Vortex Piston Engine - Prior Art Search

Recently I blundered into an obituary of a vortex-flow expert named Mikhail Goldshtik. The obituary included a list of his patented inventions, one of which is an engine that uses a vortex as a piston substitute in a combustion engine - the expansion and contraction of the vortex core providing the change in combustion-chamber volume needed to carry out a heat-engine cycle.

Interesting enough, but there was no mention in Goldshtik's patent of prior art in using vortices this way. This got my attention because, while searching for other material years ago, I blundered into a very old German paper about just such a scheme. Naturally, I can't recall the name of the inventor, the publication or any other detail that might conceivably be useful, and so far my files have turned up nothing, but the scheme itself stuck in my mind because it was so unusual and unexpected.

If anybody can steer me to this inventor or his work, I would be most grateful.