采用N2O与含金属HTPB燃料固液火箭发动机燃速试验研究

Experimental Research of Regression Rate of N2O and Metalized HTPB Hybrid Rocket Motor

Key words:  Hybrid rocket motor  Combustion efficiency  Regression rate  Metalized solid fuel CLC number:V436.2Document code:AArticle number:1001-4055(2014)03-0413-09

摘要:

为了研究含金属固体燃料固液火箭发动机的燃速及发动机的工作特征,采用N₂O氧化剂与含Al,Mg和C的HTPB基固体燃料的固液发动机进行试验研究与分析,试验在3种尺寸药柱、多种氧化剂流量下进行,获得发动机的燃速、燃烧室压强及燃烧效率等参数。为分析辐射换热对燃速的影响,把燃速分成两部分并提出相应的分析式:一部分由对流换热控制的燃速,由通过药柱通道的总质量流率来衡量；另一部分由辐射换热控制,通过燃烧产物中凝相组分对固体燃料壁面的辐射换热量决定。对试验结果进行分析发现,除富氧的情况外,热辐射控制的燃速约占总燃速的30%~60%,辐射控制燃速与对流控制燃速的比例趋势与燃烧产物中凝相组分的质量分数随氧燃比的变化规律相似。同时,试验结果显示,试验燃速总体上随着固体药柱通道中氧化剂质量流率的增加而增大。发动机的燃烧效率绝大多数位于80%~97%的范围,在化学当量比附近和富氧范围内,随着燃烧温度的降低而降低,效率曲线与理论绝热燃烧温度值的平方相似。 

Abstract:

Regression rate behavior of metalized fuel was investigated through motor experiments using the propellant of N₂O and HTPB fuel containing Al, Mg and carbon ingredients. Results of regression rate, combustion chamber pressure and combustion efficiency were obtained with three kinds of grains and multi-oxidizer mass flow rates. To analyze the effect of radiation heat flux on regression rate, equations were deduced to correlate and separate regression rate into two parts:one was convective evaluated by total mass flux and the other was radiative evaluated by radiative heat flux of condensed phase products. The radiation regression rate is about 30%~60% of total regression rate in all oxidizer to fuel mass ratio range except oxide-rich. The trends of radiation regression rate variation and its ratio to convective regression rate are analogous to condensed mass fraction of combustion products versus oxidizer to fuel mass ratio. And the regression rate generally increases with oxidizer mass flux. It also indicates that combustion efficiencies mostly between 80% and 97% are analogous to the normalized square value of theoretical combustion temperature in ranges around stoichiometric ratio and oxide-rich. 