The 46th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit (JPC) took place last week from 25th to 28th of July in Nashville, TN. This being the largest annual propulsion related conference in the world, everybody worth their salt in the propulsion and energy arena come to present their work here. I’ll provide a brief review of some of the interesting papers presented at the conference related to detonation based engines and hypersonic propulsion.
One of the first papers presented was AIAA-2010-6536- Parametric Study of Unsteady Turbine Performance Driven by a Pulse Detonation Combustor, a joint work done at the Wright Patterson Air Force Base by scientists from the Air Force Research Labs (AFRL), notably Fred Shcauer, the Air Force Institute of Technology and ISSI Inc.
ISSI is a Dayton, Ohio based research company composed of scientists involved in a wide range of fields who derive much of their funding from SBIRs. Many of their personnel are from WPAFB. ISSI was involved with AFRL in the first PDE powered flight project from January 2008.
In the above paper, a PDE combustor is mated with an automotive turbocharger, a Garrett GT28 model which has a single stage radial turbine. The PDE is run on hydrogen and air with two orifice plates for DDT. The PDE was run at 10, 15 and 20 Hz. At higher frequencies the pulsing is smoothed out and the turbine reaches “quasi-steady” state operation. They also report 70% improvement in specific work output at 10 Hz and 0.64 equivalence ratio.
Many other researchers have tried this approach of mating automotive turbochargers with PDEs. One such study was also done at UT Arlington in 2006. A video of one test run from that study can be seen here entitled “PDE turbo 15 Hz” at the bottom of the page. In that study, the PDE was run on propane-oxygen and a small electric generator was connected to the turbine (a 3K turbocharger from a Volkswagen) to produce electricity.
Eventual hybrid PDE-turbine systems will have axial turbines. Axial turbines can have multiple stages of blade sets in sequence and are more efficient. GE has done experimental work with 8 PDE combustors mated through a common plenum chamber to an axial turbine, as part of their PDE Turbine Interaction Program (PDE-TIP) which was a collaborative effort between GE and NASA. Similar work, with a single stage axial turbine (Allied Signal JFS 100-13 turbo-shaft turbine) has also been done at the University of Cincinnati, Ohio.