隨著現代光學技術以及數位影像技術的快速發展，用於流體力學中的全場光學診斷技術已獲至解決，如數位質點影像測速儀(Digital Particle Image Velocimetry, DPIV)之研發即為一例。數位質點影像測速儀是以光學方法為基礎，結合流場可視化以及數位影像處理兩種技術，因而有非接觸性的全場速度量測之特點。由於，早期所使用量測流體流動的方法，大多侷限於探針須侵入流場或僅能作單點的速度量測，致使實際流場之流體運動特性分析受到很大的限制。有鑑於此，本實驗室已著手於數位質點影像測速儀量測技術之開發，有關全場定量量測問題，已累積相當的經驗。此外，本實驗室亦有豐富的雷射都卜勒測速儀之量測經驗，且本實驗除了有前述兩種貴重儀器外，有關其操作和組構也相當地熟悉，因此對流場速度場的量測技術應可掌握，並可提供相關經驗，提供訓練人力所需之知識。我們已具備數位質點影像測速儀所需之硬體設備的整合能力，以及撰寫相關軟體運算程式的能力，本計畫將嚐試由速度場計算層次提昇至速度梯度場之計算(此為本計畫擬發展之關鍵技術一)，並且嚐試發展現行商業產品所無法提供速度場時間序列資訊(關鍵技術二)之質點影像測速技術。針對上述兩大關鍵技術，我們提出此計畫，期能建立質點影像測速技術，使其除了具備流場運動學參數之分析功能外，並具有解析流場時序特性功用，以下扼要說明空間和時間之尺度分析。 (1)空間特徵尺度分析：針對速度場，撰寫藉由中央差分法來求解速度梯度場之程式，以分析重要流體運動學參數，如渦度場、應變率場及能量消散率場等運動參數。 (2)時間特徵尺度分析：發展具有速度場時間序列資訊之質點影像測速技術，以及應用可作動態時序響應分析之小波轉換來探討流場中的時間特徵尺度之效應。由於本實驗室已有合乎計畫所要求之設備，再配合已發展成熟的二維質點影像測速技術，應可勝任本委託計畫所需之工作內容，不僅可做好硬體設備組構之技術轉移，也應可培育相關技術人力和建立流場分析之能量。 With the rapid development of modern optical techniques and digital image processing techniques, whole-field optical diagnostic, such as digital particle image velocimetry (DPIV), has been solved in fluid mechanics. The DPIV is based on the optical methods and connects both flow visualization and digital image processing technique. Hence, DPIV provides non-intrusive whole flow field velocity measurements. Because the early method of fluid flow velocity measurements are limited to intrusive technique and/or single point measurements, this limits the analysis of the fluid kinematic properties of real fluid flow. For this reason, we start to develop the DPIV and it has much experience for the whole-field velocity measurements at this stage. Besides, we also have much experience for the LDV measurement; we not only have these two equipments described above but also are familiar with its operation as well as organization, therefore, velocity measurement techniques are in the control of our lab and it can also provide related experience and information for the trained personnel. After co-operating on the hardware of DPIV and developing the algorithm of the cross-correlation method of DPIV system, we will try to improve the DPIV system in this project to the ability of the velocity gradient processing (crucial technology I) and the time sequence velocity information (crucial technology II) in which this function cannot be provided by the present commercial system.For these two crucial technology described above, this project will be systematically investigated during this work to establish such the DPIV system that it will possess abilities of both the analysis of the fluid kinematic properties and the resolution of the characteristic time sequence of the flow field. Major aspects of this research effort include: (1) The spatial characteristic scale analysis: To develop the central difference scheme to calculate the velocity gradient field, including vorticity, strain rate as well as energy dissipation rate. (2) The temporal characteristic scale analysis: To develop the technique that possesses the resolution of time sequence information as well as to apply the wavelet transformation to investigate the effect of the characteristic time scales of the flow field.We have maturely established two-dimensional DPIV system and do conform to this project. This will not only be competent to transfer the combination of hardware system but also provide the trained personnel to establish the analysis ability of the flow field. 研究期間：9104 ~ 9112
