Steve No I am not sure of anything about except that an unloaded turbine is a most dangerous load to control.I have never seen a needle control used in this type of application and suspect that there are good reasons. The time constants for acceleration and deceleration depend on the mechanical design and the efficiency of the combustion unit.these time constants will probably be quite different but until the device is run no data is available.
Response speed in a pelton wheel is much slower.
The violence seen when the needle closed the orifice is due to the energy in the mass of moving water in the pipeline. See my comments on reducing the amount of presurised fuel.
As Mahmood last posted there is no information available to him for use in estimating these requirements. I would mount a few video cameras to record the runs and a remote fuel cut off then odserve the first runs from a safe place. Remember the people that were watching Mount St. Hellens from a facing mountain about 10 miles away when it blew. Terry