Although the PDE concept has been around since the early 1940s (first explosion mode engine patent dates from 1899), PDE research has only been growing in popularity since the late 1980s. In 1986, three researchers at the Science Applications International Corporation (SAIC) in Virginia wrote a paper on PDEs (D. Helman, R. P. Shreeve, and S. Eidelman, “Detonation pulse engine,” AIAA paper 1986-1683, 22nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference, June 1986). Following this seminal paper, Eidelman and colleagues published a few more papers based on their experimental, computational and analytical findings on the benefits of PDEs. Soon, researchers around the world jumped on the PDE bandwagon. In the 1990s, Dr. Thomas Bussing was one of the early birds working on PDEs at Adroit Systems Inc. in Seattle, WA. The company was soon acquired by Pratt & Whitney. After all these years of research the PDE is still not worthy to be the main power source for any modern aircraft. There are still far too many hurdles to overcome before PDEs can be a commercially viable engine system.
So, what else can the PDE be used for besides land-based power generators and aircraft engines? Well, it turns out that detonations can be used to clean out the slag buildup inside boiler tubes. Check out this news article which mentions two patents that P&W has for removing slag buildup in coal fired boilers. P&W setup a new division called PulseDyne to sell its patented ShockSystem boiler cleaning concept. This division has now been sold to a company called EMC. Here is a link to EMC ShockSystem Inc.’s page describing the detonation slag cleaning method.
P&W has several patents on this technique. Here and here are links to two of them. But P&W (a division of United Technologies Corp. which also owns Sikorsky Helicopters, Carrier air conditioners, Otis elevators and others) is not the only aeronautical company with patents on the application of PDEs for cleaning. GE and Lockheed also have patents with variations on where and how this method is applied. It is the same idea, create an explosion within the container to be cleaned and the scales and slag buildup on the walls disintegrate into small pieces and then can be blown out with air/steam or washed out with water. Do a search for “Pulsed Detonation Slag” or “Pulsed Detonation Cleaning” on Google Patents and you will see tens of patents from the above mentioned companies as well as other companies and private individuals on PDE cleaning systems.
So it seems that PDEs are not just loud noise makers. They are a pretty clean technology too.