切向喷注的超音速气膜冷却压缩性效应的数值模拟研究

As an active aero-thermal protection mechod, supersonic film cooling with slot coolant injection contains the flow characteristic both of supersonic wall turbulence and free shear turbulence, the fruitful flow phenomenon in the field challenge the ability of numerical technique, the numerical schemes current used in supersonic film cooling are mainly second order accuracy CFD prgram. The research to carry supersonic film cooling with high resolution scheme is seldom seen. The mechnism of compressibility effect on the flow characteristic, flow structures and cooling efficiency is still unclear, there even exits contrary knowledge on the influence of compressibility effect. Up to now, there still retains too much dificiency not only on the numerical technique but also the compressibility effect on supersonic film cooling study. The objective of the present research are configure high resolution numerical technique for increasing the accuracy of aero-thermal pridiction of supersonic film cooling with a high accuracy Discontinuous Galerkin scheme, studying the ability of high resolution method for describe complex flow field and cooling efficiency pridiction in supersonic film cooling. With the numerical simulation with a range of compressibility parameter zone, we will obtain the accuracte numerical data for supersonic film cooling, study the compressibility effect on the flow characteristic and cooling efficiency by the theoretical analysis and post-data processing technique. The present research is wished to supply theory knowledge and engineering methods for supersonic film cooling.

切向喷注的超音速气膜冷却是高超声速/超声速飞行器重要的主动热防护措施之一，其流场涵盖了超声速壁湍流和自由剪切湍流的流动特征，包含丰富的流动现象，给数值模拟带来了较大的挑战，当前用于超音速气膜模拟的数值格式以二阶精度为主，缺乏采用高精度数值格式开展超音速气膜的数值；压缩性效应对于超声速气膜的流场特征、流动结构和冷却效率的影响尚不清晰，甚至存在相互矛盾的认识。目前，超声速气膜的数值模拟研究及压缩性效应尚存在诸多不足。本项目拟以数值模拟和理论分析为研究手段，构建超音速气膜的高精度间断有限元(DG)格式，开展高精度数值格式超音速气膜流动的预测能力的探讨，以期提高当前数值模拟对于飞行器气动热效应的数值预测精度。在不同压缩性效应流动参数范围开展系统的数值模拟，获得可靠的计算数据库；通过理论分析和数据后处理，探索压缩性效应对于超音速气膜的流动特征和冷却效率影响，为超音速气膜的预测提供科学依据和工程模型。

切向喷注的超音速气膜冷却是高超声速/超声速飞行器重要的主动热防护措施之一，其流场涵盖了超声速壁湍流和自由剪切湍流的流动特征，包含丰富的流动现象，给数值模拟带来了较大的挑战。目前，超声速气膜的数值模拟研究及压缩性效应尚存在诸多不足。本项目拟以数值模拟和理论分析为研究手段，对压缩性效应对冷却效率的影响展开了研究。通过引进数值方法的最新成果，改进了高精度间断有限元(DG)格式，形成数值方法具有高精度的同时，适用范围及稳定性有所提高；对自由剪切湍流及壁湍流的数值模拟，表明当前的数值模拟方法具有较高的精度及对流场的精细结构的描述能力；对文献中气膜流动的试验的模拟表明对冷却效率的预测精度能够取得较好的效果；在此基础上，开展了气膜流动的数值模拟，建立了数据库；对压缩性效应对冷却效率的影响从流场特征、理论分析及流动结构方面进行了分析；通过数据拟合及最小二乘构建了冷却效率的经验预测模型，预测结果表明模型的可靠性。