本文選題：柱面屋蓋 + 雷諾數(shù)效應�。� 參考：《哈爾濱工業(yè)大學》2015年博士論文

【摘要】：雷諾數(shù)效應一直是建筑工程抗風研究中的重要基礎性問題。近年來,各種造型新穎的大跨度屋蓋結構不斷涌現(xiàn),隨著屋蓋跨度的增加和質(zhì)量輕型化,抗風設計要求更為精細化,越來越多的學者開始關注大跨度屋蓋的雷諾數(shù)效應。眾所周知,對于曲面屋蓋結構,其氣動參數(shù)隨雷諾數(shù)變化顯著,但至今尚無系統(tǒng)研究這種雷諾數(shù)效應的影響。大跨度屋蓋結構大都處于大氣邊界層底層,其周圍氣流的繞流模式較為復雜,影響建筑雷諾數(shù)效應的因素諸多,主要包括屋蓋幾何特征、表面粗糙度和近地面高湍流度三個方面。本文基于經(jīng)典圓柱繞流的風洞試驗,驗證了試驗方法的正確性,并探討了表征雷諾數(shù)效應的關鍵氣動參數(shù)及相應的識別方法;以大跨柱面屋蓋為研究對象,采用風洞試驗的方法重點探討了不同幾何特征(包括長寬比、矢跨比)、來流湍流和表面粗糙度對柱面屋蓋雷諾數(shù)效應的影響;在此基礎上,提出了考慮雷諾數(shù)效應的風荷載估計方法,為今后的相關研究方向提供一些建議。本文主要開展了以下幾個方面的工作:(1)雷諾數(shù)效應在形式上表現(xiàn)為不同雷諾數(shù)條件下流動狀態(tài)、邊界層分離和旋渦作用的差異,進而直接影響氣動參數(shù),因而反過來從風洞測壓試驗獲得的氣動參數(shù)信息可以用于再挖掘流場特點。基于此,本文提出結合模型表面風壓分布來識別流動轉(zhuǎn)捩與邊界層分離的方法,利用譜正交分解法來識別旋渦作用,通過分析不同雷諾數(shù)下主導旋渦的作用特點,并定量評估其對脈動風壓場的能量貢獻,為結構抗風設計提供參考。(2)柱面屋蓋與圓柱的差異主要體現(xiàn)在壁面邊界的影響上,為探究其影響規(guī)律,通過在圓柱前后設置導流板的方式模擬了柱面屋蓋的邊界條件。研究發(fā)現(xiàn),前導流板的主要作用是通過增加來流湍流度促使分離邊界層提前轉(zhuǎn)捩,后導流板則抑制了尾流中的旋渦脫落。研究揭示了由于壁面邊界的存在,使得來流中產(chǎn)生附加湍流,這是造成柱面屋蓋與經(jīng)典圓柱雷諾數(shù)效應差異的根本原因。(3)幾何特征是影響柱面屋蓋雷諾數(shù)效應的主要因素。針對不同長寬比和矢跨比柱面屋蓋的雷諾數(shù)效應展開系統(tǒng)的風洞試驗研究,通過分析模型氣動參數(shù)隨雷諾數(shù)的變化規(guī)律,獲得轉(zhuǎn)捩區(qū)間大致在6.9×104~4.14×105范圍內(nèi),研究表明屋蓋長寬比的減小會推遲分離邊界層由層流向湍流的過渡,而矢跨比減小的影響則呈相反的變化趨勢。(4)在利用格柵建立的不同湍流度均勻流場中對柱面屋蓋進行變雷諾數(shù)測壓試驗。研究表明,來流湍流對雷諾數(shù)效應的影響需要從湍流度和積分尺度兩方面進行考察,流場湍流度的增加會促使分離邊界層提前轉(zhuǎn)捩,而湍流積分尺度主要對脈動風荷載的雷諾數(shù)效應存在顯著影響,在雷諾數(shù)和湍流度相同的情況下,小積分尺度湍流旋渦(0.18≤Lx/D≤0.33)更容易滲入到表面邊界層和分離剪切流中,進而增加屋蓋頂面和尾流區(qū)的風壓脈動;系統(tǒng)研究了表面粗糙度(相對粗糙度ks/D=3.0×10-4~7.5×10-4)對柱面屋蓋雷諾數(shù)效應的影響,增加表面粗糙度使得轉(zhuǎn)捩區(qū)間向低雷諾數(shù)區(qū)域平移,但值得注意的是升力系數(shù)值明顯減小,因此采用增加表面粗糙度來模擬高雷諾數(shù)的氣動特性時,需要對測量數(shù)值進一步修正,有待于更深入研究。(5)針對平均風荷載,基于理想流體勢流理論,建立了考慮雷諾數(shù)效應的風壓系數(shù)模型,適用于不同矢跨比柱面與球面屋蓋,同時結合風洞試驗數(shù)據(jù),還給出了考慮湍流度和矢跨比的風力系數(shù)模型;針對脈動風荷載,基于模糊神經(jīng)網(wǎng)絡技術,建立了大跨柱面屋蓋考慮雷諾數(shù)效應的脈動風荷載預測模型,可作為圍護結構抗風設計的有效輔助手段。
[Abstract]:Reynolds number effect has always been an important basic problem in the study of wind resistance in construction engineering. In recent years, various novel large span roof structures have emerged continuously. With the increase of roof span and light quality, the demand for wind resistance design is more refined. More and more scholars begin to pay attention to the Reynolds number effect of large span roofs. It is known that the aerodynamic parameters vary significantly with Reynolds number for a curved roof structure, but there is no systematic study of the effect of Reynolds number. The large span roof structures are mostly in the bottom of the atmospheric boundary layer, and the flow pattern around the air flow around it is more complex, and many factors affecting the Reynolds number effect, mainly including the roof geometric characteristics, Three aspects of surface roughness and high turbulence in the near ground. Based on the wind tunnel test of classical cylinder flow, the correctness of the test method is verified, and the key aerodynamic parameters and the corresponding identification methods are discussed. What characteristics (including length width ratio, sagittal span ratio), flow turbulence and surface roughness influence the Reynolds number effect of cylindrical roof; on this basis, a method of estimating wind load with Reynolds number effect is proposed, and some suggestions for future research direction are provided. The following work is carried out in this paper: (1) Reynolds number effect is in the following aspects In the form of different Reynolds number, the flow state, the boundary layer separation and the difference of vortex action are directly affected by the aerodynamic parameters. Therefore, the aerodynamic parameters obtained from the wind tunnel pressure test can be used to remine the characteristics of the flow field. Based on this, this paper proposes to identify the flow transition and the flow transition in combination with the model surface wind pressure distribution. The method of boundary layer separation, using the spectral orthogonal decomposition method to identify the vortex action, by analyzing the characteristics of the leading vortex under different Reynolds numbers, and quantifying its energy contribution to the fluctuating wind pressure field, provides reference for the design of the wind resistant structure. (2) the difference between the cylindrical roof and the cylinder is mainly reflected on the effect of the wall boundary. It is found that the main function of the front guide plate is to promote the transition of the boundary layer in advance by increasing the flow turbulence. The study reveals that the boundary of the wall exists because of the existence of the wall boundary. The fundamental reason for the difference between the cylindrical roof and the Reynolds number effect of the classical cylinder is caused by the additional turbulence in the derived flow. (3) the geometric characteristics are the main factors affecting the Reynolds number effect of the cylindrical roof. The wind tunnel test for the Reynolds number effect of the different length width ratio and the column roof roof is analyzed by the analysis of the model aerodynamic parameters. As the number of Reynolds number changes, the transition interval is roughly within the range of 6.9 x 104~4.14 x 105. The study shows that the decrease of the length and width of the roof will delay the transition from layer to turbulence, while the effect of the decrease of the vector span ratio is the opposite trend. (4) in the uniform flow field of different turbulence intensity, the cylindrical house is used in the use of grid. The study shows that the influence of the flow turbulence on the Reynolds number effect needs to be investigated from two aspects of the turbulent flow and the integral scale. The increase of the turbulent flow in the flow field will lead to the transition of the boundary layer in advance, while the integral scale of the turbulent flow has a significant influence on the Reynolds number effect of the fluctuating wind load, and the Reynolds number and the Reynolds number are significant. In the case of the same turbulence, the small integral scale turbulence vortex (0.18 < < Lx/D < 0.33) is more easily infiltrated into the surface boundary layer and the separation shear flow, and then increases the wind pressure fluctuation in the roof top surface and the wake region. The influence of the surface roughness (relative roughness of ks/D=3.0 x 10-4~ 7.5 x 10-4) on the Reynolds number effect of the cylindrical roof is studied. The surface roughness makes the transition interval shift to the low Reynolds number region, but it is worth noticing that the lift system value decreases obviously. Therefore, when the aerodynamic characteristics of high Reynolds number are simulated by increasing the surface roughness, it is necessary to further modify the measurement value. (5) for the average wind load, the ideal fluid potential flow theory is based on the mean wind load. In addition, a wind pressure coefficient model considering Reynolds number effect is established. It is suitable for different vertical and spherical surface and spherical roof. At the same time, combined with wind tunnel test data, the wind coefficient model considering turbulence intensity and vector span ratio is given. Based on the fuzzy neural network technique, a large span cylindrical roof is established to consider Reynolds number effect. The prediction model of fluctuating wind load can be used as an effective auxiliary method for wind resistant design of retaining structures.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TU311.3

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