本文選題：抗性消聲器　切入點(diǎn)：局部結(jié)構(gòu)　出處：《山東大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著工業(yè)產(chǎn)能的飛速提高,以機(jī)動車輻射噪聲為主的環(huán)境噪聲成為影響城鄉(xiāng)居民工作和生活質(zhì)量的突出問題,發(fā)動機(jī)排氣噪聲作為機(jī)動車輛整車噪聲的主要組成部分無疑是噪聲控制的重點(diǎn)。針對內(nèi)燃機(jī)排氣噪聲的控制,目前切實(shí)可行而又簡單有效的方法是在發(fā)動機(jī)排氣口處安裝消聲器；消聲器在發(fā)揮其消音降噪作用的同時(shí),還會對發(fā)動機(jī)的功率特性產(chǎn)生影響,消聲器的消聲效果和其壓力損失之間有很強(qiáng)的約束性,消聲器的壓力損失過大易造成發(fā)動機(jī)功率損失的增加；若能在減小或不改變消聲器壓力損失特性的前提下增加其消聲量,或是調(diào)整其消聲效果較好的頻段與配套發(fā)動機(jī)排氣噪聲中噪聲幅值較大的頻段向吻合,對于消聲器的優(yōu)化改進(jìn)設(shè)計(jì)具有重要意義。 抗性消聲器在工程機(jī)械領(lǐng)域應(yīng)用廣泛,從消聲機(jī)理上來講,它是利用其內(nèi)部結(jié)構(gòu)突變所造成的聲阻抗失配來實(shí)現(xiàn)消聲的,其結(jié)構(gòu)參數(shù)的改變可以調(diào)節(jié)消聲器的消聲頻率范圍和消聲量的大小；同時(shí),氣流的流動速度過大會產(chǎn)生一定的氣動噪聲,而氣流的流動速度又受到氣流通道形狀和大小的影響；所以,調(diào)節(jié)抗性消聲器的結(jié)構(gòu)參數(shù),是協(xié)調(diào)控制其綜合性能,實(shí)現(xiàn)優(yōu)化設(shè)計(jì)的核心。本文中以典型的抗性消聲器為研究對象,分析討論了局部結(jié)構(gòu)參數(shù)因素對傳遞損失、壓力損失和速度場分布的影響特征。 本文首先以簡單的抗性消聲結(jié)構(gòu)為例,對其進(jìn)行局部結(jié)構(gòu)的調(diào)整,研究傳遞損失、壓力損失和速度場分布的變化規(guī)律,結(jié)果表明,通過局部結(jié)構(gòu)的調(diào)整,可以在不改變消聲器壓力損失的情況下,調(diào)節(jié)傳遞損失特性：使消聲頻帶發(fā)生移動,增大傳遞損失幅值,以及增大消聲帶寬；并且,還可以實(shí)現(xiàn)對流場分布和局部氣流速度的調(diào)整。 進(jìn)而,在簡單結(jié)構(gòu)消聲器局部調(diào)整研究的基礎(chǔ)上,以典型的復(fù)雜結(jié)構(gòu)抗性消聲器為例展開了進(jìn)一步的研究,結(jié)果表明內(nèi)插管直徑、橫流穿孔直徑和穿孔布局的調(diào)整,對簡單結(jié)構(gòu)和復(fù)雜結(jié)構(gòu)抗性消聲器的整體性能的影響具有一致性。綜合利用本文研究的相關(guān)結(jié)論,并結(jié)合工程實(shí)踐經(jīng)驗(yàn),對某型復(fù)雜結(jié)構(gòu)抗性消聲器進(jìn)行改進(jìn)設(shè)計(jì),在通過數(shù)值仿真分析得到良好改進(jìn)效果的基礎(chǔ)上,進(jìn)行消聲器性能比較臺架試驗(yàn),結(jié)果表明,改進(jìn)結(jié)構(gòu)相對原消聲器,在壓力損失基本不變的條件下,消聲量有明顯增加。 最后,搭建了消聲器內(nèi)部流場PIV測量系統(tǒng),通過對簡單結(jié)構(gòu)抗性消聲器內(nèi)部流場的試驗(yàn)測量,觀察到了消聲器內(nèi)部的氣流運(yùn)動狀態(tài),同時(shí)也發(fā)現(xiàn)了當(dāng)前測試系統(tǒng)對煙霧粒子濃度和氣流速度的控制有待改進(jìn),改進(jìn)目標(biāo)是實(shí)現(xiàn)二者的協(xié)調(diào)控制,得到不同流速下示蹤粒子分布均勻的氣流,用于流場測量試驗(yàn),以期得到更好的PIV測量效果。
[Abstract]:With the rapid improvement of industrial production capacity, the environmental noise, which is dominated by the radiated noise of motor vehicles, has become a prominent problem affecting the quality of work and life of urban and rural residents. Engine exhaust noise, as the main component of vehicle noise, is undoubtedly the focus of noise control. At present, a feasible and simple and effective method is to install a muffler at the exhaust port of the engine. The muffler will have an impact on the power characteristics of the engine while playing its role of noise reduction. There is a strong constraint between the muffler's noise suppression effect and its pressure loss. The excessive pressure loss of the muffler can easily cause the increase of engine power loss. If the muffler's pressure loss characteristics can be reduced or unchanged, the muffler's noise loss can be increased. Or adjusting the frequency band with better noise suppression effect coincides with the frequency band with larger noise amplitude in the exhaust noise of the matching engine, which is of great significance for the optimization and improvement of the muffler design. The resistant muffler is widely used in the field of construction machinery. In terms of the mechanism of silencing, it uses the acoustic impedance mismatch caused by its internal structure mutation to realize the silencing. The change of the structure parameters can adjust the muffler's noise frequency range and noise quantity, at the same time, the flow velocity of the airflow is too large to produce certain aerodynamic noise, and the flow velocity of the airflow is affected by the shape and size of the airflow channel. Therefore, adjusting the structural parameters of the resistant muffler is the core of coordinated control of its comprehensive performance and optimal design. In this paper, the transmission loss caused by the local structural parameters is analyzed and discussed with the typical resistant muffler as the research object. The influence of pressure loss and velocity field distribution. In this paper, a simple anti-noise structure is first taken as an example to adjust the local structure, and to study the variation law of transmission loss, pressure loss and velocity field distribution. The results show that, by adjusting the local structure, The characteristics of transmission loss can be adjusted without changing the pressure loss of muffler: the frequency band of silencing is moved, the amplitude of transmission loss is increased, and the bandwidth of silencing is increased; and, The flow field distribution and local airflow velocity can also be adjusted. Furthermore, on the basis of the study of local adjustment of simple structure muffler, taking the typical complex structure resistant muffler as an example, the results show that the diameter of the intubation, the diameter of the perforation and the layout of the perforation are adjusted. It has the same effect on the whole performance of simple structure and complex structure resistant muffler. By synthetically using the relevant conclusions of this paper and combining with engineering practice, the design of a complex structure resistant muffler is improved. On the basis of numerical simulation analysis, the performance of muffler is compared with that of the original muffler. The results show that, compared with the original muffler, the silencing capacity of the improved structure is obviously increased under the condition of constant pressure loss. Finally, a PIV measurement system for the internal flow field of the muffler is set up. Through the experimental measurement of the internal flow field of the simple structure resistant muffler, the airflow state inside the muffler is observed. At the same time, it is also found that the control of smoke particle concentration and airflow velocity by the current testing system needs to be improved. The goal of the improvement is to realize the coordinated control between the two, and to obtain a uniform distribution of the tracer particles at different velocities, which can be used in the flow field measurement experiment. In order to obtain better PIV measurement results.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TB535.2

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本文編號：1590021