You're looking at some furious mini-rockets in the image above, and they're models of the Space Launch System (SLS) core stage engines. They were scaled down to 2 percent of the actual size of the flight hardware. Just a couple of toys you get when you're a NASA engineer.
[M]odels of the SLS core stage RS-25 engines and solid rocket boosters have been designed, built and hot-fire tested at sea-level conditions by Marshall Space Flight Center engineers, in close collaboration with Calspan-University of Buffalo Research Center Inc. in Buffalo, N.Y. The replicas will provide data on the convective heating environments that the base of the vehicle will experience upon ascent. The models were developed for base heating testing scheduled for this summer. When completed, SLS, NASA's new rocket, will be one of the biggest, most powerful rockets ever built.
Watch it here: