Impulse type steam turbine

The utility model discloses an impulse type steam turbine which comprises an air inlet cylinder and a rotor arranged in the air inlet cylinder, and the rotor is provided with a plurality of stages of moving blades which are arranged at intervals in the axial direction. The inner cylinder is arranged in the air inlet cylinder and outside the rotor, the inner cylinder is connected to the air inlet cylinder through a protruding part extending outwards in the radial direction at the front axial end of the inner cylinder, and a first cavity is formed between the air inlet cylinder and the inner cylinder; the first chamber communicates with a mid-downstream stage rotor blade of the plurality of stage rotor blades to allow steam from the mid-downstream stage rotor blade to flow into the first chamber. According to the impulse type steam turbine, the stress gradient of the air inlet cylinder can be reduced, thermal stress can be reduced, the creep life can be prolonged, and meanwhile steam seal leakage can be reduced