JPS5872822A - Cooling structure for gas turbine combustor - Google Patents

Abstract

PURPOSE:To improve cooling performance, by so constituting that inflow air between a casing and an external wall is led from an air opening of the external wall to an internal wall and a part of the air is led to a linear from an exhaust hole of an impinging part, in joint cooling of impingement cooling with film cooling. CONSTITUTION:Air flowed in a gap between a casing not illustrated in a sketch and an external wall 15 of a combustor from a compressor is spouted 12 from an air hole 8 for cooling toward an inner wall 16 and is run against the inner wall 16. The air is expanded radially centering around this colliding point and a part of the air is exhausted 18 within a liner from an exhaust hole 17 of the center part of the colliding part. With this, as for a jet flow 11 a flow between colliding parts is improved and thermal transfer rate is improved. The inside of the inner wall 16 is cooled from open ends of a turbine side of the external wall 15 and the inner wall 16 by a filmlike exhaust flow 13 of cooling air which has completed impingement cooling. With this constitution, cooling performance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling structure that uses both impingement cooling and film cooling, and particularly to a cooling structure suitable for a gas turbine combustor.

In recent years, there has been a trend in gas turbines to increase the temperature of combustion gas in order to improve efficiency. However, the temperature of the combustor must be kept below acceptable limits determined by the longevity and strength of the materials used. Therefore, the combustor is cooled by some method, and various cooling techniques have been developed and are still being actively researched. The combustor is cooled by various cooling methods such as convection cooling, film cooling, and impingement cooling using air that flows from the compressor between the casing and the combustor.

Among these, cooling structures that use impingement cooling and film cooling in combination are being used as the temperature of combustion gas increases.

Figure 1 shows the structure of a combustor that uses both impingement cooling and film cooling. In FIG. 1, a cooling structure using both impingement cooling and film cooling is applied only to the liner, but it can be similarly applied to the l/transition piece. The air pressurized by the compressor 1 passes through the tiff user 2 to the casing 3 and transition piece 4.
flows between. Here, except for the air for impingement cooling or film cooling of the transition piece 4, most of the outside of the air transition piece 4 is forcedly cooled by convection, and the air flows into the annular space formed by the casing 3 and the liner 5. Air hole 6 for dilution in rice 5
．． Combustion air hole7. A large number of cooling air holes 8 are provided, and the air in the annular space reaches the fuel nozzle 9 while repeatedly branching into these holes. Inside the liner 5, fuel injected from the fuel nozzle 9 and air mix, and combustion occurs. The combustion gas is mixed with air for cooling and dilution, and is supplied to the turbine 10 from the transition piece 4 at a predetermined temperature and pressure. FIG. 2 is an enlarged view of a cooling structure that uses both impingement cooling and film cooling. The outer wall 15 is made in the shape of a step, and an inner wall 1G is provided in parallel to the outer wall 15 at a distance from the outer wall 15. The air that has flowed into the space formed by the outer wall 16 and the casing 3 is blown out as a jet 12 toward the inner wall 16 from a large number of cooling air holes 8 formed in the outer wall 15.
After colliding with the inner wall 16, it flows between the outer v1''c15 and the inner wall 16 from the combustion engine 1 nozzle 1 rule toward the turbine side,
It is discharged into the liner from the open end on the turbine side. This discharge stream 13 flows in the form of a film along the next inner wall 16, separating the combustion gases of height 4.11 from the inner wall 16 and cooling the inner wall 16. In other words, the inner wall 16, which receives a lot of heat from the high-temperature combustion gas, is impingement-cooled on the outside and film-cooled on the inside.

Regarding one air hole 8 for impingement cooling, the cooling air ejected from the air hole 8 becomes a jet stream 12 that collides with the inner wall 16, and then spreads radially along the inner wall 16 centering on the stagnation point. Therefore, near the stagnation point, the flow becomes high speed and there is little development of a temperature boundary layer, resulting in a high heat transfer coefficient, but as the distance from the stagnation point increases, the flow velocity slows and the heat transfer coefficient deteriorates. As a result, the cooling of the inner wall 16 becomes non-uniform, and the temperature of the inner wall 16 is lower at the impingement portion of the jet 12 and higher between the impingement portions of the jet 12. Figures 3 and 4 respectively show the temperature distribution on the inner wall when the air holes are arranged in a base pattern and in a staggered pattern, which are typical arrangements of air holes for impingement cooling. Non-uniform combustor temperature due to such non-uniform cooling results in an increase in the amount of cooling air required to keep the hottest part of the combustor below material tolerance limits, which reduces turbine efficiency. It also causes thermal stress, resulting in loss of life and reduced reliability.

An object of the present invention is to provide a cooling structure for a gas turbine combustor that uses both impingement cooling and film cooling to improve cooling performance by increasing the flow around the control hole and increasing the heat transfer coefficient. It is in.

The feature of the present invention is that a hole is made in the middle of the collision part of the jet flow where the temperature of the inner wall of the combustor becomes high, and a part of the cooling air that was previously released from the open end on the turbine side is discharged. The purpose of this method is to improve the flow between the colliding parts of the jet stream, which has a slow flow and poor heat transfer coefficient, and to increase the heat transfer coefficient.

Embodiments of the present invention will be explained with reference to FIGS. 5 to 7.

In FIG. 5, the outer wall 15 of the combustor, which uses a combination of impingement cooling and film cooling, has a stepped structure, and the outer wall 15 has an outer wall 15 on the inside. An inner wall 16 is provided parallel to and spaced apart from γ15.

A large number of cooling air holes 8 are formed in the outer wall 15 at appropriate intervals, and air flowing from the compressor between the casing and the outer wall 15 is blown out from the cooling air holes 8 toward the inner wall 16. In the inner wall 16, a discharge hole 17 is formed in correspondence with the cooling air hole 8 formed in the outer wall 15, between the collision parts of the jet stream 12 and the middle of the collision part. Cooling air hole 8 in outer wall 15
Arrangement d of the discharge holes 17 when is the base pattern arrangement and the staggered arrangement
are shown in FIGS. 6 and 7, respectively.

In this cooling structure, air flowing from the compressor between the casing and the outer wall 15 of the combustor is blown out toward the inner wall 16 from a large number of cooling air holes 8 formed in the outer wall 15. Cooling of the outside of the inner wall 16 occurs in the process in which the jet stream 12 impinges on the inner wall 16 and spreads radially along the inner wall 16 with the stagnation point as the center. A discharge hole 17 is provided in the inner wall 16 between the collision part of the jet 12 and the collision part, and a part of the cooling air is discharged from this discharge hole 17 into the liner and collides with the collision part of the jet 12. Improved flow between departments,
Heat transfer coefficient increases. Therefore, the cooling performance of the outer side of the inner wall 16 is improved by the increase in the heat transfer coefficient between the collision parts of the jet flow 12. This time j inside the inner wall 16, the cooling air that has finished impingement I and cooling from the open ends of the outer wall 15 and the inner wall 16 on the turbine side becomes a film-like discharge flow 13 and flows along the next inner wall 16. This is done by isolating the high temperature combustion gas from the inner wall 16 and removing heat from the inner wall 16. Except for a part that is discharged from the JJI outlet 17 into the liner as a discharge stream 18, most of the cooling air H1 becomes a film-like discharge stream 13 from the open end and flows to the next inner wall 16, as in the conventional case. flows along the
Since the air that flows into the liner as a 1-in-1 outflow 18 from the cut-off control hole 17 is also used for film cooling, it has almost no adverse effect on the cooling performance. As a result, in the cooling structure of the present invention, a good cooling effect with a temperature distribution close to a uniform distribution can be obtained with a small amount of cooling air.

In FIGS. 8 and 9, a hollow cylinder 19 is provided in the inner wall 16 between the collision parts of the jet flow 12 and the collision parts. In this structure, cooling air is blown out from the hollow part of the cylinder into the liner, and the flow J'1. In addition to improving the heat transfer coefficient and increasing the heat transfer area, the cooling performance is improved by increasing the heat transfer area, and good cooling performance is obtained.

According to the present invention, by improving the flow between the colliding parts of the jet, a high heat transfer coefficient is obtained and cooling performance is improved, and high cooling performance is obtained with a small air flow rate. Turbine efficiency can be improved.

[Brief explanation of the drawing]

Figure 1 is a system diagram of the gas turbine compressor, combustor, and turbine, Figure 2 is an enlarged perspective view of a conventional cooling structure, and Figure 3
Figure 4 is a temperature distribution diagram of the inner wall of a combustor with a conventional structure.
The figure shows one embodiment of the invention. Perspective view of cooling structure, No. 6
Figures 7 and 8. FIG. 9 is a perspective view of a cooling structure according to another embodiment of the present invention. 1...Compressor%2...Diffuser, 3...Casing, 4...Transition piece, 5...Liner, 6...Air hole for dilution, 7...Air hole for combustion, 8
...Cooling air hole, 9...Combustion nozzle, 10...
Turbine, 12... Jet stream, 13... Discharge stream, 14.
・Position of cooling air holes drilled in the combustor outer wall, 15・
・・Burning cheek: Outer wall of the combustor, 16... Inner wall of the combustor, 17...
Control hole, 18...1.11 outflow, 51J Borogma l 49G ■Temporary ooooo. o, oo. ■ ■ @ ■ O early
7 Country/4 0 ■ OOO OOO○ ■ Brown 3 Country/4 ◎ ◎ ◎ ◎ ○■ ■ Oo Early 9 Flash/4 ◎ ○◎ ＠ ■ 0 ◎ ＠＠＠

Claims (1)

[Claims] 1. A combustor consisting of an outer wall with numerous cooling air holes and an inner wall that is parallel to the outer wall and in contact with high-temperature combustion gas.The combustor uses air flowing from the compressor between the casing and the outer wall. A cooling structure in which the air is ejected from the air holes toward the inner wall, and the gas is provided with a collision part of the jet flow on the inner wall and a discharge hole in the middle of the collision part for discharging a part of the air into the liner. Turbine combustor cooling structure.