超音速流場中傘狀減速機構之數值模擬

Numerical Simulations of Supersonic Aeroshell

蕭名彥(Ming-Yen Hsiao)

指導教授 ： 陳慶耀

國立交通大學/工學院/機械工程系所/碩士(2018年)

摘要

本研究為使用商用軟體Fluent模擬一酬載艙體未加裝以及加裝傘狀減速機構在超音速條件下運動之情形，探討溫度、壓力、速度、空氣密度等分布以及所產生之阻力並比較不同馬赫數下之結果。模擬目的為透過數值模型初步分析可能情況，提供將來製造、設計及優化該傘狀減速機構之參考。本文在進行該外部流流場模擬該數值模型之網格切割時，考慮被模擬物件尺寸較大，為方便電腦計算採分層局部加密節省運算空間並逼近理想結果。另外在商用軟體Fluent中，考慮超音速運動條件時氣體之可壓縮性存在該外部流流場，根據操作指引選擇Spalart–Allmaras turbulence model進行計算分析，最終設定再加入亂流黏滯度比率則可得到更接近真實情況之速度及溫度分布。未來若加入耐熱材料選用、機構之細部設計以及配合太空或低地表軌道高度等不同條件，將可能得到更詳細的結果。

關鍵字

計算流體力學 ； 超音速流場 ； 數值模擬

並列摘要

In this thesis, we utilize commercial software Fluent to simulate working situations of a re-entry capsule without and with an aeroshell. We want to get more information about air qualities like temperature, pressure, velocity and density distributions under different Mach numbers and boundary conditions. The purpose of the series of simulations is to use this numerical model to analyze some possible situations for the sake of manufacturing, designing and optimizing the shape or some details of aeroshell.
Due to large scale of the numerical model in this thesis, we separate the model into different parts and mesh specific one denser. The step would let computer save more memory spaces and calculate ideal results easily at the meanwhile. Also, for supersonic external flow, choosing Spalart–Allmaras turbulence model to conduct the numerical simulation and adding viscosity, eddy ratio and so on are the measures to get closer velocity and temperature distributions as in reality.
Considering the application of thermal tolerance materials, more detail mechanism design, outer space or low-earth-orbital conditions, we will get more complete results.

並列關鍵字

CFD ； Fluent ； Supersonic ； Aeroshell ； Numerical simulation

參考文獻

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[2] John E. Theisinger and RobertD. Braun, “Multi-Objective Hypersonic Entry Aeroshell Shape Optimization”, Journal of Spacecraft and Rockets, Vol. 46, No.5, pp. 957-966, 2009.

[3] Robert D. Braun and Robert M. Manning, “Mars Exploration Entry, Descent, and Landing Challenges”, Journal of Spacecraft and Rockets, Vol. 44, No. 2, pp. 310-323, 2007.

[4] Karl T. Edquist, Brian R. Hollis and Christopher O. Johnston, “Mars Science Laboratory Heatshield Aerothermodynamics: Design and Reconstruction”, 2013

[5] Karl T. Edquist, Artem A. Dyakonov, Michael J. Wright and Chun Y. Tang, “Aerothermodynamic Design of the Mars Science Laboratory Heatshield”, 2009.