CFD study on ducted rotors for an Urban Air Mobility (UAM) vehicle. A performance validation of coaxial rotors for an Urban Air Mobility vehicle
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Mobility engineering (MPMOB), MSc
Publicerad
Författare
Gnanaraj, Kevin
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Urban Air Mobility vehicles show promise for use as air ambulances due to the potential to decrease the area footprint of the vehicle, and also facilitates loading from both the side and back of the aircraft, improving vehicle accessibility. Challenges
remain in selecting effective propulsion systems for a proposed vehicle to be used in the Västra Götalands region of Sweden, which include the ability of commercial fixed pitch propellers to produce sufficient thrust to ensure safety in case of failure
of one of four propulsion units, composed of coaxial rotor pairs in a contra-rotating configuration.
The aerodynamics of propellers is a well studied science, and is relatively simple to predict performance of a propeller given an accurate description of its airfoil geometry from empirical relations. Much research has been done on quantifying the
performance of coaxial rotor systems, identifying theoretical empirical limits and advantages of such a configuration, allowing for more limited prediction of performance. Ducted rotors are also well studied in tubomachinery theory, and investigations have been carried out on ducted propellers, but vehicles using coaxial ducted propellers are not as common as unshrouded propellers, and thus this configuration will have to be investigated further to gain an understanding of the factors that affect system performance.
This investigation examines the feasibility of selected propellers to adequately power the proposed vehicle in single, coaxial and ducted configurations through numerical analysis and comparison to experimental data where available, and extending the numerical analysis methodology to untested propulsion configurations.
Results from the investigation revealed that geometrical accuracy of a propeller model is vital to accurately predicting performance of a propeller through numerical analysis, and comparisons to experimental data can help improve the quality of
simulated data to extend the analysis to areas where no experimental data is available.
This was the case for coaxial simulations, where the results from the single propeller simulation were compared to available experimental data, used to improve the accuracy of the simulation output data, extended to a coaxial configuration, and
verified experimentally.
The results also showed that the propellers investigated could meet the thrust requirements for a proposed vehicle under specific conditions in a coaxial configuration, which improved system efficiency over a single propeller, validating the use of
numerical simulation of a coaxial propulsion system. The limited duct simulation showed worse performance than a single propeller, but provided a starting point for improved duct design and further numerical analysis.
Beskrivning
Ämne/nyckelord
CFD , Coaxial , Commercial , Contra-Rotating , Thrust , shroud , duct , UAM , UAV , Propeller