【作者】 张威；

【导师】 严有为； 吴杰；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2022， 硕士

【摘要】 复合材料在航空航天领域得到了广泛的应用,随着未来飞行器趋向于更高速度、更远航程发展,复合材料由于其耐高温、轻量化等优点,将会扮演更加重要的作用。面向飞行器复合材料表面的边界层转捩预测方法直接决定了飞行器气动力、热的精细化设计,从而得到了广泛的关注。本论文基于理想复合材料表面假设,首先在不考虑表面粗糙度的情况下发展了线性稳定性分析(Linear Stability Theory,LST)计算程序;进一步基于线性稳定性分析针对典型模型建立了不稳定波特征值数据库,并发展了基于特征值数据库的边界层转捩预测方法;最后开展了高超声速风洞实验,对该方法进行了验证。本论文具体工作包括:选定可压缩平板和无限展长楔形板作为典型模型,基于可压缩边界层方程和可压缩线性不稳定性方程开发了生成不稳定波特征值数据库的数值程序,包括边界层流场计算模块与不稳定波特征值预测模块,并在大范围工况下开发了基本流数据库和边界层不稳定波特征值数据库。进一步,以理想可压缩平板为例,通过将数值结果和程序计算的流场剖面比较,验证了边界层流场计算模块的准确性;以标准7°半锥角尖锥为实验模型,进行了尖锥的数值计算和稳定性分析,并在高超声速风洞中利用聚焦激光干涉差分仪(Focusing Laser Differental Interferometer,FLDI)等测量手段,展示了理想表面不稳定波的特征和发展过程。对比典型位置测点上LST和实验方法测得的频域增长率情况,验证了不稳定波特征值预测模块的准确性。对不同参数对于流场剖面和特征值的影响进行分析,进一步验证了该数据库的可靠性。基于本项目开发的特征值数据库以及数据库搜索匹配功能,可以实现理想复合材料表面边界层不稳定波特征值的快速预测。以可压缩平板为例,通过数据库搜索得到其特征值用时大约2 s,相比一般的方法耗时约1 h左右,大幅提高了边界层转捩预测计算效率,有望促进边界层转捩预测的工程化应用。下一步工作将围绕真实复合材料形貌表征以及本文所建立数值程序的边界条件完善开展。更多还原

【Abstract】 Composite materials have a wide application on aerospace engineering,and it will paly a significant role in the near-future due to its advantages of high-temperature resistance as well as light structure,stimulated by the trend of faster and longer-range vehicles.The method of boundary-layer transition prediction of vehicles fabricated with composite material decides the accuracy of aerodynamic and aerothermodynamic design,attracting world-wide attention nowadays.Upon this thesis,the method of Linear Stability Theory(LST)is programmed with the assumption of smooth composite material surafce,and based on which the data-base of instability waves is built.This data-base can serve for fast prediction of boundary-layer transition in engineering,before this method has been validated with hypersonic wind tunnel experiment results.The detailed work of this thesis includes the content as follows:The compressible flat plate and the infinitely elongated wedge-shaped plate are selected as typical models.Based on the compressible boundary layer equations and the compressible linear instability equations,a program for generating the eigenvalue database of instability waves is developed,including the boundary layer flow calculation module and the instability wave eigenvalue prediction module,and the basic flow database and the boundary layer instability wave eigenvalue database under a wide range of flight conditions are built.Furthermore,taking the compressible flat plate as an example,the accuracy of the boundary layer flow calculation module is verified by the comparison between the numerical results and the flow field profiles calculated by the program.Taking the standard7° half-cone angle tip cone as the experimental model,the numerical calculation and stability analysis of the tip cone are carried out,and the perfect surface instability characteristics are demonstrated in the hypersonic wind tunnel by using Focusing Laser Differental Interferometer(FLDI)measurement technology and other measurement methods.Comparison of the growth rate in frequency domain measured by LST and the experimental method on typical location measuring points reveals that the accuracy of the eigenvalue prediction module of instability wave in this database can be verified.The precision of the eigenvalue prediction module of the instability wave in this database is thus validated.The influence of different parameters on the flow profile and eigenvalues are also analyzed,which further verifies the reliability of the database.Based on the eigenvalue database developed in this thesis,using its search and matching function,the eigenvalues of the boundary layer instability waves can be quickly predicted by comparing the basic flow property of the boundary layer flow.Taking the compressible flat plate as an example,it takes about 2 s to obtain its eigenvalues through a data-base method,while the direct searching method will take about 1 hour.It shows large potential in the of engineering application due to the large improvement of computational efficiency.The future worl will focus on the characterization of the surface of composite material and also,the boundary condition of composite material surface will be developed for the LST program.更多还原