Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

A numerical framework implemented in the open-source tool OpenFOAM is presented in this work combining a hybrid, pressure-based solver with a vapor-liquid equilibrium model based on the cubic equation of state. This framework is used in the present work to investigate underexpanded jets at engine-relevant conditions where real-gas effects and mixture induced phase separation are probable to occur. A thorough validation and discussion of the applied vapor-liquid equilibrium model is conducted by means of general thermodynamic relations and measurement data available in the literature. Engine-relevant simulation cases for two different fuels were defined. Analyses of the flow field show that the used fuel has a first order effect on the occurrence of phase separation. In the case of phase separation two different effects could be revealed causing the single-phase instability, namely the strong expansion and the mixing of the fuel with the chamber gas. A comparison of single-phase and two-phase jets disclosed that the phase separation leads to a completely different penetration depth in contrast to single-phase injection and therefore commonly used analytical approaches fail to predict the penetration depth.Comment: Preprint submitted to AIAA Scitech 2018, Kissimmee, Florid

Inoculação micorrízica e aclimatização de dois porta-enxertos de macieira micropropagados Mycorrhizal inoculation and acclimatization of two micropropagated apple rootstocks

A micropropagação e a inoculação de fungos micorrízicos arbusculares (FMA) podem melhorar a qualidade de mudas produzidas comercialmente. Essas técnicas permitem a produção de plantas homogêneas e de alta qualidade em curtos períodos de tempo, mas isso exige o conhecimento da interação entre fungos e plantas, substratos e técnicas de aclimatização e inoculação. Foi realizado um estudo em condições controladas a fim de desenvolver procedimentos para aclimatizar e inocular FMA nos porta-enxertos de macieira (Malus spp.) Marubakaido, vigoroso e com forte sistema radicular, e M.9, nanizante e com sistema radicular pouco desenvolvido. Plantas oriundas de micropropagação foram imersas em ácido indolebutírico (5miM) e transferidas para substrato à base de solo, a fim de serem enraizadas ex vitro. Antes ou após o enraizamento, inoculou-se uma mistura de isolados de Scutellospora pellucida, Glomus etunicatum e Glomus sp. A fase de enraizamento durou 21 dias, e após 51 e 81 dias avaliaram-se colonização micorrízica, altura, peso da matéria fresca e seca da parte aérea e relação entre raiz e parte aérea das plantas. A colonização micorrízica variou entre 50% e 70% para ambos porta-enxertos, tendo efeito positivo sobre o crescimento do porta-enxerto Marubakaido, enquanto o porta-enxerto M.9 teve seu desenvolvimento inibido pela presença dos FMA.<br>The combination of micropropagation and inoculation with arbuscular mycorrhizal fungi (AMF) can improve the quality of seedling plants produced on a commercial scale. These techniques allow high quality and homogeneous seedling production in a shorter period of time, but they require understanding of the interaction among fungi, plants, substrates, acclimatization and inoculation techniques. A study was performed under controlled conditions to develop procedures to acclimatize and inoculate AMF in two apple (Malus spp.) rootstocks: vigorous strong-rooted Marubakaido and the dwarfing, poorly rooted M.9. Micropropagated plants were treated with indole-butyric acid (5µM), and then transferred to a soil-based substrate for ex vitro rooting. The AMF were introduced before and after the rooting phase. A mixture of Scutellospora pellucida, two isolates of Glomus etunicatum, and Glomus sp. was utilized. The rooting phase lasted 21 days and plant growth was evaluated after 51 and 81 days under acclimatization conditions, for increase in height, shoot fresh and dry matter, root fresh matter, root-shoot ratio, and mycorrhizal colonization. Mycorrhizal root colonization ranged from 50% to 70% in both rootstocks. The mycorrhizal inoculation had a positive effect on root and shoot growth of Marubakaido rootstock plants, but had a negative effect on growth in M.9 plants