橡膠可承受巨大變形，遇熱收縮，且橡膠水球的壓力不是體積的單調函數。本研究利用這些力學性質研發一種冷充熱放的熱增壓式儲能系統。這個系統採用橡膠薄膜和水組成的橡膠水球作為儲能工具。橡膠水球在表面曲率和張力的交互作用下，體積和壓力不是單調函數的關係：隨著體積增加，壓力會依序上升(A區間)、下降(B區間)最後再上升(C區間)。透過量測水球在A、B、C區間的儲能效率與耐用度，本研究找出橡膠水球最適合的體積操作範圍。此外，本研究更進一步控制橡膠水球在充放水時的溫度，藉此模擬水球在一日日照下的熱增壓情況。實驗結果顯示，橡膠水球儲能裝置在沒有熱增壓的情況下可達到83%-96%的能量儲放效率。透過熱增壓，水球釋放的可用功更可以超過原本儲存的水壓能。

本論文將以四種不同控制模組(最佳效率追蹤、最大扭力電流抽載、三相短路和機械式剎車)組合出風機系統之控制邏輯，以進行最佳效率追求與過風速保護；並進行控制邏輯之模擬。不論是風機葉片的流體力學模擬還是控制器的邏輯設計都是為了使風力發電機系統獲的最大功率與最佳保護。但如果風機葉片和發電機沒有做匹配，則無法實現性能最佳化的風機葉片，控制器的功率也無法增加。本文使用定電壓模式(CV mode)在葉片與發電機間找出最佳效率，搭配最大扭力電流抽載、三相短路和機械式剎車設計出控制邏輯。藉由輸入隨機的風速來模擬風機的運轉。本文以一3.7 m水平軸風力發電機作為計算例，進行最佳效率追求與過風速保護模擬。

In this paper, we present a single-pressure-field two-fluid with finite volume framework to solve the motion of compressible multiphase flow. To resolve both smooth and discontinuous profiles of flow variables, we propose a generalized sharpening technique that combines the conventional monotonic upstream scheme for conservation law (MUSCL) and tangent of hyperbola interface capturing (THINC) schemes. A slope-ratio parameter is devised to determine the proportion of values obtained by MUSCL and THINC automatically. Fluxes across cell faces are evaluated by the so called “hybrid AUSMD-type algorithm”, where the mass flux and pressure on cell faces are calculated using approximate Riemann solver. A series of one- and two-dimensional two-phase flow are conducted to validate the accuracy and robustness of the proposed scheme. Furthermore, unlike the existing scheme (e.g., MUSCL), which usually suffers from numerical diffusion, the proposed scheme significantly sharpens the fluid interfaces and captures more details of wave patterns including shock waves and rarefaction fans. For the problems in which surface tension is important, the proposed method is necessary to reduce the interface thickening and increase the accuracy of curvature estimation.

Abstract: In this paper, we present a system that could generate real horizontal plane and really tiny tilting angle for free sliding of the liquid drop on superhydrophobic surface, since the droplet is really easy to move on it. Current commercial product would cause vibration while tilting the plane, which could forbid us from inducing the droplet into motion completely by gravity, especially in superhydrophobic cases. On the other hand, the resolution of tilting angle is still not small enough, usually around 0.1~1°. Therefore, we design a tilting mechanism with a low tilting step, low tilting speed, and almost no vibration. Also the method of measuring the advancing and receding contact angles of a droplet during transitional motion on a superhydrophobic tilted plane is also developed. An improved version of sub-pixel polynomial fitting (SPPF) [11] was produced for superhydrophobic contact angle measurement, which could measure the contact angles to the second decimal and produce low noise and accurate result comparing to commercial softwares (Jikan SPPF and Data Physiks SCA20).

Keywords：Superhydrophobic, real horizontal plane, tilting angle, contact angle

中文摘要
在本文中，我們提出了一個可以產生真水平面，以及可以產生非常小之傾斜角度的系統，以利液滴在超疏水表面自由滑動。目前的商業產品會在傾斜平面時引起振動，這可能使我們無法完全通過重力誘導液滴運動，特別是在超疏水的情況下。另一方面，傾斜角度的解析度仍然不夠小，通常在0.1~1°左右。因此，我們設計了一種推進步進低、速度低、幾乎沒有振動的傾斜機構。同時也透過改良一接觸角量測法（SPPF）[11]，開發了測量液滴在超疏水傾斜平面上運動時的前進和後退接觸角的方法。與商務軟體（Jikan SPPF和Data Physiks SCA20）相比，接觸角準確度可達小數點後三位的接觸角，並且結果穩定低雜訊。

關鍵字：超疏水、真水平面、傾斜角、接觸角

The two-stage 4056 axial fan is developed and utilized to provide the high-pressure sufficient airstream for taking care of this severe thermal situation. Accordingly, to meet this practical need, this research aims to design a two-stage 4056 axial-flow fan generating an adequate high-pressure cooling air with a superior power efficiency. An integrated CFD effort is used to carry out the parametric study sequentially over the inlet fan, the supporting frame, and the outlet fan for attaining a superior two-stage 4056 fan. Additionally, the supporting frame ribs of 1st-stage and 2nd-stage fans are assembled to form a complete set of stationary guiding vanes between two counterrotating fans. Thus, under the same limited geometry, the outlet flow of 1st-stage fan can move smoothly into the guiding vane to gain extra static pressure; also, the 2nd-stage fan has a good incoming flow pattern to enlarge the aerodynamic performance of this two-stage axial-flow fan.At first, under the framework of CFD tool, a systematic parametric study on the impeller is imposed to improve performance of the 1st-stage fan, which is designed with the aids of airfoil and cascade theory. Next, flow simulation is performed to provide the detailed plots for flow visualization, which is useful to construct the appropriate stationary guiding vanes. In addition, the corresponding CFD calculations show that the new guiding frame incorporated with the inlet fan can result a minor flowrate increase (5.4%, from 22 to 23.25 CFM) and a significant pressure gain (37.9%, from 30.76 to 49.51 mmAq). After that, the 2nd-stage fan is optimized with the help of numerical simulation and parametric study, which considers the hub geometry, hub-to-tip ratio, blade angles of rotor, and number of guiding vanes. Thereafter, an optimized two-stage axial-flow fan is obtained by combing the above rotors and frames with the guiding-vane ribs. This effective two-stage 4056 fan for fulfilling the thermal demand of high-end 1U server.

中文摘要:
本研究針對Leidenfrost狀態之複合液滴，探討其內部的流場特徵與蒸發情形。複合液滴是由99%正庚烷之外殼液滴與水內核液滴所組成，放置在250°C之鋸齒狀的棘輪加熱表面上，使之因Leidenfrost狀態而懸浮。由流場量測可驗證，複合液滴底部蒸氣層內之蒸氣流動在液氣界面所造成的剪力，為驅動外殼液滴內部流動之來源，庚烷流動所對應的剪力，再藉由水-庚烷界面傳遞到內核液滴，使其內部產生流動。當內核水液滴體積小於30 μl時，外殼庚烷的蒸發速率較慢，外殼液滴內存在一對旋轉方向相反的渦流對，由於內核液滴通常會偏向外殼液滴的某一側，故其存在會影響外殼液滴該側渦流的流場；而內核水液滴亦存在雙渦流，且其流態會隨內核液滴相對於外殼液滴的繞動而旋轉。反之，當內核水液滴體積超過30 μl時，複合液滴受到重力的影響變大且與蒸氣膜之接觸面積較大，造成外殼庚烷加速蒸發，大量沸騰氣泡自複合液滴底部之三相界面處生成，內核與外殼液滴之內流場較為混亂。

Abstract:
This study focused on the flow characteristics and evaporation of a compound drop in the Leidenfrost state. The compound drop was composed of a shell drop of 99% heptane and a core drop of deionized water. After formation, the compound drop was levitated on a heated ratchet surface at 250°C. The initial volume of the shell drop is fixed at 50 μl and the volume of the core drop varied from 5 μl to 100 μl. In the Leidenfrost state, vapor flow underneath the compound drop exerted shear force at the liquid-vapor interface, driving the inner flow in the shell drop, and subsequently in the core drop flow. When the volume of the core drop was smaller than 30 μl, the compound drop was an ellipsoid. Although the bottom area of the compound drop increased with the volume of the core drop, the thickness of the vapor layer remained comparable. Due to the slow evaporation of heptane, the duration of compound state was long. In the shell drop, there existed a vortex pair, which was highly affected by the presence of the core drop. In the core drop, a small pair of vortices could be found and the flow pattern was rotated accordingly when the core drop revolved with respect to the compound drop. However, when the volume of the core drop was larger than 30 μl, the compound drop was flatten due to the growing importance of the heavy core drop. As the volume of the core drop increased, the expansion of the bottom area and the sharp decrease in the thickness of the vapor layer. Both led to an argument of evaporation so that the duration of compound state was shortened. Nucleation bubbles emerged at the triple interface, and highly disturbed the inner flows of both the shell and the core drops.