Noise And Propulsive Efficiency Interactions For Rotors And Propellers At Constant Thrust

In the emerging market of Advanced Air Mobility (AAM), aerospace companies have been designing and prototyping electric and hybrid vehicles to revolutionize travel. These vehicles must have low noise and particulate emissions while also having enough propulsive efficiency to complete the mission. This thesis aims to study the relationship between noise and propulsive efficiency as related to any aircraft equipped with an electric motor and a variable pitch rotor/propeller. The combination of the electric motor with the variable pitch propeller/rotor allows for a decoupled rotational speed and torque generation, meaning that the electric motor can generate the same amount of torque while operating at different rotational speeds. This feature allows the rotor/propeller to hold constant thrust at different combinations of rotational speeds and torque, by adjusting the collective pitch of the blades. This research will show that, for a rotor at constant thrust, the minimum noise (from loading and thickness contributions) and minimum power operating points in terms of rotor RPM and collective blade pitch, are not the same thus leading to the fact that it takes increased energy to decrease noise. A MATLAB code is developed to investigate the power and noise relationship by employing several functions to integrate XFOIL and Blade Element Momentum Theory for the rotor performance calculations and WOPWOP for thickness and loading noise analysis. Broadband noise is not included in the analysis herein. In addition, this thesis will present the design and build of a rotor test stand used to test rotors to validate the simulation results and provide hardware-based solutions for the power required by a rotor in hover. Based on the experimental and simulation results, a closed form equation is also proposed that shows the power required for a rotor at constant thrust, and it can be included in a preliminary rotor performance analysis for AAM vehicle design

Integrated Flight and Propulsion Control for Novel Rotorcraft

Distributed Electric Propulsion (DEP) has increased the design space for aerospace vehicles, especially those categorized as eVTOL (Electric Vertical Take-Off and Landing). This new class of vehicles not only looks different from the typical airplane or helicopter, but functions differently as well. A robust understanding of how the vehicle is controlled in both nominal and off-nominal modes will frame the approach to certification for private and commercial VTOL aircraft. Embry-Riddle Aeronautical University’s Eagle Flight Research Center (EFRC) is researching how the various methods of DEP thrust control apply to larger eVTOL vehicle operation. Researchers will utilize a mixture of flight dynamic simulation and physical testing in collaboration with FAA experts in rotorcraft handling qualities certification. Outcomes of the research include the characterization of various DEP thrust and moment control methods and how this maps to certifiable vehicle-level attributes like handling qualities in nominal and degraded flight modes. A prototype will be built and tested showing the ability of a quad-rotor vehicle to continue flight after the loss of thrust by failure of one rotor. It is anticipated that a better understanding of the DEP units will help inform the process of certification for the emerging market of urban air mobility vehicles. The data obtained from testing will be utilized to define the possible performance parameters, which will aid in developing appropriate means of compliance for advanced fly-by-wire N-rotor eVTOL vehicles