本文選題：導(dǎo)線火蔓延 + 低壓��； 參考：《中國科學(xué)技術(shù)大學(xué)》2017年碩士論文

【摘要】：導(dǎo)線的絕緣層往往是聚合物材料,著火后容易發(fā)生持續(xù)的火蔓延現(xiàn)象。導(dǎo)線的火蔓延過程中間伴隨著絕緣層的熔融滴落現(xiàn)象,這是一個(gè)復(fù)雜、多相、物理與化學(xué)反應(yīng)的過程,并且給航空航天飛行帶來了非常大的火災(zāi)安全隱患。此外,由于航空航天器自身環(huán)境特殊性,飛機(jī)所處的環(huán)境壓力大約為80千帕,而空間站所處的又是微重力環(huán)境,氧濃度一般控制在30%左右,與地面環(huán)境有很大的不同。如果僅僅依靠地面常規(guī)的實(shí)驗(yàn)來判斷導(dǎo)線火蔓延的危險(xiǎn)性,往往不能準(zhǔn)確預(yù)測航空航天器實(shí)際應(yīng)用中的環(huán)境情況。因此,在地面環(huán)境下,建立適宜的實(shí)驗(yàn)設(shè)備模擬低壓條件和高氧濃度空間,意義顯得非常重要。本文在總結(jié)調(diào)研前人對(duì)導(dǎo)線火蔓延研究的基礎(chǔ)上,選取鎳鉻合金線芯聚乙烯絕緣層(NiCr-PE)導(dǎo)線,銅芯聚乙烯絕緣層(Cu-PE)導(dǎo)線和鎳鉻合金乙烯四氟乙烯絕緣層(NiCr-ETFE)導(dǎo)線為研究對(duì)象,自主設(shè)計(jì)了低壓實(shí)驗(yàn)艙設(shè)備和導(dǎo)線火蔓延實(shí)驗(yàn)平臺(tái),研究了不同壓力,不同氧濃度下三種導(dǎo)線的火蔓延速度和火焰形態(tài)特點(diǎn),重點(diǎn)分析了 NiCr-PE導(dǎo)線與Cu-PE導(dǎo)線熔融的熔融滴落過程,揭示了導(dǎo)線火蔓延過程中熔融滴落現(xiàn)象的機(jī)制。在理論研究方面,本文參照液滴蒸發(fā)燃燒模型,分析了 PE導(dǎo)線熔融滴落的物理過程和傳熱傳質(zhì)特點(diǎn),建立了熔融滴落的質(zhì)量守恒方程,得出了液滴直徑(D(t))的增長公式。通過對(duì)熔融液滴的受力分析,得出了熔融液滴的理論滴落周期(t0)和臨界滴落直徑(Dcr)值。在實(shí)驗(yàn)研究方面,首先根據(jù)不同壓力下的PE實(shí)驗(yàn)結(jié)果,驗(yàn)證了理論t0與Dcr的正確性。然后對(duì)比分析了 NiCr-PE導(dǎo)線與Cu-PE導(dǎo)線的火蔓延速度隨氧濃度和壓力的變化關(guān)系的區(qū)別,定義了 PE導(dǎo)線熔融滴落上限和滴落下限的概念,得出了不同氧濃度下,兩種導(dǎo)線滴落上限和滴落下限的變化規(guī)律。最后分析NiCr-PE導(dǎo)線與NiCr-ETFE導(dǎo)線的實(shí)驗(yàn)結(jié)果,對(duì)比了兩種絕緣層材料對(duì)火蔓延速度與火焰形態(tài)的影響。
[Abstract]:The insulation layer of conductor is often polymer material, which is prone to continuous fire spread after fire. The fire spread of conductor is accompanied by the melting and dropping of insulation layer, which is a complex, multiphase, physical and chemical reaction process, and brings great fire safety hazards to aerospace flight. In addition, because of the particularity of the aeronautical and spacecraft environment, the environmental pressure of the aircraft is about 80 KPA, while the space station is in the microgravity environment, the oxygen concentration is generally controlled at about 30%, which is very different from the ground environment. If we only rely on conventional experiments on the ground to judge the danger of wire fire spread, it is often not possible to accurately predict the environmental situation in the practical application of aerospace vehicles. Therefore, it is very important to establish a suitable experimental equipment to simulate the low pressure condition and the high oxygen concentration space in the ground environment. In this paper, on the basis of summarizing the previous researches on the fire spread of conductors, we select Ni-Cr alloy wire core polyethylene insulating layer (NiCr-PE) conductor, copper core polyethylene insulating layer (Cu-PEE) conductor and Ni-Cr alloy ethylene tetrafluoroethylene insulating layer (NiCr-ETFEFE) conductor as research objects. The equipment of the low-pressure experimental cabin and the experimental platform of the traverse fire spread were designed independently. The fire spread velocity and flame shape characteristics of the three kinds of conductors under different pressure and different oxygen concentration were studied. The melting and dropping process of NiCr-PE wire and Cu-PE wire is analyzed emphatically, and the mechanism of melting drop phenomenon in the process of lead fire spreading is revealed. In terms of theoretical research, the physical process and heat and mass transfer characteristics of PE wire melt drop are analyzed with reference to the droplet evaporation combustion model, the mass conservation equation of melt drop is established, and the growth formula of droplet diameter is obtained. The theoretical drop period (t 0) and the critical drop diameter (DCR) of the molten droplet are obtained by analyzing the force of the melt droplet. In terms of experimental research, the correctness of theory t0 and Dcr is verified according to the experimental results of PE under different pressures. Then, the difference between the fire spread velocity of NiCr-PE wire and Cu-PE wire with oxygen concentration and pressure is analyzed, the concepts of upper limit and lower limit of melt drop of PE conductor are defined, and the different oxygen concentration is obtained. The variation of the upper and lower drop limits of the two traverse. Finally, the experimental results of NiCr-PE and NiCr-ETFE conductors are analyzed, and the effects of two kinds of insulating materials on fire propagation speed and flame morphology are compared.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：V328;V244.12

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本文編號(hào)：1959103