Aerodynamic Optimization of the Sizing and Blade Designs of Hovering Corotating Coaxial Rotors

2022 ◽  
Author(s):  
Keen Ian Chan
Keyword(s):  
Electric Propulsion ◽  
Optimization Technique ◽  
Rotor Blades ◽  
Aerodynamic Optimization ◽  
Propulsion Systems ◽  
Aerodynamic Efficiency ◽  
Flow Phenomena ◽  
The Subject ◽  
Design Perspective ◽  
Coaxial Rotors

Corotating coaxial rotors are seeing renewed interest in distributed electric propulsion systems and electric vertical take-off and landing (eVTOL) aircraft. The recent literature reports many interesting investigations, using prescribed rotor blades, into the flow phenomena as well as aerodynamic and aeroacoustic benefits of corotating rotors. However, the subject of the design of blade geometries, optimized to a design goal, for corotating rotors is currently lacking in the literature. This paper is written from such a design perspective, by extending a previous generalized approach to the aerodynamic optimization of counterrotating rotors to corotating rotors. The previous requirement for upper and lower counterrotating rotor torques to be equal can now be lifted in the case of corotating rotors, enabling improved versatility in the optimization of corotating blade designs. The optimization is demonstrated on an application example to address the conflicting conditions that index angles (high) for aeroacoustic benefits of reduced noise are at odds with those (low) for aerodynamic efficiency. The approach demonstrated in this paper is to set the index angle for reduced noise and then recover back the aerodynamic efficiency by using the newly developed aerodynamic optimization technique.

Generalized Aerodynamic Optimization of Hovering Coaxial Rotor Blades

2019 ◽  
Vol 64 (2) ◽  
pp. 1-13
Author(s):  
Keen Ian Chan
Keyword(s):  
Optimization Technique ◽  
Rotor Blades ◽  
Aerodynamic Optimization ◽  
Coaxial Rotor ◽  
Design Variables ◽  
Generalized Momentum ◽  
Aerial Vehicle ◽  
High Figure ◽  
Optimization Methodology ◽  
Coaxial Rotors

This paper presents the development and application of a generalized approach to the aerodynamic optimization of hovering coaxial rotors. The generalization lifts the constraints of previous theories and enables dissimilar rotor diameters, dissimilar rotational speeds, and thrust-sharing percentage of the upper and lower rotors of a coaxial pair to be incorporated as design variables. This increased versatility was necessitated by the emergence of electric vertical take-off and landing unmanned aerial vehicles, which feature independently driven rotors and have unique operational requirements. The optimization methodology begins with the derivation of the generalized momentum theory for coaxial rotors, and then extending the formulation to become an optimization technique, which determines optimal combinations of rotor diameters and rotational speeds for a specified thrust-sharing percentage. These results are next used as inputs to determine the optimal dissimilar geometries for the upper and lower rotor blades. The optimization is demonstrated on a multirotor vertical take-off and landing unmanned aerial vehicle with three coaxial pairs of rotors. The results show that a high figure of merit is achieved, and this is a contributing factor in improved hover endurance.

Aerodynamic Optimization Study of a Coaxial Rotor in Hovering Flight

2012 ◽  
Vol 57 (4) ◽  
pp. 1-15 ◽  
Author(s):  
Monica Syal ◽  
J. Gordon Leishman
Keyword(s):  
Optimization Methods ◽  
Optimization Approach ◽  
Aerodynamic Optimization ◽  
Aerodynamic Efficiency ◽  
Coaxial Rotor ◽  
Optimization Study ◽  
Parametric Studies ◽  
Aerodynamic Interference ◽  
The Individual ◽  
Coaxial Rotors

A primary design goal with a coaxial rotor is to minimize the combined sources of losses on the upper and lower rotors that have their source in aerodynamic interference. To this end, parametric studies were conducted using a free-vortex wake method to study the aerodynamic interference effects of changing interrotor spacing, blade twist rates, and blade planform on the interdependent loads produced on the upper and lower rotors, respectively. A formal, multistep optimization process was then conducted by coupling the aerodynamic method to an optimization approach based on the method of feasible directions, the goal being to expeditiously find the individual blade geometries that would give the highest levels of efficiency from the coaxial as a system. Because of the inherent aerodynamic differences between the upper and lower rotors of a coaxial, it is shown that the best performing coaxial rotors may require the use of different blade shapes on each rotor, but substantially different blade designs may also achieve similar values of aerodynamic efficiency. It is also shown that the nonconvexity of the design problem for a coaxial rotor may limit the usefulness of formal optimization methods, and extensive parametric studies may still be required in the process of design.

scholarly journals Design Considerations for Autonomous Cargo Transportation Multirotor UAVs

2020 ◽  
Author(s):  
Denis Kotarski ◽  
Petar Piljek ◽  
Josip Kasać
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Electric Propulsion ◽  
Primary Research ◽  
Propulsion Systems ◽  
Design Considerations ◽  
Aerial Vehicles ◽  
Heavy Lift ◽  
The Subject ◽  
Cargo Transportation ◽  
Advanced Tool

Unmanned aerial vehicles (UAVs) have proven to be an advanced tool for a variety of applications in the civilian and military sectors. Different categories of UAVs are used in various missions and are also the subject of numerous researches. Due to their characteristics and potential in specific conditions, multirotor UAVs imposes itself as a solution for many tasks, including transport. This chapter presents a conceptual solution of autonomous cargo transportation where the primary research objective is the design of a heavy lift multirotor UAV system. The process of designing a multirotor UAV that can carry heavy lift cargo is quite challenging due to many parameters and constraints. Five selected series of electric propulsion systems are analyzed, with different multirotor configurations, and results are graphically displayed for payloads from 10 kg up to 100 kg.

Thermodynamics of Flowing Systems: with Internal Microstructure

1994 ◽  
Author(s):  
Antony N. Beris ◽  
Brian J. Edwards
Keyword(s):  
Free Energy ◽  
Theoretical Study ◽  
Flow Behavior ◽  
Irreversible Thermodynamics ◽  
Hamiltonian Mechanics ◽  
Complex Interplay ◽  
Microscopic Models ◽  
Flow Phenomena ◽  
The Subject ◽  
The Continuum

This much-needed monograph presents a systematic, step-by-step approach to the continuum modeling of flow phenomena exhibited within materials endowed with a complex internal microstructure, such as polymers and liquid crystals. By combining the principles of Hamiltonian mechanics with those of irreversible thermodynamics, Antony N. Beris and Brian J. Edwards, renowned authorities on the subject, expertly describe the complex interplay between conservative and dissipative processes. Throughout the book, the authors emphasize the evaluation of the free energy--largely based on ideas from statistical mechanics--and how to fit the values of the phenomenological parameters against those of microscopic models. With Thermodynamics of Flowing Systems in hand, mathematicians, engineers, and physicists involved with the theoretical study of flow behavior in structurally complex media now have a superb, self-contained theoretical framework on which to base their modeling efforts.

Electromagnetic emission experiences using electric propulsion systems

1989 ◽  
Vol 5 (5) ◽  
pp. 534-547 ◽  
Author(s):  
James S. Sovey ◽  
Lynnette M. Carney ◽  
Steven C. Knowles
Keyword(s):  
Electric Propulsion ◽  
Electromagnetic Emission ◽  
Propulsion Systems
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