Effect of Nozzle Inclination Angle on Fuel-Air Mixing and Combustion in a Heavy Fuel Engine

Heavy-fuel engines are widely used in UAVs(Unmanned Autonomous Vehicles)because of their reliability and high-power density.In this study,a combustion model for an in-cylinder direct injection engine has been imple-mented using the AVL FIRE software.The effects of the angle of nozzle inclination on fuel evaporation,mixture distribution,and combustion in the engine cylinder have been systematically studied at 5500 r/min and consider-ing full load cruise conditions.According to the results,as the angle of nozzle inclination increases,the maximum combustion explosion pressure in the cylinderfirst increases and then it decreases.When the angle of nozzle incli-nation is less than 45°,the quality of the mixture in the cylinder and the combustion performance can be improved by increasing the angle.When the angle of nozzle inclination is greater than 45°,however,the mixture unevenness increases slightly with the angle,leading to a deterioration of the combustion performances.When the angle of nozzle inclination is between 35°and 55°,the overall combustion performance of the engine is rela-tively good.When the angle of nozzle inclination is 45°,the combustion chamber’s geometry and the cylinder’s airflow are well matched with the fuel spray,and the mixture quality is the best.Compared with 25°,the peak heat release rate increases by 20%,and the maximum combustion burst pressure increases by 5.5%.

Intestinal Microecology in Children with Pneumonia: The Relationship Between Digestive Health and Disease Recovery

This paper explores the association between intestinal microecology and digestive health and disease recovery in children with pneumonia.Intestinal microecological imbalance is common in children with pneumonia,which is closely associated with digestive health and disease recovery.Intestinal microecological imbalance may affect digestive enzyme activity,intestinal mucosal barrier function,and nutrient absorption,which in turn affects digestive health.In addition,intestinal microecological imbalances may be associated with immune regulation,inflammatory responses,and pathogen suppression,affecting disease recovery.Strategies to regulate intestinal microecology include probiotic supplementation,dietary modification,and pharmacological treatment.Currently,the study of intestinal microecology in children with pneumonia faces challenges,and there is a need for improved research methods,individualized treatment strategies,and the development of novel probiotics.In conclusion,the intestinal microecology of children with pneumonia is closely related to digestive health and disease recovery,and the regulation of intestinal microecology is of great significance to the treatment of children with pneumonia.Furthermore,future research should further explore the application of the microecology of the intestinal microecology in the treatment of children with pneumonia.

Prediction of stable high-pressure structures of tantalum nitride TaN2

Structure searches based on a combination of first-principles calculations and a particle swarm optimization technique unravel two new stable high-pressure structures(C2/m and Cmce) for Ta N2. The structural features, mechanical properties, formation enthalpies, electronic structure, and phase diagram of Ta N2 are fully investigated. Being mechanically and dynamically stable, the two phases could be made metastable experimentally at ambient conditions.