Patent Publication Number: US-2022235937-A1

Title: Pre-vaporizing pipe, combustion assembly provided therewith and turbomachine provided therewith

Description:
The invention relates to a pre-vaporization rod for a turbomachine combustion chamber, a combustion chamber provided with this vaporization rod and a turbomachine provided with this combustion chamber. 
     The rod is usually attached to a casing in order to enter the combustion chamber via an opening thereof. 
     Such rods are known, for example, from documents FR-A-3 066 009 and WO 2015/079166. 
     The pre-vaporization rod known from document FR-A-3 066 009 comprises a main body of generally elongated shape and defining a first inner longitudinal duct in which a fuel injector is intended to be mounted, said main body comprising a first longitudinal end for attachment to a chamber wall and a second longitudinal end, and two bent arms disposed at the second longitudinal end and defining bent end pieces whose first ends are in fluid communication with said first duct and whose second ends are intended to open out into the chamber. 
     The drawback of this rod is that the bent arms generate lateral space requirement making it more difficult to withdraw the rod by passing it through the opening of the chamber. 
     Document WO 2015/079166 describes a pre-vaporization rod according to  FIG. 1 , which comprises a tubular wall  61  forming a duct  32  extending inside the combustion chamber  10 , and opening out thereinto through two end pieces  33  connected to different locations of the length of the wall  61  located at a distance from a fuel injector inserted into one end of the duct. This rod, because of the fact that the end pieces are in series, makes it easier to slide the rod into the opening of the chamber to withdraw it. 
     On the other hand, the fuel flows expelled by the two end pieces according to  FIG. 1  are too asymmetrical, which means that the combustions in the chamber at the outlet of the two end pieces are also asymmetrical. 
     The invention aims at obtaining a pre-vaporization rod for a turbomachine combustion chamber, which can at the same time be easily dismounted by sliding out of the opening of the combustion chamber and which allows better monitoring the fuel flows from the end pieces. 
     To this end, a first subject matter of the invention is a pre-vaporization rod for a combustion chamber of a turbomachine, comprising a main body of generally elongated shape, the main body comprising a first end portion delimiting an inlet duct in which a fuel injector is intended to be mounted, 
     the main body having an external surface having at least a first length extending from the end portion to at least a first fuel outlet end piece, and at least a second length, which extends the first length from the first fuel outlet end piece and which extends from the first fuel outlet end piece to at least a second fuel outlet end piece, 
     characterized in that 
     inside the main body is at least a first channel connecting the inlet duct to the first fuel outlet end piece and at least a second channel, which is separate from the first channel and which connects the inlet duct to the second fuel outlet end piece. 
     Thanks to the invention, the arrangement of the first channel can be determined independently of the arrangement of the second channel, in order to be able to create in the first and second end pieces respectively two first and second fuel flows having characteristics more similar to each other. 
     According to one embodiment of the invention, the external surface of the body comprises a main arm extending generally along a first longitudinal direction and a lateral arm connected to the main arm and deviating in a curved manner along a second direction, which is lateral relative to the first longitudinal direction, 
     the main arm connects the end portion to the first fuel outlet end piece, and 
     the second fuel outlet end piece is located in the lateral arm, at a distance from the main arm and at a distance from the first fuel outlet end piece. 
     According to one embodiment of the invention, the first the fuel outlet end piece and the second fuel outlet end piece are oriented in the same orientation of a same third fuel outlet direction. 
     According to one embodiment of the invention, the first length is taken along the shortest line of the external surface from the end portion to a first central portion of the first fuel outlet end piece, the second length is taken along the shortest line of the external surface from the first central portion of the first fuel outlet end piece to a second central portion of the second fuel outlet end piece. 
     According to one embodiment of the invention, the first channel has a first internal fuel passage length which is greater than the first length. 
     According to one embodiment of the invention, the first internal fuel passage length of the first channel is taken along a line, which is central relative to a first internal surface of the main body delimiting the first channel. 
     According to one embodiment of the invention, a first portion of a first internal fuel passage length of the first channel is located inside the second length of the external surface of the main body. 
     According to one embodiment of the invention, the first channel comprises a second portion, which is bent relative to a third portion of the first channel, connected to the second portion of the first channel. 
     According to one embodiment of the invention, the first channel comprises at least one bend located inside the second length of the external surface of the main body and between the third portion of the first channel and the second portion of the first channel. 
     According to one embodiment of the invention, the first channel adjoins a portion of the second channel inside the main body on the first length and on a fourth portion of the second length. 
     According to one embodiment of the invention, the first channel, the first fuel outlet end piece, the second channel and the second fuel outlet end piece are delimited by at least one internal wall of the main body and by the external surface of the main body, the external surface being in one single piece with the at least one internal wall. 
     According to one embodiment of the invention, the main body is a part made by additive manufacturing. 
     According to one embodiment of the invention, the pre-vaporization rod further comprises means for introducing air into the inlet duct. 
     According to one embodiment of the invention, the first channel is delimited by a first internal surface of the main body, the second channel is delimited by a second internal surface of the main body, the first internal surface of the main body has a first area which is equal, by within less than 10%, to a second area of the second internal surface of the main body. 
     A second subject matter of the invention is a turbomachine combustion assembly, comprising
         a casing,   a fuel combustion chamber disposed in the casing,   at least one pre-vaporization rod as described above, whose first end portion is mounted on the casing and whose main body enters the combustion chamber through an opening made in a wall of the combustion chamber, the first fuel outlet end piece and the second fuel outlet end piece being located in the combustion chamber,   a fuel injector being mounted in the inlet duct of the pre-vaporization rod.       

     A third subject matter of the invention is a turbomachine comprising a combustion assembly as described above. 
    
    
     
       The invention will be better understood upon reading the following description, given only by way of non-limiting example with reference to the figures of the appended drawings. 
         FIG. 1  schematically represents an example of a pre-vaporization rod according to document WO 2015/079166. 
         FIG. 2  schematically represents in longitudinal section a pre-vaporization rod according to one embodiment of the invention. 
         FIG. 3  schematically represents in perspective a combustion assembly, in which the pre-vaporization rod according to the invention can be used. 
         FIG. 4  schematically represents in partial section a combustion assembly, in which the pre-vaporization rod according to the invention can be used and in which it has been partially represented. 
         FIG. 5  schematically represents an inside view of a pre-vaporization rod according to another embodiment of the invention. 
     
    
    
     The pre-vaporization rod  5  or stick and the combustion assembly  1  according to the invention can be mounted on a turbomachine. 
     Referring to  FIGS. 1, 3 and 4 , the combustion assembly  1  comprises a casing  20 , in which the combustion chamber  10  is disposed. The combustion chamber  10  may for example comprise two respectively inner  11  and outer  12  revolution walls extending one inside the other, and connected by a chamber bottom  10  annular wall  13 . The casing  20  may also comprise an outer wall of revolution  22 , called outer shroud, extending around the combustion chamber  10 , and to which the outer wall  12  thereof is attached. 
     The combustion assembly  1  further comprises one or several pre-vaporization rods  5 . Examples of vaporization rods  300  according to document WO 2015/079166 are represented in  FIGS. 1 and 3 . 
     One or several vaporization rods  5  according to the invention can be mounted in the combustion assembly  1  of  FIGS. 3 and 4 , where they are not represented. The pre-vaporization rod(s)  5  is/are mounted on the casing  20  and/or on a wall of the combustion chamber  10 . The vaporization rod(s)  5  according to the invention can be dismounted. The pre-vaporization rod is itself attached to the combustion chamber  10 , at the outer wall or at the chamber bottom wall thereof, and enters the combustion chamber  10  through an opening  14  made in the wall. 
     In  FIGS. 2 and 5 , the pre-vaporization rod  5  according to the invention comprises a main body  50  extending in a curved manner in length. The main body  50  comprises a first end portion  51  delimiting an inlet duct  52  in which a fuel injector  40  is intended to be mounted, as represented in  FIG. 4 , for sending fuel into the rod  5 . The end portion  51  can for example be rectilinear in length. Air also enters through the duct  52 . 
     The first end portion  51  is connected to a fluid conveying section  57 , described below, for sending fuel. The fluid conveying section  57  of the main body  50  of the rod  5  may be for example curved in length. The external surface  500  of the body  50  of the rod  5  comprises a main arm  502  extending generally along (and/or around) a first longitudinal direction D 1  and a lateral arm  503  connected to the main arm  502  and deviating in a curved manner along a second lateral direction D 2  (which may for example be towards the right in  FIGS. 2 and 5 ) of the first longitudinal direction D 1 . The lateral arm  503  is bent relative to the main arm  502 . The second lateral direction D 2  can be perpendicular to the first longitudinal direction D 1 . In other embodiments, the second lateral direction D 2  can make an angle smaller than 90° or greater than 90° relative to the first longitudinal direction D 1 . 
     According to one embodiment, the main arm  502  connects the end portion  51  to the first fuel outlet end piece  53 , and the second fuel outlet end piece  54  is located in the lateral arm  503 , at a distance from the main arm  502  and at a distance from the first fuel outlet end piece  53 . 
     According to one embodiment, the first fuel outlet end piece  53 , and the second fuel outlet end piece  54  are oriented in the same orientation of the same third fuel outlet direction D 3 . For example, in  FIGS. 2 and 5 , the third fuel outlet direction D 3  is transverse or perpendicular relative to the main arm  502  and/or relative to the lateral arm  503  and/or relative to the first longitudinal direction D 1  and/or relative to the second lateral direction D 2 . 
     The fluid conveying section  57  has an external wall  505  having an external surface  500 . The external surface  500  of the main body  50  has a first non-zero length L 1  from the end portion  51  to a first fuel outlet end piece  53 . The external surface  500  of the main body  50  of the rod  5  has a second non-zero length L 2 , which extends the first length L 1  from the first fuel outlet end piece  53 . The second length L 2  extends from the first fuel outlet end piece  53  to a second fuel outlet end piece  54 , distant from the first fuel outlet end piece  53 . 
     The lengths are curvilinear. The first length L 1  can be for example taken along the shortest line of the external surface  500  from the end portion  51  to a first central portion of the first fuel outlet end piece  53 . The second length L 2  can be for example taken along the shortest line of the external surface  500  from the first central portion of the first fuel outlet end piece  53  to a second central portion of the second fuel outlet end piece  54 . In  FIGS. 2 and 5 , these lengths L 1  and L 2  are represented on the external side of the rod  5  so as not to overload the figures. 
     The fluid conveying section  57  of the main body  50  comprises a first channel  55  connecting the inlet duct  52  to the first fuel outlet end piece  53 . The first channel  55  is hollow for sending fuel and air from the inlet duct  52  to the first end piece  53 . The fluid conveying section  57  of the main body  50  comprises a second channel  56 , which is separate from the first channel  55  and which connects the inlet duct  52  to the second fuel outlet end piece  54 . The second channel  56  is hollow for sending fuel and air from the inlet duct  52  to the second end piece  54 . The first channel  55  and the second channel  56  communicate with each other only through the inlet duct  52 , for example with a plenum thereof. The first channel  55  and the second channel  56  are delimited inside the main body  50 . Of course, more than two channels and more than two end pieces can be provided. The channel  55  and/or  56  may meander inside the main body  50 . The first channel  55  is thus a first channel  55  for sending fuel and air. The first end piece  53  is thus a first fuel and air outlet end piece  53 . The second channel  56  is thus a second fuel and air sending channel  56 . The second end piece  54  is thus a second fuel and air outlet end piece  54 . 
     Thanks to the channels  55  and  56 , it is possible to better monitor at the outlet of the first and second end pieces respectively two first and second fuel flows more similar to each other, which facilitates their effective integration into the turbomachine  2 . By playing on the channels  55  and  56 , it is thus possible to guarantee the same functional, and particularly the same vaporization at the outlet of the end pieces  53  and  54  of the rod  5 , and thus iso-functional end pieces  53  and  54 . It is thus possible to obtain a better symmetry of the vaporization in the end pieces  53  and  54  and a better homogeneity of the combustion in the chamber  10 . Particularly, the invention can obtain an equivalence of the end pieces  53  and  54  in terms of performances in air permeability, residence time, wet surface, flow rate at the outlet of the end pieces  53  and  54 , fraction of fuel evaporated at the outlet of the end pieces  53  and  54 . The invention can thus reduce the functional deviations, thus limiting the risks and the costs associated with such a modification, which moreover allows significant maintenance gains. The invention can thus obtain an equivalence of the combustion at the outlet of the end pieces  53  and  54 . 
     Characteristics of arrangement of the channels  55  and  56  are described in the embodiments below. 
     According to one embodiment represented in  FIGS. 2 and 5 , the external wall  505  is connected to one or several internal walls  501 , which delimit the first channel  55  and the second channel  56 . According to one embodiment represented in  FIGS. 2 and 5 , the external wall  505  is in one integral piece with the internal wall(s)  501 . 
     According to one embodiment represented in  FIGS. 2 and 5 , the first channel  55  is delimited by a first internal surface  5041  of the main body  50 . The first internal surface  5041  is carried in part by the external wall  505  and in part by the internal wall(s)  501 . 
     According to one embodiment represented in  FIGS. 2 and 5 , the second channel  55  is delimited by a second internal surface  5042  of the main body  50 . The second internal surface  5042  is carried in part by the external wall  505  and in part by the internal wall(s)  501 . 
     According to one embodiment represented in  FIGS. 2 and 5 , the first channel  55  has a first internal fuel passage length, which is greater than the first length L 1 . Thus, the first channel  55  can be curved around the first length L 1  in order to travel through a longer path than that of the external surface  500  from the edge of the inlet duct  52  to the edge of the first end piece  53 . It is thus possible to better bring the length and/or the volume of the first channel  55  closer to the length and/or the volume of the second channel  56 , which allows obtaining more similar fuel flows in the first and second end pieces  53  and  54 . The first internal fuel passage length of the first channel  55  may be taken along a line, which is located in the first channel  55  and which is surrounded by the first internal surface  5041  of the main body  50  delimiting the first channel  55  or is central relative to the first internal surface  5041  of the main body  50  delimiting the first channel  55 . 
     The second internal fuel passage length of the second channel  56  may be taken along a line, which is located in the second channel  56  and which is surrounded by the second internal surface  5042  of the main body  50  delimiting the second channel  56  or is central relative to the second internal surface  5042  of the main body  50  delimiting the second channel  56 . 
     According to one embodiment represented in  FIGS. 2 and 5 , a first portion  551  of the first internal fuel passage length of the first channel  55  is located inside the second length L 2  of the external surface  500  of the main body  50 . The first channel  55  is thus lengthened, which allows obtaining more similar fuel flows in the first and second end pieces  53  and  54 . 
     According to one embodiment represented in  FIGS. 2 and 5 , a second portion  552  (of the first internal fuel passage length) of the first channel  55  is bent or folded along one or several bends  554  relative to a third portion  553  (of the first internal fuel passage length) of the first channel  55 , the third portion  553  being connected to the second portion  552 . The bend(s)  554  of the first channel between the third portion  553  of the first channel and the second portion  552  of the first channel may be for example located inside the second length L 2  of the external surface  500  of the main body  50 , that is to say in the first portion  551  of the first channel. It is thus possible to place more internal length of the first channel  55  in a reduced space. In this way, more symmetry between the internal lengths and volumes of the channels  55  and  56  is achieved. 
     According to one embodiment represented in  FIGS. 2 and 5 , the first channel  55  adjoins (that is to say is located next to, by being separated therefrom by at least one internal wall  501  of the main body  50 ) a portion  561  of the second channel  56  inside the main body  50  on the first length L 1  and on a fourth portion  564  of the second length L 2 . 
     According to one embodiment represented in  FIGS. 2 and 5 , the first channel  55 , the first fuel outlet end piece  53 , the second channel  56  and the second fuel outlet end piece  54  are delimited by one or several internal walls  501  of the main body  50  and by the external surface  500  of the main body  50 . The external surface  500  of the main body  50  is in one single piece with the internal wall(s)  501  of the main body  50 . Thus, a further reduced external width of the rod  5  is obtained while having more similar fuel flows at the outlet of the end pieces  53  and  54  and a more reduced weight of the rod  5 . 
     According to one embodiment, the first area of the first internal fuel passage surface  5041  of the first channel  55  is substantially equal, or equal by within less than 10%, to the second area of the second internal fuel passage surface  5042  of the second channel  56  and/or the first internal volume of the first channel  55  is substantially equal, or equal by within less than 10%, to the second internal volume of the second channel  56  and/or the first internal fuel passage length of the first channel  55  is substantially equal, or equal by within less than 10%, to the second internal fuel passage length of the second channel  56 . 
     According to one embodiment, the first flow rate/pressure characteristic of the first channel  55  is substantially equal, or equal by within less than 10%, to the second flow rate/pressure characteristic of the second channel  56 . 
     According to one embodiment represented in  FIGS. 2 and 5 , the main body  50  is a part made by additive manufacturing. This makes it easier to achieve the internal curvatures of the channels. 
     According to one embodiment represented in  FIGS. 2 and 5 , the pre-vaporization rod  5  comprises means for introducing air into the inlet duct  52 . These air introduction means may comprise in the inlet duct  52  one or several orifices  35  and/or ducts  6 , serving for the introduction of air, whose non-limiting examples are represented in  FIGS. 1 and 4 . 
     According to one embodiment, the first end portion  51  of the pre-vaporization rod(s)  5  according to the invention is mounted on the casing  20 . In this mounting position, the main body  50  of the rod  5  enters the combustion chamber  10  through an opening  14  present in a wall of the combustion chamber  10 . In this mounting position, the first fuel outlet end piece  53  and the second fuel outlet end piece  54  are located in the combustion chamber  10 . In this mounting position, a fuel injector  40  is mounted in the inlet duct  52  of each pre-vaporization rod  5 , as shown in  FIG. 4  (this element having been omitted in  FIGS. 2 and 5 ). The first end portion  51  may be located outside the combustion chamber  10 . 
     One mode of operation of the combustion assembly  1  comprising the pre-vaporization rod  5  according to the invention is described below. 
     The fuel injector  40  opens out into the inlet duct  52  to inject fuel therein. The main injector  40  injects fuel once the combustion within the chamber  10  has already been initiated by another type of injector called “starting injector”. The fuel is projected by the injector  40  into the inlet duct  52  of the rod  5 , which rod  5  is heated by the combustion taking place in the combustion chamber  10 . In contact with the walls of the rod  5 , the fuel vaporizes and mixes with air coming from one or several orifices  35  made in the wall  31  of the rod, between the outer shroud  22  of the casing  20  and the outer wall  12  of the combustion chamber. One example of disposition of orifices  35  passing through the wall of the inlet duct  52  of the rod  5  has been represented in  FIG. 1 . 
     The air-fuel mixture enters the combustion chamber  10  through the end pieces  53  and  54  of the pre-vaporization rod  5 . The fuel-air mixture ignites in the combustion chamber  10  when it exits the end pieces  53  and  54  of the rod  5 . The end pieces  53  and  54  can be oriented towards the bottom wall  13  of the chamber  10 , allowing a good combustion of the injected fuel. 
     Each pre-vaporization rod  5  can be mounted on the outer shroud  22  of the casing  20 , and enters inside the combustion chamber  10  through the opening  14  made in the outer wall  12  thereof. The end  58  of the end portion  51 , away from the fluid conveying section  57  of each pre-vaporization rod  5  can be mounted on the outer side of the outer shroud  22  of the casing  20 . To dismount the pre-vaporization rod  5 , it can be slid into the opening  14  to be withdrawn therefrom. This allows accessing the pre-vaporization rod  5 , for example to repair or replace it, from the outside of the casing  20 , without having to dismount this casing  20  or the combustion chamber  10 . 
     The pre-vaporization  30  rod  5  can enter inside the casing  20  by means of another opening  24  made in its outer shroud  22 , the opening  24  being preferably facing the opening  14  of the wall of the combustion chamber  10 , to facilitate the insertion and withdrawal of the pre-vaporization rod  5 , whose inlet duct  32  generally extends in a rectilinear manner. 
     Each pre-vaporization rod  30  can be removably mounted on the casing  20  and/or on the wall of the combustion chamber  10 , for example by bolting or screwing. This makes it easy to remove a rod to replace, repair or clean it. 
     The combustion assembly  1  may further comprise a sealing ring  50 , adapted to ensure the sealing of the combustion chamber  10  at the opening  14  and allowing the passage of the pre-vaporization rod  5  in the combustion chamber  10 . The sealing ring  15  can be disposed between an edge  140  of the opening  14  and the external surface  500  of the rod  5 . The ring  15  ensures the sealing of the wall  12 , while authorizing it to be deformed by thermal expansion during the operation of the turbomachine  2 . 
     Of course, the embodiments, characteristics, possibilities and examples described above can be combined with each other or be selected independently of each other.