In the photo here, we see a simple pulse-jet engine, in a ‘U’ shaped configuration.
The tube at the top, with the cone shaped end is the air-intake;- to start it, air is blown down there with a big fan, and fuel, in this case liquefied petroleum gas, propane, is fed in liquid form from the cylinder mounted upside down by the pilot’s feet, through a tube into the combustion chamber, where it is ignited by a spark plug. Providing the blower gets the air speed into the chamber right at the start, the propane will mix with the right amount of air, be ignited, and expand down the long u-tube, with a characteristic pulsing roar from which this simple jet gets its name. They have virtually no moving parts, and aren’t particularly controllable, with basically two settings… on, or off.
The V1 flying bomb used by the germans to wreak havoc on london in the 1940s was powered by a pulsejet.
The later V2 was a rocket.

Umm… the u-shape is not necessary in terms of making it work, the V1 was just a straight line, i think the shape here is just to make it more compact. In the event of a tumble, which seems pretty likely given the supermarket trolley and high centre of gravity, it’s worth bearing in mind that the colour of the pipes suggests steel at 850 degrees or so.
Ouch.