Tri-Rotor Propeller Design Concept, Optimization and Analysis of the Lift Efficiency During Hovering

This study introduces the simulation of a tri-rotor contra-rotating propeller for thrust force and hover lift efficiency during vertical take-off. Vertical take-off or landing is a method used by many aircraft and makes the vehicle more convenient and easier to use. The second rotor revolved in the opposite direction of the first and third rotors. The proposed multi-rotor system has NACA 0012 untwisted and symmetric airfoil and includes three rotors with two blades for each. The airflow analysis was optimized with computational fluid dynamics simulation by using different pitch combinations to achieve the highest hover lift efficiency with sufficient overall thrust value. The critical angle of attack for the chosen airfoil gave the boundary conditions for the pitch of rotors. The results showed us that the most efficient combinations for three rotors work better with an increase of pitch angle from top to bottom so that there is a difference of at least two degrees between propellers. Experiments with angles of attack within the boundary conditions showed that the blade combinations starting from three degrees and increasing values gave positive and adequate results in many cases. In addition, the results showed that a regular increase in the angle of attack does not relate to a regular increment in thrust force.