Hi Werner,
The output torque drops as the speed increases due to the rapidly rising rotational losses and smaller difference in velocity between the rotor and the nozzle. The table shown in the post of 01/02/2020 shows an example of this. Earlier posts in this thread explain what was involved in estimating the values shown in that table. I have developed spreadsheets to help estimate the performance with different energy levels, different size propellers, different rotors, and different nozzles. I compare what is estimated in these spreadsheets with any test results to check their accuracy. The post of 26/03/2020 is an example of this. With the spreadsheet used for that test, the estimated power at a speed of 30,000 rpm would be 7.5 watts and the torque would be 0.338 in-oz. If I had the ability to adjust the load to a power my turbine was capable of producing at 30,000 rpm, I could check these values. The down side to using propellers, is that the torque required to turn the propeller determines the speed the turbine can reach. The torque I obtained in this test would spin my GWS EP 2508 propeller at above its recommended operating speed and that is why I am using the larger propeller.
Hope this helps,
Byron