HySonic Technologies, founded by Dr. Carlo Scalo, addresses this call by combining its capabilities in design of acoustically absorptive high-temperature materials with Dr. Carson Slabaughs (Purdue University) well-established expertise in designing and testing of Rotating Detonation Combustors (RDC) at various scales. HySonics history in the design of acoustically absorptive material relies on a previously awarded ONR SBIR Contract (N68335-19-C-0312) where acoustically absorptive high-temperature carbon-fiber ceramics have been already developed targeting the frequency range of 100 kHz 300 kHz for hypersonic boundary layer control. In Phase 1 of the current effort, HySonic will design an acoustic benchtest apparatus, covering the 1kHz 10kHz range (relevant for RDC applications), to assess the acoustic absorption spectrum of various candidate high-temperature resistant materials. The challenge lies in balancing the acoustic absorption performance - which requires surface and volumetric porosity - with thermal and structural resistivity, which requires a material that is densified as much as possible. The same materials will also be tested in the lab-scale (4 diameter) RDC already available in Dr. Slabaughs group to assess their survivability and acoustic absorption properties in a high heat flux / shear stress environment. Computational modeling at various levels of fidelity will also be attempted with the goal of reconciling the benchtest acoustic measurements with the lab-scale RDC results. If awarded Phase II, the HySonic/Purdue team will scale this effort to a large scale RDC rig (9 diameter) already available in Dr. Slabaughs group starting in the option phase, while simultaneously pursuing updated computational results.
Benefit: Rotating detonation combustors offer two main benefits over conventional, deflagration-based combustion devices: increased thermal efficiency and increased power density. Integration with practical propulsion systems creates many challenges, including interference effects with other dynamic (acoustic) modes occurring within the engine. Spurious fluctuations in flow properties (coherent or incoherent) will negatively affect the efficiency of the main detonation wave precession. The proposed technology will function to suppress spurious dynamics with the detonation chamber, Gas turbine thrust augmentors (afterburners) are inefficient combustion devices with very low power density. Augmentor design is also an extremely challenging process due to the high likelihood for combustion instabilities to occur, and the low mechanical tolerance to the destructive action of these dynamics. Successful integration of an RDC would reduce the volume of the augmentor by an order of magnitude and, consequently lead to a significant reduction in the weigh and thermal management requirements of the device. Near-term implementation of this technology would be focused on smaller propulsion systems for cruise missiles and UAVs with the need for a high-speed dash capability. Large scale gas turbine engines, rocket engines, and other high-speed propulsion systems would also benefit from this technology. Successful outcomes of Phase I and II will dictate the commercialization strategy, which will be implemented in the final stages of Phase II aiming at full-scale RDC systems to be used as thrust augmentors for conventional turbojet engines. This application is a necessary starting point for Phase III, since there are currently not any aircraft propulsion systems powered by RDC which could be outfitted with these liners. Other potential applications include small-scale drones used for surveillance. An augmented propulsion system in this case is necessary for rapid evacuation of the surveillance space. The developed technology may be incorporated into aerospace propulsion systems in partnership with the USN. It may then soon become a part of propulsion systems to power USN aircraft to hypersonic flight, providing the capability of agile, unexpected surveillance, reconnaissance, or attack.
Keywords: Combustion, Combustion, Detonation Wave Dynamics, High Temperature Materials, Rotating Detonation Combustors, damping, acoustic absorption, Hypersonic Propulsion, frequencies
