Evaluating Aerodynamic Performance of Coaxial Rotor Separation Distance
Open Access
- Author:
- Funkhouser, Aden
- Area of Honors:
- Aerospace Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Jose Palacios, Thesis Supervisor
Namiko Yamamoto, Thesis Honors Advisor - Keywords:
- Aerospace
Coaxial Rotors
Thrust
Torque
Engineering - Abstract:
- In recent years, the need for rotorcraft capable of producing large thrust levels while maintaining a relatively small area footprint has revitalized research on the coaxial rotor system. Coaxial rotors offer potential benefits in thrust generation accompanied by a torque cancelation in the overall system that would remove the need for a torque-stabilizing tail system. The research performed for this thesis focused on experimentally evaluating the aerodynamic performance of a coaxial rotor system with respect to the blade separation distance. Rigid rotor blades were spun at various RPMs to determine if the separation distance has any effect on the thrust and torque generated by the overall coaxial system and each individual blade. The torque generation by the rotors demonstrated an adverse relationship of small magnitude, with the fluctuation varying non-linearly over the tested separation distances. However, the torque of the overall coaxial system did cancel out to negligible levels at all tested RPMs. Analysis of the acquired data suggested that while there was a relation between the aerodynamic interference experienced by the rotors and their respective aerodynamic performance, blade separation distance did not linearly affect the performance as originally expected. At certain blade separation distances, which varied with RPM, the adverse relationship between the upper and lower rotors of the coaxial rotor system did allow the upper motor to outperform its isolated, single-rotor system results by margins ranging from 3.28 percent to 10.26 percent. These elevated regions dissipated as the RPM increased and disappeared entirely at an RPM of 3000. Therefore, a coaxial rotor system’s ability to increase overall system performance by elevating the thrust production of the upper rotor above its respective isolated performance is dependent on blade separation distance and operation RPM.