A new family of engines aims to harness the power of detonation shockwaves to create ever-faster rocket engines.
One of these engines—known as a rotating detonation engine (RDE)—has shown some considerable promise, but still needs to overcome barriers or poor thrust continuity and high Mach operability (meaning it doesn’t work well under subsonic speeds)
A new engine devised by scientists at Tsinghua University in Beijing, China, uses a ram-rotor to overcome some of these challenges, but blade materials capable of withstanding the harsh environment of hypersonic travel remain a limitation.
If humans want to travel faster, they need better—and, inevitably, more complicated—engines. Recently, engineers have investigated ways to harness the chaotic power of explosions into an engine that can push past speeds far beyond the comparatively slow realm of conventional chemical combustion. These are known as detonation engines, they come in all types of designs—including pulse detonation engines, oblique detonation engines, and rotating detonation engines—and they each have their own quirks with regards to how they achieve this perilous-yet-powerful propulsion.
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Recently, rotating detonation engines (RDEs) have started to show some promise. In fact, earlier this year, the Houston-based Venus Aerospace achieved one of the longest sustained tests of its own RDE. This engine combusts its fuel and oxidizer in a rotating ring-shaped channel, and the resulting shockwaves create a sustained combustion reaction that makes the engine more efficient than conventional rockets.
Now, a new engine designed by engineers at Tsinghua University in Beijing, China is building off the success of these types of engines, but introducing a high-speed rotor to further stabilize the detonation. It’s called a ram-rotor detonation engine (RRDE), and its creators hope that it will overcome some of the shortcomings of a typical RDE—poor thrust continuity, high starting Mach numbers (meaning it operates better at super and hypersonic speeds than at subsonic speeds), and poor performance gains, for instance.
“The original intention of developing this new engine is to improve the structures of rotating detonation engines,” Haocheng Wen, co-author of an article detailing the engine in the Chinese Journal of Aeronautics, said in a press statement. “This concept is also inspired by the ram-rotor compressor.”
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The RRDE works by using a spinning rotor with blades in a stationary casing. The blades—which are distributed evenly—handle the compression, detonation combustion, and expansion in the channel between them. According to New Atlas, this allows the engine to achieve “higher thermodynamic efficiency by capitalizing on the extreme pressures and temperatures of detonation in a way no traditional ramjet engine can.”
The researchers confirm that this engine—at least, theoretically and in numerical simulations—makes huge strides in eliminating some of the weaknesses of traditional RDEs. However, the engine has a long way to go before it can say it’s truly conquered them all. For one, sustaining a detonation wave isn’t easy, and powering the added rotor requires energy. It also doesn’t help that these blades need to work in the truly hellish environment of hypersonic air flow, and there aren’t many materials in existence that are up to the task.
Luckily, the researchers have plenty of time to work out these kinks, as humanity’s need for speed shows no signs of abating.
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Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff at Gizmodo and Paste if you look hard enough.