- 學位論文
煙囪受風之動力行為研究-實場量測與風洞試驗
nvestigation of dynamic behavior of chimneys under wind load by wind tunnel test and field measurement
摘要
摘要 超高結構物最常受的外力就是來自於風的作用，故發生破壞的機率機會遠高於其他外力作用，因此，國外多位學者曾做過此類結構物的實場量測與風洞實驗，但僅對當地的環境模擬，而國內對於高聳結構物仍停留於風洞實驗室內，無法與實場相互比較，找出適合國內結構物模擬之技巧，將有助於超高結構物之發展。 本研究選擇台中火力發電廠之煙囪，為了解煙囪結構受風作用下之動力行為，在現地實場量測的項目包括風速、風向、風壓，以及煙囪結構所受的振動反應。風速、風向和風壓量測可用來建立自然流場特性和煙囪表面風壓分佈情形；振動反應的量測可求得結構物動力特性參數與振動力學行為，然後於風洞中的低雷諾數流場中，試圖以人為方式，模擬出結構在高雷諾數實場中所形成的分離及尾流流場，觀測在模擬出的高雷諾數流場中之結構反應，並與實場量測資料比較，探求風洞試驗模擬之修正方法，以驗證風洞模擬之正確性。最後則是以各種煙囪排列造成的鄰近建物效應做風洞試驗研究，並將已建立的風洞試驗模擬準則再評估，期以符合迫近流場與鄰近建物之亂流效應。
並列摘要
Abstract Chimneys are the necessary and important structures for a thermal power plant. Typically, a chimney is a tall but thin structure so that wind load is a dominant factor in the design. Wind tunnel test on a scaled-down model and observation in-situ are the suitable means to understand experimentally the dynamic behavior of the chimney under wind load. Hence, it truly needs to find the correlation of the results from the wind tunnel test with the observation in the field. Furthermore, modification in the set-up and testing technique in the wind tunnel test may also be required to simulate the dynamic behavior of a chimney under wind flow with large Reynold’s number. To achieve the goals, the work to be done is briefly described as follows: 1. The measurement in wind speeds, direction, and pressures for several existed chimneys will be carried out. Then, the wind characteristics in the field and the circumferential wind pressure along the chimneys can be established. The dynamic responses of the chimneys will also be measured for the identification on the chimneys’ dynamic characteristics and for the validation on the later wind tunnel simulation. 2. The work will be concentrated on establishing the testing techniques for wind tunnel test so that the results from the wind tunnel tests well correlate to the observation in the field. Both roughen the chimney’s surface and introducing the extra approaching turbulence techniques will be used to determine the optimal approach. For simplicity, this task will be concentrated on an isolated chimney.