麻疯树油/RP-3航油混合燃料燃烧特性实验研究

为研究麻疯树油/RP-3航空煤油混合燃料的燃烧特性,在定容燃烧弹内完成了体积混合比分别为1:0,1:1和1:3,初始温度500K,初始压力0.1MPa,当量比为0.7～1.5混合燃料的实验。分析得到了混合燃料的火焰发展特性、火焰半径变化率、拉伸火焰传播速度、马克斯坦长度、无拉伸火焰传播速度等燃料燃烧特性,并与RP-3航空煤油对比。得到以下结论:在当量比为0.7～1.2时,火焰传播稳定,火焰前锋面较光滑;在当量比增至1.3～1.5时,火焰前锋面出现大量裂纹、胞状结构和微型火团,与其他大分子碳氢燃料的燃烧性质相似;在初始温度和初始压力一定时,无拉伸层流火焰传播速度随当量比先增加后减小,在当量比为0.9～1.0附近时,无拉伸层流火焰传播速度达到最大值;混合燃料的马克斯坦长度与当量比呈反比,在当量比为0.7～1.2时,马克斯坦长度为正值,燃烧趋于稳定;在当量比为1.3～1.5时,马克斯坦长度为负值,燃烧趋于不稳定。与RP-3航空煤油对比,掺有麻疯树油时马克斯坦长度轻微降低,燃烧稳定性稍差;在当量比小于1.0时,无拉伸火焰传播速度轻微降低,在当量比大于1.0时,无拉伸火焰传播速度显著降低。     

Characterizing parameters of Jatropha curcas cell cultures for microgravity studies

Jatropha (Jatropha curcas) is a tropical perennial species identified as a potential biofuel crop. The oil is of excellent quality and it has been successfully tested as biodiesel and in jet fuel mixes. However, studies on breeding and genetic improvement of jatropha are limited. Space offers a unique environment for experiments aiming at the assessment of mutations and differential gene expression of crops and in vitro cultures of plants are convenient for studies of genetic variation as affected by microgravity. However, before microgravity studies can be successfully performed, pre-flight experiments are necessary to characterize plant material and validate flight hardware environmental conditions. Such preliminary studies set the ground for subsequent spaceflight experiments. The objectives of this study were to compare the in vitro growth of cultures from three explant sources (cotyledon, leaf, and stem sections) of three jatropha accessions (Brazil, India, and Tanzania) outside and inside the petriGAP, a modified group activation pack (GAP) flight hardware to fit petri dishes. In vitro jatropha cell cultures were established in petri dishes containing a modified MS medium and maintained in a plant growth chamber at 25 ± 2 °C in the dark. Parameters evaluated were surface area of the explant tissue (A), fresh weight (FW), and dry weight (DW) for a period of 12 weeks. Growth was observed for cultures from all accessions at week 12, including subsequent plantlet regeneration. For all accessions differences in A, FW and DW were observed for inside vs. outside the PetriGAPs. Growth parameters were affected by accession (genotype), explant type, and environment. The type of explant influenced the type of cell growth and subsequent plantlet regeneration capacity. However, overall cell growth showed no abnormalities. The present study demonstrated that jatropha in vitro cell cultures are suitable for growth inside PetriGAPs for a period of 12 weeks. The parameters evaluated in this study provide the basic ground work and pre-flight assessment needed to justify a model for microgravity studies with jatropha in vitro cell cultures. Future studies should focus on results of experiments performed with jatropha in vitro cultures in microgravity.