A fast solenoid on a charged line launches a discrete slug that travels as a recognisable object rather than a continuous stream. Fire a row of them in sequence and the eye reads motion across the ground; fire them randomly and children will chase them for an hour, which on a public plaza is the entire brief.
The engineering is in the valve, not the nozzle. Opening time has to be under 30 ms or the slug has a tail and reads as a stutter rather than a burst, and the valve has to survive several million cycles a season. We use a direct-acting stainless solenoid with a soft seat and we budget for replacing a tenth of them annually — that number goes in the maintenance schedule at tender, because a plaza with eleven dead jets looks abandoned even when a hundred are working.
Water hammer is the thing that will damage the installation. A hundred valves closing in 20 ms on a common manifold is a pressure spike that will find every weak joint you have. Accumulators on each zone, and a sequencer that is not permitted to close more than a set number of valves in the same tick.