空氣濾清器外文翻譯--一個(gè)用于內(nèi)燃發(fā)動(dòng)機(jī)進(jìn)氣系統(tǒng)的無聲空氣濾清器的虛擬設(shè)計(jì)及性能預(yù)測

1、<p><b>　　中文3230字</b></p><p>　　一個(gè)用于內(nèi)燃發(fā)動(dòng)機(jī)進(jìn)氣系統(tǒng)的無聲空氣濾清器的虛擬設(shè)計(jì)及性能預(yù)測</p><p>　　HAO Zhi-yong, JIA Wei-xin, FANG Fang </p><p>　　(College of Mechanical and Energy Engineering,

2、 Zhejiang University, Hangzhou 310027, China)</p><p>　　(Tianjin Internal Combustion Engine Research Institute, Tianjin University, Tianjin 300072,China)</p><p>　　E-mail: haozy@zju.edu.cn; jiawx@

3、zju.edu.cn</p><p>　　Received Jan. 17, 2005; revision accepted May 12, 2005</p><p>　　摘要：本文報(bào)道中采用低噪聲內(nèi)燃機(jī)進(jìn)氣系統(tǒng)開發(fā)的虛擬設(shè)計(jì)方法結(jié)合作者的研究結(jié)果。由此產(chǎn)生的高的通過噪聲水平高于在全油門的立法目標(biāo)時(shí)，發(fā)動(dòng)機(jī)轉(zhuǎn)速為5200 r/min需要邊界元輔助設(shè)計(jì)任務(wù)，按照典型的進(jìn)氣系統(tǒng)的設(shè)計(jì)與開發(fā)過程

4、。在最初的設(shè)計(jì)中，基于聲學(xué)理論和要求并考慮空間發(fā)動(dòng)機(jī)室中的約束，總體積和粗糙的內(nèi)部尺寸的測定。在詳細(xì)設(shè)計(jì)階段，確定了空氣濾清器的確切的內(nèi)部尺寸，和一個(gè)有效的方法應(yīng)用于低頻聲性能的改善。預(yù)測表明，進(jìn)氣系統(tǒng)的聲功率達(dá)到最小的進(jìn)氣系統(tǒng)噪聲降低發(fā)動(dòng)機(jī)整體噪聲。</p><p>　　關(guān)鍵詞：虛擬設(shè)計(jì);聲學(xué)性能;沉默的空氣濾清器;邊界元法（BEM）</p><p><b>　　1簡介<

5、/b></p><p>　　一個(gè)原函數(shù)的進(jìn)氣系統(tǒng)的主要功能是首先有效信道的新鮮空氣對(duì)發(fā)動(dòng)機(jī)進(jìn)氣噪聲，其次是減少排放。有一些現(xiàn)有方法的發(fā)展來提高進(jìn)氣系統(tǒng)設(shè)計(jì)一個(gè)更現(xiàn)實(shí)的方法。這些目標(biāo)包括：更有效的消聲性能，達(dá)到降低噪聲一方面日益嚴(yán)峻的立法目標(biāo)，優(yōu)化發(fā)動(dòng)機(jī)的性能和燃油經(jīng)濟(jì)性伴隨著車輛質(zhì)量的提高。</p><p>　　一個(gè)典型的程序，用于汽車發(fā)動(dòng)機(jī)進(jìn)氣系統(tǒng)的設(shè)計(jì)與開發(fā)過程中。設(shè)計(jì)過程包括仔

6、細(xì)調(diào)諧的匹配這些發(fā)動(dòng)機(jī)運(yùn)行和呼吸特性的影響，污染物排放優(yōu)化影響噪聲進(jìn)氣系統(tǒng)的所有組件，性能和經(jīng)濟(jì)性。從現(xiàn)有的或符號(hào)的系統(tǒng)布局，進(jìn)行各種性能綜合評(píng)價(jià)。這種信息可能會(huì)被適當(dāng)?shù)厥褂迷u(píng)估的各種設(shè)計(jì)目標(biāo)當(dāng)前系統(tǒng)的性能，通過對(duì)其構(gòu)成要素進(jìn)行適當(dāng)修改，為系統(tǒng)優(yōu)化設(shè)計(jì)提供理論基礎(chǔ)。</p><p>　　邊界元法廣泛應(yīng)用在進(jìn)氣和排氣系統(tǒng)的設(shè)計(jì)可以用來計(jì)算內(nèi)部，外部，或兩個(gè)領(lǐng)域的同時(shí)，只要求的空氣濾清器可分為元素的周長；和施加邊界條

7、件的緩解是另一個(gè)吸引。在本文中，邊界元法是用來預(yù)測的空氣濾清器的傳輸損耗和噪聲排放。</p><p>　　原來的進(jìn)氣系統(tǒng)設(shè)計(jì)中出現(xiàn)的水平高于在全油門和發(fā)動(dòng)機(jī)轉(zhuǎn)速在5200r/min的噪聲信號(hào)的頻譜特性的立法目標(biāo)噪聲高通連接通常是由離散的音調(diào)，對(duì)發(fā)動(dòng)機(jī)的點(diǎn)火頻率是173赫茲對(duì)應(yīng)5200 r/min內(nèi)聯(lián)四缸四沖程發(fā)動(dòng)機(jī)諧波相關(guān)的廣泛的序列占主導(dǎo)地位。在許多情況下，從主源的聲能量體分布較低的頻率成分，可能是難以控制的。

8、因此，本文提到的頻率范圍是從0到1千赫。在這個(gè)頻率范圍內(nèi)，如濾紙對(duì)集成系統(tǒng)的聲學(xué)性能的影響是微不足道的，所以濾紙不顧。噪音是從空氣濾清器入口噴出，與空氣濾清器系統(tǒng)出口連接到發(fā)動(dòng)機(jī)的進(jìn)氣。所以在發(fā)動(dòng)機(jī)空氣濾清器的出入口壓力為邊界元法的邊界條件。</p><p>　　一個(gè)降噪通常有兩部分功能的傳統(tǒng)進(jìn)氣系統(tǒng)：空氣濾清消聲器。由于空間發(fā)動(dòng)機(jī)室中的約束，重新設(shè)計(jì)的空氣凈化器結(jié)合清洗和沉默效果。在這項(xiàng)工作中，一個(gè)所謂的沉默的

9、空氣濾清器進(jìn)行了重新設(shè)計(jì)，幾何結(jié)構(gòu)確定的預(yù)測TL和邊界元的聲功率發(fā)射。同時(shí)，為了盡量減少在較低頻率的進(jìn)氣系統(tǒng)的聲功率，旁通管被添加到空氣輸送管。所產(chǎn)生的聲學(xué)性能分析表明，該方法最大限度地減少對(duì)進(jìn)氣系統(tǒng)噪聲降低發(fā)動(dòng)機(jī)整體噪聲的目標(biāo)是可行的。</p><p>　　2無聲空氣濾清器的設(shè)計(jì)</p><p>　　2.1原裝空氣濾清器的評(píng)價(jià)</p><p>　　這種原始的空氣濾

10、清器的清潔設(shè)計(jì)主要關(guān)注減少噪音排放?？諝鉃V清器的出口段是一個(gè)單位的速度振幅。</p><p>　　計(jì)算Tl時(shí)，空氣濾清器的出口部分給出了單元速度振幅模型的聲源，所有其他的表面被建模為“聲學(xué)硬”默認(rèn)情況。出口部分的聲功率可以從公式計(jì)算。所有后續(xù)的TL的預(yù)測具有相同的邊界條件。</p><p>　　預(yù)測的空氣濾清器性能。在發(fā)動(dòng)機(jī)進(jìn)氣道的聲功率級(jí)是顯示圖的噪聲源信號(hào)峰值為173赫茲的頻率諧波相關(guān)

11、的發(fā)動(dòng)機(jī)點(diǎn)火。由于發(fā)動(dòng)機(jī)燃燒分布式低頻率從100赫茲到800赫茲之間的聲音能量堆積太高，傳輸損耗在220赫茲到1千赫茲的頻率范圍內(nèi)是如此之低，噪聲排放不能最小化，所以一個(gè)沉默的空氣濾清器具有較高的TL 200赫茲到1 千赫茲的要求。</p><p>　　2.2無聲空氣濾清器的初步設(shè)計(jì)</p><p>　　如果有足夠的空間，一個(gè)復(fù)雜的結(jié)構(gòu)，可以被分配到降低進(jìn)氣噪聲排放。因此我們必須充分利用有

12、限的空間。在這項(xiàng)工作中用CAD軟件或Pro/E進(jìn)行包絡(luò)發(fā)動(dòng)機(jī)室中的其他汽車部件的剩余空間。然后從籠罩空間獲得的總體積所需的空氣濾清器。下一步是選擇合適的消聲器單元和它們的尺寸?？紤]空氣凈化效果，必須滿足兩個(gè)要求：（1）空氣流量應(yīng)等于或超過原通量值；（2）過濾面積不能降解。在這要求的基礎(chǔ)上，對(duì)消聲器單元理論初步確定開采布局?？諝鉃V清器是由兩塊隔板分隔成三個(gè)膨脹室，右擋板的中間有個(gè)洞，左擋板有四個(gè)孔的四角，濾紙放在中間膨脹室的中心。因?yàn)檫@空

13、氣濾清器的復(fù)雜性，孔的直徑大于原來的。第二個(gè)要求是在第一擋板孔的直徑和長度的二室，讓過濾面積等于原來的，然后第二膨脹室的長度可以確定。所以空氣濾清器的幾何結(jié)構(gòu)是由兩個(gè)變量確定的。</p><p>　　整體的聲學(xué)行為是三室的所有組成元件的行為總和。為了提供連續(xù)衰減譜寬的帶寬，在他們個(gè)人的貢獻(xiàn)衰減最小不應(yīng)同時(shí)發(fā)生。為了調(diào)查三室個(gè)人的聲學(xué)性能，綜合空氣濾清器被分成三個(gè)部分，其中之一是擴(kuò)張室消聲器單元，只是在兩擋板的位置

14、。邊界元法的運(yùn)行進(jìn)行計(jì)算的三個(gè)個(gè)體的聲學(xué)性能。第一室具有高和連續(xù)在300-1000赫茲頻段的衰減，并在400-800赫茲的頻率范圍的第二腔室具有高衰減的聲學(xué)性能稍微比第一個(gè)更糟。第三室性能最差，但在約230赫茲的頻率，其中第一和第二室的最小衰減，它具有更高的衰減，從而為第一和第二部分提供的補(bǔ)償效果。同時(shí)，在更高的頻率，第三部分可能是良好的聲學(xué)性能，這是在這個(gè)圖中沒有說明。請(qǐng)注意，這種單一的部分還介紹了之間存在不確定性，聲相互作用，即使他

15、們的個(gè)人表現(xiàn)，可以適當(dāng)?shù)卮砘蚪?。明確的單一部分的聲學(xué)性能的初始設(shè)計(jì)提供了重要的信息。在某些領(lǐng)域的變化，集成系統(tǒng)在獲得最佳的聲學(xué)性能的詳細(xì)設(shè)計(jì)的邊界元法計(jì)算。</p><p>　　在最初的設(shè)計(jì)，外部幾何尺寸已確定，并且已用粗糙的尺寸單位選擇消聲器。在擋板的位置和四個(gè)孔的第二隔板半徑可以改變，以達(dá)到更好的聲學(xué)性能。</p><p><b>　　2.3噪聲排放預(yù)測</b>

16、;</p><p>　　直到現(xiàn)在，我們已經(jīng)完成了總體設(shè)計(jì)的無聲空氣濾清器。為了與原來的做一個(gè)比較，的噪聲輻射進(jìn)行了預(yù)測。</p><p>　　為了驗(yàn)證設(shè)計(jì)的空氣濾清器的實(shí)用性能，在5200轉(zhuǎn)/分鐘在發(fā)動(dòng)機(jī)試驗(yàn)臺(tái)作為原始和重新設(shè)計(jì)的空氣濾清器邊界條件或噪聲源在全油門和發(fā)動(dòng)機(jī)轉(zhuǎn)速的測量是在發(fā)動(dòng)機(jī)進(jìn)氣道的聲壓，進(jìn)而預(yù)測噪聲排放進(jìn)空氣濾清器。</p><p>　　測量聲壓時(shí)

17、，空氣濾清器和發(fā)動(dòng)機(jī)的噪音屏蔽掉。此外，由于在發(fā)動(dòng)機(jī)的進(jìn)氣端口測量壓力引起的噪聲信號(hào)的空氣流的影響和誘導(dǎo)麥克風(fēng)干擾，惡化的發(fā)動(dòng)機(jī)性能的困難，麥克風(fēng)的測量定位在200毫米到進(jìn)氣端口。邊界條件施加在空氣濾清器系統(tǒng)出口處應(yīng)在測量位置上面提到的基于聲學(xué)理論從噪聲信號(hào)中提取的。</p><p>　　在進(jìn)氣道軸的點(diǎn)P的聲壓與最高的相比，在相同的距離其他點(diǎn)的入口段中心。</p><p>　　2.4盡量減

18、少額外聲功率的方法</p><p>　　在使用以前的布局的一個(gè)潛在的問題是在173赫茲的聲音從空氣濾清器的進(jìn)氣發(fā)射功率水平，頻率不為其他頻段的低?？罩妹娣e在管道連接空氣濾清器與發(fā)動(dòng)機(jī)的進(jìn)氣口表明其他一些可能的空氣清潔系統(tǒng)的改進(jìn)。本文采用旁路管來實(shí)現(xiàn)這一目標(biāo)。</p><p>　　提高TL在大約173赫茲的頻率為目標(biāo)確定尺寸LD = 980毫米。比較預(yù)測的聲學(xué)性能上的布局與管和柔性分流管的布

19、局現(xiàn)狀沒有改變。旁路管道布置的聲學(xué)性能顯著提高在大約173赫茲的頻率和519赫茲的頻率的三倍，大致對(duì)應(yīng)半波長，預(yù)計(jì)旁路管道布置TL輕度上升。</p><p>　　可以看出，無輔助空氣凈化器在173赫茲是最高的聲功率級(jí)，而旁路管空氣凈化器在這個(gè)頻率大大降低?？偮暪β仕綇?到1千赫，為無旁路管空氣清潔器110.2分貝，并為旁路管空氣清潔器105分貝。</p><p>　　請(qǐng)注意，引擎聲功率級(jí)

20、不從實(shí)驗(yàn)檢測進(jìn)氣系統(tǒng)噪聲112.2分貝和無聲的旁通管的空氣清潔器105分貝，所以重新設(shè)計(jì)的無聲空氣濾清器切實(shí)降低發(fā)動(dòng)機(jī)整體噪聲為最小的進(jìn)氣系統(tǒng)噪聲。</p><p><b>　　3結(jié)論</b></p><p>　　本文報(bào)道了一個(gè)邊界元法的輔助設(shè)計(jì)無聲空氣濾清器。在最初的設(shè)計(jì)中，基于聲學(xué)理論和要求并考慮空間約束，進(jìn)行空氣濾清器總體積、空氣濾清器的粗糙的內(nèi)部尺寸的測定。之

21、后，一個(gè)有效的方法應(yīng)用到173赫茲的頻率的聲學(xué)性能的改善。</p><p>　　邊界元法的聲學(xué)工程設(shè)計(jì)使用幫助迅速增加。本文的研究結(jié)果為無聲空氣濾清器的工程應(yīng)用指南。</p><p>　　流量的影響在本研究中并沒有考慮。雖然平均流將不會(huì)對(duì)聲學(xué)性能影響顯著，這可能對(duì)空氣凈化性能的影響和濾紙的影響被忽略，盡管它可能會(huì)影響在高頻率的空氣濾清器聲學(xué)性能。未來的研究應(yīng)包括在高頻率上的空氣凈化和過濾紙

22、上的聲學(xué)性能影響的流動(dòng)的影響。</p><p><b>　　參考文獻(xiàn)</b></p><p>　　[1] Bilawchuk, S., Fyfe, K.R., 2003. Comparison and implementation of the various numerical methods used for calculating transmission lo

23、ss in silencer systems[J]. Applied Acoustics, 64:903-916.</p><p>　　[2] Davies, P.O.A.L., 1996. Piston engine intake and exhaust system design[J]. Journal of Sound and Vibration,190:677-712.</p><p&

24、gt;　　[3] Wu, T.W., Cheng, C.Y.R., Tao, Z., 2003. Boundary element analysis of packed silencers with protective cloth and embedded thin surfaces[J]. Journal of Sound and Vibration,261:1-15.</p><p>　　Virtual d

25、esign and performance prediction of a silencing air cleaner used in an I.C. engine intake system</p><p>　　HAO Zhi-yong, JIA Wei-xin, FANG Fang </p><p>　　(College of Mechanical and Energy Enginee

26、ring, Zhejiang University, Hangzhou 310027, China)</p><p>　　(Tianjin Internal Combustion Engine Research Institute, Tianjin University, Tianjin 300072,China)</p><p>　　E-mail: haozy@zju.edu.cn; j

27、iawx@zju.edu.cn</p><p>　　Received Jan. 17, 2005; revision accepted May 12, 2005</p><p>　　Abstract: This paper reports results of the authors' studies on the virtual design method used in the

28、 development of low noise intake system of I.C. engine. The resulting high pass-by noise at level above the legislative target at full throttle when engine speed was around 5200 r/min necessitated a BEM-aided redesign ta

29、sk, following the typical process of design and development of an intake system. During the initial design, based on the acoustic theory and the requirements and considering the c</p><p>　　Key words: Virtual

30、 design; Acoustic performance; Silencing air cleaner; Boundary element method (BEM)</p><p>　　INTRODUCTION</p><p>　　The primary function of an The primary function of an intake system is firstly

31、to efficiently channel fresh air to the engine, and secondly to minimize intake noise emissions. There are a number of current approaches for developing a more realistic method to improve intake system design. The object

32、ives include more effective silencing performance to meet increasingly severe legislative targets for reduced noise on the one hand, with optimized engine performance and fuel economy accompanied by im</p><p&g

33、t;　　A typical procedure followed during the design and development of an intake system for a vehicle engine is shown. The design process includes a careful tuning of all components of the intake system that influence noi

34、se emission with optimized matching of these to the engine operational and breathing characteristics influencing pollutant emission, performance and economy. Starting with an existing or notational system layout, an inte

35、grated assessment of the various performances is performed. This</p><p>　　The BEM widely used in the design of intake and exhaust system can be used to compute the interior, exterior, or both fields simultan

36、eously and only requires that the perimeter of the air cleaner be divided into elements;and the ease in imposing the boundary condition is another attraction. In this paper BEM is used to predict the air cleaner's tr

37、ansmission loss and noise emission. </p><p>　　The redesign of the original intake system arises in connection with a high pass-by noise with level above the legislative target at full throttle with engine sp

38、eed around 5200 r/min. The spectral characteristics of the noise signal are normally dominated by an extensive sequence of discrete tones that are harmonically related to the engine firing frequency which is 173 Hz corr

39、esponding to 5200 r/min and the inline 4-cylinder 4-stroke engine. In many instances the bulk of the acoustic energy fr</p><p>　　Traditional intake system with a function of noise reduction normally has two

40、parts: air cleaner and silencer. Due to the constraint of space in the engine compartment, the redesigned air cleaner combines the effect of cleaning and silencing. In this work, a so-called silencing air cleaner was red

41、esigned, with geometrical structure determined by predicted TL and sound power emission by BEM. Also, in order to minimize the sound power of the intake system at low frequency, a bypass pipe was added </p><p&

42、gt;　　DESIGN OF THE SILENCING AIR CLEANER </p><p>　　Original air cleaner evaluation </p><p>　　This original air cleaner of mainly cleaning design paying little attention to minimizing noise emiss

43、ion is its BEM mesh. </p><p>　　During calculation of TL, the outlet section of the air cleaner is given a unit velocity amplitude to model a sound source, all other surfaces are modeled as "acoustically

44、 hard" by default . The sound power of the outlet section can be calculated from the formula. All the subsequent TL predictions have the same boundary condition. </p><p>　　The predicted air cleaner perf

45、ormance is shown The sound power level at the engine intake port is shown . The peaks of the noise source signal are harmonically related to the engine firing frequency of 173 Hz. As the bulk of the acoustic energy from

46、 the engine combustion distributed among the low frequencies from 100 Hz to 800 Hz is too high, the transmission loss at the frequency range of 220 Hz to 1 kHz is so low that the noise emission cannot be minimized, so a

47、silencing air cleaner with a h</p><p>　　Initial design of the silencing air cleaner </p><p>　　If there is sufficient space, a complex structure can be assigned to minimize the intake noise emiss

48、ion. So we must make good use of the limited space. In this work CAD software Pro/E was used to envelop the rest of the space of the other automotive components in the engine compartment. Then the total air cleaner volum

49、e required is obtained from the enveloped space. The next step is to choose appropriate silencer units and their dimensions. Considering the effect of air cleaning, two requirement</p><p>　　The overall acous

50、tic behavior is a summation of the behavior of all constituent components of the three chambers. In order to provide a wide bandwidth of continuous attenuation spectrum, the attenuation minimum in their individual contri

51、butions should not occur simultaneously. In order to investigate the individual acoustic performance of the three chambers, the integrated air cleaner was separated into three parts, one of which is a silencer unit of ex

52、pansion chamber, just at the place of the t</p><p>　　In the initial design, the external geometrical dimension is decided, and silencer unit with a rough dimension is chosen. While the position of the baffle

53、s and the radius of the four holes in the second baffle can be varied to achieve better acoustic performance. </p><p>　　Noise emission prediction </p><p>　　Until now, we have accomplished total

54、design of the silencing air cleaner. In order to make a comparison with the original, prediction of the noise emission was carried out. </p><p>　　To verify the practical performance of the redesigned air cle

55、aner, the sound pressure at the engine intake port was measured at full throttle with engine speeds at 5200 r/min at engine test bed as the boundary condition or noise source of the original and the redesigned air cleane

56、r, then predicting the noise emission from the inlet of the air cleaner. </p><p>　　When measuring this sound pressure, the air cleaner was removed, and the engine noise was shielded off. In addition, due to

57、the difficulties in measuring the pressure at the engine intake port be- cause of the air flow influence on noise signals and the induced microphone disturbance that deteriorate the engine performance, the measurement lo

58、cation of the microphone was at the place 200 mm to the intake port, and at 45 to the normal of the intake port section . The boundary condition applied at </p><p>　　The sound pressure of the point P0 at the

59、 axis of the intake port is the maximum compared to the other points with the same distance to the center of the intake port section O.</p><p>　　EXTRA METHOD TO MINIMIZE SOUND POWER</p><p>　　One

60、 potential problem in using the previous layout is that at the frequency of 173 Hz the level of sound power emitted from air cleaner's inlet is not as low as that of other frequency bands. The vacant space around the

61、 pipe connecting the air cleaner and the engine intake port suggests some other possible improvements of the air cleaner system. This paper uses a bypass pipe to achieve this goal.</p><p>　　Increasing of TL

62、at frequency of around 173 Hz being the goal determines that dimension Ld=980 mm. Compare the predicted acoustic performance between the previous layout with no change on pipe and the present layout with flexible bypass

63、pipe. The acoustic performance of the bypass pipe layout improved dramatically at frequency of around 173 Hz, and at frequency of 519 Hz, corresponding roughly to thrice of half wavelength, the TL of bypass pipe layout i

64、ncreased lightly, as expected.</p><p>　　The resulting sound power level is illustrated . It can be seen that sound power level of the without-accessory air cleaner at 173 Hz is the highest, while that of the

65、 with-bypass-pipe air cleaner at this frequency is greatly decreased. The overall sound power level from 0 to 1 kHz, for the without-bypass-pipe air cleaner is 110.2 dB, and for the with-bypass-pipe air cleaner is 105.0

66、dB.</p><p>　　Note that the engine sound power level without intake system noise from experimental testing is 112.2 dB, and the silencing air cleaner with bypass pipe is 105.0 dB, so the redesigned silencing

67、air cleaner feasibly reduced the overall engine noise by minimizing the intake system noise.</p><p>　　CONCLUSION</p><p>　　This paper reports the designing of a BEM-aided silencing air cleaner.Du

68、ring the initial design, based on the acoustic theory and the requirements and considering the constraint of space, the total air cleaner volume and the rough internal dimensions of the air cleaner were determined. After

69、 which an effective method was applied to improve the acoustic performance at frequency of 173 Hz.</p><p>　　The use of the boundary element method to help in acoustical engineering design is increasing rapid

70、ly.The study results in this paper provided guidelines for engineering application of silencing air cleaner.</p><p>　　Flow effect was not considered in this study.Although the mean flow may not have signific

71、ant effect on the acoustic performance, it may have some effects on the air cleaning performance. The effect of filter paper was ignored, although it may influence the acoustic performance of the air cleaner at high freq

72、uency. Future study should include the flow effect on the air cleaning and the influence of the filter paper on the acoustic performance at high frequency.</p><p><b>　　Reference</b></p>&l

73、t;p>　　Bilawchuk, S., Fyfe, K.R., 2003. Comparison and implementation of the various numerical methods used for calculating transmission loss in silencer systems[J]. Applied Acoustics, 64:903-916.</p><p>　

74、　Davies, P.O.A.L., 1996. Piston engine intake and exhaust system design[J]. Journal of Sound and Vibration,190:677-712.</p><p>　　Wu, T.W., Cheng, C.Y.R., Tao, Z., 2003. Boundary element analysis of packed si