本文關(guān)鍵詞： 非緊致邊界 氣動噪聲 數(shù)值預(yù)測 散射效應(yīng) 可壓縮流動　出處：《西北工業(yè)大學(xué)》2015年博士論文　論文類型：學(xué)位論文

【摘要】：非緊致結(jié)構(gòu)氣動噪聲問題廣泛地存在于航空航天、工業(yè)生產(chǎn)及交通運(yùn)輸?shù)榷鄠�領(lǐng)域。大型民航飛行器在起飛、降落或飛行階段所產(chǎn)生的氣動噪聲問題尤其嚴(yán)重,因而氣動噪聲的數(shù)值預(yù)測受到普遍的關(guān)注�；旌嫌�(jì)算氣動聲學(xué)(HCAA)方法簡單易行,具有計(jì)算復(fù)雜度低、計(jì)算效率高和成本費(fèi)用低等優(yōu)點(diǎn),被廣泛用于工程實(shí)際應(yīng)用。該方法的基本思路是將流場和聲場分開求解,結(jié)合CFD手段獲得近場流動數(shù)值解,然后通過聲傳播方程計(jì)算遠(yuǎn)場噪聲。其中,Lighthill聲比擬理論思想簡潔且適用性強(qiáng),可以快速求解噪聲傳播。為了研究非緊致結(jié)構(gòu)引起的散射效應(yīng),本文基于Lighthill聲比擬假設(shè)發(fā)展了非緊致結(jié)構(gòu)的氣動噪聲數(shù)值預(yù)測模型,主要研究工作和創(chuàng)新點(diǎn)包括如下幾個方面:(1)基于渦聲理論和壓力分解方法建立了低馬赫流動氣動噪聲的聲壓積分方程,噪聲計(jì)算包括物面散射聲壓計(jì)算和遠(yuǎn)場任意觀察點(diǎn)聲壓計(jì)算兩部分。對低馬赫數(shù)圓柱繞流氣動噪聲進(jìn)行數(shù)值預(yù)測,聲場分布特征與Curle方程一致。考察湍流脈動與噪聲傳播之間的關(guān)系,結(jié)果顯示噪聲隨頻率的變化與湍流脈動的變化趨勢一致。數(shù)值研究表明該方法能夠精確求解低馬赫數(shù)流動氣動噪聲,并且直觀的反映了旋渦與聲波之間的關(guān)系。(2)提出了一種非緊致邊界氣動噪聲輻射散射統(tǒng)一積分計(jì)算方法。該方法將流場脈動量分解為流場數(shù)值計(jì)算捕獲的主要由流體運(yùn)動引起的流動脈動分量和流場計(jì)算未捕獲的主要由噪聲傳播引起的聲學(xué)脈動分量兩部分,基于Lighthill的聲比擬理論和格林函數(shù)波動方法獲得聲學(xué)計(jì)算的統(tǒng)一積分方程。采用二階精度格式進(jìn)行可壓縮流動計(jì)算,通過統(tǒng)一積分方程得到非緊致邊界的散射聲壓,然后求解遠(yuǎn)場任意觀察點(diǎn)的聲壓。對二維、三維圓柱開展氣動噪聲數(shù)值計(jì)算,計(jì)算結(jié)果與文獻(xiàn)結(jié)果吻合。數(shù)值研究表明本文方法能夠減少流場高精度計(jì)算所需的工作量,而且能夠捕獲非緊致邊界的散射效應(yīng),同時能夠模擬可壓縮流動氣動噪聲的聲場特征。(3)針對復(fù)雜結(jié)構(gòu)、包含多個物體的物理模型及振蕩結(jié)構(gòu)的氣動噪聲問題,提出了非緊致可滲透邊界氣動噪聲數(shù)值積分計(jì)算方法。選取包圍所有物體的光滑邊界為可滲透邊界,氣動噪聲計(jì)算包含可滲透邊界散射聲壓計(jì)算和遠(yuǎn)場任意觀察點(diǎn)聲壓計(jì)算兩部分。對圓柱、Rod-Airfoil模型、30P30N翼型開展氣動噪聲數(shù)值計(jì)算,可滲透邊界積分計(jì)算方法獲得的結(jié)果與物面積分計(jì)算方法及文獻(xiàn)結(jié)果吻合。數(shù)值研究表明可滲透邊界氣動噪聲積分計(jì)算方法可以精確模擬非緊致邊界的散射效應(yīng),能夠降低計(jì)算復(fù)雜度,并有助于改善氣動噪聲的數(shù)值計(jì)算效率。(4)為避免飛行器起飛、降落或者低空飛行階段地面邊界散射聲源計(jì)算所需的工作量,結(jié)合鏡像源方法提出了半空間內(nèi)非緊致邊界氣動噪聲數(shù)值積分計(jì)算方法。通過二階精度的DES模型進(jìn)行流動數(shù)值模擬,采用非緊致邊界積分方法進(jìn)行散射聲場計(jì)算。首先,對半空間內(nèi)圓柱、NACA0012翼型及30P30N翼型開展氣動噪聲數(shù)值計(jì)算,結(jié)果表明半空間內(nèi)地面邊界的散射效應(yīng)引起聲場復(fù)雜且劇烈的變化。其次,開展亞音速方腔流動噪聲數(shù)值預(yù)測,計(jì)算結(jié)果與高精度計(jì)算氣動聲學(xué)方法吻合,聲壓級隨頻率呈現(xiàn)逐漸遞減的變化趨勢。數(shù)值研究表明本文方法能夠模擬非緊致邊界和半空間邊界的散射效應(yīng),無需求解地面邊界散射聲源,顯著提高了半空間氣動噪聲的數(shù)值計(jì)算效率。(5)結(jié)合自由空間聲傳播方程,建立了運(yùn)動非緊致邊界時域格林函數(shù)積分方程,借助該方程和Lighthill聲比擬理論可以考慮任意邊界情形的噪聲分布。選取圓柱為研究對象,在圓柱附近放置靜止和運(yùn)動點(diǎn)聲源,所獲得的遠(yuǎn)場噪聲分布與解析解吻合,時域噪聲的特征變化符合聲波傳播規(guī)律。對低馬赫數(shù)流動圓柱繞流噪聲進(jìn)行數(shù)值預(yù)測,時域計(jì)算方法獲得的結(jié)果與頻域方法的結(jié)果及實(shí)驗(yàn)數(shù)據(jù)吻合,遠(yuǎn)場噪聲隨時間呈現(xiàn)周期性變化,噪聲分布特征與流場脈動一致。數(shù)值研究表明本文方法可以考慮噪聲的瞬時特征分布,并且能夠精確模擬非緊致邊界的散射效應(yīng)。
[Abstract]:The non compact structure of the aerodynamic noise problem exists widely in many fields of aerospace, industrial production and transportation. Large civil aircraft during takeoff, landing or flight phase generated by the aerodynamic noise problem is particularly serious, so the numerical aerodynamic noise prediction has attracted universal attention. A hybrid computational aeroacoustics (HCAA) the method is simple and has low computational complexity, high computational efficiency and low cost advantages, is widely used in engineering practice. The basic idea of this method is to solve the flow field and sound field separation, combined with the CFD method to obtain numerical solutions of near field and far field noise, through the sound propagation equation. The Lighthill acoustic analogy theory of simple and strong applicability, can quickly solve the noise propagation. In order to study the scattering effect caused by the non compact structure, the Lighthill acoustic analogy hypothesis is developed based on non compact The aerodynamic noise prediction model, the main research work and innovations are as follows: (1) the pressure integral equation of vortex sound theory and method to establish the low pressure decomposition of Maher flow aerodynamic noise based on noise calculation including surface scattering pressure calculation and far-field arbitrary observation point pressure calculation of two parts. Low Maher number flow around a cylinder dynamic noise numerical prediction of acoustic field distribution, consistent with the Curle equation. To study the relationship between turbulence and noise propagation, the results showed that the changing noise with frequency changes and turbulence is consistent with the trend. The numerical results show that the method can accurately solve the low Maher number flow aerodynamic noise, and intuitive the reflects the relationship between vortex and sound. (2) proposed a method to calculate the non compact boundary aerodynamic noise radiation scattering. This method will be unified integral flow pulsation decomposition Capture for numerical calculation of flow field is mainly caused by the motion of the fluid flow fluctuation and flow field calculation are not captured by the acoustic ripple component is mainly caused by the noise propagation in two parts, the unified Lighthill acoustic analogy theory and Green function method for calculating acoustic wave based on integral equation. Using two order accuracy scheme for compressible flow computation. Get the scattering pressure non compact boundary through unified integral equations, then solving the far field sound pressure of arbitrary observation point. The two-dimensional, three-dimensional cylindrical of aerodynamic noise numerical calculation, the calculation results with the literature results. The numerical results show that this method can reduce the computation required for high precision field workload, scattering and capture the non compact at the same time boundary, can simulate the flow characteristics of the aerodynamic noise field can be compressed. (3) aiming at the complex structure, comprising a plurality of physical objects The model and the oscillatory structure of the aerodynamic noise problem, put forward the calculation method of aerodynamic noise can be non compact numerical integral gas permeable boundary. Select all objects surrounded by smooth boundary for permeable boundary, the aerodynamic noise calculation includes a permeable boundary scattering pressure calculation and far-field arbitrary observation point pressure calculation of the cylindrical part two, Rod-Airfoil model 30P30N, carry out the airfoil aerodynamic noise numerical calculation method for seepage boundary integral results obtained with the surface integral calculation method and literature results. The numerical results show that the scattering effect of permeable boundary integral aerodynamic noise calculation method can accurately simulate the non compact boundary, can reduce the computational complexity, and computational efficiency help to improve the aerodynamic noise. (4) in order to avoid the aircraft take-off, landing or low altitude flight phase ground boundary scattering source to calculate the required workload, combined with The image source method puts forward the calculation method of the half space boundary non compact aerodynamic noise numerical integration. Numerical simulation of flow through the DES model with two order accuracy, using non compact boundary integral method for scattering field calculation. Firstly, the half space within the cylinder, the NACA0012 airfoil and 30P30N airfoil aerodynamic noise to carry out the numerical calculation results show that the scattering effect in the half space ground boundary changes caused by complex and intense field. Secondly, carry out numerical flow noise in subsonic cavity prediction results with high precision computational aeroacoustics method consistent with the frequency of sound pressure level showed a trend of gradually decreasing. The numerical results show that this method can simulate the scattering effect of non compact boundary and half space the border, there is no need to solve the surface boundary scattering source, significantly improve the computational efficiency of the numerical aerodynamic noise of half space gas. (5) combined with the free space of sound The propagation equation is established, the movement of non compact time-domain Green function boundary integral equation, the equation and Lighthill acoustic analogy can be considered noise distribution of arbitrary boundary conditions. The cylinder as the research object, placing the stationary and moving point source in cylindrical near the far field noise distribution agreement with analytical solution, change characteristics of time domain the noise with sonic wave propagation. The low Maher number flow around a circular cylinder flow noise numerical prediction, time domain calculation method to obtain the results and the frequency-domain method results and experimental data, the far-field noise time periodic, noise distribution is consistent with the flow pulsation. The numerical results show that this method can consider the distribution of instantaneous characteristics noise, scattering effect and can accurately simulate the non compact boundary.

【學(xué)位授予單位】：西北工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TB53
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本文編號：1491133