Pre-diffuser for a gas turbine engine

1. A pre-diffuser downstream of a compressor section of a gas turbine engine, comprising:

a multiple of diffusion passage ducts manufactured of sheet metal;

a full ring ring-strut-ring structure that comprises a multiple of diffusion passages that each communicate with one of the multiple of diffusion passage ducts to extend the diffusion passage of the ring-strut-ring structure downstream along a respective flow passage, each diffusion passage in the ring-strut-ring structure comprises a diffusion passage inlet and a diffusion passage exit adjacent to a respective one of the multiple of diffusion passage ducts welded to the ring-strut-ring structure;

an exit guide vane ring upstream of the ring-strut-ring structure, the exit guide vane ring comprises a multiple of upstream exit guide vanes (EGVs) that split the flow into two adjacent diffusion passage inlets;

a multiple of hollow struts of the full ring ring-strut-ring structure, each of the multiple of hollow struts align with a respective one of the multiple of upstream exit guide vanes, each of the multiple of hollow struts comprises a cavity in communication with a diffuser side of the pre-diffuser through a passage to permit diffusion air from the diffuser side of the pre-diffuser to be received into the respective cavity wherein the passage has a passage opening located on a downstream surface of each of the multiple of hollow struts, and the passage opening is the only inlet or outlet to the cavity for fluidic contact with air outside the cavity.

2. The pre-diffuser as recited in claim 1 , wherein each of the diffusion passages in the ring-strut-ring structure comprises an inlet to a pre-diffuser and a diffusion passage exit that mates with the diffusion passage duct.

3. A pre-diffuser for a gas turbine engine, comprising:

an exit guide vane ring having a multiple of exit guide vanes defined around an engine longitudinal axis;

a full ring ring-strut-ring structure adjacent to the exit guide vane ring to form a multiple of diffusion passages defined around the engine longitudinal axis, an inlet to each of the multiple of diffusion passages smaller than an exit from each of the multiple diffusion passage through the ring-strut-ring structure;

a diffusion passage duct attached to the ring-strut-ring structure at the exit from each of the multiple of diffusion passages, the diffusion passage duct manufactured of sheet metal and welded to the ring-strut-ring structure;

an outer radial interface between a radial outer surface of a ring-strut-ring structure and the exit guide vane ring, the outer radial interface being a full hoop structure; and

an anti-rotation feature between the ring-strut-ring structure and the exit guide vane ring, the anti-rotation features inboard of the multiple of diffusion passages;

a hot fairing radial flange that extends radially inward from the ring-strut-ring structure and an exit guide vane radial flange that extends radially inward from the exit guide vane ring;

a static structure flange that abuts the hot fairing radial flange;

a clamp ring that abuts the exit guide vane radial flange;

a multiple of fasteners that fasten the clamp ring to the static structure flange; and

a multiple of hollow struts of the full ring ring-strut-ring structure, each of the multiple of hollow struts align with a respective one of the multiple of upstream exit guide vanes, each of the multiple of hollow struts comprises a cavity in communication with a diffuser side of the pre-diffuser through a passage to permit diffusion air from the diffuser side of the pre-diffuser to be received into the respective cavity, wherein the passage has a passage opening located on a downstream surface of each of the multiple of hollow struts, and the passage opening is the only inlet or outlet to the cavity for fluidic contact with air outside the cavity.

4. The pre-diffuser as recited in claim 3 , further comprising a seal located between the exit guide vane radial flange and the hot fairing radial flange.

5. The pre-diffuser as recited in claim 1 , further comprising:

an exit guide vane radial flange 152 that extends transversely from the exit guide vane ring;

a full ring hot fairing radial flange 150 that extends transversely from the ring-strut-ring structure parallel to the exit guide vane radial flange of the exit guide vane ring.

6. The pre-diffuser as recited in claim 1 , further comprising a first anti-rotation feature on one side of the full ring hot fairing radial flange and a second anti-rotation feature on an opposite side of the full ring hot fairing radial flange, wherein the first anti-rotation feature engages an exit guide vane ring and the second anti-rotation feature engages a static structure.

7. The pre-diffuser as recited in claim 1 , wherein each of the multiple of hollow struts are airfoil shaped.

8. The pre-diffuser as recited in claim 1 , wherein the diffuser air facilitates thermal control of the ring-strut-ring structure.

9. The pre-diffuser as recited in claim 8 , wherein the full ring ring-strut-ring structure is a cast component, the diffuser air permits a reduced mass of the cast ring-strut-ring structure.