Fuel admission tube for enhanced mixing in gaseous fuel engine and engine operating method

A method of operating an engine system comprising:

• feeding intake air from an upstream intake air feed opening through a common air cavity to a plurality of intake ports in an engine housing;
• feeding a gaseous fuel through a plurality of fuel passages in a plurality of fuel admission tubes each extending through the common air cavity to one of the plurality of intake ports;
• admitting some of the intake air through at least one mixing air opening in each of the plurality of fuel admission tubes into the respective fuel passage at a location that is fluidly between a fuel inlet and a fuel outlet of the respective fuel admission tube;
• and
• conveying the intake air and gaseous fuel from each of the plurality of intake ports into a plurality of engine cylinders for combustion through a first intake valve opening located downstream from the intake air feed opening and through a second intake valve opening located downstream from the first intake valve opening.

A fuel admission tube for a gaseous fuel engine comprising:

• a tube body including an outer tube surface, and an inner tube surface forming a fuel passage defining a curvilinear tube axis line and extending between a first axial end including a connector forming a fuel inlet, and a second axial end forming a fuel outlet;
• and
• the tube body including a plurality of mixing air openings formed therein and fluidly connected to the fuel passage;
• wherein the plurality of mixing air openings have an axial distribution.

A fuel admission tube for a gaseous fuel engine comprising:

• a tube body including an outer tube surface, and an inner tube surface forming a fuel passage defining a curvilinear tube axis line and extending between a first axial end including a connector forming a fuel inlet, and a second axial end forming a fuel outlet;
• and
• the tube body including at least one mixing air opening formed therein and fluidly connected to the fuel passage;
• wherein the tube body includes a conduit piece and an attached end cap forming the fuel outlet, and the at least one mixing air opening includes a plurality of mixing air openings formed in the end cap.