TECHNICAL FIELD

The application relates generally to gas turbine engines and, more particularly, to compressor diffusers therefor.

BACKGROUND

Diffuser pipes are provided in certain gas turbine engines for directing flow of compressed air from an impeller of a centrifugal compressor to an annular chamber containing the combustor, while diffusing the high speed air. The diffuser pipes are typically circumferentially arranged at a periphery of the impeller, and are designed to transform kinetic energy of the flow into pressure energy. Diffuser pipes may provide a uniform exit flow with minimal distortion, as it is preferable for flame stability, low combustor loss, reduced hot spots etc.

While longer diffuser pipes may accomplish better diffusion, spatial constraints of the gas turbine engine may restrict their length. Large flow diffusion in diffuser pipes over insufficient pipe length may result in thick and weak boundary layer buildup on the wall of the diffuser pipe. To compensate for a shorter length, many diffuser pipes have a tight bend. Turbulence and other non-streamline behavior of the flow at the bend may lead to pressure losses and decrease efficiency of the diffuser pipe, and therefore of the compressor.

SUMMARY

There is therefore provided a compressor diffuser for a gas turbine engine comprising: at least one diffuser pipe having a tubular body defining an internal flow passage extending therethrough, the tubular body including a first portion extending in a first direction, a second portion extending in a second direction different from the first direction, and a curved portion fluidly linking the first portion and the second portion; and a splitter vane disposed within the internal flow passage of the curved portion of the tubular body, the splitter vane defining a convergent flow passage between itself and a radially inner wall of the curved portion, and the splitter vane defining a divergent flow passage between itself and a radially outer wall of the curved portion.

There is also provided a method for diffusing fluid flow in a compressor, comprising: conveying fluid flow through a diverging internal flow passage of a compressor diffuser, the internal flow passage including at least one curved portion; splitting the fluid flow into first and second fluid passages defined within the internal flow passage, the first and second fluid passages being at least partially located within the curved portion; converging fluid flow through the first fluid passage; and diffusing fluid flow through the second fluid passage.

There is further provided a centrifugal compressor, comprising: an impeller having an inner hub with a plurality of vanes extending therefrom, the impeller being rotatable within an outer shroud about a central longitudinal axis, the impeller having a radial impeller outlet; and a diffuser configured to diffuse gas received from the impeller outlet, the diffuser comprising: at least one diffuser pipe having a tubular body defining a flow passage extending therethrough, the tubular body including a first portion extending in a first direction, a second portion extending in a second direction different from the first direction, and a curved portion fluidly linking the first portion and the second portion; and a splitter vane disposed within the internal flow passage of the curved portion of the tubular body, the splitter vane defining a convergent flow passage between itself and a radially inner wall of the curved portion, and a divergent flow passage between the splitter vane and a radially outer wall of the curved portion.

There is alternately provided a compressor diffuser for a gas turbine engine comprising: at least one diffuser pipe having a tubular body defining an internal flow passage extending therethrough, the tubular body including a first portion extending in a first direction, a second portion extending in a second direction different from the first direction, and a curved portion fluidly linking the first portion and the second portion; and a splitter vane disposed within the internal flow passage of the curved portion of the tubular body, the splitter vane defining a convergent flow passage between itself and a radially inner wall of the curved portion.

There is alternately provided a method for diffusing fluid flow in a compressor, comprising: conveying fluid flow through a diverging internal flow passage of a compressor diffuser, the internal flow passage including at least one curved portion; splitting the fluid flow into first and second fluid passages defined within the internal flow passage, the first and second fluid passages being at least partially located within the curved portion; and converging fluid flow through the first fluid passage.

There is alternately provided a centrifugal compressor, comprising: an impeller having an inner hub with a plurality of vanes extending therefrom, the impeller being rotatable within an outer shroud about a central longitudinal axis, the impeller having a radial impeller outlet; and a diffuser configured to diffuse gas received from the impeller outlet, the diffuser comprising: at least one diffuser pipe having a tubular body defining a flow passage extending therethrough, the tubular body including a first portion extending in a first direction, a second portion extending in a second direction different from the first direction, and a curved portion fluidly linking the first portion and the second portion; and a splitter vane disposed within the internal flow passage of the curved portion of the tubular body, the splitter vane defining a convergent flow passage between itself and a radially inner wall of the curved portion.

There is alternately provided a compressor diffuser for a gas turbine engine comprising: a plurality of diffuser pipes each having a diverging tubular body defining a flow passage extending fully therethrough, the tubular body including a first portion extending in a first direction, a second portion extending in a second direction different from the first direction, and a curved portion interconnecting the first portion and the second portion; and a plurality of splitter vanes each extending into the flow passage of a corresponding diffuser pipe and disposed at least partially within the curved portion between an inner and an outer wall thereof, the splitter vane extending a length between a leading edge and a trailing edge, a first side of the splitter vane converging along the length toward one of the inner and outer walls, and an opposed second side of the splitter vane diverging along the length away from the other one of the inner and outer walls.

There is alternately provided a method for diffusing fluid flow, comprising: conveying fluid flow through a diverging tubular body having a first portion extending in a first direction, a second portion extending in a second direction different from the first direction, and a curved portion interconnecting the first portion and the second portion; splitting fluid flow at the curved portion of the tubular body into a first fluid passage and a second fluid passage; and converging fluid flow through the first fluid passage, and diffusing fluid flow through the second fluid passage.

There is alternately provided a centrifugal compressor, comprising: an impeller having an inner hub with vanes thereon and rotatable within an outer shroud about a central longitudinal axis, the impeller having a radial impeller outlet; and a diffuser operable to diffuse gases received from the impeller outlet, the diffuser comprising: a plurality of diffuser pipes each having a diverging tubular body defining a flow passage extending fully therethrough, the tubular body including a first portion extending in a first direction, a second portion extending in a second direction different from the first direction, and a curved portion interconnecting the first portion and the second portion; and a splitter vane extending into the flow passage and disposed at least partially within the curved portion between an inner and an outer wall thereof, the splitter vane extending a length between a leading edge and a trailing edge, a first side of the splitter vane converging along the length toward one of the inner and outer walls, and an opposed second side of the splitter vane diverging along the length away from the other one of the inner and outer walls.

