高密度烃在冲压发动机再生冷却中适用性研究

Adaptability study on regeneratively cooled ramjet engine of high density hydrocarbon

关键词:  冲压发动机  高密度烃  再生冷却  热沉  结焦  实验研究

Key words:  Ramjet engine  High density hydrocarbon  Regenerative cooling  Heat sink  Coking  Experimental study

摘要:

为了研究高密度烃是否适用于宽域可调亚燃冲压发动机再生冷却，分析了高密度烃再生冷却关键表征指标及其实验方法研究现状，然后模拟再生冷却系统典型冷却通道结构，在背压3.5 MPa和6.0 MPa工况下，采用单管直流电加热实验系统，开展了HD-01高密度烃热沉及结焦特性研究。研究结果表明：在3.5 MPa背压实验中，出现了燃料温度振荡、管路热声振荡和外壁温度异常升高现象；而在6.0 MPa背压实验中，未发生管路热声振荡现象，燃料温度和外壁温度升高过程均较为平稳。3.5 MPa背压和6.0 MPa背压两种工况的HD-01高密度烃600 ℃热沉均大于1.8 MJ/kg，在整个实验温度范围内，热沉上升速率变化不明显，表明在600 ℃内燃料的裂解率不大。在600 ℃进行长时间加热结焦实验时，加热管进出口压差非常稳定，均没有超过30 kPa，没有出现结焦堵塞使压力急剧上升的情况，表明HD-01高密度烃在600 ℃以内结焦率很低。从热沉及结焦特性两个关键指标分析可知，HD-01高密度烃适用于最高马赫数5.0的宽域可调亚燃冲压发动机再生冷却。高密度烃用于再生冷却时，冷却通道的设计压力应高于其临界压力值3.6 MPa，并留有足够裕度，以保证发动机再生冷却在全域全温范围内稳定可靠工作。

Abstract:

In order to study whether high density hydrocarbon applies to regenerative cooling of wide range adjustable ramjet， the research status of key indexes and test methods of high density hydrocarbon regenerative cooling is analyzed. And then in connection with the typical pipe of regenerative cooling， a single-pipe direct-current heating experimental system was used to test the heat sink and coking characteristics of HD-01 high density hydrocarbon， with back pressures of 3.5 MPa and 6.0 MPa. The results show that it appears oscillation of the outlet fuel temperature and pipe thermoacoustic， and abnormal rise of outer wall temperature on the pressure of 3.5 MPa. But the pipe thermoacoustic oscillation don’t occur at the pressure of 6.0 MPa. The outlet fuel temperature and outer wall temperature rise stably. The heat sinks of HD-01 high density hydrocarbon at 600 ℃ are both greater than 1.8 MJ/kg at the pressure of 3.5 MPa and 6.0 MPa， and the rising rates of heat sink are not obvious within the scope of the experimental temperature， it shows that the fuel cracking rates are not obvious within 600 ℃. In the heating coking experiment of HD-01 high density hydrocarbon at 600 ℃ for a long time， the differential pressure during the heating pipe inlet and outlet is very stable， it is never overrun 30 kPa，and it doesn’t happen that the pressure rises sharply by coking blockage， which indicates that the coking rate of HD-01 high density hydrocarbon is very low within 600 ℃. According to the results of the heat sink and coking characteristics， HD-01 high density hydrocarbon can meet the regenerative cooling of wide range adjustable ramjet that its max Mach number is 5.0. To ensure the stable and reliable operation of regenerative cooling of ramjet in wide airspace and full temperature， design pressure of regenerative cooling must be higher than 3.6 MPa that it is the critical pressure of HD-01 high density hydrocarbon， and sufficient margin is reserved.