低空探空火箭的氣動力性質模擬

Abstract

探空火箭(sounding rocket)是太空運載工具的一種，採取省去導引及控制系統來降低成本，利用機翼或裙狀外型來進行氣動力控制，保持火箭穩定飛行。探空火箭主要功能為運送精密探測儀器進入地球軌道進行自然現象的探測行為。探空火箭飛行在不同的階段：在不同速度情況下有次音速、穿音速、超音速到極超音速等階段；大氣密度也隨著不斷攀升的高度而變動，此時火箭會經歷連續流場、過度流場以及稀薄氣體流場。在探空火箭的氣動以及熱傳系統設計領域中，各具特色的飛行環境的所造成不同的氣動及熱傳模擬方法的建構是非常重要的。UNIC-UNS是一套求解Navier-Stokes方程式的程式，在這份研究當中，我們利用這個程式來模擬探空火箭在不同飛行階段與各具特色的大氣環境中，氣動及熱傳情況。我們首先必須做網格測試來選擇最有效率的網格數量，再利用此網格來進行不同飛行階段：不同的馬赫數、大氣密度以及飛行攻角的氣動力性質模擬。最後再比較層流模組跟紊流模組模擬出來的結果。由結果可以看出，當雷諾數小於105時，使用層流模組模擬出來的結果較準，當雷諾數大於106時，使用紊流模組模擬出來的結果較準，而雷諾數介於這兩者中間的流場條件，則視為過度區，用此兩種流場型態去模擬都不能夠得到非常準確的結果。

Sounding rocket is one kind of launch vehicles. It uses aerodynamic self-control to keep the stability of the rocket in the period of flying. A sounding rocket is used to carry a payload into the orbit or out Earth’s gravity entirely. The sounding rocket flies through different velocities, such as subsonic, sonic, supersonic and hypersonic. Atmospheric density varies with the height, so the sounding rocket flies over the continuous flow, transitional flow and rare flow. To the aerodynamics force and heat transfer design systems of the sounding rocket, it is very important to overcome the aerodynamics and heat transfer problems caused by different kinds of flight environment. In this study, we apply a parallelized Navier-Stokes equation solver, named UNIC-UNS, to simulate aerodynamics and heat transfer condition of sounding rocket at different stages of flight. We make the grid convergence test first to choose the most efficient grids. We simulate aerodynamics with different stages, Mach numbers, atmospheric densities and attack angles. 2. When Re<105, and Re>106, we can use laminar and turbulent flow model respectively. When 105<Re<106, we can consider it as the transitional regime.