本文選題：水平圓管 + 自然對流��； 參考：《湖北工業(yè)大學》2015年碩士論文

【摘要】：自然對流圓管溫度檢測及換熱分析對能源動力和生產安全具有重大的推動作用。激光干涉法將溫度場激發(fā)的非均勻折射率編碼于條紋的光強中,結合Gladstone-Dale關系式,實現(xiàn)從折射率到密度、濃度、溫度等的無損全場檢測。首先,對比各類干涉法的原理及應用,橫向剪切類和全息類的競爭力較強。橫向剪切類共光路的結構緊湊,抗振性優(yōu)良,無需高精度的光學元件,條紋實時輸出,條紋是剪切前后的兩波面在重疊區(qū)的綜合效果。大剪切量時則得到完全錯開的兩個類似于雙曝光全息的簡單條紋,無需要迭代還原。剪切干涉條紋易受光學像差的影響,出現(xiàn)背景條紋,條紋復雜度增加。雙曝光全息干涉在同一全息干板上分別曝光畸變前后的波面,復位再現(xiàn)后易輸出直觀顯示畸變波面信息的無限寬條紋。完全抵消了外界干擾產生的附加相位,只需一張干涉圖就能重建畸變波面。綜合考慮,本文擬以橫向大剪切干涉和雙曝光全息為實驗手段,檢測2種尺寸的自然對流水平圓管溫度場。其次,模擬和細化橫向大剪切(無待測圓管)純背景干涉條紋。根據(jù)初級像差理論,利用MATLAB軟件模擬光學像差和附加相位差對純背景條紋的影響,驗證了實際光學系統(tǒng)中存在的離焦和球差。以入射——出射偏轉角為切入點,探討剪切量對成像復雜度的影響,得出最佳常規(guī)偏轉角60°。根據(jù)圖像形態(tài)學理論,利用MATLAB軟件細化暗條紋,實現(xiàn)條紋中心提取的多樣性。然后,利用橫向大剪切干涉儀紀錄1號水平圓管(長度直徑之比8.4)從高壁溫425℃自然降至室溫15.88℃的420幅干涉圖系列。利用MATLAB自編編程快速提取干涉圖的Red分量,通過峰谷點輔助確定條紋中心。采用有無圓管的兩張干涉圖法獲得畸變波面相位,完全抵消了光學系統(tǒng)誤差。反演圓管周圍的二維溫度場,與熱電偶測量誤差在0.19%以內。采用多項式和指數(shù)函數(shù)擬合溫度場,50℃低溫穩(wěn)態(tài)擬合時兩者結果均較好,400℃高溫擬合時多項式優(yōu)于指數(shù)。最后,利用雙曝光全息術探索2號水平圓管(長度直徑之比14.0)從壁溫82℃降至室溫22.1℃的換熱規(guī)律。利用MATLAB程序快速輔助確定條紋中心,直接從一張干涉圖中提取相位分布,重建二維溫度場。提取壁面的溫度梯度,計算表征換熱強度的局部和平均Nu,擬合出的Nu經驗公式與已有結果基本一致。
[Abstract]:The measurement of natural convection tube temperature and heat transfer analysis play an important role in promoting energy power and production safety. The nonuniform refractive index excited by the temperature field is encoded into the intensity of the fringe by laser interferometry, and the nondestructive full-field detection from refractive index to density, concentration and temperature is realized by combining the Gladstone-Dale relation. Firstly, compared with the principle and application of various kinds of interferometry, transverse shearing and holography are more competitive. The transverse shearing common optical path is compact in structure, excellent in vibration resistance, and no high precision optical element is needed. The fringe is the real time output of the stripe, and the fringe is the comprehensive effect of the two wavefront before and after shear in the overlapping region. Two simple fringes like double exposure holography are obtained with large shearing, and there is no need for iterative reduction. The shearing interference fringes are easily affected by optical aberration, and the background fringes appear and the fringes complexity increases. Double exposure holographic interference on the same holographic dry plate before and after exposure distortion of the wavefront, after reset and reproduction easy to output visual display distortion wave surface information infinite wide fringe. It completely cancels the additional phase generated by external interference and can reconstruct the distorted wave surface with only one interferogram. In this paper, the temperature field of two kinds of natural convection horizontal tube is measured by means of transverse large shear interference and double exposure holography. Secondly, the pure background interference fringes are simulated and refined. Based on the primary aberration theory, the effects of optical aberration and additional phase aberration on pure background fringes are simulated by using MATLAB software, and the defocus and spherical aberrations in practical optical systems are verified. The influence of shearing on the imaging complexity is discussed by using the incident-exit deflection angle as the starting point, and the optimal conventional deflection angle of 60 擄is obtained. According to the theory of image morphology, MATLAB software is used to refine dark fringes to realize the diversity of fringes center extraction. Then, a series of 420 interferograms of horizontal tube No. 1 (ratio of length and diameter, 8.4) from high wall temperature 425 鈩，

本文編號：1937987