小型航空发动机燃烧室参数化数值模拟方法研究

发布时间：2018-12-11 18:28

【摘要】：随着计算机技术的不断发展,航空发动机的设计越来越依赖于数值模拟,但实体建模和网格划分以及计算模型的发展成为了制约CFD充分发挥潜力的瓶颈问题。因此,本文基于小型航空发动机燃烧室对参数化前处理方法、多孔介质模型、甩油盘模型和计算结果后处理块进行了研究,并发展了燃烧室参数化分析系统。本文针对某型回流燃烧室和折流燃烧室进行了参数化前处理方法的研究。燃烧室的参数化建模利用UG/GRIP语言进行编程,采用编程模块化和建模模块化设计,提高了参数化建模程序的拓展性、更新能力以及通用性,并为满足复杂构型建模的需要,提供了几何特征的描述方法的接口程序。网格划分方面,利用ICEM的脚本文件进行开发,设计人员可通过新建、修改和编辑ICEM的脚本文件,实现网格快速准确的重划分,从而实现自动化网格划分。本文基于商业软件FLUENT,利用UDF和C语言开发了适用于燃烧室的计算模型。针对带有多斜孔发散冷却结构的燃烧室的计算,为避免燃烧室建模复杂性、网格量大和计算机的限制等问题,引入多孔介质方法,结合多斜孔发散冷却技术的理论基础对Fluent中多孔介质模型进行完善。通过对三维多孔发散冷却结构的数值计算验证了该模型,结果表明:多孔介质模型能准确得到壁面温度参数,计算结果与未使用多孔介质模型的计算相似度较高。将甩油盘燃油出口参数与甩油盘结构参数建立联系并模型化,开发了甩油盘雾化模型,输出可供Fluent调用的dpm文件,避免了简化处理中存在的问题,使得甩油盘燃油雾化效果更接近实际情况。为方便设计人员直接得到所设计燃烧室的性能参数,开发了计算结果后处理模块,将Fluent的监视文件直接快速地转换为燃烧室状态参数输出,并与试验结果进行对比求得相对误差。最后,在本课题组的燃烧室初步方案设计系统的基础上,将参数化前处理方法、多孔介质模型、甩油盘雾化模型和计算结果后处理模块集成形成燃烧室参数化分析系统,并将该系统应用于某型回流燃烧室和某型折流燃烧室上。通过对某型回流燃烧室的应用主要验证了本系统的参数化前处理方法的可靠性,统计结果发现:利用本方法可减少燃烧室设计过程中建模和网格划分的90%以上的工作量,并且实体建模和网格划分准确合理。通过对某型折流燃烧室的应用,验证了系统中多孔介质模型和甩油盘模型的准确性,验证结果表明:多孔介质模型能较准确模拟燃烧室壁温的分布情况,节省计算资源;甩油盘模型能准确地模拟甩油盘实际燃油喷射效果,燃油分布均匀合理,可以灵活修改燃油喷射点、出口粒径、速度分量和燃油流量。
[Abstract]:With the development of computer technology, the design of aeroengine relies more and more on numerical simulation. However, the development of solid modeling, mesh generation and computing model has become a bottleneck problem that restricts CFD to realize its full potential. Therefore, based on the combustion chamber of small aero-engine, the parameterized pre-treatment method, porous media model, oil plate model and post-processing block are studied, and the parameterized analysis system of combustion chamber is developed. In this paper, the parameterized pretreatment method for a reflux combustion chamber and a baffle combustor is studied. The parameterized modeling of combustion chamber is programmed by UG/GRIP language, and the programming modularization and modeling modularization are adopted to improve the expansibility, updating ability and generality of the parameterized modeling program, and to meet the needs of complex configuration modeling. An interface program for describing geometric features is provided. In the aspect of grid division, the script file of ICEM is used to develop it. The designer can create, modify and edit the script file of ICEM to realize the quick and accurate repartition of grid, so as to realize the automatic grid division. In this paper, a computational model for combustion chamber is developed by using UDF and C language based on commercial software FLUENT,. Aiming at the calculation of combustor with multi-slant hole divergent cooling structure, in order to avoid the complexity of combustion chamber modeling, the large mesh and the limitation of computer, the porous media method is introduced. The porous media model in Fluent is improved based on the theory of multi-hole divergent cooling technology. The model is verified by numerical calculation of three-dimensional porous divergent cooling structure. The results show that the porous media model can accurately obtain the wall temperature parameters, and the calculation results are similar to those of the non-porous media model. By establishing and modeling the fuel outlet parameters and the structure parameters, the atomization model is developed, and the dpm file that can be called by Fluent is output, which avoids the problems existing in the simplified processing. The atomization effect of the fuel is closer to the actual situation. In order to obtain the performance parameters of the designed combustion chamber directly, the post-processing module of the calculation results is developed, and the monitoring files of the Fluent are converted directly and quickly into the output of the state parameters of the combustion chamber. The relative error is obtained by comparing with the experimental results. Finally, on the basis of the preliminary scheme design system of combustion chamber of our group, the parameterized pre-treatment method, porous media model, atomization model of oil jitter and post-processing module of calculation results are integrated to form a parameterized analysis system for combustion chamber. The system is applied to a reflux combustion chamber and a baffle combustor. The reliability of the parameterized pre-processing method of the system is mainly verified by the application of a reflux combustion chamber. The statistical results show that the workload of modeling and meshing in the design process of the combustion chamber can be reduced by more than 90% by using this method. And entity modeling and mesh generation are accurate and reasonable. The accuracy of the porous media model and the oil plate model in the system is verified by the application of a certain type of baffle combustor. The results show that the porous media model can accurately simulate the wall temperature distribution of the combustor and save the calculation resources. The model can accurately simulate the actual fuel injection effect, the fuel distribution is even and reasonable, and the fuel injection point, outlet particle size, velocity component and fuel flow rate can be flexibly modified.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V231.2

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