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中文核心期刊

基于代理模型的高速圆锥边界层来流慢声波感受性系数建模

RECEPTIVITY COEFFICIENT MODEL OF HIGH-SPEED CONE BOUNDARY LAYERS TO FREESTREAM SLOW ACOUSTIC WAVES BASED ON SURROGATE MODEL

  • 摘要: 流动状态从层流到湍流的转捩过程会导致飞行器表面热流和摩阻急剧增加, 进而对飞行器气动性能带来严峻挑战, 因此转捩预测成为工程设计需要考虑的重要因素. 基于线性稳定性理论的eN方法是转捩预测最常用的方法, 但该方法忽略了边界层对外界扰动的感受性, 导致其转捩预测结果仍存在理论上的不确定性, 有必要建立考虑感受性的eN方法. 通过引入能够表征感受性结果的感受性系数, 并结合外界扰动信息将其作为eN积分的初值, 是实现感受性考虑的一种有效办法. 然而感受性受钝度、壁温、单位雷诺数、扰动频率等众多因素影响, 且作用规律复杂, 难以构建涵盖所有因素的感受性系数关系式. 本文采用代理模型这一基于样本数据快速分析的方法, 基于前期计算的变关键参数如钝度、壁温、单位雷诺数和扰动频率的圆锥边界层感受性系数样本, 建立了能够反应相应关键参数影响的感受性系数模型, 并通过了对该模型的可靠性校验, 有助于下一步改进转捩eN方法. 此外, 还初步开展了感受性对转捩预测的影响分析, 发现考虑感受性有利于提升边界层第一模态对转捩的作用影响力, 忽略感受性将低估第一模态对转捩的贡献.

     

    Abstract: The transition process from laminar to turbulent flow can lead to a dramatic increase in the heat flux and frictional drag on aircraft surfaces, thereby posing severe challenges to aerodynamic performance. Consequently, transition prediction has become a critical factor to consider in engineering design. The eN method, based on linear stability theory, is the most widely adopted methodology for transition prediction. However, this method fails to account for the boundary layer receptivity to external disturbances, leading to theoretical uncertainties in its prediction results. Thus, developing an eN method capable of incorporating boundary layer receptivity has become an essential requirement. The receptivity coefficient, which quantifies the level of receptivity, can reflect the results of receptivity, and combining it with external disturbances as the initial value of eN integration is a commonly used approach. However, there are many factors influencing receptivity (such as bluntness, wall temperature, unit Reynolds number, and disturbance frequency) and the influence patterns are complex, making it difficult to establish a relationship for the receptivity coefficient that accounts for numerous factors. Surrogate model, a data-driven analytical technique leveraging sample datasets, which is the method for rapid analysis based on sample data, are beneficial for establishing a mathematical model of the receptivity coefficient. In this study, a surrogate model is employed to construct a receptivity coefficient model based on previously calculated samples of cone boundary-layer receptivity coefficients for varying key parameters such as bluntness, wall temperature, unit Reynolds number, and frequency. The reliability of the proposed model has been validated, providing a foundation for enhancing the eN method in future studies. Additionally, a preliminary analysis of the influence of receptivity on transition prediction reveals that accounting for receptivity enhances the role of the boundary-layer first mode in driving transition. Neglecting receptivity could lead to a significant underestimation of the first mode’s contribution to the transition process.

     

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