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  本文選題：貫流風(fēng)機(jī) + 多孔結(jié)構(gòu)��； 參考：《華東理工大學(xué)》2012年碩士論文

【摘要】：近年來貫流風(fēng)機(jī)的氣動(dòng)性能與噪聲問題備受關(guān)注。本文以一種使用多孔蝸舌的貫流風(fēng)機(jī)為主要研究對(duì)象,結(jié)合實(shí)驗(yàn)測(cè)量與數(shù)值模擬方法對(duì)其內(nèi)部流場(chǎng)與氣動(dòng)噪聲開展了研究。 使用低壓高頻響壓力傳感器和四通道動(dòng)態(tài)壓力測(cè)試系統(tǒng)測(cè)量三種轉(zhuǎn)速下風(fēng)機(jī)內(nèi)部四個(gè)監(jiān)測(cè)點(diǎn)的脈動(dòng)壓力,以分析噪聲源的特性。通過對(duì)脈動(dòng)壓力數(shù)據(jù)的Fourier變換,進(jìn)行頻譜分析得到流場(chǎng)中噪聲源的的頻譜信息。結(jié)果表明風(fēng)機(jī)出口與蝸舌處的脈動(dòng)壓力幅值最大,為主要的噪聲源。另外,頻譜特性顯示多孔蝸舌方案對(duì)于550～2500Hz頻率段噪聲有明顯的改善作用。 采用大渦模擬數(shù)值方法,對(duì)比研究了不同蝸舌方案的貫流風(fēng)機(jī)內(nèi)流特征。三維與二維數(shù)值模擬結(jié)果表明葉輪進(jìn)氣段及風(fēng)機(jī)出口處存在大量多尺度的旋渦運(yùn)動(dòng),且蝸殼后壁面易形成與葉輪旋轉(zhuǎn)方向相反的大尺度渦團(tuán)。通過監(jiān)測(cè)點(diǎn)的脈動(dòng)壓力頻譜分析,其氣動(dòng)噪聲呈現(xiàn)寬頻特性,且壓力脈動(dòng)特性與實(shí)驗(yàn)結(jié)果良好吻合。 為了研究多孔介質(zhì)對(duì)于流體發(fā)聲的影響與作用機(jī)理,本文在多孔介質(zhì)流動(dòng)理論的基礎(chǔ)上對(duì)Powell渦聲方程修正,提出一種包含多孔介質(zhì)和自由空間的Powell渦聲方程通用形式,其中經(jīng)典的Powell渦聲方程可視為修正方程孔隙率ε=1的特殊情況。通過方程聲源項(xiàng)的求解,對(duì)修正方程進(jìn)行了初步的探討。結(jié)合大渦模擬結(jié)果,采用FW-H積分求解方程對(duì)貫流風(fēng)機(jī)的遠(yuǎn)場(chǎng)噪聲進(jìn)行了預(yù)測(cè),比較了風(fēng)機(jī)蝸舌改造前后各聲源面的噪聲變化情況。 最后,針對(duì)多翼離心風(fēng)機(jī)出口流量的不均勻性,提出并設(shè)計(jì)了一種導(dǎo)流板結(jié)構(gòu)以調(diào)節(jié)出口流場(chǎng)。為了驗(yàn)證方案的可行性,本文對(duì)內(nèi)部流場(chǎng)和出口總壓升進(jìn)行了分析,結(jié)果表明該方案能夠滿足設(shè)計(jì)要求。
[Abstract]:In recent years, the aerodynamic performance and noise of tubular fan have attracted much attention. In this paper, the flow field and aerodynamic noise of a tubular fan with a porous cochlear tongue are studied by means of experimental measurement and numerical simulation. In order to analyze the characteristics of noise source, the pulsating pressure of four monitoring points in the fan was measured by using a low pressure high-frequency pressure sensor and a four-channel dynamic pressure measurement system. The spectrum information of the noise source in the flow field is obtained by the Fourier transform of the pulsating pressure data. The results show that the pulsating pressure amplitude at the outlet of fan and cochlea tongue is the largest and is the main noise source. In addition, the spectral characteristics show that the porous cochlear tongue scheme can significantly improve the 550~2500Hz frequency segment noise. In this paper, the characteristics of the inner flow of the tubular fan with different cochlear tongue schemes are compared by using the large eddy simulation method. Three-dimensional and two-dimensional numerical simulation results show that there are a large number of multi-scale vortex motion in the inlet section of the impeller and the outlet of the fan, and large scale vortex clusters are easily formed on the back wall of the volute, which is opposite to the rotating direction of the impeller. Through the spectrum analysis of the pulsating pressure at the monitoring point, the aerodynamic noise shows a wide frequency characteristic, and the pressure pulsation characteristic is in good agreement with the experimental results. In order to study the effect and mechanism of porous media on the sound of fluid, the Powell vortex-acoustic equation is modified on the basis of the flow theory of porous media, and a general form of Powell vortex-acoustic equation including porous media and free space is proposed. The classical Powell vortex-acoustic equation can be regarded as a special case of modified equation porosity 蔚 ~ (1). By solving the sound source term of the equation, the modified equation is preliminarily discussed. Combined with the results of large eddy simulation, the far-field noise of the tubular fan was predicted by using the FW-H integral solution equation, and the noise changes of each sound source plane before and after the reconstruction of the fan's cochlear tongue were compared. Finally, aiming at the inhomogeneity of the outlet flow of multi-wing centrifugal fan, a flow guide plate structure is proposed and designed to adjust the outlet flow field. In order to verify the feasibility of the scheme, the internal flow field and total outlet pressure rise are analyzed in this paper. The results show that the scheme can meet the design requirements.
【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】：2012
【分類號(hào)】：TH432

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