Turbomachine with a diffuser

A turbomachine comprising:

• an annular combustion chamber;
• a centrifugal compressor;
• an annular diffuser enabling the flow of gas leaving the compressor to be diffused and directing this flow of gas towards the combustion chamber, the diffuser comprising:
• an upstream portion oriented radially and presenting diffusion passages connected to the outlet from the compressor;
• an intermediate portion that is elbow-shaped;
• and a downstream portion having a series of circularly spaced-apart flow-straightening vanes;
• and
• an outer casing surrounding the outside of the combustion chamber and the downstream portion;
• wherein the flow stream in the downstream portion is delimited externally by the outer casing, the outer casing presenting a shoulder against which an outer downstream edge of the intermediate portion comes into abutment;
• wherein the flow-straightening vanes are not fastened to the outer casing;
• wherein, when cold there exists clearance between the flow-straightening vanes and the outer casing.