Constant Volume Combustion (CVC), pulse detonation and constant detonation, should be about 10% more efficient than conventional combustors, and they are looking for the technology to bridge the gap between the top end limit of turbines and the bottom end limit of scramjets.

They are looking at an 80k lb demonstrator, and the turbines would be cocooned at around Mach 3, and the CVC would operate from Mach 1.5 to Mach 4+.

While I am familiar with the PDE, the CDE is new to me:

Various CVC concepts are likely to be proposed, says Bussing. “We’ve left the door open. They include classic [pulsed-detonation engines] in which tubes can be arranged axially, valved at the front and back, or they could be rotating or stationary, or they could be valveless.” By contrast, the CDE (sometimes called a continuous-detonation wave engine) typically includes a combustion chamber consisting of an annular cylindrical tube with one end closed and the other open. A mixture of fuel and oxidizer is injected from the closed end through a ring slit or a number of regularly arranged small holes, and the detonation wave travels in a clockwise or counterclockwise direction. Exhaust products flow toward the open end and discharge through a diverging nozzle at supersonic speeds.