Certain cooktop appliances include gas burners for heating cooking utensils on the cooktop appliances. The gas burners may operate at a variety of flow rates in order to vary a heat output of the gas burners. The heat output of the gas burners is generally low at low flow rates and high at high flow rates. However, operating at high flow rates can be problematic. In particular, flames of the gas burners tend to lift at high flow rates. Various solutions have been proposed to alleviate or reduce flame lift at high flow rates.
For example, certain gas burners include burner heads with ledges above main flame ports of the gas burners. The ledges reduce a vertical velocity component of fuel flowing by the ledges in order to increase localized mixing and reduce flame lift at high flow rates. However, the ledges are generally cast as part of the burner head, and the flames can significantly heat the burner heat during operation of the gas burner. Thus, the burner head is generally cast from a material that is robust to high temperatures, and such materials are generally expensive and can comprise a significant portion of an overall cost of the gas burner.
As another example, certain gas burners include small retention ports in addition to larger main ports. The retention ports are generally positioned above main ports of the gas burner, and fuel from the small retention ports can stabilize flames at the larger main ports in order to reduce flame lift at high flow rates. However, effects of the retention ports are generally limited to a top portion of flames of the main ports, and lifting at a bottom portion of the flames is still problematic. Other gas burners include retention ports drilled into a burner body below the main ports. However, such retention ports are expensive to machine and clog easily with debris from cooking utensils above the gas burners. In addition, fuel from such retention ports also limits entrainment of secondary air for flames at the main ports, and lack of secondary air can cause poor combustion and flame coalescence at the main ports.
Accordingly, a gas burner with features for limiting flame lifting when a flow rate of gaseous fuel through the gas burner is high would be useful. In particular, a gas burner with features for limiting flame lifting while the gas burner is operating at a high flow rate without restricting a flow of secondary air to the flames would be useful.