本文選題：摩擦因子 + 流動壓降　； 參考：《中國科學(xué)技術(shù)大學(xué)》2017年碩士論文

【摘要】：強磁場的應(yīng)用領(lǐng)域非常廣泛,在材料科學(xué)、生物工程與醫(yī)療以及各種工業(yè)和農(nóng)業(yè)應(yīng)用方面均能發(fā)揮重要作用,強磁場實驗裝置能為這些領(lǐng)域的探索研究提供必要的實驗環(huán)境。40-T混合磁體項目是由國家發(fā)改委資助、由中國科學(xué)院強磁場科學(xué)中心承擔(dān)建設(shè)的國家大科學(xué)實驗裝置"穩(wěn)態(tài)強磁場實驗裝置"的主要建設(shè)內(nèi)容之一。該試驗裝置于2016年年底在32mm室溫孔徑中獲得40-T穩(wěn)態(tài)磁場,它由外超導(dǎo)磁體和內(nèi)水冷磁體組成,其中外超導(dǎo)磁體線圈由Nb3Sn管內(nèi)電纜導(dǎo)體(CICC)繞制而成,采用4.5K超臨界氦對26條線圈通道進(jìn)行迫流冷卻。CICC導(dǎo)體由多股超導(dǎo)股線和銅線經(jīng)過多級扭絞然后包套于不銹鋼鎧甲內(nèi)而成,屬于內(nèi)冷導(dǎo)體。超臨界氦在CICC導(dǎo)體內(nèi)部流動,受到摩擦阻力作用產(chǎn)生壓降和熱耗散,同時帶走導(dǎo)體在勵磁過程中產(chǎn)生的熱量。CICC摩擦因子的測量與分析是優(yōu)化磁體線圈冷卻策略、提高磁體運行性能的有效途徑。本文旨在通過分析超臨界氦在40-T混合磁體外超導(dǎo)磁體各線圈的摩擦因子,以優(yōu)化磁體低溫冷卻回路和熱力學(xué)工況,從而提高40-T混合磁體外超導(dǎo)磁體的低溫穩(wěn)定性,為該裝置達(dá)到更高的磁場提供保障。Katheder經(jīng)驗公式被廣泛地用于CICC摩擦因子的計算,但由于40-T混合磁體線圈各支路的CICC導(dǎo)體結(jié)構(gòu)獨特,若采用該公式來計算40-T混合磁體外超導(dǎo)磁體線圈內(nèi)的流動摩擦因子,會存在較大誤差,因此,需要修正Katheder經(jīng)驗公式來輔助該裝置線圈內(nèi)的流動狀態(tài)和壓降等方面的分析和研究。本文通過采用氦流體進(jìn)行建模分析的方法對磁體運行數(shù)據(jù)進(jìn)行分析處理,同時應(yīng)用機器學(xué)習(xí)算法中的局部加權(quán)線性回歸算法,排除了大量的異常點,修正了因雷諾數(shù)分布不均造成的擬合結(jié)果偏差。本文通過分析計算所得到的CICC摩擦因子計算公式與實驗數(shù)據(jù)具有很高的一致性,將為40-T混合磁體外超導(dǎo)磁體的熱工水力分析、冷卻回路優(yōu)化和低溫穩(wěn)定性改善奠定基礎(chǔ)。
[Abstract]:Strong magnetic fields are widely used and can play an important role in material science, bioengineering and medicine, as well as in various industrial and agricultural applications. The high magnetic field experimental device can provide the necessary experimental environment for the exploration and research in these fields. The. 40-T mixed magnet project is funded by the National Development and Reform Commission. One of the main contents of the steady state high magnetic field experimental device, which is constructed by the strong Magnetic Field Science Center of the Chinese Academy of Sciences. The device obtained a 40-T steady-state magnetic field in the 32mm aperture at room temperature at the end of 2016. It consists of an outer superconducting magnet and an internal water-cooled magnet, in which the outer superconducting magnet coil is wound by a cable conductor in a Nb3Sn tube. 26 coils are cooled by 4.5K supercritical helium. CICC conductors are made up of multi-strand superconducting wires and copper wires, which are wrapped in stainless steel armour after multi-strand twisted and then wrapped in stainless steel armour. The measurement and analysis of the supercritical helium flow inside the CICC conductor resulting in pressure drop and heat dissipation due to friction resistance, and the measurement and analysis of the friction factor caused by the conductor in the excitation process are the optimization of the cooling strategy of the magnet coil. An effective way to improve the performance of magnets. In this paper, the friction factors of superconducting magnets outside 40-T mixed magnets are analyzed to optimize the low temperature cooling loop and thermodynamic conditions of supercritical helium magnets, so as to improve the low temperature stability of superconducting magnets outside 40-T mixed magnets. Katheder empirical formula is widely used to calculate the friction factor of CICC, but because of the unique structure of CICC conductor in each branch of 40-T mixed magnet coil, If this formula is used to calculate the flow friction factor in the superconducting magnet coils outside 40-T mixed magnets, there will be large errors. Therefore, it is necessary to modify Katheder's empirical formula to assist the analysis and study of the flow state and pressure drop in the coil of the device. In this paper, the method of modeling and analyzing the helium fluid is used to analyze and process the operation data of the magnet. At the same time, the local weighted linear regression algorithm in the machine learning algorithm is used to eliminate a large number of outliers. The deviation of fitting result caused by uneven distribution of Reynolds number is corrected. The formula of CICC friction factor obtained by analysis and calculation is in good agreement with the experimental data, which will lay a foundation for thermohydraulic analysis of superconducting magnets outside 40-T mixed magnets, optimization of cooling circuit and improvement of low temperature stability.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O441

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