High-order computational fluid dynamics tools for aircraft design

Trends and emerging research directions of sustainable aviation: A bibliometric analysis

This study aims to conduct a bibliometric analysis to determine trends and emerging research directions of sustainable aviation between 2001 and 2023. 726 studies indexed in the Web of Science were examined through VOSviewer software. Science mapping and performance analyses were implemented to demonstrate a systematic quantitative review and the characteristics of the research area. Moreover, by using co-occurrence of keywords, citation, bibliographic coupling, co-authorship, and co-citation analyses, the trends of the research area were revealed in detail. Findings indicated that the publications on sustainable aviation literature were mainly conducted between 2020 and 2023. Research areas of the publications were mainly on "engineering" and "energy fuels". In terms of number of the publications, "International Journal of Sustainable Aviation Fuel" was the most productive source and Heyne was the most productive author. Co-occurrence analysis demonstrated that "sustainable aviation fuel" was the most frequently used keyword. Furthermore, sustainable aviation research has shifted in focus toward more challenging and technology-oriented research over time. Citation analysis indicated that the most cited author was Heyne, the most cited study was Ma et al.'s study on "Aviation biofuel from renewable resources: routes, opportunities and challenges" and the most cited sources was "Energy". Among countries, the U.S.A was the most cited country and Chinese Academy of Sciences was the most cited organization. Bibliographic analysis showed that Heyne was the author with the highest connection strength. Co-authorship analysis demonstrated that Washington State University was the most collaborative organization. Finally, co-citation analysis of cited references indicated that fundamental subjects and related references were mainly sustainable aviation fuel, production of sustainable aviation fuel and its use in aviation studies. It is anticipated that results of this study would contribute to sustainable aviation research and ensure guidance and new perspectives for future research topics and directions on sustainable aviation.

State-of-the Art-Powerhouse, Dam Structure, and Turbine Operation and Vibrations

Dam and powerhouse operation sustainability is a major concern from the hydraulic engineering perspective. Powerhouse operation is one of the main sources of vibrations in the dam structure and hydropower plant; thus, the evaluation of turbine performance at different water pressures is important for determining the sustainability of the dam body. Draft tube turbines run under high pressure and suffer from connection problems, such as vibrations and pressure fluctuation. Reducing the pressure fluctuation and minimizing the principal stress caused by undesired components of water in the draft tube turbine are ongoing problems that must be resolved. Here, we conducted a comprehensive review of studies performed on dams, powerhouses, and turbine vibration, focusing on the vibration of two turbine units: Kaplan and Francis turbine units. The survey covered several aspects of dam types (e.g., rock and concrete dams), powerhouse analysis, turbine vibrations, and the relationship between dam and hydropower plant sustainability and operation. The current review covers the related research on the fluid mechanism in turbine units of hydropower plants, providing a perspective on better control of vibrations. Thus, the risks and failures can be better managed and reduced, which in turn will reduce hydropower plant operation costs and simultaneously increase the economical sustainability. Several research gaps were found, and the literature was assessed to provide more insightful details on the studies surveyed. Numerous future research directions are recommended.