臺灣博碩士論文加值系統

當高速水流通過噴嘴注入水中時，流體之壓力低於飽和蒸氣壓，在噴嘴和射
流周圍會產生空蝕(Cavitation)現象，此具有空蝕現象的水射流稱為“空蝕射流
(Cavitation jet)”。當空蝕射流接觸水下物體表面時，水流在短時間經壓力變化造
成氣泡的生成與破裂，形成連續且破碎衝擊力量，因此空蝕射流應用於機械、船
舶、消防等領域，常用於清潔、除垢、破壞等作業。
本文利用 Ansys Fluent 內之混合(Mixture)模組、空蝕模組 Schnerr Zwart-GerberBelamri（ZGB）及紊流模組，配合不同的入口壓力，應用在常見的空蝕射流噴嘴，
將數值模擬結果之氣相體積分布及流場速度分布做比較，以此分析其空蝕現象對
流場之影響，為空蝕射流提供理論參考。

When a high-speed water flow is injected into the water through a nozzle, the
pressure of the fluid is lower than the saturated vapor pressure, and cavitation occurs
around the nozzle and the jet. This water jet with cavitation phenomenon is called
"cavitation jet." When the cavitation jet comes into contact with the surface of an
underwater object, the pressure changes in the water flow within a short period to cause
the formation and rupture of bubbles, forming a continuous and crushing impact force.
Therefore, the cavitation jet is used in machinery, ships, fire fighting and other fields, and
is often used for the operations such as cleaning, decontamination and destruction, etc.
This study uses the Mixture module, cavitation module Schnerr Zwart-GerberBelamri (ZGB) and the turbulence module in Ansys Fluent, with different inlets pressure,
and applies them to the common cavitation jet nozzles. The volume distribution of the air
phase and the velocity distribution of the flow field from the numerical simulation results
are compared to analyze the influence of the cavitation phenomenon on the flow field and
provide a theoretical reference for the cavitation jet.

第一章 緒論 1
1.1 空蝕現象 1
1.2 空蝕射流 2
1.3 文獻回顧 3
1.4 研究目的 4
1.5 章節介紹 4
第二章 理論分析 5
2.1 ANSYS FLUENT簡介 5
2.2 多相流模型 5
2.3 空蝕模型 6
2.4 紊流模型 7
2.4.1 RANS Models 7
2.4.2 RANS-LES Hybrid Models 8
2.4.3 Filter-based model (FBM) 9
2.4.4 Density-correction-based model (DCM) 9
2.5 空蝕數 10
第三章 模擬過程 11
3.1 模擬步驟 11
3.3 噴嘴模型 13
3.4 網格劃分 14
3.5 邊界條件 15
第四章 模擬結果與討論 17
4.1 紊流模型之影響 17
4.2 模擬結果與實驗之驗證 18
4.3 氣相體積分布與速度分布之比較 19
4.4 不同入口壓力之氣相體積分佈圖 22
4.5 入口壓力對空蝕數之影響 33
第五章 結論與建議 35
參考文獻 36
附錄 37

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