Publication Date


Document Type


Committee Members

Mitch Wolff, Ph.D. (Advisor); Rory Roberts, Ph.D. (Committee Member); José Camberos, Ph.D. (Committee Member); Levi Elston, M.S. (Other)

Degree Name

Master of Science in Mechanical Engineering (MSME)


Two sub-systems that present a significant challenge in the development of high performance air vehicle exceeding speeds of Mach 5 are the power generation and thermal management sub-systems. The air friction experienced at high speeds, particularly around the engine, generates large thermal loads that need to be managed. In addition, traditional jet engines do not operate at speeds greater than Mach 3, therefore eliminating the possibility of a rotating power generator. A multi-mode water-based Rankine cycle is an innovative method to address both of these constraints of generating power and providing cooling. Implementing a Rankine cycle-based system allows for the waste heat from the vehicle to be used to meet the onboard power requirements. This application of a Rankine cycle differs from standard power plant applications because the transient system dynamics become important due to rapid changes in thermal loads and electrical power requirements. Both an experimental and computational investigation is presented. An experimental steady state energy balance was used to determine a 5.1% and 11.5% thermal and Second Law efficiency, respectively. Transient testing showed an increase in power generation of 283% in 30.5 seconds when starting from idle, with a steady state power generation of 230 W. In addition to the power generation, the experimental system removed 10.7 kW from the hot oil loop which emulates a typical aircraft cooling fluid. Experimental results were used in the development of dynamic computational models using OpenModelica, an opensource modeling tool. Deviation between model and experimental results was within 5% for component models and 3.5% when analyzing the system energy balance. Testing of the vehicle level model included steady state, transient, and simulated mission, which was used to characterize performance and develop the system controls. During transient testing, the system controls demonstrated the ability to meet both the cooling and power requirements of the system through rapid response times and minimal temperature overshoot (2.72%). The development and testing of this model provides an opportunity for scaling and optimization of a combined power and thermal management system across a wide range of vehicle sizes and operating conditions.

Page Count


Department or Program

Department of Mechanical and Materials Engineering

Year Degree Awarded