DRAFT

Mechanical and Civil Engineering Seminar

Thursday, December 15, 2022
9:00am to 10:00am
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Gates-Thomas 135
Studies on Off-Nominal Rotor Aerodynamics for eVTOL Aircraft
Ellande Tang, Graduate Student, Mechanical and Civil Engineering, California Institute of Technology,

Ph.D. Thesis Defense

Seminar Title:

Studies on Off-Nominal Rotor Aerodynamics for eVTOL Aircraft

Abstract:

As electric Vertical Takeoff and Landing (eVTOL) aircraft become increasingly common, improved understanding of rotor aerodynamics in the off-nominal conditions the rotors will experience becomes ever more important. A better fundamental understanding of these effects can help inform vehicle design, leading to lower power consumption and improved performance. This thesis will cover a selection of topics to gain a better understanding of the expected rotor aerodynamics associated with use in this class of vehicle, as well as the development of tools to aid in the studies and an analysis of the impact of the effects.

To consider special effects on a rotor in hover on such a vehicle, the first topic is the study of obstructions in the upstream of a propeller, representing the effects of a wing or fuselage blocking a propeller's inlet. The next is the effect of forward flight on the forces produced by a rotor. Lifting rotors are often used in eVTOL aircraft as the craft transitions to forward flight, so a study of their performance in forward flight as well as a model are presented. Having examined rotor-wing interactions in hover and isolated rotor performance in forward flight, the next step is to examine rotor-wing interactions in forward flight. A design of an integrated test stand for studying the aerodynamic interactions between lifting propellers and a wing in low-speed, transitional forward flight is presented as well as the subsequent results.

The development and implementations of two tools to aid in the work are also discussed. The first is a rapid, low-cost method of extracting the geometry of a propeller using photogrammetry which is subsequently used in simulations. The second is low-cost and accessible multi-axis force sensor used in the integrated test stand for propeller-wing interaction studies.

To assess the impact of the findings, the experimental results and models developed are then taken into consideration by applying them to models of existing eVTOL. The change in predicted of hover and transition performance is studied with and without the implementation of models developed in this work.

For more information, please contact Jenni Campbell by email at [email protected] or visit https://www.mce.caltech.edu/seminars.