超燃冲压发动机流场一维平均方法研究

Study of One-Dimensional Averaging Methods in Scramjet

关键词:  超燃冲压发动机  一维平均方法  面积加权平均  流量加权平均  流量/动量/能量守恒方法  动量/能量/熵守恒方法

Key words:  Scramjet  One-dimensional averaging method  Area weighted averaging  Mass weighted averaging  CMME method  CMES method

摘要:

介绍了多种平均方法，包括常用的流量或面积加权平均方法，以及CMME(流量/动量/能量守恒)方法和CMES(动量/能量/熵守恒)方法。以超燃冲压发动机进气道-燃烧室构型为对象，研究了不同平均方法得到的等效一维结果差异，以及不同平均方法的入口参数对超燃燃烧室一维计算结果的影响。结果表明:在超燃燃烧室多维热态仿真数据分析时，推荐使用通量守恒方法；CMES方法能准确的保留总压信息，CMME方法得到的总压损失会大于实际，在处理总压恢复性能时，CMES方法更优；亚燃模态时，CMME方法和CMES方法均不能反映隔离段激波串的渐变压缩；超燃模态时，CMES方法能较好地保持动量的近似守恒，在亚燃模态则较差；不同平均方法得到燃烧室入口参数的一维计算结果与三维流场等效一维沿程静压分布均存在一定偏差，Case1流量加权平均解误差高达27.8%，通量守恒解误差仅约13%，Case2流量加权平均解误差为14.9%，通量守恒解误差仅约5%，说明CMME方法与CMES方法符合程度更高，推力计算结果更为可信。

Abstract:

Various averaging methods were introduced，including common mass or area weighted averaging method，including the conserved mass/momentum/energy (CMME) method and the conserved mass /energy/entropy (CMES) method. A model containing scramjet inlet and combustor was used to reveal the difference between different averaging methods，and effects of entrance data from different averaging methods on combustor one-dimensional analysis. Results show that the conserved methods are recommended when dealing with scramjet combustor. The CMME method can conserve accurate total pressure，while the CMES method will cause virtual total pressure loss，so the CMME method is recommended in dealing with total pressure recovery. In subsonic combustion mode，both conserved methods cannot predict the gradual compression in isolator. In supersonic combustion mode，the CMES method can hold better approximate conservation of momentum，which is worse in subsonic combustion mode. Combustor one-dimensional analysis results of entrance data from different averaging methods are compared. Derivation of Case 1 result by mass weighted averaging method is up to 27.8%，which by the conserved methods are only about 13%. Derivation of Case 2 result by mass weighted averaging method is up to 14.9%，which by the conserved methods is only about 5%. Results all show some deviation with equivalent one-dimensional result of multi-dimensional flow field，but the CMME and CMES methods fit better，and its computed thrusts are more reliable.