【摘要】：空調(diào)室內(nèi)機主要包括橫流風(fēng)機和換熱器,其氣動性能和氣動聲學(xué)問題被廣泛關(guān)注。橫流風(fēng)機由于其獨一無二的幾何結(jié)構(gòu),其內(nèi)部存在穩(wěn)定的偏心渦結(jié)構(gòu),降低了橫流風(fēng)機系統(tǒng)的效率,因此研究橫流風(fēng)機的內(nèi)部流動機理,特別是偏心渦的起源及發(fā)展規(guī)律具有重要的科學(xué)意義。氣流經(jīng)過空調(diào)室內(nèi)機時隨機產(chǎn)生的尖嘯噪聲對人體的舒適性有直接影響,因此有必要針對噪聲產(chǎn)生的特性及發(fā)生機理展開詳細(xì)研究,進(jìn)而為空調(diào)室內(nèi)機的設(shè)計提供可靠的理論基礎(chǔ)。本文以橫流風(fēng)機為研究對象,通過實驗和數(shù)值模擬手段詳細(xì)研究了橫流風(fēng)機內(nèi)部偏心渦啟動、發(fā)展的規(guī)律,提出了控制偏心渦系統(tǒng)能量損失的方法,即在靠近蝸舌附近位置加裝可調(diào)節(jié)角度的進(jìn)口導(dǎo)葉,從而有效地減小了偏心渦的區(qū)域,增大了通流區(qū)域,提高了橫流風(fēng)機的氣動性能。同時,本文以換熱器作為研究對象,通過氣動聲學(xué)實驗詳細(xì)測量了氣流經(jīng)過換熱器時產(chǎn)生隨機噪聲的環(huán)境,并通過熱線實驗和數(shù)值模擬手段分析了噪聲產(chǎn)生的機理,建立了適用于空調(diào)室內(nèi)機換熱器噪聲的聲學(xué)模型。本文首先采用流動可視化實驗方法對橫流風(fēng)機啟動和穩(wěn)定工況時偏心渦的產(chǎn)生及發(fā)展進(jìn)行測量,精確捕捉到了偏心渦產(chǎn)生及穩(wěn)定發(fā)展的流動圖像。同時,使用商業(yè)軟件FLUENT對穩(wěn)定發(fā)展階段的橫流風(fēng)機內(nèi)部流動細(xì)節(jié)進(jìn)行非穩(wěn)態(tài)數(shù)值模擬,并與流動可視化實驗結(jié)果相結(jié)合,從質(zhì)量和能量兩方面分析了橫流風(fēng)機偏心渦穩(wěn)定存在的原因,并采用正交分解法和渦動力學(xué)原理分析了氣流二次回流進(jìn)入橫流風(fēng)機時葉片流動分離產(chǎn)生的脫落渦對偏心渦的影響,較為完整地提出了偏心渦產(chǎn)生及發(fā)展的機理。在明確了偏心渦產(chǎn)生及發(fā)展機理的基礎(chǔ)上,提出并設(shè)計了在蝸舌附近加裝進(jìn)口可調(diào)導(dǎo)葉的改進(jìn)措施。通過數(shù)值模擬手段對進(jìn)口可調(diào)導(dǎo)葉的安裝角度進(jìn)行分析,結(jié)合總壓、相對總壓、扭矩系數(shù)等參數(shù)確定了能夠有效提高橫流風(fēng)機性能的進(jìn)口導(dǎo)葉角度,從而能夠有效地減小二次回流進(jìn)入葉片時的流動分離,減小偏心渦的區(qū)域,增大通流區(qū)域的區(qū)域,提高橫流風(fēng)機的氣動性能。然后通過氣動性能實驗對數(shù)值模擬結(jié)果進(jìn)行驗證。結(jié)果表明,在流量不變的條件下,其功耗較不加進(jìn)口導(dǎo)葉的原型機而言降低約3%。本文還針對氣流經(jīng)過換熱器時會隨機產(chǎn)生的尖嘯噪聲展開研究。首先通過氣動聲學(xué)實驗研究了噪聲發(fā)生的特性,通過氣流大小、方向、換熱器表面層數(shù)及換熱器空腔數(shù)目等參數(shù)確定了噪聲的特性,通過流速與頻率之間的關(guān)系確定這種噪聲是一種氣動聲學(xué)噪聲,然后通過熱線測速儀和數(shù)值模擬手段詳細(xì)研究了隨機噪聲產(chǎn)生的機理,在此基礎(chǔ)上,提出了適用于換熱器噪聲的Hill-hill noise聲學(xué)模型,通過大量的實驗數(shù)據(jù)建立了Hill-hill noise噪聲的空腔剪切層自激振蕩頻率預(yù)測公式,并明確了噪聲的特性及產(chǎn)生機理。
[Abstract]:The indoor air conditioning unit mainly includes crossflow fan and heat exchanger, and its pneumatic performance and pneumatic acoustics are widely concerned. Because of its unique geometric structure, there is a stable eccentric vortex structure in the crossflow fan, which reduces the efficiency of the crossflow fan system. Therefore, the internal flow mechanism of the crossflow fan is studied. In particular, the origin and development of eccentric vortexes are of great scientific significance. The random screeching noise produced by air flow through the indoor unit of air conditioning has a direct impact on the comfort of human body, so it is necessary to study the characteristics and mechanism of noise in detail. Furthermore, it provides a reliable theoretical basis for the design of indoor air conditioning unit. In this paper, taking crossflow fan as the research object, the law of starting and developing eccentric vortex in crossflow fan is studied in detail by means of experiment and numerical simulation, and the method of controlling the energy loss of eccentric vortex system is put forward. That is to say, the inlet guide vane with adjustable angle is installed near the worm tongue, so that the eccentric vortex area is effectively reduced, the flow area is increased, and the pneumatic performance of the crossflow fan is improved. At the same time, taking the heat exchanger as the research object, the environment of random noise produced by air flow passing through the heat exchanger is measured in detail by Aeroacoustics experiment, and the mechanism of noise generation is analyzed by hot wire experiment and numerical simulation. An acoustic model suitable for the noise of heat exchanger in air conditioning room is established. In this paper, the flow visualization experiment method is used to measure the generation and development of eccentric vortex in the starting and stable working conditions of crossflow fan, and the flow image of eccentric vortex generation and stable development is accurately captured. At the same time, the commercial software FLUENT is used to simulate the flow details of the crossflow fan in the stable development stage, which is combined with the experimental results of flow visualization. The causes of eccentric vortex stability of crossflow fan are analyzed from two aspects of mass and energy. The influence of shedding vortex produced by blade flow separation on eccentric vortex is analyzed by orthogonal decomposition method and vortex dynamics principle, and the mechanism of eccentric vortex generation and development is put forward completely. On the basis of defining the generation and development mechanism of eccentric vortex, the improvement measures of installing inlet adjustable guide vane near worm tongue are put forward and designed. The installation angle of the inlet adjustable guide vane is analyzed by numerical simulation, and the angle of the inlet guide vane which can effectively improve the performance of the crossflow fan is determined by combining the total pressure, relative total pressure, torque coefficient and other parameters. Thus, the flow separation when the secondary reflux enters the blade can be effectively reduced, the area of eccentric vortex can be reduced, the area of the flow region can be increased, and the pneumatic performance of the crossflow fan can be improved. Then the numerical simulation results are verified by the pneumatic performance experiment. The results show that the power consumption of the prototype without inlet guide vane is about 3% lower than that of the prototype without imported guide vane under the condition of constant flow rate. In this paper, the screeching noise which will be randomly generated when the air flow passes through the heat exchanger is also studied. Firstly, the characteristics of noise are studied by Aeroacoustics experiment, and the noise characteristics are determined by the parameters such as the size of air flow, the direction, the number of layers on the surface of heat exchanger and the number of cavities of heat exchanger. It is determined that the noise is a kind of pneumatic acoustic noise by the relationship between velocity and frequency, and then the mechanism of random noise is studied in detail by hot wire velocimeter and numerical simulation. A Hill-hill noise acoustic model for heat exchanger noise is proposed. The prediction formula of self-excited oscillation frequency of cavity shear layer for Hill-hill noise is established through a large number of experimental data, and the characteristics and generation mechanism of noise are clarified.
【學(xué)位授予單位】：上海交通大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TB657.2

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