Patent Publication Number: US-10782017-B2

Title: Wing vaned flame shaper

Description:
FIELD 
     This disclosure relates generally to flame shapers located downstream of ignition in burners, for example burners in furnace systems, and furnace systems including such flame shapers downstream of ignition. 
     BACKGROUND 
     Burners used for heating in gas furnaces typically discharge a flame into a heat exchanger. Depending on the shape of the flame and the flows of the combusting gases, the flame may impinge on the tube of the heat exchanger. This impingement creates a hot spot at the point of contact, which reduces both heat exchanger efficiency and lifetime. Burners may use venturi tubes to control the shape and size of the flame. In some gas burners, swirlers may be used prior to ignition to direct the flow of air and/or fuel prior to combustion. 
     BRIEF SUMMARY 
     This disclosure relates generally to flame shapers located downstream of ignition in burners, for example burners in furnace systems, and furnace systems including such flame shapers downstream of ignition. More particularly, this disclosure relates to flame shapers and furnace systems including flame shapers that include a plurality of turning vanes, configured to induce a swirl in an ignited flame passing through the flame shaper. 
     Flame shapers according to this disclosure result in improved heat transfer, reduced emissions, reduced noise, low-pressure drop of flow through the combustion system, and improved mixing between fuel-rich and fuel-lean regions of a flame. Flame shaper embodiments herein may improve mixing to reduce impingement and improve heat transfer. Flame shaper embodiments may reduce emissions by improving mixing of fuel and air and thus also produce more efficient combustion. Flame shapers according to this disclosure may reduce noise by producing fuel-air mixing with less turbulence and less aggressive mixing. Flame shapers according to this disclosure may provide lower pressure drop by allowing more flow through the flame shaper compared to other designs and reducing the turbulence when mixing the fuel and air. 
     In an embodiment, a gas furnace burner system includes an ignition source and a flame shaper located downstream of the ignition source. The ignition source is configured to ignite a fuel-air mixture to produce a flame. The flame shaper includes an opening and plurality of turning vanes extending from the opening, the turning vanes configured to induce a swirl in the flame. 
     In an embodiment, a heat exchanger tube is downstream of the flame shaper with respect to the direction of flow. In an embodiment, the opening of the flame shaper has a diameter that is at or about 50% to at or about 90% of a diameter of the heat exchanger tube. 
     In an embodiment, the flame shaper has a central portion which does not obstruct the flame. In an embodiment, the gas furnace burner system further includes a flame holder, and a diameter of the central portion is equal to a diameter of the flame holder. 
     In an embodiment, each of the turning vanes have an axial twist and a radial twist over their length. 
     In an embodiment, the fuel-air mixture is a partial premix of fuel and air. In an embodiment, a gas furnace is operated by a method including providing a fuel-air mixture including fuel, igniting the fuel-air mixture using an ignition source to produce a flame, directing an airflow and the flame through a flame shaper inducing a swirl in the flame to form a swirl-mixed flame and directing the swirl-mixed flame into a heat exchanger. In an embodiment, the flame shaper includes a plurality of turning vanes. 
     In an embodiment, the fuel-air mixture is a partial premix of fuel and air. 
     In an embodiment, the flame shaper has a center of an opening that is unobstructed. In an embodiment, the opening of the flame shaper is has a diameter that is between at or about 50% and at or about 90% of a diameter of a tube of the heat exchanger. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an embodiment of a flame shaper for a burner in a gas furnace. 
         FIG. 2  shows a turning vane of an embodiment. 
         FIG. 3A  shows an embodiment of the flame shaper relative to portions of the flame directed through the flame shaper. 
         FIG. 3B  shows a side view of an embodiment of the flame shaper relative to portions of the flame directed through the flame shaper. 
         FIG. 4  shows an embodiment of a gas furnace burner and heat exchanger system including a flame shaper. 
         FIG. 5A  shows an embodiment of a flat sheet of metal prepared for formation into a flame shaper embodiment by a series of cuts. 
         FIG. 5B  shows a flame shaper embodiment prepared by performing twisting operations on a sheet of metal cut according to  FIG. 5A . 
         FIG. 6  shows alternative embodiments for flame shapers. 
         FIG. 7  shows a chart of measurements of normalized sound intensity versus the leaving centerline temperatures at the heat exchanger in various burner and heat exchanger configurations including flame shapers. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure relates generally to flame shapers located downstream of ignition in burners, for example burners in furnace systems, and furnace systems including such flame shapers downstream of ignition. More particularly, this disclosure relates to flame shapers and furnace systems including flame shapers that include a plurality of turning vanes, configured to induce a swirl in a flame that is ignited and then passes through the flame shaper. 
       FIG. 1  shows an embodiment of a flame shaper for a burner in a gas furnace. Flame shaper  10  includes an opening  12  through which the flame is directed, with a plurality of turning vanes  14  distributed around the edge of opening  12  and projecting towards a center portion  16  of the flame shaper  10 . The center portion  16  of opening  12  in flame shaper  10  is not obstructed by any of the plurality of turning vanes  12 . 
     Flame shaper  10  is a device located downstream of an ignition source (shown as  46  in  FIG. 4 ) that ignites a fuel-air mixture that includes fuel and air to produce a flame. The fuel may be, for example, natural gas. The ignited flame is directed through flame shaper  10  prior to entering a heat exchanger (not shown) where the flame exchanges heat with a fluid, for example air, to be directed into a space by a furnace system. The fuel-air mixture and ignited flame have a direction of flow from a fuel source, to the ignition source, and through the flame shaper  10  towards the interior of the heat exchanger. In an embodiment, flame shaper  10  is formed by cutting and twisting a metal sheet. In an embodiment, flame shaper  10  is formed through casting. Flame shaper  10  is not limited to a method of manufacture and may be manufactured by any suitable process or technique or materials to obtain the flame shaper structure suitable herein. 
     Flame shaper  10  is configured to induce a swirl in the flame as it passes through flame shaper  10 . Flame shaper  10  is made of materials capable of maintaining their shape when exposed to the heat produced by the flame of the main burner, for example between 1000 and 1400° F. The materials include, but are not limited to for example, ceramics or steel such as aluminized or stainless steel and the like. Flame shaper  10  promotes mixing of the core flow of fuel and air with additional air to control the combustion reaction, controlling the shape and length of the flame and promoting efficient combustion to reduce emissions and waste. Flame shaper  10  controls the flow of fuel and air out of the burner and into the heat exchanger, and therefore influences the pressures within the burner and, for example, the pumping requirements for fuel used in the gas furnace. 
     Opening  12  is an opening in flame shaper  10  through which the flame passes. Opening  12  is defined by an outer perimeter  18  and has a substantially unobstructed center portion  16  having diameter D 2 . The size of opening  12  may be based on the size of the heat exchanger receiving flame from flame shaper  10 . For example, the diameter D 1  of opening  12  may be in the range of at or about 50% to at or about 90% of the diameter of the heat exchanger tubes. In an embodiment, the diameter of opening  12  is at or about 80% of the diameter of the tube of the heat exchanger receiving flame from flame shaper  10 . A plurality of turning vanes  14  extend from the outer perimeter  18  into the opening  12 . 
     A plurality of turning vanes  14  are distributed around the perimeter  18  of opening  12 . Each of the plurality of turning vanes  14  is at least in part angled with respect to the direction of flow. The plurality of turning vanes  14  are configured to induce swirling in a flame passing through flame shaper  10 . In an embodiment, each of the plurality of turning vanes  14  are shaped such that they are twisted in both the radial and axial directions. Twisting in the radial direction is a twist in the turning vane  14  with respect to a center of the opening  12 . Twisting in the axial direction is a twist in a length direction from a leading edge to a trailing edge of the turning vane with respect to the direction of flow. The shape of turning vane  14  may be a wing shape. In an embodiment, the turning vanes  14  of the flame shaper  10  become closer to parallel with the direction of flow as they extend from the outer perimeter  18  into opening  12 . In an embodiment, the turning vanes  14  may be substantially perpendicular to the direction of the flame at the outer perimeter  18  of opening  12 . Flame shaper  10  may include, for example, five to nine turning vanes  14 . In an embodiment, the plurality of turning vanes  14  includes seven turning vanes. 
     Center portion  16  of opening  12  in flame shaper  10  is an open area configured to allow an ignited fuel-rich core flow to pass through. Center portion  16  is not substantially obstructed by features of flame shaper  10 , including the plurality of turning vanes  14 . In an embodiment, the tips of each of the plurality of turning vanes may be located in center portion  16 . In an embodiment, the tips of each of the plurality of turning vanes have a major axis parallel to the direction of flow of the fuel-rich core flow passing through center portion  16 . In an embodiment, center portion  16  is completely unobstructed, with no elements in the path of the flame through center portion  16 . Center portion  16  may have a diameter D 2  approximately equal to a diameter of a flame holder on a burner face of a burner providing flame to flame shaper  10 . The burner face and flame holder are shown in  FIG. 4  and described in more detail below. In an embodiment, the diameter of a flame holder may be defined by the distance between the outermost openings on the burner face. 
       FIG. 2  shows one of the plurality of turning vanes  14  included in the embodiment shown in  FIG. 1 . In an embodiment, each of the plurality of turning vanes  14  has the same shape. In an embodiment, the shape of turning vane  14  may be a wing shape. Turning vane  14  has a base  142  at which it meets the perimeter  18  of the opening  12  of flame shaper  10 , a twisting portion  144  extending from the base  142 , and tip  146  at the end of twisting portion  142 . Twisting portion  144  has a leading edge  148  and a trailing edge  150 . Turning vane  14  has a length L from the leading edge  148  to the trailing edge  150 . In an embodiment, the length L of turning vane  14  is less at or near the tip  146  than at the base  142 . In an embodiment, length L of the turning vane  14  decreases gradually from the base  142  towards the tip  146 . In an embodiment, leading edge  148  forms an undercurve and trailing edge  150  forms an overcurve as turning vane  14  twists as it extends from base  142  towards tip  146 . 
     Base  142  is where turning vane  14  meets the perimeter  18  of the opening  12  of flame shaper  10 . In an embodiment, base  142  is integral with flame shaper  10 . In an embodiment, turning vane  14  is joined to flame shaper  10  at base  142 . In an embodiment, turning vane  14  may is substantially perpendicular to a direction of flow through flame shaper  10  at base  142 . 
     Twisting portion  144  is the portion of turning vane  14  extending into opening  12  of the flame shaper from base  142 . In twisting portion  144 , the turning vane may have a twist in the radial direction and a twist in the axial direction. Twisting in the radial direction is a twist in the turning vane  14  with respect to a center of the opening  12 . In an embodiment, the twist in the radial direction is a continuous twist over the length of turning vane  14  from base  142  to tip  146  that turns tip  146  away from the center portion  16  of opening  12  of the flame shaper  10 . Twisting in the axial direction is a twist in a major axis of the cross-section of the turning vane with respect to the direction of flow. In an embodiment, the twist in the axial direction may be a continuous twist from the major axis of the cross-section of the turning vane  14  being substantially perpendicular to the direction of flow at base  142  to the major axis of the cross-section of the turning vane  14  being substantially parallel to the direction of flow at tip  146 . 
     Tip  146  is the end of the turning vane  14  that is opposite base  142 . In an embodiment, the major axis of the cross-section of turning vane  14  is substantially parallel to the direction of flow at tip  146 . In an embodiment, tip  146  is outside of the center portion  16  of opening  12  of flame shaper  10 . 
     Leading edge  148  is an edge of turning vane  14 . In an embodiment, trailing edge  148  may be closer to the source of the flame passing through flame shaper  10  than the base  142  over at least a portion of twisting portion  144 . In an embodiment, leading edge  148  is a first point of contact between a flame and flame shaper  10 . 
     Trailing edge  150  is the edge of turning vane  14  opposite leading edge  148 . In an embodiment, leading edge  148  is further away from the source of the flame passing through flame shaper  10  than base  142  over at least a portion of twisting portion  144 . In an embodiment, trailing edge  150  is a final point of contact between a flame and flame shaper  10 . 
       FIG. 3A  shows the embodiment of the flame shaper of  FIG. 1  relative to portions of the flame directed through the flame shaper  10 . At the outermost edges of opening  12  is the fuel-lean periphery  20 , which is primarily air, drawn in through air intakes of the burner. In mixing zone  22 , there is mixing of air and fuel. At the center is fuel-rich core  24 , which primarily passes through the substantially unobstructed center portion  16  of the flame shaper  10 . A portion of the fuel-rich core  24  may travel through a portion of flame shaper  10  where tips of the plurality of turning vanes  14  are in the path of the fuel-rich core. The terms fuel-lean and fuel-rich are relative terms that describe the relative proportions of fuel versus air in the zones relative to one another. The variance in relative concentrations of fuel and air may vary continuously with radial distance from the center of flame shaper  10 . The fuel-rich core  24 , fuel-lean periphery  20 , and mixing zone  22  are defined by the relative quantities of fuel and air passing through that region of flame shaper  10 . Fuel-rich core  24  is where a flow primarily including fuel passes through flame shaper  10 . Fuel-lean periphery  20  is where a flow primarily including air passes through flame shaper  10 . Mixing zone  22  is where a flow which includes a mixture of fuel and air is mixed by swirling induced as the fuel and air pass through flame shaper  10 . In an embodiment, the sources of fuel and air are positioned such that the flow at the core is fuel-lean and the flow at the periphery is fuel-rich. 
       FIG. 3B  shows another view of an embodiment of the flame shaper of  FIG. 1  relative to portions of the flame directed through the flame shaper. As shown in  FIG. 3A , flow through the flame shaper includes a fuel-lean periphery  20 , a mixing zone  22 , and a fuel-rich core  24 . Ignited fuel and air  26  are directed from an ignition source (not shown) towards the flame shaper  10 . A secondary flow of air  28  enters the burner (not shown) including flame shaper  10  and passes through the flame shaper  10 , which induces mixing of the secondary flow of air  28  with the ignited fuel and air  26 . 
     Ignited fuel and air  26  is a flame including fuel and air that are undergoing a combustion reaction following ignition by an ignition source. Ignited fuel and air is a flame that is directed through the flame shaper  10 . Ignited fuel and air  26  is directed towards and through the flame shaper  10 . Ignited fuel and air  26  may be a partial premix of fuel and air that is ignited by an ignition source. A partial premix may be a mix of air and fuel having enough oxygen to begin combustion but lacking sufficient oxygen to fully react the fuel. Ignited fuel and air  26  may be ignited by an ignition source (not shown) to begin combustion of the fuel and air, and then directed through flame shaper  10 . Ignited fuel and air  26  is the primary component of fuel-rich core  24 , and a portion of what is mixed in mixing zone  22  is from the ignited fuel and air  26 . 
     Secondary flow of air  28  is a flow of air into a burner including the flame shaper. Secondary flow of air  28  provides additional oxygen for the combustion reaction. Secondary flow of air may be introduced, for example, by an air intake, for example one or more ports located upstream of the flame shaper  10  with respect to the flow of the ignited fuel and air  26 . At the outer perimeter  18  of the opening  12  of the flame shaper  10 , the secondary flow of air  28  may travel perpendicular to the direction of flow of the ignited fuel and air  26 . The secondary flow of air  28  may be the primary component of fuel-lean periphery  20 , and a portion of what is mixed in mixing zone  22 . 
       FIG. 4  shows an embodiment of a burner and heat exchanger system  40 . Burner and heat exchanger system  40  includes burner  42 , flame shaper  50 , and heat exchanger  52 . Burner  42  includes a fuel source  44 , ignition  46 , and burner face  48 . Flame leaving burner  42  passes through flame shaper  50  and enters heat exchanger  52 . 
     Fuel source  44  provides fuel that is combusted to provide the heat distributed by gas furnace system  44 . Fuel source  44  may be, for example, an inlet connected to a manifold or a gas valve of a gas furnace. In an embodiment, fuel source  44  provides a partial premix of air as well as fuel. In an embodiment, partial premixing of air and fuel occurs after fuel has been provided to the burner by fuel source  44 . Fuel from fuel source  44  travels through burner  42  in a direction of flow from fuel source  44  to burner face  48 , where it exits burner face  48  through one or more openings. The fuel and air leaving through the openings of burner face  48  of burner  42  passes over ignition  46 , is ignited by ignition  46  to produce a flame, and the flame travel towards flame shaper  50 . 
     Ignition  46  initiates combustion of fuel from fuel source  44 . Ignition  46  may be, for example, a spark or a hot surface ignition, a pilot light, or other suitable ignition sources. Examples of hot surface ignitions include, for example, silicon carbide or silicon nitride hot surface ignitions. Ignition  46  is upstream of flame shaper  50  with respect to the direction of flow, and the flame from the combustion of the fuel and air mixture initiated by ignition  46  then travels through the flame shaper  50 . Ignition  46  may be located in a gap  58  between a burner face  48  and flame shaper  50 . 
     The fuel or a fuel-air premix provided by fuel source  44  and any additional primary air taken into burner  42  exits burner  42  at burner face  48 . Burner face  48  includes one or more openings through which the fuel-air mixture exits burner  42 . The one or more openings may include one or more flame holders, which are openings capable of supporting a flame. The flame holders may be the outermost openings on burner face  48 . The diameter from a flame holder to an opposite flame holder on burner face  48  may define diameter D 4 . Diameter D 2  of a center portion of flame shaper  50  may be about the same size as diameter D 4  from flame holder to opposite flame holder on burner face  48 . The flow exiting burner face  48  then passes over ignition  46 . A gap  58  exists between burner face  48  and flame shaper  50 . In an embodiment, air in or entering through gap  58  provides additional oxygen to the fuel-air mixture exiting burner face  48  and being ignited by ignition  46 . Air from gap  58  may form the primary component of a fuel-lean periphery of flow through flame shaper  50 , such as fuel-lean periphery  20  shown in  FIG. 3A  and  FIG. 3B . Air from gap  58  may be secondary flow of air  28  shown in  FIG. 3B . 
     Flame shaper  50  is a flame shaper configured to promote mixing of the combusting fuel-air mixture of the flame with secondary air. In an embodiment, flame shaper  50  induces a swirl in the combusting fuel-air mixture and secondary air. In an embodiment, flame shaper  50  is the flame shaper  10  as shown in  FIG. 1 . The flame, after passing through flame shaper  50 , enters heat exchanger  52 . Flame shaper  50  has an opening having a diameter D 1 . D 1  may be between 50% and 90% of the diameter D 3  of a tube of heat exchanger  52 . The opening of flame shaper  50  has a center portion having a diameter D 2 . D 2  may approximately equal a diameter D 4  measured from flame holder to flame holder on the openings in burner face  48 . 
     Heat exchanger  52  allows for the exchange of heat between the flame leaving flame shaper  50  and air moving through a furnace including the burner and heat exchanger system  40 . The tube may be, for example, U-shaped, with a turn  54 . In an embodiment, the flame may contact a surface of the heat exchanger at the turn. In heat exchanger  52 , the heat given off by the flame is transferred to an airflow, the airflow used to heat a structure such as a dwelling. Heat exchanger  52  has an outlet  56  at an end opposite the end receiving the flame from flame shaper  50 . 
       FIG. 5A  shows an embodiment of a flat sheet of metal prepared for formation into a flame shaper embodiment by a series of cuts.  FIG. 5B  shows a flame shaper embodiment prepared by performing twisting operations to a sheet of metal cut according to  FIG. 5A . 
       FIG. 5A  shows the cuts made to a flat sheet of material in an embodiment. Flat sheet  60  of material such as steel is cut to create open portions  62  defining the perimeter of an opening of the flame shaper  70 . Cuts  64  are made to separate the ends  66  of turning vanes  68  from one another at the center of the opening of the flame shaper. 
     Flat sheet of material  60  is the material from which flame shaper  70  is manufactured. Flat sheet of material  60  is a sheet of ductile, heat resistant material such as steel Flat sheet of material  60  is cut and twisted to produce a flame shaper  70 . Flame shaper  70  may be an embodiment such as flame shaper  10  shown in  FIG. 1 . 
     Open portions  62  define the opening of and turning vanes  68  of a flame shaper  70 . Open portions  62  include an arc portion forming the perimeter of the opening. Open portions may be created by making a plurality of cuts in the flat sheet of material  60 . In an embodiment, the open portions  62  may be formed by making cuts and also bending portions of the flat sheet of material  60  such that the bent portions do not substantially affect the flame, instead of fully removing the material corresponding to the open portion  62 . In an embodiment, the open portions may be formed by, for example, making the arc cut defining the perimeter of the opening and making one cut separating the open portion from a leading or trailing edge of one of turning vanes  68 , while the material corresponding to the open portion remains connected to the other of a leading or trailing edge of another one of turning vanes  68 . 
       FIG. 5B  shows a flame shaper  70  formed by twisting portions of the cut metal sheet of  FIG. 5A  to shape the turning vanes. Ends  66  of each of turning vanes  68  are twisted such that they do not obstruct the center  72  of an opening in the flame shaper  70 . The twisting of material is such that the turning vanes twist from being substantially perpendicular to the direction of flow at the perimeter of the opening to being at an acute angle or parallel to the direction of flow at the ends  66  of each of the turning vanes  68  closest to the opening. Each of turning vanes  68  may have a wing shape following twisting of material. 
     In an embodiment where a cut is not made to fully separate the open portions  62  from the turning vanes, the material still present in open portions  62  may be twisted into a position to reduce the effect of the material on the shape of a flame, for example by twisting the material such that it is parallel to the direction of flow. 
       FIG. 6  shows alternative embodiments of flame shapers. Flame shaper  70  is the embodiment shown in  FIG. 5 .  FIG. 6  shows a crossed-slot flame shaper embodiment  92 , a toothed opening flame shaper embodiment  94 , a cut plate flame shaper embodiment  96 , a drilled hole flame shaper embodiment  98 , and a toothed cut plate flame shaper embodiment  100 . The embodiments shown in  FIG. 6  may be located to shape an ignited flame from a burner before it enters a heat exchanger of a furnace. 
     Crossed-slot flame shaper embodiment  92  includes two overlapping slots  102  that allow a flame to pass through the crossed-slot flame shaper embodiment  92 . In an embodiment, the slots  102  are perpendicular to one another. In an embodiment, the slots overlap in a central portion which is unobstructed. 
     Toothed opening flame shaper embodiment  94  includes a circular opening  104  into which a plurality of teeth  106  project. In an embodiment, the plurality of teeth  106  are triangular in shape, with a point towards the center of opening  104 . Each of the teeth  106  are flat, and have a plane perpendicular to the direction of flow through the toothed opening flame shaper embodiment  94 . In an embodiment, the toothed opening flame shaper includes seven teeth. 
     Cut plate flame shaper embodiment  96  includes two semi-circular openings  108 . In an embodiment, the two semi-circular openings  108  are configured to allow a flame to pass through the cut plate flame shaper embodiment  96 . Between the semi-circular holes  108  are ribs and central portion  110 , which obstructs flow through a portion cut plate flame shaper embodiment  96 , including a center of the cut plate flame shaper embodiment  96 . 
     Drilled hole flame shaper embodiment  98  includes a plurality of drilled holes  112  that allow a flame to pass through the drilled hole flame shaper embodiment  98 . In an embodiment, the plurality of drilled holes may be formed into an array having a pattern within a circular shape. The drilled hole flame shaper embodiment  98  may aggressively promote turbulent mixing of fuel and air in flame passing through the flame shaper. In an embodiment, the drilled holes  112  are each approximately 0.075 inches in diameter 
     Toothed cut plate flame shaper embodiment  100  includes two openings  114  similar to openings  108  and the central portion  110  of the cut plate flame shaper embodiment  96 . In an embodiment, the toothed cut plate flame shaper  100  further includes a plurality of teeth  116  extending into the openings  112 . The plurality of teeth  116  are triangular in shape, with a point towards the center of opening  104 . Each of the teeth  116  are flat, and have a plane perpendicular to the direction of flow through the toothed cut plate flame shaper embodiment  100 . 
       FIG. 7  shows a chart of measurements of normalized sound intensity versus the leaving centerline temperatures at the heat exchanger in various burner and heat exchanger configurations including flame shapers. A normalized sound intensity, based on the amplitude of sound waves, normalized to the amplitude of sound waves produced by a burner operated without a flame shaper, is measured for various temperatures at which burners are operated with the tested flame shapers. As shown in the chart of  FIG. 7 , most flame shaper designs produce significantly more noise when the burner and heat exchanger are operated at a cooler leaving centerline temperature (e.g. the temperature at a point in the center of the flame at a distance downstream of the flame shaper). However, a swirl flame shaper including turning vanes and configured to induce swirl in a combusting fuel-air mixture, such as flame shaper  10  or flame shaper  50 , produces a normalized sound intensity result  80  that is less than the noise level of a standard burner flame, in this case the flame of a 0.9 inch venturi at standard temperatures  82 , even when the flame shaper according to an embodiment is operated at significantly lower leaving centerline temperatures. The normalized sound intensity result  80  of the swirl flame shaper breaks from the trend line  84  produced by other flame shaper designs as they are operated at different leaving centerline temperatures. Flame shaper embodiments are thus shown to provide significantly lower leaving centerline temperatures, indicating more efficient combustion, without the significant additional noise caused by other flame shaper designs which produce more aggressive and turbulent mixing of fuel and air. 
     ASPECTS 
     It is understood that any of aspects 1-8 may be combined with any of aspects 9-13. 
     Aspect 1 
     A gas furnace burner system, comprising: 
     an ignition source, configured to ignite a fuel-air mixture to produce a flame; 
     a flame shaper, located downstream of the ignition source with respect to a direction of flow of the flame, wherein the flame shaper comprises: 
     an opening; and 
     a plurality of turning vanes extending from a perimeter of the opening, wherein the plurality of turning vanes are configured to induce a swirl in the flame. 
     Aspect 2 
     The gas furnace burner system according to aspect 1, further comprising a heat exchanger tube located downstream of the flame shaper with respect to the direction of flow, wherein the heat exchanger tube receives the flame after the flame passes through the flame shaper. 
     Aspect 3 
     The gas furnace burner system according to aspect 2, wherein the opening has a diameter that is between at or about 50% and at or about 90% of a diameter of the heat exchanger tube 
     Aspect 4 
     The gas furnace burner system according to any of aspects 1-3, wherein the flame shaper has a central portion wherein the flame is unobstructed in the central portion of the flame shaper. 
     Aspect 5 
     The gas furnace burner system according to aspect 4, further comprising a flame holder and wherein a diameter of the central portion is equal to a diameter of the flame holder. 
     Aspect 6 
     The gas furnace burner system according to any of aspects 1-5, wherein each of the plurality of turning vanes have an axial twist and a radial twist over the length of the turning vane. 
     Aspect 7 
     The gas furnace burner system according to any of aspects 1-6, wherein the fuel-air mixture is partially premixed fuel and air. 
     Aspect 8 
     The gas furnace burner system according to any of aspects 6-7, wherein the air intake comprises a plurality of ports. 
     Aspect 9 
     A method of operating a gas furnace, comprising: 
     providing a fuel-air mixture comprising a fuel; 
     igniting the fuel-air mixture using an ignition source to produce a flame; 
     directing an airflow and the flame through a flame shaper, the flame shaper inducing a swirl in the airflow and the flame to form a swirl mixed flame; and 
     directing the swirl mixed flame into a heat exchanger of the gas furnace, wherein the flame shaper comprises a plurality of turning vanes. 
     Aspect 10 
     The method according to aspect 9, wherein the airflow is provided by an air intake located between the ignition source and the flame shaper with respect to the direction of travel of the flame. 
     Aspect 11 
     The method according to any of aspects 9-10, wherein the fuel-air mixture is a partial premix of air and the fuel. 
     Aspect 12 
     The method according to any of aspects 9-11, wherein the flame shaper further comprises a center of an opening, wherein the center of the opening is unobstructed. 
     Aspect 13 
     The method according to aspect 12, wherein the opening of the flame shaper has a diameter that is between at or about 50% and at or about 90% of a diameter of a tube of the heat exchanger. 
     The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.