Diffusor without any pulsation of the shock boundary layer, and a method for suppressing the shock boundary layer pulsation in diffusors

A turbine, comprising:

• a rotor;
• a casing for receiving a flow of fluid to drive said rotor, said rotor being disposed in said casing and being driven by the fluid;
• and
• a diffusor for decelerating the fluid, said diffusor being disposed in said casing downstream of said rotor in a flow direction of the fluid, said diffusor including:
• at least one wall forming a channel for receiving the fluid, said at least one wall having an inlet, an outlet, and at least one opening for receiving an energizing fluid to be transported selectively into said channel, said inlet having a relatively smaller inlet flow cross section and said outlet having a relatively larger outlet flow cross section;
• said channel defining an axial direction, the fluid entering the diffusor in said axial direction;
• and
• said channel defining a radial direction, the fluid discharging from the diffusor in said radial direction.

A low-pressure steam turbine, comprising:

• a rotor;
• a casing for receiving a flow of fluid to drive said rotor, said rotor being disposed in said casing and being driven by the fluid;
• and
• a diffusor for decelerating the fluid, said diffusor being disposed in said casing downstream of said rotor in a flow direction of the fluid and having at least one wall forming a channel for receiving the fluid, said at least one wall having an inlet, an outlet, and at least one opening for receiving an energizing fluid to be transported selectively into said channel, said inlet having a relatively smaller inlet flow cross section and said outlet having a relatively larger outlet flow cross section.

A gas turbine, comprising:

• a rotor;
• a casing for receiving a flow of fluid to drive said rotor, said rotor being disposed in said casing and being driven by the fluid;
• and
• a diffusor for decelerating the fluid, said diffusor being disposed in said casing downstream of said rotor in a flow direction of the fluid and having at least one wall forming a channel for receiving the fluid, said at least one wall having an inlet, an outlet, and at least one opening for receiving an energizing fluid to be transported selectively into said channel, said inlet having a relatively smaller inlet flow cross section and said outlet having a relatively larger outlet flow cross section.

A water turbine, comprising:

• a rotor;
• a casing for receiving a flow of fluid to drive said rotor, said rotor being disposed in said casing and being driven by the fluid;
• and
• a diffusor for decelerating the fluid, said diffusor being disposed in said casing downstream of said rotor in a flow direction of the fluid and having at least one wall forming a channel for receiving the fluid, said at least one wall having an inlet, an outlet, and at least one opening for receiving an energizing fluid to be transported selectively into said channel, said inlet having a relatively smaller inlet flow cross section and said outlet having a relatively larger outlet flow cross section.

A Francis turbine, comprising:

• a rotor;
• a casing for receiving a flow of fluid to drive said rotor, said rotor being disposed in said casing and being driven by the fluid;
• and
• a diffusor for decelerating the fluid, said diffusor being disposed in said casing downstream of said rotor in a flow direction of the fluid and having at least one wall forming a channel for receiving the fluid, said at least one wall having an inlet, an outlet, and at least one opening for receiving an energizing fluid to be transported selectively into said channel, said inlet having a relatively smaller inlet flow cross section and said outlet having a relatively larger outlet flow cross section.

A method for preventing shock boundary layer pulsations in a diffusor, which comprises:

• measuring pressures of a moving fluid in a diffusor in a non-stationary manner;
• evaluating amplitudes and frequencies of the measured pressures;
• and
• feeding energizing fluid into the diffusor if the amplitudes within a predetermined frequency band exceed a threshold value.

A method for preventing shock boundary layer pulsations in a diffusor, which comprises:

• measuring pressures of a moving fluid at various locations in a diffusor;
• evaluating amplitudes and frequencies of the measured pressures;
• and
• feeding energizing fluid into the diffusor if the amplitudes within a predetermined frequency band exceed a threshold value.