根据国外相关文献整理得出了包含83种组分550步基元化学反应的肼类燃料/红烟硝酸(RFNA)详细化学反应动力学模型,并针对常规隐式和显式多步数值积分方法求解刚性化学反应动力学方程出现的质量分数为负值问题。提出了一种新型变步长隐式差分迭代算法,然后针对发动机开机启动过程的低压环境,采用该化学反应动力学模型及算法对自燃推进剂化学着火延迟进行了数值模拟,得出了RFNA组分含量、O/F混合比、环境压力及温度对着火延迟时间的影响。结果表明:当RFNA中的二氧化氮含量较低时,适当增加二氧化氮含量或提高O/F混合比都可缩短化学着火延迟时间,但前者的效果更为明显;当环境压力和温度较低时,提高温度或压力能明显缩短化学着火延迟时间,但随着温度和压力的增大,这两者对化学着火延迟时间的影响会逐渐削弱。
A detail hydrazine derivatives/red fuming nitric acid (RFNA) chemical reaction kinetic model consisting of 550 elementary reactions among 83 species was constituted based on several foreign relevant literatures, and a newly implicit interactive difference algorithm with variable time steps was proposed to tackle the problem of mass fraction non-positive in the integration procedure of stiff chemical kinetic equations using common implicit and explicit integral algorithm. The chemical delay time of hypergolic propellant was simulated using the chemical kinetic model and the algorithm on the condition of rocket engine low pressure start, and the impact of RFNA component content, O/F mix ratio, temperature and pressure on the chemical delay time was analyzed. The results show that increasing nitrogen dioxide and O/F mix ratio both could reduce the chemical delay time at low concentration of nitrogen dioxide, but the former factor is much more distinct. Increasing temperature and pressure could also improve chemical delay time at low temperature and low pressure environment, but the effect would vanish gradually with much more increase of temperature and pressure.