Abstract
Electrical propulsion has been identified as one of the key fields of future research within the aerospace sector. The Institute of Aeronautical Engineering at the Universität der Bundeswehr München aims to contribute to the ongoing development of small-sized electrical ducted fan engines with a thrust in the range of 100 N. A special emphasis is placed on electrically powered contra-rotating fan stages. When compared to a conventional rotor–stator stage, contra-rotating fan stages allow for a more compact design, considering a given pressure ratio, or an increased pressure ratio at a constant fan diameter. Since numerous new aircraft concepts are presently being developed, a high demand for compact and powerful electrically driven engines arises. Electrically driven contra-rotating fan engines provide a high potential in terms of compactness, emissions and efficiency. Using electric motors offers the ability to overcome common issues, such as design and integration of a contra-rotating stage into a gas turbine. An innovative new engine design featuring such a contra-rotating stage is developed and tested at one of the Institute’s test benches for electrical propulsion. Key components are two brushless motors powering the fan stage, one for each rotor. Various operation points are investigated experimentally during an extensive test campaign. Experimental results are compared to results of numerical simulations computed by ANSYS CFX. Results indicate a good agreement between experiment and simulation. The engine is running very smooth throughout all tested operation points. Yet, intensive heating up of the electric motors and high-temperature zone are found to be an issue at higher rotation speeds.
Highlights
During the last decades, the worldwide aerospace sector has been undergoing a remarkable development, as a variety of new business segments has been established and expanded in parallel to commercial, general and military aviation [1]
This paper addresses advantages and drawbacks of contra-rotating fans, their design in general and in particular, Fig. 1 Contra-rotating fan engine considering the contra-rotating fan engine (CRF) owned by the Institute
For the sake of clarity, we present all relevant parameters as a function of the mass flow, where we will highlight our operation points
Summary
The worldwide aerospace sector has been undergoing a remarkable development, as a variety of new business segments has been established and expanded in parallel to commercial, general and military aviation [1]. These new business segments are still evolving, including fields such as urban mobility, delivery services or surveillance missions. A number of contemporary aircraft concepts already moved away from combustion engines toward electrical motors. Especially light aircraft for general aviation purposes have been equipped with electrical engines
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