自從2011年東北大地震及地震引發的大海嘯導致福島第一核電廠的七級嚴重事故後，大眾對於核能電廠安全性的要求及關注大幅度地提高，因此核能安全與地震之關聯性需要重新研究及分析，但目前缺乏關於強制震動對雙相流影響之資料，因此本論文旨在探討強制震動時雙相流空泡分率改變情況，以提高核能電廠安全度，並且降低地震對於核能電廠的影響及風險。本論文利用垂直矩形管作為實驗流道，由於缺乏此幾何形狀管道之文獻可供參考，因此先規劃16種水流量與30種空氣流量進行無震動狀態之雙相流分析，後續搭配偏心輪系統產生5種介於0-2赫茲之震動，針對氣泡流及彈狀流流譜規劃42種流量條件進行實驗。實驗量測方式為利用8對位於流管入水口上方57水力直徑位置之電導度計量測電壓值變化，並利用Maxwell方程式進行空泡分率轉換，以分析暫態變化、時間平均值及最大空泡分率值等數據。本論文根據無震動實驗結果，發現低空氣流量下，空泡分率將呈現平均分布；在較高空氣流量時，氣泡往中心聚集造成空泡分率呈現中心高分佈。強制震動實驗結果發現強制震動有機會對於空泡分率暫態變化及最大空泡分率值產生影響，但並不改變時間平均空泡分率。對於局部空泡分率而言，當流量條件較靠近氣泡-彈狀流轉換邊界時，氣泡會因為震動引發氣泡聚集合併現象，最高將提高50%的最大空泡分率。以高速影像拍攝結果分析，發現震動提供流體外加力量造成流譜內部擾動增加，增加流動複雜性並產生週期性變化。
此論文提供了實驗上的證據，證明強制震動在特定流量、頻率條件下，將造成暫態空泡分率變化、氣泡尺寸改變，並初步建立強制震動與雙相流流譜變化之資料庫，使其可用於提高核能電廠安全度，並且降低地震對於核能電廠的影響及風險。

After the severe accident at Fukushima Daiichi NPP in 2011, the safety concerns of NPP safety have been highlighted. However the effect of the fluid dynamics caused by the earthquake vibration was not fully understood yet. Therefore, the evaluation of NPP safety under seismic vibration should be restudied and analyzed. In this study, experimental tests are carried out to investigate the two-phase flow behavior under vertical forced vibration. The two-phase flow operating conditions covered the ranges of 0.04m/s ≦ Jf ≦ 1.00m/s and 0.01m/s ≦ Jg ≦ 0.40m/s. An eccentric cam with ±3.5cm displacement was utilized to operate the vibration at a low frequency(up to 120 RPM). In order to measure local void signals, 8 conductivity sensors with a distance of 2.5cm between each sensors were set at about 57Dh above the water inlets. Besides, the visualization region was also settled at the height of 47Dh with a high speed camcorder. Local void fraction signals and vibration acceleration were acquired for 120 seconds by NI-6255 DAQ with a fixed 1000Hz sampling rate. The results showed that the flow regimes would change under specific flow conditions and the maximum void fraction would become at most 150% with a higher vibration frequency and acceleration. In addition, the time-averaged void fraction had no significant changes, but the instantaneous void fraction signals were affected by the vibration and the possible reason is that the high acceleration caused the void/fluid structure changes.

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