Static Testing and Multidisciplinary Modeling of the Electric Propulsion System of an Aquatic Small Uncrewed Aerial Vehicle
Restricted (Penn State Only)
- Author:
- Lenze, Victoria
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 19, 2024
- Committee Members:
- Julia Cole, Thesis Advisor/Co-Advisor
Chris Rahn, Committee Member
Robert Kunz, Professor in Charge/Director of Graduate Studies
Timothy W. Simpson, Thesis Advisor/Co-Advisor - Keywords:
- Aquatic sUAV
sUAV
BLDC Motor
ESC
Electronic Speed Controller
Propeller Modeling
Electric Propulsion System
sUAS
Aerial Aquatic
QPROP
RANS CFD
Dynamic Similarity
Electrical Component Modeling
Low Reynolds Number Flows
In-Ground Effect
Dynamometer
Blade Torsional Deformation
Blade Twist
Shear Center
Uncrewed Aerial Vehicle
Unmanned Aerial Vehicle
Thrust Stand
Static
Static Testing - Abstract:
- There is a growing interest in the design and performance of aquatic small uncrewed aerial vehicles (sUAV) to accomplish tasks in both aquatic and aerial domains. To support the development of these systems, an aerial electronic speed controller (ESC)-motor-propeller combination was statically tested in both air and water, and the test data was then compared to multidisciplinary predictions. Three fluid models of increasing fidelity were considered; the first relied on classical blade-element momentum theory, the second was based on blade-element and vortex theory via XFOIL and QPROP, and the third applied a Navier-Stokes-based computational fluid dynamics (CFD) analysis to the system. While an aerial propulsion system can function underwater, it operates at a much lower range of rotational speeds in the denser fluid. Application of partial dynamic similarity with respect to torque and/or thrust coefficients revealed that the rotational speeds in water should be approximately 3.5% of those in air – an effect verified experimentally. Test and model results were compared, and the underwater operating conditions were mimicked in air using a hysteresis dynamometer. This was done to isolate the underwater operating point of the motor from the thermal/fluid effects from operating the motor underwater, and to separate the potential un-modeled physics in the propeller analysis from the difference in fluids. The dynamometer tests revealed that the motor was unable to reach the operating conditions of high torque loads at low rotational speeds in air. This led to separate fits in air and water of the thermal motor model parameters that improved the matching of the model results. The low-order design, QPROP, and CFD models were in agreement with each other and test data in both fluids when paired with ESC and motor efficiency models and required the addition of pitch for predicting underwater performance. A structural model examining the difference across fluids of the moment about the shear center supports the theory that the propeller deforms torsionally along the blade during underwater operation, justifying the models’ incorporation of additional pitch. Further investigation is necessary to more fully understand the identified hydrodynamic differences between the fluids and low-Reynolds number operating cases, and to predict blade deflection of aerial propellers before use in underwater environments.