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首页> 外文学位 >An experimental investigation of reacting and nonreacting coaxial jet mixing in a laboratory rocket engine.
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An experimental investigation of reacting and nonreacting coaxial jet mixing in a laboratory rocket engine.

机译：在实验室火箭发动机中进行反应性和非反应性同轴射流混合的实验研究。

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Coaxial jets are commonly used as injectors in propulsion and combustion devices due to both the simplicity of their geometry and the rapid mixing they provide. In liquid rocket engines it is common to use coaxial jets in the context of airblast atomization. However, interest exists in developing rocket engines using a full flow staged combustion cycle. In such a configuration both propellants are injected in the gaseous phase. In addition, gaseous coaxial jets have been identified as an ideal test case for the validation of the next generation of injector modeling tools. For these reasons an understanding of the fundamental phenomena which govern mixing in gaseous coaxial jets and the effect of combustion on these phenomena in coaxial jet diffusion flames is needed.;A study was performed to better understand the scaling of the stoichiometric mixing length in reacting and nonreacting coaxial jets with velocity ratios greater than one and density ratios less than one. A facility was developed that incorporates a single shear coaxial injector in a laboratory rocket engine capable of ten atmospheres. Optical access allows the use of flame luminosity and laser diagnostic techniques such as Planar Laser Induced Fluorescence (PLIF).;Stoichiometric mixing lengths (LS), which are defined as the distance along the centerline where the stoichiometric condition occurs, were measured using PLIF. Acetone was seeded into the center jet to provide direct PLIF measurement of the average and instantaneous mixture fraction fields for a range of momentum flux ratios for the nonreacting cases. For the coaxial jet diffusion flames, LS was measured from OH radical contours. For nonreacting cases the use of a nondimensional momentum flux ratio was found to collapse the mixing length data. The flame lengths of coaxial jet diffusion flames were also found to scale with the momentum flux ratio but different scaling constants are required which depended on the chemistry of the reaction. The effective density ratio was measured which allowed the flame lengths to be collapsed to the nonreacting scaling relation. The equivalence principle of Tacina and Dahm was utilized to compare the theoretical and measured effective density ratios.
机译：同轴射流由于其几何形状的简单和它们提供的快速混合而通常被用作推进和燃烧装置中的喷射器。在液体火箭发动机中，通常在喷丸雾化的情况下使用同轴射流。然而，存在对开发使用全流量分级燃烧循环的火箭发动机的兴趣。在这种构造中，两种推进剂都以气相注入。此外，气体同轴射流已被确认为验证下一代喷油器建模工具的理想测试案例。由于这些原因，需要了解控制气态同轴射流混合的基本现象以及同轴射流扩散火焰中燃烧对这些现象的影响。;进行了一项研究，以更好地理解反应和燃烧过程中化学计量混合长度的标度速度比大于1且密度比小于1的非反应同轴射流。开发了一种设备，该设备在具有十个大气压的实验室火箭发动机中集成了单剪切同轴喷射器。光学通道允许使用火焰发光度和激光诊断技术，例如平面激光诱导荧光（PLIF）。化学计量混合长度（LS）（定义为沿着化学计量条件发生的中心线的距离）是使用PLIF测量的。将丙酮播种到中心射流中，以提供非反应情况下一系列动量通量比的平均和瞬时混合物馏分场的直接PLIF测量。对于同轴射流扩散火焰，从OH自由基轮廓测量LS。对于非反应情况，发现使用无量纲动量通量比会使混合长度数据崩溃。还发现同轴射流扩散火焰的火焰长度与动量通量比成比例，但是需要不同的成比例常数，这取决于反应的化学性质。测量有效密度比，该密度比使火焰长度收缩至非反应比例关系。塔西纳（Tacina）和达姆（Dahm）的等效原理用于比较理论和实测有效密度比。

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