本文選題：離心噴嘴 + 幾何參數(shù)��； 參考：《南京航空航天大學(xué)》2016年碩士論文

【摘要】：離心噴嘴廣泛應(yīng)用于航空發(fā)動機(jī)燃燒室中,是將液態(tài)燃油破碎成油霧滴的裝置,直接影響火焰穩(wěn)定、燃燒效率、污染物排放等燃燒室性能。影響離心噴嘴性能的因素很多,其中噴嘴內(nèi)部流動特性是關(guān)鍵因素之一。本文即以此為對象,開展了離心噴嘴內(nèi)部流動特性和燃油霧化性能的研究。首先進(jìn)行了數(shù)值計算研究,通過計算方法研究,獲得了基于VOF隱式解的計算方法,并應(yīng)用此計算方法計算了一種典型離心噴嘴,獲得了不同供油壓差、旋流室長度、旋流室直徑、噴口長度、噴口直徑、旋流槽進(jìn)口面積、旋流室收斂角下離心噴嘴的流場,得到了各參數(shù)變化下離心噴嘴內(nèi)流特性與霧化性能變化的規(guī)律。此外,對放大尺寸的離心噴嘴進(jìn)行了計算,驗證了算法的準(zhǔn)確性并發(fā)現(xiàn)在高雷諾數(shù)下,離心噴嘴的流動特征基本不變。由于測試技術(shù)的限制,試驗研究基于本文所設(shè)計的大尺寸透明離心噴嘴,研究主要包括離心噴嘴旋流室內(nèi)切向速度,軸向速度,流量特性,霧化錐角,液膜厚度,霧化粒徑。結(jié)果表明:(1)在旋流室內(nèi),切向速度沿半徑呈指數(shù)分布且分布沿軸向基本一致。而對于軸向速度,在旋流室內(nèi)半徑較大處,流動幾乎滯止,隨著半徑的降低,軸向速度突然產(chǎn)生一個階躍并保持穩(wěn)定至空氣渦半徑處。這說明工質(zhì)主要從半徑較小的空氣渦處流向噴口。在試驗參數(shù)范圍內(nèi),根據(jù)各幾何參數(shù)對切向速度的影響總結(jié)了旋流室內(nèi)切向速度公式。(2)獲得當(dāng)Ap/Dsdo在0.38至1.05,Ds/do在3至7.5,Ls/Ds在0.57至1.33,lo/do在0.17至1,流量系數(shù)、液膜厚度、霧化錐角、SMD關(guān)于各無量綱參數(shù)的變化規(guī)律,并總結(jié)了流量系數(shù)與霧化錐角的無量綱經(jīng)驗公式。(3)壓差對離心噴嘴流量系數(shù)幾乎無影響。隨著壓差的增大,液膜厚度降低,霧化錐角增大并在達(dá)到最大錐角后趨于不變,離心噴嘴內(nèi)切向速度與軸向速度增大。數(shù)值計算與試驗結(jié)果存在誤差,但規(guī)律基本一致。試驗的結(jié)果將對深入了解燃油霧化機(jī)理和性能變化的規(guī)律,具有重要理論和應(yīng)用價值。
[Abstract]:Centrifugal nozzle is widely used in the combustion chamber of aero-engine. It is a device to break liquid fuel into droplets, which directly affects the performance of combustion chamber such as flame stability, combustion efficiency, pollutant emission and so on. There are many factors affecting the performance of centrifugal nozzles, among which the internal flow characteristics of centrifugal nozzles are one of the key factors. In this paper, the internal flow characteristics and fuel atomization performance of centrifugal nozzle are studied. First of all, the numerical calculation is carried out, and the calculation method based on the implicit solution of VOF is obtained, and a typical centrifugal nozzle is calculated by using this method. The different oil supply pressure difference and the length of swirl chamber are obtained. The flow field of centrifugal nozzle under swirl chamber diameter, nozzle length, nozzle diameter, swirl groove inlet area and convergent angle of swirl chamber is obtained. In addition, the accuracy of the algorithm is verified by the calculation of the centrifugal nozzle with enlarged size, and it is found that the flow characteristics of the centrifugal nozzle are basically unchanged at high Reynolds number. Due to the limitation of testing technology, the experimental research is based on the large size transparent centrifugal nozzle designed in this paper. The research mainly includes tangential velocity, axial velocity, flow characteristic, atomization cone angle, liquid film thickness and atomization particle size. The results show that the tangential velocity distributes exponentially along the radius in the swirl chamber and is basically consistent with the axial distribution. For axial velocity, the flow is almost stagnant where the radius of the swirl chamber is large. With the decrease of radius, the axial velocity suddenly produces a step and remains stable to the radius of the air vortex. This indicates that the working fluid mainly flows from the air vortex with small radius to the nozzle. In the range of test parameters, the tangential velocity formula of swirl chamber is summarized according to the influence of geometric parameters on tangential velocity.) when Ap/Dsdo is between 0.38 and 1.05g Dsrdo between 3 and 7.5 L / s, the flow coefficient and liquid film thickness are 0.17 to 1. The variation of dimensionless parameters in SMD of atomization cone angle is studied. The dimensionless empirical formula of flow coefficient and atomization cone angle is summarized. The pressure difference has little effect on the flow coefficient of centrifugal nozzle. With the increase of pressure difference, the thickness of liquid film decreases, the atomization cone angle increases and the maximum cone angle is reached, and the tangential velocity and axial velocity increase in the centrifugal nozzle. There is an error between the numerical calculation and the experimental results, but the law is basically consistent. The experimental results will be of great theoretical and practical value for further understanding the mechanism of fuel atomization and the law of performance change.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：V231.2

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本文編號：1960142