A rotary apparatus (100) for inputting
thermal energy into fluidic medium is provided, the apparatus comprises: a casing (20) with at least one inlet (11) and at least one outlet (12); a rotor comprising at least one row of rotor blades (3) configured as impulse
impeller blades arranged over a circumference of a rotor hub (3a) mounted onto a rotor shaft (1); at least one row of stationary
nozzle guide vanes (2) arranged upstream of the at least one row of the rotor blades, respectively; and at least one row of stationary diffuser vanes (4) arranged downstream of the at least one row of the rotor blades, respectively. The apparatus is configured to impart an amount of
thermal energy to a
stream of fluidic medium directed along a flow path formed inside the casing between the inlet and the outlet by virtue of a series of energy transformations occurring when said
stream of fluidic medium successively passes through the blade / vane rows formed by the
nozzle guide vanes (2), the rotor blades (3) and the diffuser vanes (4), respectively, wherein, in said apparatus, a space (5) formed between an exit from the at least one row of diffuser vanes (4) and an entrance to the at least one row of
nozzle guide vanes (2) in a direction of the flow path formed inside the casing (20) between the inlet (11) and the outlet (12) is made variable to regulate the amount of
thermal energy input to the
stream of fluidic medium propagating through the apparatus. Related uses and a method for inputting thermal energy into a fluidic medium are further provided.