Turbine wastegate having a fluidic sealing arrangement and a method of testing thereof

A turbine comprising:

• a turbine housing defining a turbine inlet upstream of a turbine wheel and a turbine outlet downstream of the turbine wheel;
• a wastegate passage connecting the turbine inlet and the turbine outlet;
• a wastegate valve comprising a movable valve member;
• the wastegate valve having an open state in which a first gas may pass between the turbine inlet and turbine outlet via the wastegate passage and a closed state in which the valve member prevents said first gas from passing between the turbine inlet and the turbine outlet via the wastegate passage;
• wherein the valve member is mounted to an actuation member, the actuation member passing through a bore of the turbine housing and being movable so as to move the wastegate valve between the open and closed states;
• wherein the turbine comprises a fluid conduit configured to deliver a second gas to the bore so as to form a fluidic seal between the bore and the actuation member so as to prevent the passage of said first gas along the bore;
• and
• wherein the actuation member and the bore define a clearance therebetween, the clearance being free of mechanical sealing elements.