Development of helium turbine with variable nozzle opening

A helium turbine with a variable nozzle opening has been developed, which will reduce the mass flow rate of the turbine under partial refrigeration. The effect on reducing the mass flow rate of a turbine was measured as a function of refrigeration power, and compared with that of a turbine with fixed nozzle opening. Operation at a refrigeration power of 0.5 kW, for example, required a mass flow rate of 0.027 kg/s for the turbine with a fixed nozzle opening, however, only 0.016 kg/s was regnired for the turbine with a variable nozzle opening at the nozzle opening of 40 %. (author).