傳統的數值分析程式，由於沒有適當的資料結構來管理資料個體間之相關性，不僅使程式功能的彈性受到極大的限制，且常需耗費大量的時間在於依照輸入檔的格式建立輸入檔，有修改不易以及不容易掌握輸出資料是否正確的缺點，甚至因為不了解資料結構的意義，而發生重大的錯誤。本研究旨在建立一交談式水下推進噴嘴性能分析程式，以視窗架構顯示系統，改善人與電腦之操作介面，使得噴嘴設計者，無需記憶繁雜的輸入格式，而能輕易的掌握輸入及輸出結果。
本研究以視覺化軟體 Visual Basic結合Fortran程式寫成的執行檔及微軟視窗(Microsoft Windows)環境，建立一套適用於個人電腦，並具有前置處理程式(輸入資料視窗系統) 、核心程式(流場分析之 Fortran 程式) 、及後置處理程式(結果輸出視窗系統)之交談式噴嘴流場及性能分析程式。噴嘴之流場計算係以一維兩相汽液雙流體模型為基礎，由於一維模型簡單實用，所需之計算時間較短，因此特別適用於噴嘴之初步設計。計算結果將提供兩相流體之速度、壓力、氣泡尺寸之變化及空泡比等定量資料，以作為噴嘴細部設計及推進性能之評估參考。

Traditional programs of numerical analysis do not have appropriate data structures to manage the correlation between individual items. This causes the extreme limitation of flexibility of the programs and wastes lots of time in establishing input files according to the designed formats. Moreover, the data files of these are hard to be modified. The output information may be misunderstood, or even are misused to cause fatal error. This study aims at the design of an interactive computer program for performance analysis of underwater propulsion nozzles. The program is constructed under the windows system and, therefore, offers a user-friendly operational interface. The nozzle designers do not need to memorize the complicated data formats and can handle the input and output files easily.

The present program integrates the environment of the Microsoft Windows and Fortran codes using Visual Basic. The whole program consists of a pre-processor (a window system for data input), core programs (Fortran codes for flow analysis), and a post-processor (a window system for data output). The flows in the nozzle are calculated using a one-dimensional gas/liquid two-fluid model. The simplicity and practicality of the one-dimensional model assure less computational time and, therefore, the suitability for initial design of the nozzles. Distributions of the two-phase velocities, pressure, bubble size, and void fraction are presented based on the computational results. These data can then be used to refine the design of the nozzle and to evaluate its propulsion performance.

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