How to fix the rotational speed of a water turbine?

Hello everyone,
I have a question about the design of the water turbine experiment.
I have read a journal paper " Experimental characterization of a five blade tubular propeller for pipe inline installation", and it designed a test rig to perform different discharge Q and head H in a fixed rotational speed.
The paper said that
"To assess the performance of the turbine, measurements were performed in the installation covering a range of flows between and 50 m3/h and keeping the rotating speed constant. For each value of rotational speed imposed by the generator, between 50 and 2750 rpm, the flow was progressively varied to generate measurement points of flow, pressure and torque."
I would like to know is it possible to fix the rotational speed of the turbine in varied flow condition. If so, how could it be fixed (such as the mechanism of the generator that imposes on the turbine described by the paper)?
Thanks in advance.

Alan Hsu
I thought I'd skim read the paper but Google can't find it.

So I'm clueless about what a fixed speed rotation turbine meter is. Why would anyone mess with an efficient means of flow measurement for clean liquids, ie, a turbine meter. Probably a marketing white paper trying to seduce the curious to buy an experiemental flop to offset the development costs. Who knows?


These ivory tower egghead papers are written by people who need to be published to get a "degree" and who don't have the first clue about technical terms and functions. What is the generator? What is the turbine? What is the range of flows between?

Hypotheticals and nonsense. All.

'Nuff said.