Session: Government Agency Student Posters

Paper Number: 173299

Numerical Modeling of Immersion Cooling for Interior Permanent Magnet Synchronous Motors 

High-specific-power electric motors are critical to realizing the next generation of electrified aircraft propulsion (EAP) systems. As aviation moves toward cleaner and more efficient propulsion technologies, the ability to deliver high power output per unit mass becomes increasingly important. However, with increasing power density, these motors face escalating thermal management challenges. Excessive heat in the stator windings and magnetic components not only degrades performance but also threatens the long-term reliability and safety of the propulsion system. Traditional cooling strategies, such as air or pumped liquid cooling, are often inadequate in addressing the intense heat fluxes generated in these high-performance motors. Thus, innovative thermal management solutions are required to ensure both efficient operation and thermal integrity. To address this challenge, this work presents an advanced immersion cooling technology specifically designed for electric motors used in EAP. This approach involves submerging the stator end windings directly in a thermally conductive dielectric liquid pool. It offers significant advantages over conventional air or pumped-liquid cooling, as it enhances convective heat transfer at critical hot spots and minimizes the temperature gradient within the windings. In contrast to existing oil-immersion cooling techniques, which are often constrained by motor geometry or thermal bottlenecks, the presented technology incorporates a high-slot-density design with reduced electrical losses, enabling more compact and efficient thermal management.

The present work centers on two mini-statorette test articles derived from a full-scale interior permanent magnet synchronous motor, i.e., a 90° arc segment and a linearized straight section. Both designs have been tailored for compatibility with NASA Glenn Research Center’s coil-level thermal test rig, to enable controlled evaluation of immersion cooling strategies. A multiphysics simulation model is developed using ANSYS Fluent to predict temperature distributions within the statorette windings. On the one hand, the model applies a uniform volumetric heat source to represent Joule heating to provide a baseline for thermal performance evaluation. Subsequently, the model will incorporate spatially resolved electromagnetic loss data from ANSYS Maxwell for a more accurate representation of real-world thermal gradients and local hotspots. To further understand the cooling performance, a parametric study is performed to analyze the temperature distribution, maximum winding temperature, and the overall thermal resistance at varying flow rate, fluid inlet temperature, statorette orientation, and winding heat generation rate. The findings will provide critical insights into how design and operational variables influence cooling efficiency. This immersion cooling strategy aims to reduce thermal resistance at the stator end windings, mitigate local overheating, and enhance motor reliability. The results from this research will inform the co-design of thermal and electromagnetic features in aerospace motors and directly support NASA’s strategic initiatives in developing high-efficiency electric propulsion systems for future sustainable aviation.

Presenting Author: Daniel Curl University of Arkansas

Presenting Author Biography: Daniel Curl is a Master of Science student in the Department of Mechanical Engineering at the University of Arkansas. He obtained his B.S.M.E. degree, summa cum laude, from the University of Arkansas as a First-Ranked Senior Scholar in May 2025. His research is focused on experimental and numerical investigation of electric motor cooling and two-phase immersion cooling of computer chips.

Authors:

Daniel Curl University of Arkansas
Md Jabed Hossain University of Arkansas
Roy Mccann University of Arkansas
Han Hu University of Arkansas