Research on the Hydrodynamic Characteristics of High-Speed Water Entry of a Supercavitating Projectile(II)

瀏覽統計 Email 通知 RSS Feed

簡歷

基本資料

Project title

Code/計畫編號

NSC94-2623-7019-001

Translated Name/計畫中文名

超高速彈體入水超空化水動力特性研究(II)

Project Coordinator/計畫主持人

Ching-Yeh Hsin

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Systems Engineering and Naval Architecture

Website

https://www.grb.gov.tw/search/planDetail?id=1060177

Year

2005

Start date/計畫起

01-01-2005

Expected Completion/計畫迄

01-12-2005

Bugetid/研究經費

300千元

ResearchField/研究領域

機械工程

"超高速彈體入水產生超空化，物理現象相當複雜，至目前為止，其研究主要集中於實驗方面，藉由實驗觀察不同入水狀態下的流體，並試圖了解入水後的運動軌跡。本研究藉由數值計算，對於入水時的水動力特性進行了解，從而可以進行相關的分析與設計。本研究由巨觀的角度，應用數值方法解析彈體入水後的流體特性與受力計算。在第一年研究中，假設彈體以一定常速度垂直入水，使得此問題簡化為軸對稱體的問題。在勢流流場的假設下，應用的數值方法為邊界元素法，空化之模擬則承襲解析螺槳空化流場的方法，將已有的“部分空化”計算方法延伸為超空化模式，至於自由液面的模擬，則以鏡像之邊界條件模擬。在第二年的計畫中，重點有二，一為對於自由液面的考量，一是三維的計算。對於自由液面，我們將整合入水與自由液面的變化，應用 Lagrangian-Eulerian 方法進行計算，首先計算現有時間段的空化問題，由時間段步進方法決定新的彈體位置，考量自由液面之影響，更新彈體位置，進行小板的重置，再計算超空化問題，迭算至收斂為止。另一方面，對於空化的計算，將加入不同入水角的計算，也就是三維的計算，此方面的計算，由於以Lagrangian-Eulerian 方法考量自由液面相當困難，因此自由液面的考量仍以鏡像的方法考慮。" "The physical phenomenon of high-speed water entry of a supercavitating projectile is very complicated since it involves the interactions of body, liquid and gas. From the literatures, most of the related researches investigated the flow field and motion of body after water entry by experiments. The objective of proposed plan is to understand the hydrodynamic characteristics of high-speed water entry by using computational tools. This research will investigate the problem through a macro view, and apply numerical methods to the analysis of flow field and to the computations of forces. In the first year, a boundary element method based on the potential flow is used, and the method used for the analysis of propeller blade cavitations is extended from the current partial-cavitation model to super-cavitation model. The free-surface effect is simulated by the image. In the second year, we will emphasize on two topics. The first one is the consideration of free-surface effect, and the second one is the three-dimensional calculations. The free-surface effect will be considered with the water entry problem, and the Lagrangian-Eulerian method is used for the simulation. Once the position of a projectile is determined, the cavitation effect will be computed and the time-marching scheme will determine the new position of this projectile. The new flow filed around the projectile will be computed, and a new position will then be calculated. An iterative procedure is needed for the computation. For the three-dimensional water entry problem, that is, a projectile entering water with different angles, the scheme developed in the first year will be used and extended; however, the free-surface effect will still be simuated by an image."

Keyword(s)

入水
超空化
水動力
水彈力
水彈道
邊界元素法
Lagrangian-Eulerian
water entry
super-cavitation
hydrodynamics
hydro-elasticity
hydroballistics
boundary element method
Lagrangian-Eulerian

DSpace CRIS

Research on the Hydrodynamic Characteristics of High-Speed Water Entry of a Supercavitating Projectile(II)

基本資料

Description