Turbine

A variable geometry turbine comprising:

• a turbine wheel supported for rotation about a turbine axis;
• a turbine housing comprising a first volute for receiving a first exhaust gas stream from a first fluid source and a second volute for receiving a second exhaust gas stream from a second fluid source;
• the first volute and the second volute being separated by a dividing wall;
• and
• an inlet passageway surrounding the turbine wheel and fluidly connected to the first volute and the second volute;
• the inlet passageway at least partially defined between a first wall member and a second wall member opposite the first wall member, the first wall member being moveable along the turbine axis to vary a size of the inlet passageway;
• wherein a tip of the dividing wall defines a first radius (R1) relative to the turbine axis, and a radially outermost part of the first wall member positioned within the inlet passageway defines a second radius (R2) relative to the turbine axis,
• wherein the first radius (R1) is at least 1% larger than the second radius (R2);
• and
• wherein the first radius (R1) is at most 25% larger than the second radius (R2).