engine [1], generator and radiator fan, are measured by sound intensity method. A sound intensity probe with two microphones (Bamp;K 4183) of 12 mm distance is used [2]. A measuring grid wall with a grid size of 200 mm height and 200 mm width is installed at 0.75 m in front of the centerline of the generator set as shown in Fig. 1(a) and another measuring grid wall with a grid size of 290 mm height and 290 mm width at the front of the radiator. Fig. 2(a–c) present the results of 1/3 octave sound intensity spectrum analysis. The symbol ^ in any bar in Fig. 2 indicates the intensity of the sound reversing to the source. The units of sound intensity and A-weighted sound power are W/m2 and dB, respectively. Fig. 2(a) presents the sound intensity spectrum at the grid position in front of the engine exhaust manifold located around the cross point of the 4th row and 4th column grid lines on the measuring wall. The spectrum reveals that a dominant noise reaching the A-weighted sound intensity level of 99 dB arises in the 1/3 octave band centered at 1000 Hz. The overall A-weighted sound power radiated from the engine is 108 dB.

Fig. 1. Grid wall for sound intensity measurement and a typical diesel engine generator set without any special anti-noise measures.

In Fig. 2(b), showing the sound intensity spectrum at the grid position in front of the generator cooling fan located around the cross point ofthe 6th row and 2nd column grid lines on the measuring wall for the generator, the 1/3 octave band centered at 500 Hz appears to be the most troublesome frequency band, in which A-weighted sound intensity level from the generator cooling fan reaches up to 102 dB. On considering that the blade rotation frequency of the cooling fan of the generator is 450 Hz, it is apparent that the high noise in this band is due to the blade rotation. The overall A-weighted sound power of the generator is 110 dB. Fig. 2(c), giving the sound intensity spectrum emitted from the radiator fan located around the cross point of the 5th row and 4th column grid lines on the measuring wall for the radiator, reveals that the 1/3 octave hand centered at 200 Hz, which encompasses the blade rotation frequency 217 Hz, of the radiator fan, is most problematic, generating A-weighted sound intensity of 112 dB. These experimental facts provide some important guides for us to adopt ventilation ducts with silencing capability of low frequency noise. But straight ducts are ways for the noise to pass out through and act as effective noise transmitters. In order to interrupt noise flow effectively, the ducts should be bent in some angles.

2.1. Initial design of the acoustic enclosure and ventilation duct silencers

Our acoustic enclosure design is performed for a heavy duty diesel engine generator set with a high electric power supplying capacity above 320 kW, the specifi- cation of which is given in Table 1. The main idea in our design, different from conventional diesel engine generator sets covered with simple enclosures, is to install the ventilation ducts and impose silencing function on them.

Initial spatial configuration of the generator system with an acoustic enclosure and ventilation ducts is laid out by the rule of thumb, paying attention to the maintenance feasibility and space utility, to conform to the following requirements and specifications.

1. The acoustically designed generator set should satisfy that length is smaller than 5.

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