Session: 06-12 Pressure gain combustion II

Submission Number: 179193

Experimental and Numerical Analysis of a Thin-Walled Rotating Detonation Combustor for Hydrogen-Fueled Microgas Turbines 

Rotating detonation combustors (RDC) have become an attractive alternative to traditional deflagrative combustors and even other methods of detonation such as pulse detonating combustors. RDCs offer significant efficiency advantages over conventional combustion systems, including up to a 15% increase in total pressure gain and a 5% improvement in thermal efficiency.  This paper focuses on designing a rotating detonation combustion (RDC) engine with minimal wall thickness to enhance manufacturability and ease of repeated testing, with the ultimate goal of replacing a deflagrative combustor in a 12 kW Microgas Turbine and uses hydrogen with a low-loss compact RDE design.  In addition to structural considerations, the design incorporates film cooling to enable operation for approximately 60 seconds during testing.  The system utilizes an upstream compressor and heat exchanger operating at 78% and 85% efficiency, respectively. Downstream the combustor is an axial turbine that operates at a mass flow of around 140 grams/s and temperatures of 1142 K, with an overall net output of 12 kW at a net efficiency of 21.85%. The paper starts with the design of the combustor. By implementing a 0D analysis involving isentropic relations, injector correlations, and film cooling models, along with measurements of the current combustor, the initial sizing and geometry were produced. The design's feasibility is then evaluated using 3D unsteady RANS CFD in Metacomp’s CFD++ and meshing in Fidelity Pointwise. Hot flow modeling utilizing an ideal gas assumption and 2 equation k-SST URANS turbulence model in a 1-step hydrogen reaction mechanism and a 7-step hydrogen reaction mechanism revealed a mixing-limited problem. Research on injector types and back pressure to induce turbulent mixing supported by simulations sweeps are done in CONVERGE CFD solver, which is then used for the final design. The final manuscript will incorporate experimental long duration tests with pressure and thrust measurements to demonstrate effective coupling with the upstream and downstream components.

Presenting Author: Rodrigo Dacosta North Carolina State University

Presenting Author Biography: Rodrigo Dacosta is a graduate student in Aerospace Engineering at North Carolina State University, focusing on advanced propulsion systems and detonation-based combustion. At the BEFAST Lab, he researches novel propulsion methods and rotating detonation combustors for power generation applications, using numerical modeling, CFD analysis, and experimental validation. He also serves as the Launch Vehicle Chief Engineer for NC State’s Liquid Rocketry Lab and has completed internships at Eaton in both design and field service roles. His technical skills include MATLAB, Python, ANSYS FEA, CFD++, and CONVERGE, with experience in structural design, system integration, and turbomachinery.

Authors:

Rodrigo Dacosta North Carolina State University
John Grunenwald North Carolina State University
Eduardo Leite De Moraes North Carolina State University
Nathaniel Michnoff North Carolina State University
Cedric Devriese University of Mons
James Braun North Carolina State University
Lucas Nicol North Carolina State University