本論文針對小型雙推進劑NTO/MMH液態火箭引擎燃燒室，以數值方法模擬其燃燒流場。並探討不對稱噴注衝擊霧化產生之液膜彎曲角對小型液態火箭引擎燃燒室流場之影響。數值模擬結果發現，當NTO往燃燒室壁方向噴注，而MMH往燃燒室中心方向噴注時，噴注衝擊NTO/MMH動量比分佈會影響液膜擴散面之偏移方向與液膜呈現彎曲之形狀。當霧化擴散面中心之NTO/MMH動量比增加，霧化扇面外緣之NTO/MMH動量比減少時，液膜擴散面中心會往壁面偏移，液膜呈現向燃燒室中心彎曲之內包形狀，燃燒效率較低。但是當霧化擴散面中心之NTO/MMH動量比減少，霧化扇面外緣之NTO/MMH動量比增加時，液膜擴散面中心會往燃燒室中心偏移，液膜呈現向燃燒室壁面彎曲之外包形狀，燃燒效率較高，但容易導致燃燒室壁面局部高溫之現象。

方格區塊結構格點(block-structured mesh)能降低中心軸附近產生之數值誤差，但是由於雙推進劑噴注之不對稱性，使得燃燒室壁面的方格格點產生數值上之不對稱性，導致燃燒室壁面的物理現象產生局部性之差異。本研究另外採取圓柱座標形態之格點做比較，軸對稱的形態相較於卡式座標有較佳之對稱性及均勻性，並能降低壁面格點不對稱性所產生之數值誤差，將可提供較為準確之結果。然而，增加側面擴散角會使霧化液滴產生相互碰撞混合，甚至有穿透式霧化的現象發生，對於燃燒室整體的液滴混合及燃燒效率有較佳的影響。縮小正面擴散角會增加液滴的燃燒混合反應，拉長了霧化面外圍液滴與燃燒室壁之間的距離，使得燃燒室前端之局部高溫的現象較不明顯，但是不同液膜彎曲模式下之偏移角使得霧化扇面外緣之液滴噴向燃燒室壁，會導致燃燒更為接近燃燒室壁面，造成燃燒室壁面後段會有較明顯的局部高溫條紋產生。

In this thesis, the combustion flow in a small bipropellant liquid rocket combustor is numerically simulated. In the present study, how the curvature of the liquid sheet generated by the asymmetric impingement of unlike-doublet injection affects the combustion flow of a bipropellant liquid rocket engine is explored numerically. Numerical results obtained from the present study reveal that the NTO stream is injected in the direction toward the chamber wall and the MMH stream toward the center of the chamber, the distribution of the NTO/MMH momentum ratio determines the deflection angle and shape of the liquid sheet. As the central NTO/MMH momentum ratio is larger, the liquid sheet deflects from the center of the chamber toward the chamber wall, and the concave side of the liquid sheet faces the center of the chamber. Under such a circumstance, the combustion efficiency is lower. On the other hand, as the central NTO/MMH momentum ratio is smaller, the liquid sheet deflects from the chamber wall toward the chamber center, and the concave side of the liquid sheet faces the chamber wall. In this case, the combustion efficiency is relatively higher. However, it may also lead to a high temperature around the chamber wall.

The square block-structured mesh can decrease the numerical error around the center axis. But due to the asymmetry of bipropellant injection, the square grid around the chamber wall will produce the numerical asymmetry, and cause the local differences in physical phenomenon on the chamber wall. In addition, the research adopts the grid of cylindrical coordinate which the symmetrical style of axis has a nice symmetry and uniform to compare with the grid of right triangle coordinate, and decrease the numerical error because of the asymmetry of grid on the chamber wall. This will provide more accurate result. However, to increase the sideward deviation angle will make the atomizated droplets collide with each other, mix, and even the phenomenon of penetrative atomization occur that has a nice influence in the mixture of droplets and combustion efficiency. When the front spray angle decrease, the droplets will increase the combustion mixed reaction, and expand the distance between the droplets around the liquid sheet and the chamber wall. This make the local high temperature phenomenon appear unclearly in front of the chamber wall, but in different curvature cases of liquid sheet, the deflection angle makes the droplets around the liquid sheet inject toward the chamber wall, causes the combustion toward the chamber wall nearly, and will have more clear local high temperature striation in back of the chamber wall.

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