Liquid fuel injector

Abstract

A liquid fuel injector includes a cylindrical center body including a center axis, an annular shroud concentrically disposed outside the center body, an annular fuel injection body disposed between and concentrically with the center body and the shroud, and including a fuel passage formed therein, a plurality of inner swirl vanes that are arranged in an equal cycle in an inner air passage between the center body and the fuel injection body, and are provided with an inner swirl vane action surface on an upstream side, a plurality of outer swirl vanes that are arranged in an equal cycle in an outer air passage between the fuel injection body and the shroud, and an outer swirl vane action surface on the upstream side.

Claims

1. A liquid fuel injector comprising: a cylindrical center body including a center axis, an annular shroud concentrically disposed outside the cylindrical center body in a radial direction, an annular fuel injection body disposed between and concentrically with the cylindrical center body and the annular shroud, and including a liquid fuel passage formed therein, a plurality of inner swirl vanes that are arranged in an equal cycle in a circumferential direction in an annular inner air passage formed between the cylindrical center body and the annular fuel injection body, and comprise an inner swirl vane action surface on an upstream side in an airflow direction in the inner annular air passage, and a plurality of outer swirl vanes that are arranged in an equal cycle in the circumferential direction in an annular outer air passage formed between the annular fuel injection body and the annular shroud, and comprise an outer swirl vane action surface on an upstream side in an airflow direction in the annular outer air passage, wherein at least one and a part of the one of an inner swirl vane action surface profile that is an intersection line between the inner swirl vane action surface and a plane including the center axis and the radial direction, and an outer swirl vane action surface profile that is an intersection line between the outer swirl vane action surface and the plane including the center axis and the radial direction are inclined with respect to the radial direction, and in a case where each of the inner swirl vane action surface profile and the outer swirl vane action surface profile is a straight line or a curved line, an angle from a straight line extending in the radial direction through an upstream end of the inner swirl vane action surface profile, to the inner swirl vane action surface profile or a tangent line in an inclined part of the inner swirl vane action surface profile is an inner swirl vane inclination angle, an angle from a straight line extending in the radial direction through an upstream end of the outer swirl vane action surface profile, to the outer swirl vane action surface profile or a tangent line in an inclined part of the outer swirl vane action surface profile is an outer swirl vane inclination angle, each of the inner swirl vane and outer swirler vane inclination angles is defined as an angle less than 90° that takes a positive or negative sign when measured clockwise or counterclockwise, and the inner swirl vane inclination angle and the outer swirl vane inclination angle are both positive, or different in the sign from each other and an absolute value of the inner swirl vane inclination angle and an absolute value of the outer swirl vane inclination angle are both 45° or more.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic cross-sectional view of an entire air-blast type liquid fuel injector according to a first embodiment of the present disclosure.

(2) FIG. 2 is a schematic cross-sectional view showing a main part of the air-blast type liquid fuel injector of FIG. 1.

(3) FIG. 3A is a schematic cross-sectional view showing a main part of an air-blast type liquid fuel injector according to a second embodiment of the present disclosure.

(4) FIG. 3B is a schematic cross-sectional view showing a main part of an air-blast type liquid fuel injector according to a third embodiment of the present disclosure.

(5) FIG. 3C is a schematic cross-sectional view showing a main part of an air-blast type liquid fuel injector according to a fourth embodiment of the present disclosure.

(6) FIG. 4 is a schematic cross-sectional view showing a main part of a conventional air-blast type liquid fuel injector.

MODE FOR CARRYING OUT THE DISCLOSURE

(7) Hereinafter, description will be made as to embodiments of the present disclosure in detail with reference to the drawings.

(8) FIG. 1 is a schematic cross-sectional view of an entire air-blast type liquid fuel injector according to a first embodiment of the present disclosure. Note that in the present description, an upstream side and a downstream side in air and liquid fuel flow directions described later will be referred to as a front side and a rear side, respectively.

(9) A liquid fuel injector 100 is provided with a cylindrical center body 110 having a center axis C, an annular shroud 130 concentrically disposed outside the center body 110 in a radial direction, and an annular fuel injection body 120 disposed between and concentrically with the center body 110 and the shroud 130.

(10) The fuel injection body 120 includes an outer wall and an inner wall that are annular, and includes an annular liquid fuel passage Pf formed between these two walls. Furthermore, a liquid fuel inflow port 120p is formed in a front end portion of the annular outer wall of the fuel injection body 120.

(11) An inner air passage Pai and an outer air passage Pao that are annular are formed between the center body 110 and the fuel injection body 120 and between the fuel injection body 120 and the shroud 130, respectively. Then, a plurality of inner swirl vanes 115 and outer swirl vanes 125 are arranged in an equal cycle in a circumferential direction in the inner air passage Pai and the outer air passage Pao, respectively.

(12) Air flows into each of the inner air passage Pai and the outer air passage Pao as shown by each of arrows Fai and Fao in FIG. 1, and is swirled during passing through each of the inner swirl vane 115 and the outer swirl vane 125, and the air flows outward into a combustion chamber CC as swirling flow including a circumferential velocity component.

(13) The liquid fuel flows into the annular liquid fuel passage Pf through the liquid fuel inflow port 120p formed in the front end portion of the outer wall of the fuel injection body 120, and is injected from a rear end portion of the fuel injection body 120 into the combustion chamber CC as shown by an arrow Ff in FIG. 1, to form an annular liquid film. At this time, shearing force acts on the injected liquid fuel, the shearing force being caused by a difference in velocity from airflow including the circumferential velocity component as described above and flowing outward from each of the inner air passage Pai and the outer air passage Pao, and consequently, the liquid fuel is atomized.

(14) Also in the air-blast type liquid fuel injector 100 of the present disclosure, each of the inner swirl vane 115 and the outer swirl vane 125 is formed as a helical vane, and this helical vane is formed so that each of cross sections 115S and 125S (see FIG. 2) in a plane including the center axis C (each of paper surfaces of FIG. 1 and FIG. 2) is inclined with respect to a direction substantially perpendicular to the center axis C (the radial direction). This respect will be described in detail as follows.

(15) FIG. 2 is a schematic cross-sectional view showing a main part of the liquid fuel injector 100. Note that the drawing only shows a cross section of one side (upside) with respect to the center axis C.

(16) As shown in FIG. 2, the inner swirl vane 115 disposed in the inner air passage Pai has the cross section 115S in the plane (the paper surface of FIG. 2) including the center axis C, the cross section being inclined outward in the radial direction toward the rear side (the downstream side) (in other words, at least a part of an optional portion of the cross section 115S is located on an outer side in the radial direction as compared with a portion located in front of (on the upstream side of) the above optional portion).

(17) In this illustrated example, the inner swirl vane 115 is formed so that an intersection line (hereinafter, referred to as an inner swirl vane action surface profile) 115W between a surface located on the upstream side, i.e., an inner swirl vane action surface having a function of swirling the airflow and the plane (the paper surface of FIG. 2) including the center axis C becomes a straight line or a curved line inclined (having an angle) outward in the radial direction toward the rear side (the downstream side).

(18) Then, a predetermined angle that is not 0°, i.e., an inner swirl vane inclination angle θi is formed between a straight line 115R extending in the radial direction through a start point 115i that is a front end (an upstream end) of the inner swirl vane action surface profile 115W and at least a part of the inner swirl vane action surface profile 115W.

(19) The inner swirl vane inclination angle θi is an angle less than 90° that takes a positive or negative sign in a case where an angle from the straight line 115R to the inner swirl vane action surface profile 115W is measured clockwise or counterclockwise, and it is preferable that an absolute value |θi| of the angle is 45° or more (|θi|≥45°). In the illustrated example, the sign of θi is positive, i.e., θi>0°, and hence preferably θi≥45°.

(20) Similarly, the outer swirl vane 125 disposed in the outer air passage Pao has the cross section 125S in the plane (the paper surface of FIG. 2) including the center axis C, the cross section being inclined inward in the radial direction toward the rear side (the downstream side) (in other words, at least a part of an optional portion of the cross section 125S is located on an inner side in the radial direction as compared with a portion located in front of (on the upstream side of) the above optional portion).

(21) In this illustrated example, the outer swirl vane 125 is formed so that an intersection line (hereinafter, referred to as an outer swirl vane action surface profile) 125W between a surface located on the upstream side, i.e., an outer swirl vane action surface having a function of swirling the airflow and the plane (the paper surface of FIG. 2) including the center axis C becomes a straight line or a curved line inclined (having an angle) inward in the radial direction toward the rear side (the downstream side).

(22) Then, a predetermined angle that is not 0°, i.e., an outer swirl vane inclination angle θo is formed between a straight line 125R extending in the radial direction through a start point 125i that is a front end (an upstream end) of the outer swirl vane action surface profile 125W and at least a part of the outer swirl vane action surface profile 125W.

(23) The outer swirl vane inclination angle θo, similarly to the inner swirl vane inclination angle θi, is also an angle less than 90° that takes a positive or negative sign in a case where an angle from the straight line 125R to the outer swirl vane action surface profile 125W is measured clockwise or counterclockwise, and it is preferable that an absolute value |θo| of the angle is 45° or more (|θo|≥45°). In the illustrated example, the sign of θo is negative, i.e., θo<0°, and hence preferably θo≤−45°.

(24) Note that in the above, description has been made on assumption that each of the inner swirl vane action surface profile 115W and the outer swirl vane action surface profile 125W is the straight line. However, in a case where these profiles are curved lines, angles between tangent lines of the curved lines in inclined parts and the straight lines 115R, 125R are the inner swirl vane inclination angle θi and the outer swirl vane inclination angle θo, respectively.

(25) In a case where, as shown by the arrows Fai and Fao, the airflow passes through the inner air passage Pai and the outer air passage Pao in which the inner swirl vane 115 and the outer swirl vane 125 having configurations described above are arranged, respectively, velocity distributions (radial distributions of axial velocity components) at outlets of the respective air passages are denoted with Vi1 and Vo1, respectively.

(26) In these distributions, the velocity distribution Vi1 at the outlet of the inner air passage Pai is a distribution having a peak shifted to an outer side in the radial direction as compared with a velocity distribution Vi in a conventional liquid fuel injector 1 (see FIG. 4). This peak is shifted because the inner swirl vane action surface profile 115W of the inner swirl vane 115 disposed in the inner air passage Pai is inclined outward in the radial direction toward the rear side (the downstream side).

(27) The velocity distribution Vo1 at the outlet of the outer air passage Pao is a distribution having a peak shifted to an inner side in the radial direction as compared with a velocity distribution Vo in the conventional liquid fuel injector 1 (see FIG. 4). This peak is shifted because the outer swirl vane action surface profile 125W of the outer swirl vane 125 disposed in the outer air passage Pao is inclined inward in the radial direction toward the rear side (the downstream side).

(28) The peak in each of these velocity distributions Vi1 and Vo1 is located remarkably close to the flow of the film-like liquid fuel injected from the fuel injection body 120, and hence a degree of contribution to atomization of the liquid fuel noticeably increases. Therefore, according to the liquid fuel injector 100 of the present disclosure, liquid fuel atomization of a high level can be achieved under the same air flow rate (or pressure loss), and an air flow rate (or pressure loss) required to achieve liquid fuel atomization of the same level can be minimized.

(29) In the above, the embodiment has been described in which for a purpose of maximizing a performance of atomizing the liquid fuel, the inner swirl vane action surface profile 115W is inclined outward in the radial direction toward the rear side (the downstream side), and the outer swirl vane action surface profile 125W is inclined inward in the radial direction toward the rear side (the downstream side). However, effects different from those described above can be obtained by inclining the inner swirl vane and the outer swirl vane in another aspect.

(30) FIG. 3A to FIG. 3C are schematic cross-sectional views showing main parts of air-blast type liquid fuel injectors of further embodiments of the present disclosure.

(31) In a liquid fuel injector 200 of a second embodiment of the present disclosure shown in FIG. 3A, an inner swirl vane action surface profile 215W is inclined outward in a radial direction toward a rear side (a downstream side) in the same manner as in the liquid fuel injector 100 of the first embodiment, while an outer swirl vane action surface profile 225W is inclined outward in the radial direction toward the rear side (the downstream side) conversely to the liquid fuel injector 100 of the first embodiment. In this case, signs of an inner swirl vane inclination angle θi and an outer swirl vane inclination angle θo are both positive, i.e., θi>0° and θo>0°, and hence preferably θi≥45° and θo≥45°.

(32) In a case where, as shown by arrows Fai and Fao, the airflow passes through an inner air passage Pai and an outer air passage Pao in which an inner swirl vane 215 and an outer swirl vane 225 having configurations described above are arranged, respectively, velocity distributions (radial distributions of axial velocity components) at outlets of the respective air passages are denoted with Vi2 and Vo2, respectively.

(33) In these distributions, the velocity distribution Vi2 at the outlet of the inner air passage Pai is similar to the velocity distribution Vi1 in the liquid fuel injector 100 of the first embodiment, but the velocity distribution Vo2 at the outlet of the outer air passage Pao is a distribution having a peak shifted to an outer side in the radial direction as compared with the velocity distribution Vo in the conventional liquid fuel injector 1 (see FIG. 4).

(34) These velocity distributions Vi2 and Vo2 are combined, to improve a level of atomization of liquid fuel, by use of a peak of the velocity distribution Vi2 that is located remarkably close to flow of the film-like liquid fuel injected from a fuel injection body 220. At the same time, a mixture of air and liquid fuel injected from the liquid fuel injector 200 can be dispersed broadly to a region that is away from a center axis C to an outer side in the radial direction in a combustion chamber CC, by use of a peak of the velocity distribution Vo2 that is located close to an outer end of the outer air passage Pao in the radial direction (in FIG. 3A, an outer edge Bo2 and an inner edge Bit of flow of the mixture of air and liquid fuel injected from the liquid fuel injector 200 are shown with broken lines, to see the outer edge Bo2 of these edges).

(35) By use of such a configuration, a combustion region in the combustion chamber CC can be appropriately adjusted in accordance with a purpose.

(36) For example, in a case where an injected mixture of air and liquid fuel is required to be dispersed broadly to a region in a vicinity of a center axis C in a combustion chamber CC while improving a level of atomization of the liquid fuel, as in a liquid fuel injector 300 of a third embodiment of the present disclosure shown in FIG. 3B, an outer swirl vane action surface profile 325W may be inclined inward in a radial direction toward a rear side (a downstream side) in the same manner as in the liquid fuel injector 100 of the first embodiment, while an inner swirl vane action surface profile 315W may be inclined inward in the radial direction toward the rear side (the downstream side) conversely to the liquid fuel injector 100 of the first embodiment. In this case, signs of an inner swirl vane inclination angle θi and an outer swirl vane inclination angle θo are both negative, i.e., θi<0° and θo<0°, and hence preferably θi≤−45° and θo≤−45°.

(37) In a case where, as shown by arrows Fai and Fao, airflow passes through an inner air passage Pai and an outer air passage Pao in which an inner swirl vane 315 and an outer swirl vane 325 having configurations described above are arranged, respectively, velocity distributions (radial distributions of axial velocity components) at outlets of the respective air passages are denoted with Vi3 and Vo3, respectively.

(38) In these distributions, the velocity distribution Vo3 at the outlet of the outer air passage Pao is similar to the velocity distribution Vo1 in the liquid fuel injector 100 of the first embodiment, but the velocity distribution Vi3 at the outlet of the inner air passage Pai is a distribution having a peak shifted to an inner side in the radial direction as compared with the velocity distribution Vi in the conventional liquid fuel injector 1 (see FIG. 4).

(39) These velocity distributions Vi3 and Vo3 are combined, to improve a level of atomization of liquid fuel, by use of a peak of the velocity distribution Vo3 that is located remarkably close to flow of the film-like liquid fuel injected from a fuel injection body 320. At the same time, a mixture of air and liquid fuel injected from the liquid fuel injector 300 can be concentrated in a vicinity of a center axis C in a combustion chamber CC, by use of a peak of the velocity distribution Vi3 that is located close to an inner end of the inner air passage Pai in the radial direction (in FIG. 3B, an outer edge Bo3 and an inner edge Bi3 of flow of the mixture of air and liquid fuel injected from the liquid fuel injector 300 are shown with broken lines, to see the inner edge Bi3 of these edges).

(40) Note that in a case where dispersing an injected mixture of air and liquid fuel broadly to both a region in a vicinity of a center axis C and a region away to an outer side in a radial direction in a combustion chamber CC is required rather than improving a level of atomization of the liquid fuel, as in a liquid fuel injector 400 of a fourth embodiment of the present disclosure shown in FIG. 3C, an inner swirl vane action surface profile 415W may be inclined inward in the radial direction toward a rear side (a downstream side), and an outer swirl vane action surface profile 425W may be inclined outward in the radial direction toward the rear side (the downstream side). In this case, a sign of an inner swirl vane inclination angle θi is negative, i.e., θi<0°, and a sign of an outer swirl vane inclination angle θo is positive, i.e., θo>0°, and hence preferably θi≤−45° and θo≥45°.

(41) Consequently, flow of the mixture of air and liquid fuel injected from the liquid fuel injector 400 can be dispersed broadly to both a region in a vicinity of the center axis C and a region away to an outer side in the radial direction in the combustion chamber CC, as shown by an outer edge Bo4 and an inner edge Bi4 of the injector.

(42) Note that in the above, description has been made as to a case where each of the inner swirl vane and the outer swirl vane is formed as the helical vane so that the cross section in the plane including the center axis is inclined with respect to the direction substantially perpendicular to the center axis (the radial direction), but the liquid fuel injector of the present disclosure is not limited to this case. That is, in the liquid fuel injector of the present disclosure, only one swirl vane of the inner swirl vane and the outer swirl vane may be the helical vane of the above described aspect, and the other swirl vane may be another helical vane (i.e., the vane formed so that the cross section in the plane including the center axis extends in the direction substantially perpendicular to the center axis C (the radial direction)). In other words, in the liquid fuel injector of the present disclosure, at least one of the inner swirl vane and the outer swirl vane is formed as the helical vane of the above described aspect.

(43) As described above, the liquid fuel injector of the present disclosure can be adapted to one of purposes of improving the level of the liquid fuel atomization and of dispersing the injected mixture of air and liquid fuel, by changing the velocity distribution in the air passage in which the swirl vane is disposed (the radial distribution of the axial velocity component) through adjustment of a cross-sectional shape of the swirl vane in the plane including the center axis.

(44) (Aspects of the Present Disclosure)

(45) A liquid fuel injector of a first aspect of the present disclosure is provided with a cylindrical center body including a center axis, an annular shroud concentrically disposed outside the center body in a radial direction, an annular fuel injection body disposed between and concentrically with the center body and the shroud, and including a liquid fuel passage formed therein, a plurality of inner swirl vanes that are arranged in an equal cycle in a circumferential direction in an annular inner air passage formed between the center body and the fuel injection body, and are provided with an inner swirl vane action surface on an upstream side in an airflow direction in the inner air passage, and a plurality of outer swirl vanes that are arranged in an equal cycle in the circumferential direction in an annular outer air passage formed between the fuel injection body and the shroud, and are provided with an outer swirl vane action surface on an upstream side in an airflow direction in the outer air passage, wherein at least one and a part of the one of an inner swirl vane action surface profile that is an intersection line between the inner swirl vane action surface and a plane including the center axis, and an outer swirl vane action surface profile that is an intersection line between the outer swirl vane action surface and the plane including the center axis are inclined with respect to a direction perpendicular to the center axis.

(46) In the liquid fuel injector of a second aspect of the present disclosure, in a case where each of the inner swirl vane action surface profile and the outer swirl vane action surface profile is a straight line, an angle from a straight line extending in the direction perpendicular to the center axis through an upstream end of the inner swirl vane action surface profile to the inner swirl vane action surface profile is referred to as an inner swirl vane inclination angle, an angle from a straight line extending in the direction perpendicular to the center axis through an upstream end of the outer swirl vane action surface profile to the outer swirl vane action surface profile is referred to as an outer swirl vane inclination angle, and each of these inclination angles is defined as an angle less than 90° that takes a positive or negative sign when measured clockwise or counterclockwise, at least one of an absolute value of the inner swirl vane inclination angle and an absolute value of the outer swirl vane inclination angle is larger than 0°.

(47) In the liquid fuel injector of a third aspect of the present disclosure, in a case where each of the inner swirl vane action surface profile and the outer swirl vane action surface profile is a curved line, an angle from a straight line extending in the direction perpendicular to the center axis through an upstream end of the inner swirl vane action surface profile to a tangent line in an inclined part of the inner swirl vane action surface profile is referred to as an inner swirl vane inclination angle, an angle from a straight line extending in the direction perpendicular to the center axis through an upstream end of the outer swirl vane action surface profile to a tangent line in an inclined part of the outer swirl vane action surface profile is referred to as an outer swirl vane inclination angle, and each of these inclination angles is defined as an angle less than 90° that takes a positive or negative sign when measured clockwise or counterclockwise, at least one of an absolute value of the inner swirl vane inclination angle and an absolute value of the outer swirl vane inclination angle is larger than 0°.

(48) In the liquid fuel injector of a fourth aspect of the present disclosure, the inner swirl vane inclination angle is larger than 0°, and the outer swirl vane inclination angle is smaller than 0°.

(49) In the liquid fuel injector of a fifth aspect of the present disclosure, the inner swirl vane inclination angle is 45° or more, and the outer swirl vane inclination angle is −45° or less.

(50) In the liquid fuel injector of a sixth aspect of the present disclosure, the inner swirl vane inclination angle is larger than 0°, and the outer swirl vane inclination angle is larger than 0°.

(51) In the liquid fuel injector of a seventh aspect of the present disclosure, the inner swirl vane inclination angle is 45° or more, and the outer swirl vane inclination angle is 45° or more.

(52) In the liquid fuel injector of an eighth aspect of the present disclosure, the inner swirl vane inclination angle is smaller than 0°, and the outer swirl vane inclination angle is smaller than 0°.

(53) In the liquid fuel injector of a ninth aspect of the present disclosure, the inner swirl vane inclination angle is −45° or less, and the outer swirl vane inclination angle is −45° or less.

(54) In the liquid fuel injector of a tenth aspect of the present disclosure, the inner swirl vane inclination angle is smaller than 0°, and the outer swirl vane inclination angle is larger than 0°.

(55) In the liquid fuel injector of an eleventh aspect of the present disclosure, the inner swirl vane inclination angle is −45° or less, and the outer swirl vane inclination angle is 45° or more.

EXPLANATION OF REFERENCE SIGNS

(56) 100 liquid fuel injector 110 center body 115 inner swirl vane 115W inner swirl vane action surface profile 120 fuel injection body 125 outer swirl cane 125W outer swirl vane action surface profile 130 shroud C center axis Pai inner air passage Pao outer air passage Pf liquid fuel passage θi inner swirl vane inclination angle θo outer swirl vane inclination angle