【作者】 李超；

【导师】 徐惊雷；

【作者基本信息】 南京航空航天大学 ， 航空宇航推进理论与工程， 2009， 硕士

【摘要】 本文首先利用特征线法获得了二维非对称喷管型面的设计程序。设计过程中采用热理想气体模型,即Cp仅是温度的函数。考虑了燃气是混合气体的事实,其比热可根据燃气各个组分的比热得到。另外还讨论了不同余气系数下燃气比热随温度变化的规律。然后利用该程序,设计了一系列非对称喷管构形,讨论了不同非对称因子G和不同截短程度时喷管的性能,最后确定选择非对称因子G等于0.3,上壁面长度等于800mm,下壁面长度等于200mm的SERN截短型面,作为整个TBCC排气系统的基准型面。在此基础之上,构建了二维上下并联式TBCC排气系统的气动方案以及几何调节方案。其次,对该排气系统气动方案进行了详细的二维流场计算研究,通过对计算结果的分析,本文认为在涡轮发动机单独工作时,冲压通道必须打开,并且确定了各个马赫数下唇口板角度的最佳位置。利用非定常模型以及动网格技术,对模态转换过程0～30s进行了数值模拟。结果显示,整个过程中排气系统推力平稳增加,用以平衡飞行姿态调整导致的阻力增加,总的推力系数也随时间的推移而逐渐增加;升力则在t=5s左右达到最大值之后,在涡轮发动机加力关闭过程中,突然降低。在Ma=3.0~4.0飞行范围内,推力系数在Ma=3.25左右达到最高,此时最接近理想膨胀;且欠膨胀时升力性能较好。最后还根据非支配排序遗传算法编制了多目标优化程序,并将其和商用计算流软件Fluent以及网格划分软件ICEM相结合,构成了流场参数的多目标优化平台。利用该平台,对利用下唇口二次流喷射改善SERN低马赫工况下性能的问题进行了初步优化。更多还原

【Abstract】 The designing program of SERN(Single Expansion Ramp Nozzle) was provided based on the Method of characteristics (MOC) in this paper. The thermally perfect gas model was used in the program,where Cp was only the function of temperature.The Cp of the gas could be obtained by the species of the mixture.There were different Cp value under the different air-residual-coefficient also.A series of two-dimensional SERN configurations were obtaind by the designing program.The performance of the nozzle under the different parameter G and different truncated degree was investigated.As a result,the countour with the G=0.3, 800mm upper wall and 200mm low flap was selected as the base contour of the TBCC exhaust system. Then the aerodynamic scheme and the geometry adjust scheme of a two-dimensional over/under TBCC exhaust system was constructed.The aerodynamic performance of the over/under TBCC exhaust system was investigated particular with the Fluent.The numerical results indicated that: when the turbine working alone,the ramjet dypass must be open, and the best position of the low flap for each Mach number was obtained also. The performance during the mode transition process of the exhaust system was investigated using unsteady model and dynamic mesh method. Results of the analysis indicated that the thrust of the over/under TBCC exhaust system increased steadily, the thrust coefficient increased slightly also. However, there appeared a great and sudden decrease in the lift of the exhaust system when the turbine afterburner was turned off. At the range of Ma=3.0 to Ma=4.0, thrust coefficient arrived its maximum at the Ma=3.25, when the SERN was closed to ideal expansion condition.The lift performance was better under the under-expanded condition.A multi-objective optimization program was obtained based on the nondominated sorting genetic algorithms(NSGA),and a optimization platform was constructed which integrate the NSGA module and the Fluent,ICEM software together.The platform was used in improving the off-design performance of the SERN by secondary injection at the tip of the low flap.更多还原