The limited energy density of batteries generates the need for high-performance power sources for emerging eVTOL applications with radical operational improvement…
The limited energy density of batteries generates the need for high-performance power sources for emerging eVTOL applications with radical operational improvement potential over traditional aircraft. This paper aims to evaluate on-design and off-design recuperated turbogenerator performances based on newly developed compression loaded ceramic turbines, the Inside-out Ceramic Turbine (ICT), in order to select the optimum engine configuration for sub-megawatt systems.
System-level thermal engine modeling is combined with electric generators and power electronics performance predictions to obtain the Pareto front between efficiency and power density for a variety of engine designs, both for recuperated and simple cycle turbines. Part load efficiency for those engines are evaluated, and the results are used for an engine selection based on a simplified eVTOL mission capability.
By operating with high turbine inlet temperature, variable output speed and adequately sized recuperator, a turbogenerator provides exceptional efficiency at both nominal power and part load operation for a turbomachine, while maintaining the high power density required for aircraft. In application with a high peak-to-cruise power ratio, such power source would provide eight times the range of battery-electric power pack and an 80% improvement over the state-of-the-art simple cycle turbogenerator.
The implementation of a recuperator would provide additional gains especially important for military and on-demand mobility applications, notably reducing the heat signature and noise of the system. The engine low-pressure ratio reduces its complexity and combined with the fuel savings, the system could significantly reduce operational cost.
Implementation of radically new ICT architecture provides the key element to make a sub-megawatt recuperated turbogenerator viable in terms of power density. The synergetic combination of a recuperator, high temperature turbine and variable speed electric generator provides drastic improvement over simple-cycle turbines, making such a system highly relevant as the power source for future eVTOL applications.
This paper seeks to present recent work demonstrating the feasibility of Microbots' mobility in rough terrain. Microbots are a new search and rescue concept based on the…
This paper seeks to present recent work demonstrating the feasibility of Microbots' mobility in rough terrain. Microbots are a new search and rescue concept based on the deployment of teams of small spherical mobile robots. In this concept, hundreds to thousands of cm‐scale, sub‐kilogram Microbots are released over a search site such as collapsed building rubble or caves. Microbots use hopping, bouncing, and rolling to infiltrate subterranean spaces in search of possible survivors.
The feasibility of the Microbot mobility concept is evaluated through laboratory prototypes and mobility simulations.
Experimental studies have demonstrated the feasibility of using dielectric elastomer actuators (DEAs) to generate autonomous hops. High‐efficiency hydrogen fuel cells were shown to be able to power DEAs. Simulation results show that Microbots of proper diameter and hop height can successfully traverse very rough terrains.
The implication of this research is that small hopping robots are appropriate for certain search and rescue missions. The limitation of the research to date is that issues of control, path planning, and communication have not yet been addressed.
Key technologies of the Microbot mobility, that use high‐energy‐density micro fuel cells combined with low cost and lightweight DEAs, are feasible. These technologies have the potential to make a significant impact on the search and rescue robots.
These results suggest that a team of Microbots‐based DEAs and micro fuel cells can be a useful and effective tool for search and rescue operations.