【作者】 李大鹏；

【导师】 王振国；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2006， 博士

【摘要】 本文采用理论、试验与数值仿真相结合的手段,对煤油在超声速气流中的火焰传播与扩散、火焰维持、稳定燃烧过程以及燃烧室工作过程进行了深入研究,然后应用这些研究成果对双模态冲压发动机构型进行改进,设计了多凹腔构型发动机,并对此发动机的燃烧性能以及工况转换过程进行了直连式和自由射流试验研究,取得了很多有意义的成果。研究了不同点火方式下煤油在超声速气流中的火焰传播与火焰维持等过程,发现在点火阶段,燃烧室内存在火焰加速传播过程,并且火焰可以在超燃燃烧室内实现逆流传播。实验还发现超燃燃烧室内的着火区域由回流区内的亚声速维持火焰与超声速主流中的扩散火焰组成。对目前广泛采用的超燃流场一维分析模型进行了总结与分析,指出了模型存在的不足,提出了适合强预燃激波条件下的一维分析模型,并在直连式试验中得到了验证,准确度较高。进一步分析和总结了绝热的双流管拟正激波无波模型,将计算结果与一维分析模型结果进行对比,指出了不同面积分布率一维模型计算结果的本质。最后通过改进,提出了一种带加热的拟正激波无波模型,通过仿真计算,指出了一维模型参数计算准确性的相关问题,加深了对超声速燃烧流场的理解。进行了多个凹腔间的相互作用机理研究,发现采用多凹腔构型总体上可以提高液体煤油的燃烧效率。根据研究结果设计了多凹腔构型发动机,并在直连式试验系统上,进行了Ma=4、5、6三种条件下的燃烧性能试验,实现了多种燃烧模态,验证了多凹腔构型双模态发动机的优越性,得出了提高发动机燃烧性能的方法。基于直连式试验系统,进行了模态转换相关技术的试验工作,实现了多种模拟条件下的工况转换过程,并进行了模态转换前后的发动机性能对比。将以上研究成果应用于实际单模块双模态冲压发动机的设计与自由射流试验中,进行了Ma=4、5、6条件下的发动机性能与工况转换研究,顺利实现了发动机的点火、火焰维持与燃烧工况转换过程,并获得了净正推力。更多还原

【Abstract】 The flame propagation, flame holding, stable combustion of kerosene in supersonic flow and dynamic working process of combustor were studied in detail by means of theoretical analysis, experimental investigation and numerical simulation. In this way, the configuration of dual-mode ramjet combustor was improved, a multi-cavity type emerged as the times require. The combustion performance and mode transition of this type of ramjet were conducted by both direct-connect and free-jet hot tests, many significant results were acquired.The process of flame propagation and holding were investigated experimentally by different ways of ignition. It is found that flame can be accelerated and spread upstream in the phase of ignition of certain cases, and the supersonic combustion flow field was made up of the resident flame in subsonic recirculating zone and diffusive flame in supersonic main flow.By comparing different 1-d models which were adopted for analyzing supersonic flow field, the limitations of these models turned up. A new 1-d model fitted for strong precombustion shockwave was put forward, which was validated by the direct-connect hot tests. Moreover, through analyzing the adiabatic no-shock pseudo-shock model for dual-mode combustor, different results derived from this model and 1-d models were given, the essence of calculating by using 1-d model with different area distribution was pointed out. Finally, the supersonic flow field was simulated with a modified non-adiabatic no-shock pseudo-shock model, the veracity of 1-d models by using different parameter was considered.It is found that multi-cavity type of combustor could improve both combustion efficiency and engine performance while investigating the mechanism of the interaction of cavities. The combustion performance of this type of combustor was tested on the direct-connect test-bed under the condition simulated Ma4, 5 and 6. These are of use to enhance the performance of dual-mode ramjet combustor.The combustion mode transition under various simulating conditions was carried out basing on the direct-connect test-bed, the contrast between pre-transition and after-transition engine performance was given.Finally, several free-jet tests were conducted under the condition of Ma4, 5 and 6 with a full size dual-mode ramjet engine. The flame holding and combustion mode transition were achieved under all incoming flow conditions. Positive thrust of this dual-mode ramjet engine was obtained.更多还原