Patent Application
20140230442
1. Field of the Invention
The present invention relates to a gas turbine combustor equipped with a heat-transfer device.
2. Description of the Related Art
The background art of the present technical field is described in Japanese Patent No. 3967251 as below. “In a heat-transfer device for performing thermal exchange between an attachment member and a heat-transfer medium, longitudinal vortex generating devices are installed, which are configured to generate longitudinal vortices each having the rotational axis extending in the flow direction of the heat-transfer medium and to stir the heat-transfer medium flowing through the overall passage. The longitudinal vortices generating devices thus configured are installed in parallel in the flow direction of the heat-transfer medium, and between the longitudinal vortex generating devices thus installed in parallel, a plurality of turbulent-flow enhancement devices are installed, which break a boundary-layer occurring in the heat-transfer medium stirred by the longitudinal vortex generating device.” The manufacturing method of the heat-transfer device mainly includes a process in which one end face of an attachment member having a short size is cut and then folded by means of a pressing machine, thereby forming longitudinal vortex generating devices and a process in which the attachment member is bent into a cylindrical shape. A plurality of the attachment members are manufactured and overlapped one on another to form a combustor liner. Thereafter, the turbulent-flow enhancement devices with rib configuration are installed on the outer circumferential surface of the combustor liner by welding or by blazing to complete the combustor liner.
The background art of the present technical field is described also in JP-62-131927-A. This publication describes “a cooling method which combines impingement jet cooling and cooling using projection fins”. The background art of the present technical field is described also in JP-4-116315-A. This publication describes the fact that “the temperature distribution of a combustor liner is made uniform by changing the heat-transfer coefficient of fins”. The background art of the present technical field is described also in JP-6-221562-A. This publication describes the fact that “the temperature distribution of a combustor liner is made uniform by changing the heat-transfer coefficient of fins”. The background art of the present technical field is described also in JP-9-196377-A. This publication describes the fact that “a combustor liner structure which is provided with a spiral rib on the outer circumferential portion thereof, thereby maintaining necessary cooling performance with such a small pressure loss as not to impair the efficiency of the overall gas turbine and concurrently allowing for reduced combustion oscillation stress”. The background art of the present technical field is described also in JP-2000-320837-A. This publication describes the fact that “guide fins are installed on the outer circumferential side of the liner and the inner circumferential side of the air transfer casing, thereby increasing flow velocity to achieve the improvement of a heat-transfer effect”.
It is an object of the present invention to provide a gas turbine combustor that can suppress an increase in pressure loss while improving product reliability.
To solve the above problem, for example, a configuration described in claims is adopted.
According to an aspect of the present invention, there is provided a gas turbine combustor comprising: a combustor liner on an inner circumferential side; an air transfer casing on an outer circumferential side, the combustor liner and the air transfer casing defining therebetween an annular passage for a heat-transfer medium; and vortex generating devices disposed on an inside surface of the air transfer casing, the vortex generating devices each generating vortices or longitudinal vortices each having a rotational axis extending in a flow direction of the heat-transfer medium.
According to the combustor liner on the inner circumferential side and the air transfer casing on the outer circumferential side which define the annular passage therebetween, preferably, vortex generating devices for generating vortices or longitudinal vortices each having a vortex having a rotational axis extending in the flow direction of the heat-transfer medium are installed on the inside surface of the air-transfer casing. In addition, turbulent-flow enhancement devices for breaking a boundary-layer occurring in the heat-transfer medium are installed on the outside surface of the combustor liner.
Preferably, the vortex generating devices for generating vortices or longitudinal vortices each having a rotational axis extending in the flow direction of the heat-transfer medium are formed on the surface of an attachment member by a forming process. Then, after the attachment member is bent into a cylindrical shape, the cylindrical attachment member is inserted into the inner circumferential side of the air transfer casing. Thus, the vortex generating devices are formed on the inside surface of the air transfer casing.
Preferably, impingement jet cooling holes are added on the air transfer casing provided with the vortex generating devices at a position downstream of the vortex generating devices.
Preferably, the vortex generating devices forming rows installed in parallel to each other are installed in the axial direction such that their installation phases are changed for each row.
The present invention can provide a gas turbine combustor that can suppress an increase in pressure loss while improving product reliability.
Preferred embodiments of the present invention described below relate to gas turbine combustors equipped with a heat-transfer device. In particular, the embodiments relate to a gas turbine combustor equipped with a device that enhances heat-transfer between fluid and an attachment member due to forced convection, i.e., a heat-transfer device that allows a heat-transfer medium to flow along the surface of the attachment member and performs heat exchange between the attachment member and the heat-transfer medium.
For forced convection heat transfer, enhancement of heat-transfer needs to suppress an increase in pressure loss in order to improve efficiency. For example, to improve the efficiency of a gas turbine, it is necessary to increase the temperature of combustion gas. Along with the increased temperature of combustion gas, it is needed to enhance the cooling of a liner. However, a method of further enhancing cooling needs to avoid an increase in pressure loss. Under such situations, impingement jet cooling may increase in pressure loss along with the increased jet flow velocity in some cases. In addition, fin cooling tends to increase in pressure loss along with the increase number of fins. Enhancement of turbulent flow using ribs has a small pressure loss; however, it is not expected to substantially improve cooling performance even if an interval between the ribs is narrowed. Therefore, the cooling enhancement resulting from the increased number of the ribs has a limit.
Because of this, a large number of combustor liners equipped with a heat-transfer device have been proposed to achieve an improvement in heat-transfer coefficient while suppressing an increase in pressure loss. One of the specific examples is a combustor liner that is provided, on the outside surface thereof, with plate-like vortex generating devices and turbulent-flow enhancement devices with rib configuration. With this, cooling performance is improved with a small pressure loss. The basic structure of such a technology is such that the heat-transfer device is installed on the surface of the combustor liner which is located on a higher-temperature side. Therefore, the number of component parts to be attached to the surface of the combustor liner and the number of welding places are increased. Thus, due to increased manufacturing costs and from the view point of thermal strength, a high cost and much time are required to secure product reliability.
JP-2000-320837-A discloses a specific example in which guide fins are installed on each of the outside surface of a combustor liner and the inside surface of an air transfer casing. The combustor described in JP-2000-320837-A is basically structured such that the sectional area of an annular passage defined between the combustor liner and the air transfer casing is narrowed or reduced by the installation of the guide fins. In this way, the flow velocity of passing air, i.e., of a passing heat-transfer medium is increased, thereby achieving an improvement of a heat-transfer effect. However, the increased flow velocity increases a pressure loss, which contributes to the lowering efficiency of the overall gas turbine.
Considering these circumferences, a heat-transfer device for equipment is provided, which suppresses an increase in pressure loss while improving product reliability. For example, one of the equipment is equipped with vortex generating devices which are configured to maintain necessary cooling performance with a pressure loss at which the lowering of the gas turbine efficiency is suppressed at a minimum level and to improve the reliability of structural strength. In addition, the vortex generating devices are configured to increase premixed combustion air to achieve low-NOx and also to improve heat-transfer performance, i.e., a cooling effect more.
According to a more specific example, a gas turbine combustor equipped with a heat-transfer device includes a combustor liner which defines an inner circumferential side of an annular passage for a heat-transfer medium and an air transfer casing which defines an outer circumferential side of the annular passage for a heat transfer medium; wherein the outer circumferential side air transfer casing is provided, on its inside surface, with vortex generating devices each for generating vortices, specifically, longitudinal vortices each having a rotational axis extending in the flow direction of the heat-transfer medium.
According to another specific example, for a combustor liner which defines an inner circumferential side of an annular passage and for an air transfer casing which defines an outer circumferential side of the annular passage; the air transfer casing is provided, on its inside surface, with vortex generating devices each for generating vortices, i.e., longitudinal vortices each having a rotational axis extending in the flow direction of a heat-transfer medium; in addition, the combustor liner is provided, on its outside surface, with turbulent-flow enhancement devices for breaking a boundary-layer occurring in the heat-transfer medium.
According to still another specific example, vortex generating devices each for generating vortices, i.e., longitudinal vortices each having a rotational axis extending in the flow direction of a heat-transfer medium are formed in the surface of an attachment member by a forming process, and after the attachment member is bent into a cylindrical shape, the cylindrical attachment member is inserted into the inner circumferential surface of the air transfer casing. Thus, the vortex generating devices are formed on the inside surface of the air transfer casing.
According to still another specific example, impingement jet cooling holes are additionally formed at a position downstream of vortex generating devices installed on an air transfer casing.
According to yet another specific example, vortex generating devices forming rows installed in parallel to each other are installed in an axial direction such that their installation phase are changed for each row.
With the configurations as described above, the heat-transfer device is installed on the inside surface of the air transfer casing; therefore, an increase in pressure loss can be suppressed while improving product reliability. Because of the reduced number of component parts to be mounted on the combustor liner, the number of welded places can be reduced. Therefore, an improvement in the reliability of the combustion liner and the longer operating life along therewith can be achieved. The reduced number of the welded places can suppress also the deformation of the combustor liner. Further, the vortex generating devices are installed on the inside surface of the air transfer casing. Therefore, the flexibility of mounting of the turbulent-flow enhancement devices installed on the outside surface of the combustor liner is increased, thereby achieving an improvement of a local cooling effect.
Specific embodiments of the present invention will hereinafter be described with reference to the drawings. Incidentally, the present invention is widely applied to equipment provided with a heat-transfer device; however, a gas turbine combustor which is used in a high-temperature state and has flow in a turbulent flow field is described as a main example.
Air 5 which is a heat-transfer medium flows through the annular passage. Specifically, the heat-transfer medium, or air 5, supplied from a compressor is used as fluid for cooling the combustor liner 1 while flowing through the annular passage between the combustor liner 1 and the air transfer casing 2. Thereafter, the heat transfer medium is supplied into the combustor liner while being divided into air 6 for premixed burning and air 9 for diffusion burning, which are each used as air for burning. Combustion gas 31 passes through the inside of the combustor liner 1 and is supplied to a turbine via the transition piece 3.
Flowing of the heat-transfer medium while being largely stirred performs, considering a case of e.g. a gas turbine combustor, exchange of heated air and cool air by longitudinal vortices if a vortex generating device is installed in the annular passage defined between the combustor liner and the air transfer casing. As a result, the heat-transfer medium with low temperature will constantly be supplied to the surface of the combustor liner. Thus, convection cooling on the surface of the combustor liner can efficiently be performed.
Further, since a long axis direction of a turbulence-flow enhancement device 11 installed on the surface of the combustor liner is made to intersect the main stream direction of the heat-transfer medium, separation vortices occur near the wall surface of the combustor liner. These separation vortices have a large effect of breaking the boundary-layer of the heat-transfer medium occurring close to the wall surface. Therefore, the combination use of the turbulent-flow enhancement device and the vortex generating device provides a larger cooling-enhancement effect. The height h of the turbulent-flow enhancement device 11 is determined with consideration of the liner re-adhesion distance of a separation vortex.
In general, it is qualitatively known that the re-adhesion distance L=10h (ten times the height). Therefore, it is basically assumed that the height h of the turbulent flow enhancement device 11 in each embodiment of the present invention is about one to several millimeters. Additionally, it is assumed that the vortex generating device 10 is formed to have an elevation angle γ of 10° to 20° and a height H of ¼ to ½ of the passage through which the heat-transfer medium passes.
The descriptions of the overall configuration of a gas turbine and of detailed operation of a combustor including fuel nozzles are omitted in each of embodiments. Instead, the contents of Japanese Patent No. 3967521 should be referred to. The air transfer casing is a cylindrical structure which is installed on the outer circumferential side of the combustor liner in order to adjust the flow velocity and drift of air to be supplied to the combustor.
As illustrated in an enlarged detailed view in
The vortex generating devices 10 by which the rotational directions of the vortices generated as above are opposite to each other are disposed as a pair. The longitudinal vortices which rotate inversely to each other interact with each other. The longitudinal vortices can efficiently be generated and held. Thus, sufficient cooling can be done with a small pressure loss, whereby an increase in pressure loss can be suppressed while improving product reliability. A plurality of the paired vortex generating devices are disposed in the circumferential direction of the air transfer casing at equal intervals so as to form a row. Lastly, a plurality of such rows are arranged in the flow direction, which makes it possible to cool the overall combustor liner effectively.
In contrast to this, the vortex generating devices 10 are installed on the inside surface of the air transfer casing 2 in the present embodiment. The merit of this configuration exists in suppression of increase in pressure loss while improving the reliability of a product as the gas turbine combustor equipped with the heat-transfer device. Additionally, since the vortex generating devices 10 are installed on the air transfer casing 2 which is located on a low-temperature member side, the welded portion of the vortex generating device has less thermal fatigue. Since the number of parts to be attached to the combustor liner is reduced, the number of welded portions can be reduced, which can achieve cost reduction and suppress the deformation of the combustor liner. In other words, unlike the combustor liner, the air transfer casing is used to define the annular passage through which a heat-transfer medium flows; therefore, it is always in a low-temperature state, that is, the air transfer casing requires no cooling. Thus, a material used for fabricating the air transfer casing may be an inexpensive material, such as carbon steel.
Further, since the vortex generating devices are installed on the air transfer casing side, the vortex generating devices, which are the heat-transfer device, can continuously be used as it is without replacement even if the combustor liner is replaced. The combustor liner, unlike the air transfer casing, has a main function to isolate high-temperature combustion gas 31 from air 5 which is a heat-transfer medium. Therefore, the combustor liner needs to be constantly cooled to a given temperature or lower. If deformation due to welding occurs in the combustor liner, a balance of cooling air loses locally, which probably leads to the burnout of the combustor liner due to lack of the amount of cooling air. However, in the present invention, the number of component parts to be mounted on the combustor liner is reduced to reduce the number of welding places. Thus, the deformation of the combustor liner can be suppressed, thereby improving product reliability.
Besides, JP-2000-320837-A describes “the effect of improving heat-transfer coefficient by increasing the velocity of the flow in the annular passage close to the combustion cylinder by means of only the guide fins installed on the external cylinder of the combustion cylinder”. Specifically, the guide fins are intermittently installed on the inside surface of the air transfer casing at an angle of 30° to 60° relative to the mainstream direction. This narrows or reduces the sectional area of the annular passage to increase the velocity of passing air as a heat-transfer medium, thereby achieving an improvement of a heat-transfer effect, i.e., a cooling effect. However, the increase in flow velocity leads to an increase in pressure loss.
Focusing on the generating vortices, the configuration in which the guide fins are intermittently installed in the circumferential direction of the outside surface of the combustor liner illustrated in JP-2000-320837-A, is a configuration in which transverse vortices, i.e., planer vortices are generated on the surface of the combustor liner when a heat-transfer medium or air passes through a gap between both ends of the guide fins. These transverse vortices can break the boundary-layer on the surface of the combustor layer; therefore, the cooling effect can locally be improved. However, the transverse vortices, i.e., the planer vortices are gradually increased in temperature as they flow in the downstream direction, which gradually lowers the heat-transfer property, i.e., the cooling performance.
In contrast to this, since the vortex generating device 10 of the present embodiment has an angle of as acute as 10° to 20° relative to the mainstream direction, the sectional area of the inside of the annular passage is not substantially reduced, so that an increase in pressure loss can be suppressed. Further, the vortex generating devices installed in parallel constantly produce longitudinal vortices in the annular passage; therefore, the cool heat-transfer medium or air is stirred over the whole area of the passage, which prevents cooling property from being lowered.
A brief description is here given of a method for manufacturing the heat-transfer device with the vortex generating devices 10. The sheet-like attachment member 19 is subjected to the forming process by means of a pressing machine to form the vortex generating means 10 each having a given elevation angle relative to the flow direction. A plurality of the attachment members 19 each having the vortex generating devices 10 thus formed are installed in parallel in the flow direction. The vortex generating devices are formed to have such elevation angles that vortices generated by the vortex generating devices adjacent to each other have rotational directions opposite to each other.
According to this manufacturing method, the sheet-like attachment member 19 is subjected to an integral forming process to easily manufacture the heat-transfer device equipped with the vortex generating devices by making a die. Additionally, because of the simplified manufacturing method, a cost reduction can be achieved.
This is because the separation vortices formed by the turbulent-flow enhancement devices 11 break the boundary-layer close to the wall surface of the combustor liner, so that the cool air carried by longitudinal vortices from the air transfer casing 2 side can effectively be used to cool the combustor liner 2. According to the configuration of the present embodiment concurrently including the vortex generating devices 10 and the turbulent flow enhancement devices 11 which are installed on the outside surface of the combustor liner so as to break the boundary-layer occurring in the heat-transfer medium, it is possible to further improve cooling efficiency. Therefore, an effect of improving product reliability and an effect of suppressing an increase in pressure loss can be provided more remarkably.
That is to say, as illustrated in an enlarged detailed view of
In comparison with the conventional cooling configuration using impingement jet cooling, the configuration of the present embodiment can realize sufficient cooling performance without the formation of the immoderately increased number of the impingement jet cooling holes 20, by the synergetic effect with the longitudinal vortices formed by the vortex generating devices 10. Thus, an increase in pressure loss can be suppressed.
Further, as illustrated in an arrow view of
The inward guide vanes 21 and the vortex generating devices 10 are concurrently used in a local region that particularly needs a cooling effect. This can effectively improve the cooling of the combustor liner 1. The inward guide vane 21 increases a pressure loss because it has fluid resistance greater than that of the vortex generating device. However, the inward guide vanes 21 forcibly change the direction of flow of the heat-transfer medium; therefore, the overall combustor liner can effectively be cooled.
These turbulent-flow enhancement devices 11 have a large effect of breaking the boundary-layer close to the wall surface of the combustor liner. Therefore, combination use with the vortex generating devices 10 installed on the inside surface of the air transfer casing further increases a cooling enhancement effect.
According to the configuration of the present embodiment, a pair of longitudinal vortices, a 1A-vortex and a 1B-bortex, generated by the upstream side longitudinal vortex generating devices flows toward the downstream side. Before long, the pair of longitudinal vortices is sucked in and stirred by a 3B-vortex generated by the downstream side vortex generating device. This action repeats for each row of the vortex generating devices as the longitudinal vortices flow downstream. Therefore, the longitudinal vortices different in phase from each other are formed in the annular passage. This produces a larger stirring effect, thereby improving an effect of cooling the combustor liner.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-030550 | Feb 2013 | JP | national |
