本文選題：調(diào)節(jié)閥　切入點(diǎn)：流致振動(dòng)噪聲　出處：《華東理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：調(diào)節(jié)閥在工業(yè)管路系統(tǒng)中應(yīng)用十分廣泛,是管路系統(tǒng)的主要噪聲源之一。內(nèi)部湍流流動(dòng)產(chǎn)生的流體動(dòng)力學(xué)噪聲(流致噪聲)是調(diào)節(jié)閥噪聲的主要成分。相關(guān)研究表明,在大型管道系統(tǒng)的調(diào)節(jié)閥附近,其噪聲可高達(dá)100多分貝,導(dǎo)致至少兩個(gè)方面的潛在危害：一方面是在此工作環(huán)境下的工作人員的身心健康；另一方面,噪聲的產(chǎn)生必然伴隨著劇烈的振動(dòng),這加劇了調(diào)節(jié)閥及其鄰近管路的損壞,使工業(yè)生產(chǎn)及人員安全面臨巨大的風(fēng)險(xiǎn)。隨著1997年我國(guó)《中華人民共和國(guó)環(huán)境噪聲污染防治法》的頒布,環(huán)境噪聲污染的防治和生活環(huán)境改善要求的提高,對(duì)調(diào)節(jié)閥產(chǎn)生的噪聲進(jìn)行深入研究以有效地對(duì)其進(jìn)行控制,是十分重要而有意義的課題。本文以熱力發(fā)電機(jī)組中的一種最小流量調(diào)節(jié)閥為研究對(duì)象,由內(nèi)而外地計(jì)算了其在內(nèi)部湍流作用下使得閥門壁面結(jié)構(gòu)振動(dòng)進(jìn)而產(chǎn)生的外部噪聲。閥門外部噪聲的計(jì)算考慮了流致振動(dòng)噪聲產(chǎn)生的兩重機(jī)理,即聲壁面壓力脈動(dòng)AWPF及湍流壁面壓力脈動(dòng)TWPF,并分析了二者在不同頻率段的作用效果。首先采用LES/Lighthill聲類比混合計(jì)算方法計(jì)算得到調(diào)節(jié)閥內(nèi)部聲場(chǎng),并提取內(nèi)壁面處的聲壓即聲壁面壓力脈動(dòng)作為流致振動(dòng)噪聲的第一種激勵(lì),再?gòu)恼{(diào)節(jié)閥內(nèi)部非穩(wěn)態(tài)流場(chǎng)中直接提取內(nèi)壁面處的湍流脈動(dòng)壓力即湍流壁面壓力脈動(dòng)作為流致振動(dòng)噪聲的第二種激勵(lì)。然后將兩種激勵(lì)加載到調(diào)節(jié)閥外部流致振動(dòng)噪聲計(jì)算的聲振模型中,計(jì)算得到其外部聲場(chǎng),并分析外部監(jiān)測(cè)點(diǎn)的聲壓級(jí)頻譜曲線。分析結(jié)果表明：調(diào)節(jié)閥外部某位置的聲壓級(jí)是兩種噪聲產(chǎn)生機(jī)理共同作用的結(jié)果,在800Hz以下的低頻段,湍流壁面壓力脈動(dòng)單獨(dú)作用下的聲壓級(jí)較大,而在800Hz以上的頻率段,聲流壁面壓力脈動(dòng)單獨(dú)作用下的聲壓級(jí)較大,且二者共同作用下的聲壓級(jí)均與較大者接近。通過比較調(diào)節(jié)閥內(nèi)、外聲場(chǎng)的監(jiān)測(cè)點(diǎn)聲壓級(jí)頻譜曲線,得出結(jié)論：調(diào)節(jié)閥外部聲場(chǎng)產(chǎn)生的主要原因是其下閥腔部位湍流流場(chǎng)中存在的大尺度漩渦。所以,若要有效降低此調(diào)節(jié)閥的外部噪聲,可以通過破壞該位置湍流流場(chǎng)中存在的大尺度漩渦實(shí)現(xiàn)。結(jié)合國(guó)家自然科學(xué)基金項(xiàng)目中多孔結(jié)構(gòu)的降噪方法,通過對(duì)閥座進(jìn)行結(jié)構(gòu)改造,在調(diào)節(jié)閥下閥腔位置加入多孔結(jié)構(gòu)來破壞此位置存在的大尺度漩渦,以此來降低調(diào)節(jié)閥產(chǎn)生的噪聲。最終通過計(jì)算對(duì)比結(jié)構(gòu)改造前后的調(diào)節(jié)閥內(nèi)部流場(chǎng)、內(nèi)部聲源、內(nèi)部聲場(chǎng)、外部聲場(chǎng),證實(shí)了此降噪方案的可行性。
[Abstract]:The control valve is widely used in the industrial pipeline system and is one of the main noise sources in the pipeline system. The hydrodynamic noise (fluid-induced noise) generated by the internal turbulent flow is the main component of the regulating valve noise. In the vicinity of a control valve in a large pipeline system, the noise can be as high as more than 100 decibels, resulting in at least two potential hazards: on the one hand, the physical and mental health of the staff working in this environment; on the other hand, The noise must be accompanied by violent vibration, which exacerbates the damage to the regulating valve and its adjacent pipes. With the promulgation of the Law of the people's Republic of China on Prevention and Control of Environmental noise pollution in 1997, the prevention and control of environmental noise pollution and the improvement of living environment are required. It is very important and meaningful to study the noise produced by the regulating valve in order to control it effectively. In this paper, a kind of minimum flow regulating valve in the thermal generator set is taken as the research object. The external noise caused by the vibration of the valve wall structure under the action of internal turbulence is calculated from the inside out. The calculation of the external noise of the valve takes into account the double mechanism of the fluid-induced vibration noise. That is, acoustic wall pressure pulsation (AWPF) and turbulent wall pressure pulsation (TWPF), and their effects at different frequencies are analyzed. Firstly, the internal sound field of the control valve is calculated by using LES/Lighthill acoustic analogy mixing calculation method. The sound pressure at the inner wall is extracted as the first excitation of the fluid-induced vibration noise. The turbulent pulsation pressure at the inner wall is extracted directly from the unsteady flow field of the regulating valve, that is, the turbulent wall pressure pulsation as the second excitation of the flow-induced vibration noise. Then the two kinds of excitation are loaded into the external flow-induced vibration of the regulating valve. In the acousto-vibration model of dynamic noise calculation, The external sound field is calculated and the spectrum curve of sound pressure level is analyzed. The results show that the sound pressure level at a certain position outside the control valve is the result of the interaction of two kinds of noise generation mechanisms, and the frequency range below 800 Hz is low frequency. The sound pressure level of turbulent wall pressure pulsation is larger than that of the acoustic flow wall pressure pulsation in the frequency range above 800 Hz, and the sound pressure level is larger under the single action of the wall pressure pulsation on the turbulent wall. And the sound pressure levels under the combined action of both are close to those of the larger ones. By comparing the spectrum curves of the sound pressure levels at the monitoring points inside and outside the regulating valves, It is concluded that the main cause of the external sound field of the regulating valve is the large scale swirl in the turbulent flow field in the lower valve cavity. Therefore, if the external noise of the regulating valve is to be effectively reduced, It can be realized by destroying the large scale vortex existing in the turbulent flow field in this position. Combining with the noise reduction method of the porous structure in the project of National Natural Science Foundation of China, the valve seat can be reconstructed by means of structural modification. In order to reduce the noise produced by the control valve, the porous structure is added to the position of the valve cavity under the control valve to destroy the large scale vortex in this position. Finally, the internal flow field, the internal sound source and the internal sound field of the control valve before and after the structural modification are calculated and compared. The external sound field proves the feasibility of the noise reduction scheme.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TH134

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