Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1692
標題: 氣壓水箭之推進性能分析
Propulsion Performance Analysis Gas-Pressurized Waterjet Rocket
作者: 陳永堅
Chan, Yuan-Jan
關鍵字: Gas-Pressurized;氣壓水箭;Transport Analysis;Wood Rocket;Propulsive Efficiency;輸送分析;木頭火箭;推進效率
出版社: 機械工程學系
摘要: 
欲設計一個高推進效率的先進水箭噴嘴系統,須先建立推進理論分析
和流體力學數值分析方法。本文乃參照李興軍所提出之拉氏雷諾輸送公式
與推進系統動力功率分析推導出的通化公式以進行先進水箭推進理論分析
。因傳統上利用高速出口噴流以提昇推力的方式,易造成相當大的動能損
失,有鑑於此,本文利用擴管升壓的方式來達成推力的提昇,並以紊流模
式來計算水箭噴嘴內流場速度與壓力分佈。箭體漸擴噴嘴系統的流場常夾
雜管壁附近之回流形成類似墨西哥帽式之速度分布,並使出口壓力下降,
所以,以大幅擴管並不能確保箭體噴嘴的推力上昇。故吾人做擴張管和收
縮管數值研究,發現擴管 6.5度左右的推進效率較高,同時發現在擴管噴
嘴 6.5度狀態下改變流場進口速度或改變箭體速度其效率亦可改善。故實
際設計水箭時可配合箭體狀況及內壓,再改變水箭噴嘴尺寸與尺度等參數
,以期獲得理想的推進效率。

In quest of better propulsive efficiency for the gas-
pressured waterjetrocket , first we must establish genuine
propulsive theoretical fluid dynamics analysis methods. In this
paper , we generally refer Lagrangian Reynolds transport
equation and propulsion power equations developed by Hsing-Juin
Lee to analyze the propulsion theory of gas-pressurized waterjet
rocket.The traditional scheme of high speed exit jet flow to
increase waterjet thrustwill usually involve large kinetic
energy loss. We propose to diverge thewaterjet nozzle to
increase the outlet pressure. In that sense , we use
theturbulent model to calculate the velocity and pressure fields
of waterjet nozzle flow. The velocity flow field of divergent
nozzle often blends with secondary back flows to form velocity
distribution like a maxican chapeau.Therefore , an overly
diverged nozzle cannot ensure upswing for the thrustof a
waterjet rocket rocket. While carrying out the numerical
analysis of thedivergent nozzle and convergent nozzle with 6.5
angle shows better performance. Meanwhile , we may also change
the inlet flow or rocket velocities to upgrade its propulsion
efficiency. In practical design of awaterjet rocket , we may try
to match the rocket system parameters with the fluid pressure ,
nozzle size , curvature , and etc., in order to improve its
propulsive efficiency.
URI: http://hdl.handle.net/11455/1692
Appears in Collections:機械工程學系所

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