An apparatus for burning of a gaseous fuel includes a gas manifold comprising a blast tube with an axis of rotation and an outer wall; a center bluff body disposed inside the blast tube; a plurality of aerodynamic blocks circumferentially distributed in the annular space between the blast tube and the center bluff body, creating passage channels for combustion air between the aerodynamic blocks; two injector nozzles located inside the wake zone of each of the aerodynamic block and are fluidically communicating to the gas manifold; an air control mechanism comprising a center hub and a plurality of air control modules. The control modules fit through the passage channels. Each air control module comprises an air deflector located at the outer edge of a passage channel.