NL2032035B1

NL2032035B1 - Marine gas turbine with special-shaped lobe ejector mixer

Info

Publication number: NL2032035B1
Application number: NL2032035A
Authority: NL
Inventors: Sun Haiou; Hu Yanchen; Ma Hongfei; Zhang Limin; Zhou Shaowei; Fu Hao; Wang Zhongyi; Luan Yigang; Yin Yue
Original assignee: Univ Harbin Eng
Priority date: 2021-07-15
Filing date: 2022-05-31
Publication date: 2023-09-11
Also published as: NL2032035A; CN113464277A

Abstract

A. purpose of the present invention. is to provide a marine gas turbine with a special—shaped, lobe ejector mixer, the special— shaped, lobe ejector mixer is installed, between. an upper thick exhaust pipe and a gas turbine exhaust pipe port, the gas turbine exhaust pipe port is connected to a gas outlet of the gas turbine by a gas turbine turning exhaust pipe, a bottom portion of the special—shaped lobe ejector mixer is provided with a bottom flange, the bottom flange is connected to a ring frame by a ring frame connecting piece, and the ring frame is sheathed under an 1 annular protrusion of the gas turbine exhaust pipe port. The present invention may better adapt to an exhaust ejector system of the marine gas turbine, and may better generate "streamwise vortex" and "orthogonal vortex" to entrain cold air.

Description

P1334 /NL

MARINE GAS TURBINE WITH SPECIAL-SHAPED LOBE EJECTOR MIXER

TECHNICAL FIELD

The present invention relates to a gas turbine, in particular to a marine gas turbine.

BACKGROUND ART

While the marine gas turbine is in operation, the temperature is high. If cooling measures are not adopted, the temperature in an engine crankcase and its adjacent compartments may be too high, and even the service life of some components may be shortened, and the working stability of the gas turbine and its auxiliary systems is reduced. Therefore, a set of an intake and exhaust system is designed for the marine gas turbine, which includes an exhaust ejection system. A part of the function of the exhaust ejection system is to introduce cold air into an engine compartment by a shear force of an airflow, as to reduce the temperature of the compartment and components, and another part of the function is to mix the cold air with a high-temperature gas, as to reduce the temperature of the gas before it is discharged into the atmos- phere. An exhaust pipe port of the marine gas turbine usually uses a conventional ejection mixing form, namely: a gas exhaust pipe is tapered, the pipe port is circular, and there is a certain ejec- tion gap between it and an outer box, as to achieve the effect of ejection mixing. However, with the improvement of the performance of the gas turbine, the ejection performance may no longer satisfy the actual requirements.

An ejector mixer of a conventional nozzle mainly relies on the action of a mainstream viscous shear force to pump and mix a secondary flow. The rate of ejection mixing is slower. For gas turbine applications, a longer mixing pipe may cause the higher wall friction and the higher weight penalty. Therefore, the appli- cation of such conventionally shaped nozzles in the ejector mixers is greatly limited. Thus, by changing the shape of the nozzle and using lateral circulation between the primary and secondary flows,

the concept of enhanced mixing is emerged.

A lobe nozzle formed by bending a thin wall of the exhaust pipe port into a periodic lobe shape changes the flow field of ejection mixing. At an outlet section of the lobe nozzle, bounded by the contour of a lobe, the primary flow rate has an outward lateral component along a wave crest, and the secondary flow rate has an inward lateral component along a wave trough. Therefore, on both sides of the lobe, a pair of circulations with opposite di- rections is formed, and the size of the circulation is related to the height of the lobe. The large-scale reciprocal vortices thus generated are inviscid, and have convective properties. The direc- tion of the vortex is the same as the flow direction, and it is called as a "streamwise vortex".

The lobe nozzle with this shape not only has the "streamwise vortex" to enhance the mixing between the primary and secondary flows, but also under a condition of the same outlet cross- sectional area, the lobe nozzle further has a function of enhanc- ing viscous shear mixing between the primary and secondary flows by increasing the perimeter of an outlet boundary. Therefore, it may achieve full mixing of fluid in the shorter mixing pipe. Ex- perimental results show that: the lobe ejector mixer with the good performance is not only shorter in size and lighter in mass com- pared with a corresponding conventional nozzle ejector mixer, but also the ejection flow ratio of the former is almost 2 times greater than that of the latter.

The lobe ejector mixer is mostly used in an infrared suppres- sor of a helicopter. In 1988, Toulmay F.'s article "Internal Aero- dynamics of Infrared Suppressors for Helicopter Engines" introduc- es in detail a mature application of the lobe ejector mixer in a tail portion of an SA356C helicopter and a working principle thereof. A lobe ejector mixer structure mentioned in the article is the most commonly used and the most widely used. The character- istics of this conventional lobe ejector mixer is that the angles of outward expansion and inward shrinkage are fixed, and do not change with the height of the ejector mixer, that is to say, its inner and outer walls are all straight lines with a fixed inclina- tion angle along a shape line in an axial direction, and side walls of each outward expansion lobe are parallel to each other.

This designing way is related to its working environment. A gas discharged from a tail portion of the gas turbine of the helicop- ter is not changed in direction, and is ejected from the rear lobe ejector mixer, and the velocity field of the gas is almost uni- form. In addition, the diameter of the rear exhaust pipe port is larger than the maximum diameter of the lobe, and there is a large mixing gap, which is easy to generate a mixing layer that is not destroyed, and design a reasonable mixing length. The working en- vironment and internal flow field of the common lobe ejector mixer mentioned in the article are very different from that of the ejec- tor mixer applied to ships.

SUMMARY

A purpose of the present invention is to provide a marine gas turbine with a special-shaped lobe ejector mixer which may improve the ejection performance of an exhaust ejection system of the ma- rine gas turbine.

The purpose of the present invention is achieved in this way:

The present invention is a marine gas turbine with a special- shaped lobe ejector mixer, characterized by including the special- shaped lobe ejector mixer, an upper thick exhaust pipe, and a gas turbine exhaust pipe port, wherein the special-shaped lobe ejector mixer is installed between an upper thick exhaust pipe and a gas turbine exhaust pipe port, the gas turbine exhaust pipe port is connected to a gas outlet of the gas turbine by a gas turbine turning exhaust pipe, a bottom portion of the special-shaped lobe ejector mixer is provided with a bottom flange, the bottom flange is connected to a ring frame by a ring frame connecting piece, and the ring frame is sheathed under an annular protrusion of the gas turbine exhaust pipe port. The special-shaped lobe ejector mixer includes an outward expansion lobe and an inward shrinkage lobe, the outward expansion lobe and the inward shrinkage lobe are ar- ranged at intervals along the circumference, the outward expansion lobe includes a large outward expansion lobe and a small outward expansion lobe, the small outward expansion lobe is located at one side away from the gas turbine, and the number is smaller than the number of the large outward expansion lobes. An axis of the spe- cial-shaped lobe ejector mixer is coincided with an axis of the gas turbine exhaust pipe port.

The present invention may further include: 1. An outer side of the outward expansion lobe is an outer wall surface, an inner side of the inward shrinkage lobe is an in- ner wall surface, side surfaces of the outward expansion lobe and the inward shrinkage lobe are side wall surfaces, the outer wall surface, the inner wall surface and the side wall surface are arc- tangent. 2. A circumferential shape line of the inner wall surface and the outer wall surface is a concentric circular arc using the axis as a center of a circle, and the radius of the circular arc is varied with the height. 3. An axial shape line of the outer wall surface is a circu- lar arc, and the radius of circular arc is decreased with the in- crease of an outward expansion distance.

The advantages of the present invention are as follows: the present invention may better adapt to an exhaust ejector system of the marine gas turbine, and may better generate "streamwise vor- tex" and "orthogonal vortex” to entrain cold air. While a larger shear perimeter and a reasonable ejection gap are guaranteed, by a special-shaped structure design, especially a special design of different lobe sizes and shapes and arc-shaped outer walls, the present invention may generate a free mixing layer with the better performance, make full use of energy of an uneven high-speed gas, and obtain a reasonable mixing length. The most important thing is to avoid the high-speed gas from impacting on a wall surface prem- aturely, destroying the vortex structure, damaging the free mixing layer, and shortening the mixing length.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structure schematic diagram of the present inven- tion;

FIG. 2a is a B perspective view, and FIG. 2b is a C perspec- tive view;

FIG. 3 is a D perspective view;

FIG. 4 is an E perspective view;

FIG. 5a is an F perspective view, FIG. 5b is a G perspective view, and FIG. 5c is an H perspective view; and

FIG. 6a is an I perspective view, and FIG. 6b is a J-J per- 5 spective view.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention is described in more detail below in combination with the drawings:

In combination with FIGS. 1-6b, a special-shaped lobe ejector mixer 1 used for an exhaust pipe port of a marine gas turbine in- volved in the present invention is installed above a gas turbine exhaust pipe port 2. While the gas turbine is in operation, a mainstream high-temperature gas is ejected from a tail gas outlet 2, and passes through a gas turbine turning exhaust pipe 3 to reach the gas turbine exhaust pipe port 2. After that, the gas passes through the special-shaped lobe ejector mixer 1 and flows upwards. At the same time, due to a shear force and an entrainment effect, cold air around the special-shaped lobe ejector mixer 1 in a box 5 is mixed, and flowed together towards an upper thick ex- haust pipe 6, and enters a subsequent exhaust structure. Due to a "pumping" effect, the cold air in the box 5 is drawn and mixed by a mainstream gas, and the cold air needs to be sucked from the outside. The flow direction of the cold air and the mainstream flow direction are given in FIG. 1, the cold air plays a role of cooling the box and components, and the overall working stability is improved.

In combination with FIG. 1, FIG. 2 and FIG. 3, an axis of the ejector mixer 1 is coincided with an axis of the gas turbine ex- haust pipe port 2. The size ratio of the special-shaped lobe ejec- tor mixer 1 and the box 5 is as shown in FIG. 1, and the total number of lobes 7, 8, and 10 is 12. There is a small outward ex- pansion lobe 10, and it is located at one side away from the gas turbine. The lobes are evenly distributed along the circumference.

Arc surfaces 11 and 12 connecting inner and outer wall surfaces 13 and 14 and a side wall 9 are tangent to it. A circumferential shape line of the inner and outer wall surfaces 13 and 14 is a concentric circular arc using the axis as a center of a circle, and the radius of the circular arc is varied with the height. A circumferential shape line of the inner wall surface 8 is a con- centric circular arc using the axis as a center of a circle, and an axial shape line is a straight line forming a certain angle with an axis of the pipe port. A circumferential shape line of the outer wall surface 13 is a concentric circular arc using the axis as a center of a circle, and an axial shape line is a circular arc. A radial shape line of the side wall 9 is perpendicular to the inner and outer wall surfaces, and an axial shape line is par- allel to the axis of the pipe port.

In combination with FIG. 1, FIG. 2 and FIG. 3, while the gas flows through the lobe ejector mixer, at an outlet section of the lobe, there is a "streamwise vortex" to strengthen mixing between the primary and secondary flows, and under a condition of the same outlet cross-sectional area, the lobe nozzle further has a func- tion of enhancing viscous shear mixing between the primary and secondary flows by increasing the perimeter of an outlet boundary.

Therefore, it may achieve full mixing of fluid in the shorter mix- ing pipe. A gap between the box 5 and the exhaust pipe port 2 is very narrow, a flow direction distance is short, and the arc- shaped outer wall 13 may adjust a gas direction while a larger ex- pansion angle is guaranteed. To a certain extent, the larger ex- pansion angle may guarantee the generation of the "streamwise vor- tex". The mixing gap, the development of the free mixing layer and the mixing length are important indicators of the ejector mixer. A reasonable expansion angle and a radian of the outer wall 13 may obtain a reasonable mixing gap, and more importantly, a better de- velopment situation of the free mixing layer is obtained. If a folded plate is used instead of an arc plate, namely two planes are bent, it may limit the formation of the "streamwise vortex", and reduce the ejection performance. Since the side wall of each lobe is not parallel, a low pressure is generated in the process that the gas flows to the outward expansion lobe, which promotes the formation of "streamwise vortex" and improves the ejection performance. Because the velocity of one side, away from the gas turbine, in the exhaust pipe port is high, it is necessary to ad-

just the size of the outward expansion lobe 10 at one side away from the gas turbine, thereby the mixing gap and the mixing length are adjusted, the energy of the high-speed gas is fully used, and the ejection amount is increased.

A ring frame 16 is sheathed under an annular protrusion of the gas turbine exhaust pipe port 2, and the ring frame 16 is con- nected with a bottom flange 18 of the ejector mixer by a bolt, to achieve the installation of the ejector mixer.

In order to assemble conveniently, the bottom flange 18 of the ejector mixer and its matched ring frame 16, as well as a lifting lug 15 required for the installation, are designed. The ring frame 16 is connected with the bottom flange 18 of the ejec- tor mixer by the bolt, the ring frame 16 is provided with a screw through hole, a hole in the flange 18 is a light through hole, and the number of the holes is greater than the number of the lobes.

The ring frame 16 is composed of two semi-circular ring frames, the two semi-circular ring frames are connected by a connecting block and a bolt, and an inside shape line of the ring frame 16 is matched with an outside shape line of the pipe port 2. The lifting lug 15 is installed in an upper position of the outer wall 13 of the lobe, and it is recommended to install 4 lifting lugs 15 to maintain the balance.

Under working conditions of the gas flow rate of 85 kg/s and the temperature of 773 K, it is assumed that the wall surface is adiabatic, and the cold air temperature is 300 K. The proportion of the special-shaped lobe ejector mixer used for the exhaust pipe port of the marine gas turbine and the box of the present inven- tion is shown in FIG. 1, and it is suggested that the main struc- tural dimension of the special-shaped lobe ejector mixer used for the exhaust pipe port of the marine gas turbine of the present in- vention is: 12 lobes in total, which are evenly distributed along the circumference of the circular exhaust pipe port 2. Wherein, there are 12 inward shrinkage lobes in the same size, 1 small out- ward expansion lobe, and 1 large outward expansion lobe. The size of the exhaust pipe port 2 is 1330 mm. The outer wall 13 of the large outward expansion lobe 7 is perpendicular to the flow direc- tion shape line with the maximum outer diameter of 1530 mm, and parallel to the flow direction shape line with the maximum outer diameter of 210 mm. The outer wall 13 of the small outward expan- sion lobe 10 is perpendicular to the flow direction shape line with the maximum outer diameter of 1400 mm, and parallel to the flow direction shape line with the maximum outer diameter of 230 mm. The diameter of the outer arc wall surface connecting the out- er wall surface and the side wall surface is 60 mm. The lobe ejec- tor mixer is 145 mm in height excluding the bottom flange 18, and the height of the bottom flange is 10 mm. The lobe ejector mixer is about 3 mm in thickness excluding the bottom flange 18. Numeri- cal simulation shows that the ejection amount of the system with- out a lobe ejector mixer is 2.6 kg/s, the ejection amount of the system with a certain conventional lobe ejector mixer with good performance is 7.5 kg/s, and the ejection amount of the system with the special-shaped lobe ejector mixer of the present inven- tion is 10.9 kg/s, the improvement effect of the ejection perfor- mance is apparent.

In combination with FIG. 1, FIG. 3 and FIG. 4, the special- shaped lobe ejector mixer 1 used for the exhaust pipe port of the marine gas turbine involved in the present invention is installed above the gas turbine exhaust pipe port 2. Normally, a circular protrusion is reserved above the gas turbine exhaust pipe port 2 so that a component may be added later. The bottom flange 18 of the special-shaped lobe ejector mixer of the present invention is connected with the ring frame 17 by the bolt, and the ring frame 17 is locked on the outer side of the circular protrusion of the exhaust pipe port 2, to achieve the additional installation. For the working stability, it is recommended that 30 bolts are used.

The bottom flange 18 of the ejector mixer is drilled with a light through hole, and the ring frame 17 is drilled with a screw through hole. This design may make the special-shaped lobe ejector mixer easy to detach and install in repair or special circumstanc- es.

In combination with FIG. 4 and FIG. 5, the ring frame 17 is composed of two semicircles, each semicircle has connecting pieces at both ends, and each connecting piece is recommended to be fixed with 3 bolts, and a total of 6 bolts are required for assembly.

Holes in the connecting pieces are all light through holes, and the bolt need to be matched with a nut. In view of the assembly and stress relief, after the ring frame is tightly locked, a 10 mm gap is reserved between the connecting pieces. The shape of the inner side of the ring frame 17 needs to match the shape of the annular protrusion reserved above the gas turbine exhaust pipe port 2. In view of the assembly, the height of the ring frame is about 10 mm lower than the protrusion.

In combination with FIG. 2, FIG. 3 and FIG. 6, during the in- stalling and detaching processes of the special-shaped lobe ejec- tor mixer 1, it is necessary to lift with an "inverted chain", and it is recommended to install four lifting lugs 15 for lifting and placement. The suggested installation locations are given in FIG. 2 and FIG. 3, and the suggested processing dimensions are given in

FIG. 6.

Claims

CONCLUSIESCONCLUSIONS

1. Gasturbine voor schepen met een speciaal gevormde lobbenejec- tormixer, met het kenmerk, dat deze de speciaal gevormde lob- benejectormixer, een bovenste dikke uitlaatpijp en een uit- laatpijppoort van een gasturbine omvat, waarbij de speciaal ge- vormde lobbenejectormixer is geïnstalleerd tussen de bovenste dik- ke uitlaatpijp en de uitlaatpijppoort van een gasturbine, waarbij de uitlaatpijp van de gasturbine is verbonden met een gasuitlaat van de gasturbine door een draaiende uitlaatpijp van de gas- turbine, waarbij een onderste gedeelte van de speciaal gevormde lobbenejectormixer is voorzien van een onderflens, de onderflens is verbonden met een ringframe door een ringframe-verbindingsstuk, en het ringframe is omhuld onder een ringvormig uitsteeksel van de uitlaatpijppoort van de gasturbine, de speciaal gevormde lob- benejectormixer omvat een buitenwaartse expansielob en een naar binnenwaartse krimplob, de buitenwaartse expansielob en de binnen- waartse krimplob met tussenpozen langs de omtrek zijn gerang- schikt, de buitenwaartse expansielob een grote buitenwaartse ex- pansielob en een kleine buitenwaartse expansielob omvat, waarbij de kleine buitenwaartse expansielob zich bevindt aan één kant die weg is gericht van de gasturbine, en waarbij het aantal kleiner is dan het aantal grote buitenwaartse expansielobben, waarbij een as van de speciaal gevormde lobbenejectormixer samenvalt met een as van de uitlaatpijppoort van de gasturbine.1. Marine gas turbine with a special shaped lobe ejector mixer, characterized in that it includes the special shaped lobe ejector mixer, an upper thick exhaust pipe and an exhaust pipe port of a gas turbine, the special shaped lobe ejector mixer being installed between the upper thick exhaust pipe and the exhaust pipe port of a gas turbine, wherein the exhaust pipe of the gas turbine is connected to a gas exhaust of the gas turbine by a rotating exhaust pipe of the gas turbine, wherein a lower portion of the specially shaped lobe ejector mixer is provided with a bottom flange, the bottom flange is connected to a ring frame by a ring frame connecting piece, and the ring frame is enveloped under an annular protrusion of the exhaust pipe port of the gas turbine, the special shaped lobe ejector mixer includes an outward expansion lobe and an inward contraction lobe, the outward expansion lobe and the inward contraction lobe are arranged at intervals along the periphery, the outward expansion lobe comprising a large outward expansion lobe and a small outward expansion lobe, the small outward expansion lobe being located on one side facing away from the gas turbine, and wherein the number is less than the number of large outward expansion lobes, wherein an axis of the specially shaped lobe ejector mixer coincides with an axis of the exhaust pipe port of the gas turbine.

2. Gasturbine voor schepen met de speciaal gevormde lobbenejec- tormixer volgens conclusie 1, met het kenmerk, dat een buitenzijde van de buitenwaartse expansielob een buitenwandoppervlak is, een binnenzijde van de binnenwaartse krimplob een binnenwandoppervlak is, zijoppervlakken van de buitenwaartse expansielob en de binnen- waartse krimplob zijwandoppervlakken zijn, waarbij het buitenste wandoppervlak, het binnenste wandoppervlak en het zijwandoppervlak boograaklijnen zijn.A marine gas turbine with the specially shaped lobe ejector mixer according to claim 1, characterized in that an outer side of the outward expansion lobe is an outer wall surface, an inner side of the inward shrinkage lobe is an inner wall surface, side surfaces of the outward expansion lobe and the inner forward shrink lobe are sidewall surfaces, where the outer wall surface, the inner wall surface, and the sidewall surface are arc tangents.

3. Gasturbine voor schepen met de speciaal gevormde lobbenejec-3. Gas turbine for ships with the specially shaped lobe ejection

tormixer volgens conclusie 2, met het kenmerk, dat een omtreksvormlijn van het binnenste wandoppervlak en het buitenste wandoppervlak een concentrische cirkelboog is die de as als mid- delpunt van een cirkel gebruikt, en de straal van de cirkelboog wordt gevarieerd met de hoogte.tor mixer according to claim 2, characterized in that a contour shape line of the inner wall surface and the outer wall surface is a concentric circular arc using the axis as the center of a circle, and the radius of the circular arc is varied with the height.

4. Gasturbine voor schepen met de speciaal gevormde lobbenejec- tormixer volgens conclusie 2, met het kenmerk, dat een axiale vormlijn van het buitenste wandoppervlak een cirkelboog is, en de cirkelboogstraal kleiner wordt met de toename van een naar buiten gerichte uitbreidingsafstand.A marine gas turbine with the specially shaped lobe injector mixer according to claim 2, characterized in that an axial shape line of the outer wall surface is a circular arc, and the arc radius becomes smaller with the increase of an outward extension distance.