Researchers in Purdue University’s College of Engineering are testing a patented Tesla-valve-inspired injection manifold design that could improve the performance of rotating detonation engines (RDEs), which are being developed as next-generation solutions in the field of jet and rocket propulsion.
According to Li Qiao (pictured above), a professor in the School of Aeronautics and Astronautics who is conducting numerical demonstrations on the design, RDEs convert chemical energy into thrust, with a flame travelling through the engine at supersonic speed, which can be ten times faster than in a traditional engine.
‘RDEs are much more efficient than traditional engines, consuming less fuel and achieving high power of thrust in much less time,’ Qiao said. ‘An RDE has no moving parts – turbines or compressors – which makes it less complex and less expensive to manufacture.’
However, RDEs face stability drawbacks, Qi explained. The pressure behind a detonation wave in the engine is enormous, but there’s high pressure on the wave to move backward. That pressure could reverse the flow of the fuel and oxidiser injectors.
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‘If the injection flow goes backward, the engine can lose power and power generation is lost,’ Qiao said. ‘The pressure may cause oscillation, too, which causes damage to the fuel-injection system.’
Qiao said Purdue’s Tesla-valve-designed injection manifold sustains a stable shock wave in RDEs, maintaining detonation and thrust while preventing the reverse flow. ‘Tesla valves allow fluids to flow in one direction but make it virtually impossible for them to travel in another,’ she said. ‘Tesla valves are already frequently used in other fluid devices, but ours is the first proposal to use them as injection manifolds in RDEs.’
During numerical demonstrations on the injection manifold design, Qiao discovered that in traditional designs, a significant amount of flow made its way back to the inlet where the fuel was injected. ‘In tests of the Tesla-valve-inspired injection manifold design, very little flow returned to the inlet,’ Qiao said. ‘The majority of flow was self-impinged at the corresponding Tesla valves.’
Qiao and her team is looking to further perfect the design, which can be integrated into existing engine systems. ‘We would be happy to work with industry and the federal government to apply this valve concept for specific engines in commercial and defence applications,’ Qiao said.