外文翻译一个用于内燃发动机进气系统的无声空气滤清器的虚拟设计及性能预测

1、个用于内燃发动机进气系统的无声空气漉消器的虚拟设计及性能预溜一个用于内燃发动机进气系统的无声空气滤清器的虚拟设计及性能预测HAO Zhi-yong, JIA Wei-xin FANG Fang(College of Mechanical and Energy Engineenng, Zhejiang Umx-crsity; Hangzhou 310027, China)(Tianjin Internal Combustion Engine Research Institute, Tianjin Umveisity, Tianjin 300072,China)E-皿山 haozy, jiawxR

2、eceived Jan. 17, 2005, revision accepted May 12,2005摘要：本文报道中采用低噪声内燃机进气系统开发的虚拟设计方法结介作者的研究结果。由 此产生的高的通过噪声水平高于在全油门的立法目标时，发动机转速为5200r/min需要边界 元辅助设计任务，按照典型的进气系统的设计与开发过程。在最初的设计中，基于声学理论 和要求并考虑空间发动机室中的约束，总体积和粗糙的内部尺寸的测定。在详细设计阶段, 确定了空气滤清器的确切的内部尺寸，和一个有效的方法应用于低频声性能的改善。预测表 明，进化系统的声功率达到最小的进气系统噪声降低发动机整体噪声。关键词：虚拟设计

3、;声学性能;沉默的空气滤清器;边界无法（BEM）1简介一个原函数的进气系统的主要功能是首先有效信道的新鲜空气对发动机进 气噪声，其次是减少排放。有一些现有方法的发展来提高进气系统设计一个更现 实的方法。这些目标包括：更有效的消声性能，达到降低噪声一方面口益严峻的 立法目标，优化发动机的性能和燃油经济性伴随着车辆质量的提高。一个典型的程序，用于汽车发动机进气系统的设计与开发过程中。设计过程 包括仔细调谐的匹配这些发动机运行和呼吸特性的影响，污染物排放优化影响噪 声进气系统的所有组件，性能和经济性。从现有的或符号的系统布局，进行各种 性能综合评价。这种信息可能会被适当地使用评估的各种设计目标当前系

4、统的性 能，通过对其构成要素进行适当修改，为系统优化设计提供理论基础。边界元法广泛应用在进气和排气系统的设计可以用来计算内部，外部，或两 个领域的同时，只要求的空气滤清器可分为元素的周长：和施加边界条件的缓解 是另一个吸引。在本文中，边界元法是用来预测的空气滤清器的传输损耗和噪声 排放。原来的进气系统设计中出现的水平高于在全油门和发动机转速在520017111m 的噪声信号的频谱特性的立法目标噪声高通连接通常是由离散的音调，对发动机 的点火频率是173赫兹对应5200 t/niin内联四缸四冲程发动机谐波相关的广泛的 序列占主导地位。在许多情况下，从主源的声能量体分布较低的频率成分，可能 是难

5、以控制的。因此，本文提到的频率范围是从0到1千赫。在这个频率范围内， 如灌纸对集成系统的声学性能的影响是微不足道的，所以滤纸不顾。噪音是从空 气滤清器入口喷出，与空气滤清器系统出口连接到发动机的进气。所以在发动机 空气滤清器的出入口压力为边界兀法的边界条件。一个降噪通常有两部分功能的传统进气系统：空气滤清消声器。由于空间发 动机室中的约束，重新设计的空气净化器结合清洗和沉默效果。在这项工作中， 一个所谓的沉默的空气滤清器进行了重新设计，几何结构确定的预测TL和边界 元的声功率发射。同时，为了尽量减少在较低频率的进气系统的声功率，旁通管 被添加到空气输送管。所产生的声学性能分析表明，该方法最大限

6、度地减少对进 气系统噪声降低发动机整体噪声的目标是可行的。2无声空气滤清器的设计2.1 原装空气滤清器的评价这种原始的空气滤清器的清洁设计主要关注减少噪音排放。空气滤清器的出 口段是一个单位的速度振幅。计算T1时，空气滤清器的出口部分给出了单元速度振幅模型的声源，所有 其他的表面被建模为“声学硬”默认情况。出口部分的声功率可以从公式计算。 所有后续的TL的预测具有相同的边界条件。预测的空气滤清器性能。在发动机进气道的声功率级是显示图的噪声源信号 峰值为173赫兹的频率谐波相关的发动机点火。由于发动机燃烧分布式低频率从 100赫兹到800赫兹之间的声音能量堆积太高，传输损耗在220赫兹到1 T赫

7、兹 的频率范围内是如此之低，噪声排放不能最小化，所以一个沉默的空气滤清器具 有较高的TL 200赫兹到1赫兹的要求。2.2 无声空气滤清器的初步设计如果有足够的空间，一个复杂的结构，可以被分配到降低进气噪声排放。因 此我们必须充分利用有限的空间。在这项工作中用CAD软件或Pio/E进行包络 发动机室中的其他汽车部件的剩余空间。然后从笼罩空间获得的总体积所需的空 气滤清器。下一步是选择合适的消声器单元和它们的尺寸。考虑空气净化效果， 必须满足两个要求：（1）空气流量应等于或超过原通量值；（2）过滤面积不能降 解。在这要求的基础上，对消声器单元理论初步确定开采布局。空气滤清器是由 两块隔板分隔成三

8、个膨胀室，右挡板的中间有个洞，左挡板有四个孔的四角，滤 纸放在中间膨胀室的中心。因为这空气滤清器的复杂性，孔的直径大于原来的。 第二个要求是在第一挡板孔的直径和长度的二室，让过滤面积等于原来的，然后 第二膨胀室的长度可以确定。所以空气滤清器的几何结构是由两个变量确定的。整体的声学行为是三室的所有组成元件的行为总和。为了提供连续衰减谱宽 的带宽，在他们个人的贡献衰减最小不应同时发生。为了调查三室个人的声学性 能，综合空气滤清器被分成三个部分，其中之一是扩张室消声器单元，只是在两 挡板的位置。边界元法的运行进行计算的三个个体的声学性能。第一室具有高和 连续在300-1000赫兹频段的衰减，并在40

9、0-800赫兹的频率范围的第：腔室具 有高衰减的声学性能梢微比第一个更糟。第三室性能最差，但在约230赫兹的频 率，其中第一和第二室的最小衰减，它具有更高的衰减，从而为第一和第二部分 提供的补偿效果。同时，在更高的频率，第三部分可能是良好的声学性能，这是 在这个图中没有说明。请注意，这种单一的部分还介绍了之间存在不确定性，声 相互作用，即使他们的个人表现，可以适当地代表或建模。明确的单一部分的声 学性能的初始设计提供了重要的信息。在某些领域的变化，集成系统在获得最佳 的声学性能的详细设计的边界元法计算。在最初的设计，外部几何尺寸已确定，并且已用粗糙的尺寸单位选择消声器。 在挡板的位置和四个孔的

10、第二隔板半径可以改变，以达到更好的声学性能。2.3 噪声排放预测直到现在，我们已经完成了总体设计的无声空气滤清器。为了与原来的做一 个比较，的噪声辐射进行了预测。为了验证设计的空气滤清器的实用性能，在5200转/分钟在发动机试验台作 为原始和重新设计的空气滤清器边界条件或噪声源在全油门和发动机转速的测 量是在发动机进气道的声压，进而预测噪声排放进空气滤清器。测量声压时，空气滤清器和发动机的噪音屏蔽掉。此外，由于在发动机的进 气端口测量压力引起的噪声信号的空气流的影响和诱导麦克风干扰，恶化的发动 机性能的困难，麦克风的测量定位在200亳米到进气端口。边界条件施加在空气 滤清器系统出口处应在测量位

11、置上面提到的基于声学理论从噪声信号中提取的。在进气道轴的点P的声压与最高的相比，在相同的距离其他点的入口段中 心。2.4 尽减少额外声功率的方法在使用以前的布局的一个潜在的问题是在173赫兹的声音从空气滤清器的 进气发射功率水平，频率不为其他频段的低。空置面积在管道连接空气滤清器与 发动机的进气口表明其他一些可能的空气清洁系统的改进。本文采用旁路管来实 现这一目标。提高TL在大约173赫兹的频率为目标确定尺寸LD = 980毫米。比较预测 的声学性能上的布局与管和柔性分流管的布局现状没有改变。旁路管道布置的声 学性能显著提高在大约173赫兹的频率和519赫兹的频率的三倍，大致对应半波 长，预计

12、旁路管道布置TL轻度上升。可以看出，无辅助空气净化器在173赫兹是最高的声功率级，而旁路管空气 净化器在这个频率大大降低。总声功率水平从0到1赫，为无旁路管空气清洁 器110.2分贝，并为旁路管空气清洁器105分贝。请注意，引擎声功率级不从实验检测进气系统噪声112.2分贝和无声的旁通 管的空气清洁器105分贝，所以重新设计的无声空气滤清器切实降低发动机整体 噪声为最小的进气系统噪声。3结论本文报道了一个边界元法的辅助设计无声空气滤清器。在最初的设计中，基 于声学理论和要求并考虑空间约束，进行空气滤清器总体积、空气滤清器的粗糙 的内部尺寸的测定。之后，一个有效的方法应用到173赫兹的频率的声学

13、性能的 改善。边界元法的声学工程设计使用帮助迅速增加。本文的研究结果为无声空气滤 清器的工程应用指南。流量的影响在本研究中并没有考虑。虽然平均流将不会对声学性能影响显 著，这可能对空气净化性能的影响和滤纸的影响被忽略，尽管它可能会影响在高 频率的空气滤清器声学性能。未来的研究应包括在高频率上的空气净化和过滤纸 上的声学性能影响的流动的影响。5一个用于内燃发动机进气系统的无声空气灌消器的虚拟设计及性能预测参考文献1 Bilau chuk, S.，Fyfe, K.R., 2003. Companson and iniplementation of the vanous numerical meth

14、ods used for calculating transmission Loss m alencer systemsJ. Applied Acoustics, 64 903-916.2 Davies, P.O.A.L., 1996. Piston engine intake and exhaust system designJ. Journal of Sound and Vibration,190 677-712.3 Wu, T.W, Cheng, C YR, Tao, Z,，2003. Boundary dement analysis of packed silencers with p

15、rotective cloth and embedded thin surfacesJ. Journal of Sound and Vibration,261 1-15.6个用于内燃发动机进气系统的无声空气漉清器的虚拟设计及性能预测Virtual design and performance prediction of a silencing aircleaner used in an LC. engine intake systemHAO Zhi-yong, JIA Wei-xui FANG Fang(College of Mechanical and Energy Engineering,

16、 Zhejiang University; Hangzhou 310027, China)(Tianjin Internal Combustion Engine Research Institute, Tianjin Univeisity, Tianjin 300072,China)E-mail: haozy, jKHvxReceived Jan. 17, 2005, revision accepted May 12,2005Abstract： This paper reports results of the authors* studies on the virtual design me

17、thod used in the 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/mn necessitated a BEM-aided redesign task following the typical process of design and development of an

18、intake system During the miUal design, based on the acoustic theory and the requirements and considenng the constraint of space in rhe engine compartment, total volume and rough mteraal dimensions were determined. During the detailed design, the exact internal dimensions of the air cleaner were dete

19、nmned, and an effective method was applied to improve the acoustic perfwmance at low frequency. The predicted sound power of the intake system indicated that the objective of reduang the overall engine noise by nMnunizing intake system noise 3as achieved.Key words: Virtual design, Acoustic perfonmnc

20、e, Silencing air cleaner, Bouiidarv element method (BEM)INTRODUCTIONThe primary function of an The primary function or an intake system is firstly to efficiently channel fresh air to the engine, and secondly to numiiuze intake noise emissions. There are a number of current approaches for developing

21、a more realistic method to improve intake system design. The objectives include more effective silenang performance to meet increasingly severe legislative targets for reduced noise on the one hand, with optimized engine perfornxmce and fuel economy accompanied by improvements in vehicle quality on

22、the other handA typical procedure followed dunng 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 noise emission with optimized matching of these to the engine 7一个用于内燃发动机进气

23、系统的无声空气灌消器的虚拟设计及性能预测operational and breathing charactensues influenang pollutant emission, perfomnnce and economy. Starting with an existing or notational system Layout, an integrated assessment of the various performances is performed. This infonmtion may then be used appropriately to assess curren

24、t system performance in terms of the various design objectives, to provide rational basis for systeimtic optimization of the design by implementing appropriate modifications to its constituent elements.The BEM widely used in the design of intake and exhaust system can be used to compute the interior

25、, exterior, or both fields simultaneously and only requires that the perimeter of the air cleaner be divided into elements,and the ease in imposing the boundary condition is another attractioa In this paper BEM is used to predict the air cleaner's transmission loss and noise emission.The redesig

26、n 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 speed around 5200 r/rnm. The spectral characteristics of the noise signal are normally dominated by an extensive sequence of discrete tones that are lia

27、rnionically related to the engine firing frequency which is 173 Hz corresponding to 5200 r/nun and the inline 4-cyknder 4-stroke engine. In anny instances the bulk of the acoustic energy from the primary source is distnbuted among the lower frequency* components that may be difficult to control. Thu

28、s frequency range this paper referred to is from 0 to 1 kHz. In this frequency range, as the uifluence of filter paper on acoustic perfonimice of integrated system is trivial, so filter paper is disregarded. The noise is emitted from the inlet of the air cleaner, and die outlet of the air cleaner sy

29、stem connects to the inlet of the engine. So the pressure at the inlet of the engine or the outlet of rhe air cleaner is the boundary condition for the BEM.Traditional intake system with a function of noise reduction normally has two parts air deaner and silencer. Due to the constraint of space in t

30、he engine compartment, the redesigned air cleaner combines the effect of cleaning and sdenang. In this work, a so-called silenang air cleaner was redesigned, geometrical strucnire deteranned by predicted TL and sound pove【 emission by BEM. Also, in order to minimize the sound power of rhe intake sys

31、tem at low frequency, a bypass pipe was added to the air-channeling pipe. Analysis of the resulting acoustic perfonmnee showed tint the method is feasible for the goal of educing the overall engine noise by mnimizing the intake system noiseDESIGN OF THE SILENCING AIR CLEANEROriginal air cleaner eval

32、uationThis onginal air cleaner of mainly cleaning design paying little attention to iniiunnzing noise emission is its BEM meshDuring calculation of TL, the outlet section of the air cleaner is given a unit veloaty amplitude to model a sound source, all other surfaces are modeled as "acousticall

33、y 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 condRioaThe predicted air cleaner performance is shown The sound po er level at the engine intake port is shown . The peaks of the noise source

34、 signal are harniomcally related to the engine firing frequency of 173 Hz. As the bulk of the acoustic energy from 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 em

35、ission cannot be mimmized, so a silencing air cleaner with a higher TL at 200 Hz to 1 kHz is required.Initial design of the silencing air cleanerIf there is sufficient space, a complex structure can be assigned to minimize the intake noise emission. So we must make good use of the limited space. In

36、this work CAD software Pro/E was used to envelop the rest of the space of the other automotive components m the engine compartment. Then the total air deaner volume required is obtamed from rhe enveloped space. The next step is to choose appcopnate silencer units and their dimensions. Considering di

37、e effect of air deaiung, two requirements must be satisfied (1) The air flux should equal to or exceed the value of original flux, (2) The filtering area must not be degraded. Based on the requirements and the theory of the silencer units, an initial layout was deter- mined. The air cleaner is separ

38、ated into three expansion chambers by two baffles, the nghr baffle has a hole in the middle, and the Left baffle has four holes at its four comers respectively The filter paper is placed at the center of the middle expansion chamber. The diameter of the hole in rhe right baffle is detemuned by the f

39、irst requiremenr, because of the complexity of this air cleaner, the diameter of the hole is bigger than the cnginal one. The second requirement relates to the diameter of the hole in the first baffle and the length of the second chamber, after letung the filtering area be equal to the original one,

40、 then the length of rhe second expansion chaniber can be determined. So the geometncal structure of the air cleaner is set by two variables.The overall acousuc behavior is a sumimtion of the behavior of all constituent components of the tliree chambers. In order to provide a wide bandwidth of contin

41、uous attenuation 叩ectru1nl the attenuation minimum in their individual contnbutions should not occur simultaneouslv In Jorder to investigate rhe individual acoustic perfofinance of the three chambers, the integrated air cleaner was separated into three parts, one of which is a silencer unit of expan

42、sion chamber just at the place of the two baffles. BEM run was performed to calculate the individual acoustic perfoiLiimce of the three chambers. The first chamber has lugh and continuous attenuation at die frequency" band 比 300-1000 Hz, and the acoustic performance of the second chamber which

43、has higli attenuation at the frequency range of 400-800 Hz is a shade worse than that of the first one. The rlurd chamber has the worst performance, but at the frequency- of about 230 Hz, where the first and the second chamber have minimal attenuation it has higher attenuation, thus providing compen

44、sation effect for the first aod second parts. Also, at higher frequency, the third pan possibly represents good acoustic performance, which is not illustrated in this figure.Note that the acoustic interactions that exist between such single parts also introduced unccnainties, even when their individ

45、ual perfonmnee can be appropnately represented or modeled. Clear understanding of the acoustic performance of the single part gives significant inforimtion for initial design . The integiated system with changes in some areas is calculated by the method of BEM in rhe detailed design to gain the best

46、 acoustic performance.In the initial design, the external geometncal dimension is decided, and silencer unit with a rough dimension is chosen. While the position of the baffles and the radius of the four holes in the second baffle can be varied to achieve better acoustic perfomnnce.Noise emission pr

47、edictionUntil noxx; we have accomplished total design of the silencing air deaner. In order to make a companson with the onginal, prediction of the noise emission was earned out.To verity the practical perfomunce of the redesigned air cleaner, the sound pressure at the engine intake port was measure

48、d at full throttle with engine speeds at 5200 r/min at engine test bed as die boundary condition or noise source of the original and the redesigned air cleaner, then predicting the noise emission from the inlet of the air cleaner.When measuiing this sound pressure, the air cleaner was removed, and t

49、he engme noise was shielded off. In addition, due to the difficulties in measunng the pressure at the engine intake pon be- cause of the air flow influence on noise signals and the induced microphone disturbance that detenorate the engine performance, rhe measurement Location of the microphone was a

50、t the place 200 min to the intake port, and at 45 to the nonnal of the intake port section . The boundary condition applied at the outlet of the air cleaner system should be extracted from the noise signals at the measurement Location mentioned above based on acoustic theorvThe sound pressure of the

51、 point P0 at die axis of the intake port ls the maximum compared to the other points with the same distance to the center of the intake pon section O.EXTRA METHOD TO MINIMIZE SOUND POWEROne potential problem in using the previous layout is that at the frequency" of 173 Hz die Level of sound poe

52、r emitted from air cleaners inlet is nor as low as that of other frequency bands. The vacant space around the 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.Increasing o

53、f TL at frequency of around 173 Hz being the goal detemuncs that dimension Ld=980 nim. Compare the predicted acoustic performance between the previous layout with no change on pipe and the present layout with flexible bypass pipe. The acousttc performance of the bypass pipe layout improved draimtica

54、lLy 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 increased Lightly, as expected.The resulung sound power level is illustrated . It can be seen that sound poA'er Level of the without-accessory air cleaner at 173 Hz is the highest, while that of the uith-bypass-pipe air cleaner ar this frequency is greatly decreased. The overall sound pove【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 dB.Note that