US20130174837A1

US20130174837A1 - Burner flame stability chamber

Info

Publication number: US20130174837A1
Application number: US13/344,626
Authority: US
Inventors: Paul Bryan Cadima
Original assignee: General Electric Co
Current assignee: Haier US Appliance Solutions Inc
Priority date: 2012-01-06
Filing date: 2012-01-06
Publication date: 2013-07-11

Abstract

A burner body is disclosed for use in a gas burner assembly. The burner body includes a sidewall and a main gas conduit, the main gas conduit having an inlet and an outlet; a plurality of primary burner ports disposed within the sidewall so as to be in communication with the outlet of the main gas conduit; a simmer flame port disposed within the sidewall in a spaced relation with the primary burner ports for providing a reignition source therefore; and a stability chamber disposed within the burner body, wherein the stability chamber comprises at least a first expansion region and a second expansion region, wherein the second expansion region has a greater volume than the first expansion region.

Description

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to gas appliances, such as gas ranges, and more particularly, to stability chambers for use in such gas appliances.
Atmospheric gas burners are often used as surface units in household gas cooking appliances. A significant factor in the performance of gas burners is their ability to withstand airflow disturbances in the surroundings, such as room drafts, rapid movement of cabinet doors, and rapid oven door manipulation. Manipulation of the oven door is particularly troublesome because rapid openings and closings of the oven door often produce respective under-pressure and over-pressure conditions within the oven cavity. Since the flue, through which combustion products are removed from the oven, is sized to maintain the desired oven temperature and is generally inadequate to supply a sufficient air flow for re-equilibration, a large amount of air passes through or around the gas burners. In particular, pressure fluctuations from, for example, cabinet or door openings, cause the structures to expand or contract (e.g., the sheet metal deflects) and this structural movement pumps air into adjacent cavities, causing the temporary under or over pressure conditions. This surge of air around the gas burners, due to over pressure or under pressure conditions in the oven cavity, is detrimental to the flame stability of the burners and extinguish the flames. This flame stability problem is particularly evident in sealed gas burner arrangements, referring to the lack of an opening in the cooktop surface around the base of the burner to prevent spills from entering the area beneath the cooktop.
Flame instability is caused by the low pressure drop of the fuel/air mixture passing through the burner ports of a typical rangetop burner. Although there is ample pressure available in the fuel, the pressure energy is used to accelerate the fuel to the high injection velocity required for primary air entrainment. Relatively little of this pressure is recovered at the burner ports. A low pressure drop across the ports allows pressure disturbances propagating through the ambient to easily pass through the ports, momentarily drawing the flame towards the burner head and leading to thermal quenching and extinction.
An additional problem is that rapid adjustments of the fuel supply to a gas burner from a high burner input rate to a low burner input rate often will cause flame extinction when the momentum of the entrained air flow continues into the burner even though fuel has been cut back, resulting in a momentary drop in the fuel/air ratio, causing extinction.
A number of techniques have been proposed or suggested for improving stability performance. U.S. Pat. No. 5,133,658, for example, employs an expansion chamber to improve flame stability. The disclosed gas burners have a plenum ahead of a number of main burner ports. An expansion chamber inlet is located in the plenum, adjacent the main flame ports. When a negative pressure disturbance enters the burner (suction, for example, from the opening of an oven door), the pressure drop and flow velocity through the main burner ports are momentarily reduced causing unwanted extinction of the main burner flames. The expansion chamber flame, however, is less susceptible to extinction due to the damping effect described in earlier art. Although such gas burners having an expansion chamber provide somewhat improved stability performance at simmer settings, disturbances continue to cause unwanted extinction. Furthermore, these expansion chambers have excessively large flames at higher burner input rates.
U.S. Pat. No. 5,800,159 overcomes the issue of excessively large flames using a stability chamber that is insensitive to turn-down. The flame from the stability chamber port, however, is dissimilar to the flames from the other ports and gives the burner a non-symmetric flame appearance. In addition, stability chambers have an inherently lazy plume of gas exiting the chamber during operation, due to the slow velocity of the fuel mixture exiting the chamber. The slow velocity of the fuel mixture reduces the kinetic energy of the flame and hence the ability to entrain secondary air. Drafts, whether induced by the local gas flow of the burner itself or by external influences such as room drafts or drafts induced by the burner exhaust rising, can push or pull the lazy plume exiting the chamber into a flame from an adjacent burner port. When this occurs, the two flames tend to coalesce and become starved for air locally at the relatively higher flow rates. This, in turn, causes this plume of flame to reach longer for more air and impinge on cool surrounding surfaces such as the cookware above the burner. The cool surfaces quench the flame, preventing complete combustion, and carbon or soot formation may occur. To reduce this tendency to coalesce, the distance between the stability chamber and the adjacent ports is increased. However, when this is done, it becomes more difficult for the chamber's flame to reignite the adjacent ports after an unwanted flame extinction due to the larger distance between flames.
Thus, there remains a need for an improved atmospheric gas burner that is better able to withstand airflow disturbances, especially during low burner input rates. Yet another need exists for stability chambers that improve the ability of the chamber to mechanically relight extinguished flames of the adjacent flame ports in the burner at low flow rates, without sacrificing performance at high flow rates.

BRIEF DESCRIPTION OF THE INVENTION

As described herein, the exemplary embodiments of the present invention overcome one or more disadvantages known in the art.
One aspect of the present invention relates to a burner body for use in a gas burner assembly. The burner body comprises: a sidewall and a main gas conduit, the main gas conduit having an inlet and an outlet; a plurality of primary burner ports disposed within the sidewall so as to be in communication with the outlet of the main gas conduit; a simmer flame port disposed within the sidewall in a spaced relation with the primary burner ports for providing a reignition source therefore; and a stability chamber disposed within the burner body, wherein a first interior region of said stability chamber has a primary expansion angle substantially between said main gas conduit and said sidewall and wherein a second exterior region of said stability chamber has a secondary expansion angle substantially along said sidewall and wherein said secondary expansion angle is greater than said primary expansion angle.
Another aspect of the present invention relates to a gas cooking appliance comprising such a burner body.
Yet another aspect of the present invention relates to a stability chamber for use within a burner body of a gas burner assembly. The stability chamber includes a first interior region having a primary expansion angle substantially between an interior tubular main gas conduit and an exterior sidewall of said burner body; and a second exterior region having a secondary expansion angle substantially along said sidewall and wherein said secondary expansion angle is greater than said primary expansion angle.
Advantageously, illustrative embodiments of the present invention provide the ability to improve the ability of the stability chamber to mechanically relight extinguished flames of adjacent flame ports at low flow rates, without sacrificing performance at high flow rates.
These and other aspects and advantages of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. Moreover, the drawings are not necessarily drawn to scale and, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an exploded perspective view of a prior art as burner assembly incorporating a stability chamber to improve stability performance;

FIG. 2 is a cross-sectional plan view through line 2-2 of FIG. 1;

FIG. 3 illustrates the burner body of FIGS. 1 and 2 in further detail;

FIG. 4 illustrates an exemplary burner body in accordance with the present invention;

FIG. 5 is a top, sectional view of the exemplary burner body of FIG. 4;

FIGS. 6A and 6B illustrate the conventional stability chamber of FIG. 3 and exemplary stability chamber of FIG. 4, respectively, when operating at higher flow rates; and

FIGS. 7A and 7B illustrate the conventional stability chamber of FIG. 3 and exemplary stability chamber of FIG. 4, respectively, when operating at lower flow rates.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE INVENTION

One or more illustrative embodiments of the invention will be described below in the context of an oven appliance. However, it is to be understood that embodiments of the invention are not intended to be limited to use with any particular gas appliance. Rather, embodiments of the invention may be applied to and deployed in any other suitable environment in which it would be desirable to relight extinguished flames of adjacent flame ports in a gas burner.
As illustratively used herein, the term “appliance” is intended to refer to a device or equipment designed to perform one or more specific functions. This may include, but is not limited to, equipment for consumer use, e.g., a gas range on a freestanding oven. This may include, but is not limited to, any equipment that is useable in household or commercial environments.
While the methods and apparatus are herein described in the context of a gas-fired cooktop, as set forth more fully below, it is contemplated that the herein described methods and apparatus may find utility in other applications, including, but not limited to, gas heater devices, gas ovens, gas kilns, gas-fired meat smoker devices, and gas barbecues. In addition, the principles and teachings set forth herein may find equal applicability to combustion burners for a variety of combustible fuels. The description below is therefore set forth only by way of illustration rather than limitation, and any intention to limit practice of the herein described methods and apparatus to any particular application is expressly disavowed.
FIG. 1 is an exploded perspective view of a prior art gas burner assembly 10 incorporating a stability chamber to improve stability performance, and FIG. 2 is a cross-sectional plan view through line 2-2 of FIG. 1. An atmospheric gas burner assembly 10 includes a burner body 12 having a frustum-shaped solid base portion 14 and a cylindrical sidewall 16 extending axially from the periphery of base portion 14, as shown in the illustrative embodiment of FIGS. 1 and 2. A main gas conduit 18 having an entry area 19 and a burner throat region 20 is open to the exterior of burner body 12 and defines a passage which extends axially through the center of burner body 12 to provide fuel/air flow along path “A” (FIG. 2) to burner assembly 10. As used herein, the term “gas” refers to a combustible gas or gaseous fuel mixture.
Burner assembly 10 is attached, in a known manner, to a support surface of a gas cooking appliance such as a range or a cooktop. A cap 22 is disposed over the top of burner body 12, defining therebetween an annular main fuel chamber 24, an annular diffuser region 25 (FIG. 2), and a stability chamber 26, typically wedge-shaped. A toroidal-shaped upper portion 27 of burner body 12, immediately bordering burner throat 20, in combination with cap 22 defines annular diffuser region 25 therebetween. Cap 22 can be fixedly attached to sidewall 16 (FIG. 1) or can simply rest on sidewall 16 for easy removal. While one type of burner is described and illustrated, the instant invention is applicable to other types of burners, such as stamped aluminum burners and separately mounted orifice burners.
As shown in FIG. 2, annular main fuel chamber 24 is defined by an outer surface 28 of toroidal shaped upper surface 27, an inner surface 29 of sidewall 16 (FIG. 1), an upper surface 30 of base portion 14, and cap 22. A plurality of primary burner ports 32 are disposed in sidewall 16 of burner body 12 so as to provide a path to allow fluid communication with main fuel chamber 24, each primary burner port 32 being adapted to support a respective main flame 33 (FIG. 2). Primary burner ports 32 are typically, although not necessarily, evenly spaced about sidewall 16. As used herein, the term “port” refers to an aperture of any shape from which a flame may be supported.
At least one simmer flame port 34 is disposed in sidewall 16 (FIG. 1) of burner body 12 so as to provide a path to allow fluid communication with stability chamber 26. Simmer flame port 34 is substantially isolated from main fuel chamber 24 and is adapted to support a simmer flame 35. Simmer flame port 34 is adjacent to primary burner ports 32 to provide a re-ignition source to primary burner ports 32 if flameout occurs. While a single simmer flame port 34 is shown in the drawings, the present invention may include one or more additional simmer flame ports 34. Typically, simmer flame port 34 has an open area five to fifteen times larger than a respective primary burner port 32.
A gas feed conduit 36 (FIG. 2) comprises a coupling 38 disposed on one end for connection to a gas source 40 via a valve 42 (shown schematically in FIG. 2). Valve 42 is controlled in a known manner by a corresponding control knob on the gas cooking appliance to regulate the flow of gas from gas source 40 to gas feed conduit 36. The other end of gas feed conduit 36 is provided with an injection orifice 44. Injection orifice 44 is aligned with main gas conduit 18 so that fuel, discharged from injection orifice 44, and entrained air are supplied to main fuel chamber 24 and stability chamber 26 via main gas conduit 18 along path “A” of FIG. 2.
As shown in FIGS. 1 and 2, stability chamber 26 is substantially isolated from main fuel chamber 24 such that stability chamber 26 is not in immediate fluid communication with main fuel chamber 24 and is therefore relatively independent of primary burner ports 32. Stability chamber 26 is defined on each side by a pair of radially extending baffles 50 a and 50 b (FIG. 1), on the bottom by an upper surface 46 (FIG. 2) of burner body 12, and on the top by cap 22. An end wall 52 positioned proximate burner throat 20 further defines stability chamber 26 so as to substantially isolate stability chamber 26 from main fuel chamber 24. In an exemplary embodiment, as best shown in FIG. 2, upper surface 46 of burner body 12 is configured such that stability chamber 26 has a shallow depth at the narrow end of stability chamber 26 closest to burner throat 20 and transitions to a deeper, wider section when closest to simmer flame port 34.
In the embodiment of FIGS. 1 and 2, stability chamber 26 further comprises two stability inlets 60 a and 60 b. Stability inlets 60 a, 60 b are disposed within respective baffles 50 a, 50 b such that stability inlets 60 a, 60 b are positioned so as to be substantially symmetrical on each side of stability chamber 26 proximate end wall 52 and correspondingly proximate burner throat 20. Stability inlets 60 a, 60 b are substantially perpendicular to the direction of the flow of gas radially outward from burner throat 20 and are tangentially fed the fuel/air mixture by static pressure at that location, as discussed below. The stability chamber 26 may include one or more stability inlets. Stability inlet(s) 60 a, 60 b are positioned at burner throat 20. This arrangement improves stability performance by permitting an effectively smaller stability chamber inlet to be utilized while retaining sufficient gas flow. Additionally, an aesthetically pleasant reduced stability flame size is created at higher burner input rates. For a more detailed discussion of a prior art gas burner assembly 10 incorporating a stability chamber, see, for example, U.S. Pat. No. 5,800,159, incorporated by reference herein.
FIG. 3 illustrates the burner body 12 of FIGS. 1 and 2 in further detail. As shown in FIG. 3, the exemplary burner body 12 comprises a frustum-shaped solid base portion 14 and a cylindrical sidewall 16 extending axially from the periphery of base portion 14. A main gas conduit 18 having a burner throat region 20 is open to the exterior of burner body 12 and defines a passage which extends axially through the center of burner body 12 to provide fuel/air flow as discussed above in conjunction with FIG. 2.
As shown in FIG. 3, stability chamber 26 is substantially isolated from main fuel chamber 24 such that stability chamber 26 is not in immediate fluid communication with main fuel chamber 24 and is therefore relatively independent of primary burner ports 32. Stability chamber 26 is defined on each side by a pair of radially extending baffles 50 a and 50 b, on the bottom by an upper surface 46 of burner body 12, and on the top by a cap (not shown in FIG. 3). An end wall 52 positioned proximate burner throat 20 further defines stability chamber 26 so as to substantially isolate stability chamber 26 from main fuel chamber 24. As shown in FIG. 3, upper surface 46 of burner body 12 is configured such that stability chamber 26 has a shallow depth at the narrow end of stability chamber 26 closest to burner throat 20 and transitions to a deeper, wider section when closest to the broader end of stability chamber 26, adjacent the simmer flame port 34 (not shown in FIG. 3).
FIG. 4 illustrates an exemplary burner body 112 in accordance with the present invention. As shown in FIG. 4, the exemplary burner body 112 comprises a frustum-shaped solid base portion 114 and a cylindrical sidewall 116 extending axially from the periphery of base portion 114, in a similar manner to FIG. 3. A main gas conduit 118 having a burner throat region 120 is open to the exterior of burner body 112 and defines a passage which extends axially through the center of burner body 112 to provide fuel/air flow as discussed above in conjunction with FIG. 2.
As shown in FIG. 4, a stability chamber 126 in accordance with the present invention is substantially isolated from main fuel chamber 124 such that stability chamber 126 is not in immediate fluid communication with main fuel chamber 124 and is therefore relatively independent of primary burner ports 132, in a similar manner to FIG. 3. A first expansion region of stability chamber 126 is defined on each side by a pair of radially extending baffles 150 a and 150 b, on the bottom by an upper surface 146 of burner body 112, and on the top by a cap (not shown in FIG. 3). An end wall 152 positioned proximate burner throat 120 further defines stability chamber 126 so as to substantially isolate stability chamber 126 from main fuel chamber 124. As shown in FIG. 4, upper surface 146 of burner body 112 is configured such that stability chamber 126 has a shallow depth at the narrow end of stability chamber 126 closest to burner throat 120 and transitions to a deeper, wider section when closest to the broader end of stability chamber 126, adjacent the simmer flame port 134 (not shown in FIG. 4).
According to one aspect of the present invention, as discussed further below in conjunction with FIG. 5, stability chamber 126 has a further expansion region with a wider section when closest to the broader end of stability chamber 126, adjacent the simmer flame port 134 (not shown in FIG. 4). In this manner, the disclosed stability chamber 126 adds an additional volume expansion in an additional expansion region 180 (FIG. 5) at the exit of the chamber 126. This exit expansion allows the chamber flame to expand laterally under low flow conditions while minimizing the lateral expansion at higher flow rates since the flame velocity at the exit of the stability chamber 126 has a greater radial magnitude relative to the rate of lateral expansion when the flow rate is at a higher firing rate. As discussed further below, the additional volume expansion 180 at the exit of the chamber 126 may result from the end portion of the chamber side wall forming a second expansion angle relative to the primary chamber wall expansion angle, or it may be a radius at the exit. This feature reduces the effective distance between the chamber walls and the adjacent ports at low flows, while maintaining a higher true distance between those geometries as high flows where separation is needed. In other words, at higher flow rates, the exiting gas overlooks the additional expansion, while at lower flow rates, the exiting gas expands further.
FIG. 5 is a top, sectional view of the exemplary burner body 112 of FIG. 4. As shown in FIG. 5, the stability chamber 126 has a primary expansion angle 170, in a similar manner to the conventional stability chambers 26 discussed above, as well as a secondary expansion angle 175, associated with the additional expansion region 180 provided by the present invention. As shown in FIG. 5, the secondary expansion angle 175 is greater than the primary expansion angle 170. In one exemplary embodiment, the primary expansion angle 170 can be, for example, 20 degrees, and the secondary expansion angle 175 can be, for example, 120 degrees.
In addition, the additional expansion region 180 of the present invention is also characterized by a first distance to adjacent port 190, which is the distance between the end of additional expansion region 180 and the adjacent main flame port 160, and a second distance to adjacent port 195, which is the distance between the baffles 150 a and 150 b of the stability chamber 126 and the adjacent main flame port 160, as shown in FIG. 5. In one exemplary embodiment, the first distance to adjacent port 190 can be, for example, 0.150 inches and the second distance to adjacent port 195 can be, for example, 0.09 inches.
The distinction between “higher flow rates” and “lower flow rates” is a parametric value that is proportional to the size of the burner. Low flow rates are typically approximately 1/10 to 1/12 of the maximum burner rate. For example, a burner that is sized to produce 12,000 Btu/hr at maximum flow would be capable of supporting a low flow rate of 1000 to 1,200 Btu/hr with an effective stability chamber. Without an effective stability chamber, the burner would be able to support a ratio of ⅙ of the maximum burner rate, so the burner would not be able to support a flow rate that is significantly lower than approximately 2000 Btu/hr. Thus, any flow rate higher than ⅙ of the maximum burner rate is considered a high flow rate.
FIGS. 6A and 6B illustrate the prior art stability chamber 26 of FIG. 3 and stability chamber 126 of the present invention (FIG. 4), respectively, when operating at higher flow rates. As indicated above, at higher flow rates, the disclosed stability chamber 126 minimizes the lateral expansion at higher flow rates since the flame velocity at the exit of the stability chamber 126 has a greater radial magnitude relative to the rate of lateral expansion when the flow rate is at a higher firing rate. The additional expansion region 180 maintains a higher true distance between those geometries at high flows where separation is needed. Thus, at higher flow rates, the exiting gas overlooks the additional expansion region 180, in a similar manner to the conventional stability chamber 26.
Generally, gas flames expand due to the inherent expansion of combustion by-products and secondary effects of buoyancy and air entrainment. This expansion is shown in FIGS. 6A and 6B as a vector, VL. There is also a velocity vector Vn due to the momentum of the gas mixture being ejected from the burner ports. As shown in FIGS. 6A and 6B, at high flow rates, the velocity Vn is dominant and the secondary expansion angle of the exemplary additional expansion region 180 has negligible effect on the separation of the chamber flame relative, as shown by gap 198.
FIGS. 7A and 7B illustrate the prior art stability chamber 26 of FIG. 3 and stability chamber 126 of the present invention (FIG. 4), respectively, when operating at lower flow rates. As indicated above, the exit expansion of the additional expansion region 180 allows the chamber flame to expand further laterally under low flow conditions. The additional volume expansion 180 reduces the effective distance 198 between the chamber walls 150 a, 150 b and the adjacent ports 160 at low flow rates. Thus, as shown in FIG. 7B at lower flow rates, the exiting gas expands further than with the prior art stability chamber 26 associated with FIG. 7A. As shown in FIG. 7B, at lower flow rates, the secondary expansion of the additional expansion region 180 at the chamber exit further reduces the velocity Vn, increasing the expansion vector VL, thereby improving the cross-talk to flames of the adjacent ports 160.
Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to exemplary embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. Moreover, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Furthermore, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Claims

What is claimed is:

1. A burner body for use in a gas burner assembly, said burner body comprising:

a sidewall and a main gas conduit, said main gas conduit comprising an inlet and an outlet;

a plurality of primary burner ports disposed within said sidewall so as to be in communication with said outlet of said main gas conduit;

a simmer flame port disposed within said sidewall in a spaced relation with said primary burner ports for providing a reignition source therefore; and

a stability chamber disposed within said burner body, wherein a first interior region of said stability chamber has a primary expansion angle substantially between said tubular main gas conduit and said sidewall and wherein a second exterior region of said stability chamber has a secondary expansion angle substantially along said sidewall and wherein said secondary expansion angle is greater than said primary expansion angle.

2. The burner body of claim 1, wherein said second exterior region comprises a radius at an exit of said stability chamber.

3. The burner body of claim 1, wherein said stability chamber is defined on each side by a pair of radially extending baffles, on the bottom by an upper surface of said burner body, on the top by a cap, and by an end-wall at said outlet so as to extend from said outlet to said simmer flame port.

4. The burner body of claim 3, wherein said upper surface is configured such that a depth of said stability chamber at an end of said stability chamber closest said outlet has a value less than a depth of said stability chamber at an end closest to said simmer flame port.

5. The burner body of claim 1, wherein said stability chamber minimizes a lateral expansion of a gas at relatively high flow rate.

6. A gas cooking appliance comprising a burner body, said burner body comprising:

a stability chamber disposed within said burner body, wherein a first interior region of said stability chamber has a primary expansion angle substantially between said main gas conduit and said sidewall and wherein a second exterior region of said stability chamber has a secondary expansion angle substantially along said sidewall and wherein said secondary expansion angle is greater than said primary expansion angle.

7. The gas cooking appliance of claim 6, wherein said second exterior region comprises a radius at an exit of said stability chamber.

8. The gas cooking appliance of claim 6, wherein said stability chamber is defined on each side by a pair of radially extending baffles, on the bottom by an upper surface of said burner body, on the top by a cap, and by an end-wall at said outlet so as to extend from said outlet to said simmer flame port.

9. The gas cooking appliance of claim 8, wherein said upper surface is configured such that a depth of said stability chamber at an end of said stability chamber closest said outlet has a value less than a depth of said stability chamber at an end closest to said simmer flame port.

10. The gas cooking appliance of claim 6, wherein said stability chamber minimizes a lateral expansion of a gas at relatively high flow rate.

11. A stability chamber for use within a burner body of a gas burner assembly, said stability chamber comprising:

a first interior region comprising a primary expansion angle substantially between an interior tubular main gas conduit and an exterior sidewall of said burner body; and

a second exterior region comprising a secondary expansion angle substantially along said sidewall and wherein said secondary expansion angle is greater than said primary expansion angle.

12. The stability chamber of claim 11, wherein said second exterior region comprises a radius at an exit of said stability chamber.

13. The stability chamber of claim 11, wherein said stability chamber is defined on each side by a pair of radially extending baffles, on the bottom by an upper surface of said burner body, on the top by a cap, and by an end-wall at said outlet so as to extend from said outlet to said simmer flame port.

14. The stability chamber of claim 13, wherein said upper surface is configured such that a depth of said stability chamber at an end of said stability chamber closest said outlet has a value less than a depth of said stability chamber at an end closest to said simmer flame port.

15. The stability chamber of claim 11, wherein said stability chamber minimizes a lateral expansion of a gas at relatively high flow rate.