Low NO.sub.x staged combustor with swirl suppression

摘要

In a low NO.sub.x stage combustor, the hot fuel rich combustion gases exit the primary combustion chamber through a constriction including a throat portion and pass into a secondary combustion chamber wherein burning is completed by injection of secondary air such as the exhaust from a turbine. Swirl is imparted to the primary gas stream in the primary combustion chamber so as to cause the primary gas stream to fill the entire primary combustion chamber and for increasing the residence time within the primary chamber for reducing fuel NO.sub.x emissions. Swirl suppression means are employed in the throat of the flow constrictor, between the primary and secondary combustion chambers, for suppressing swirl in the outermost regions of the primary gas stream so as to reduce turbulent mixing with the injected, secondary air thereby reducing the peak flame temperature in the secondary combustion chamber and for reducing thermal NO.sub.x emissions. The swirl suppression means comprises means for roughing the throat of the flow constrictor such as by forming lands and grooves in a castable, refractory material lining the interior wall of the throat.