CN104879782A - Novel asymmetric flame stabilizer - Google Patents

Abstract

The invention provides a novel asymmetric flame stabilizer which has low pressure losses and can significantly improve the combustion efficiency. The shape of the section of the novel asymmetric flame stabilizer is composed of a straight line and two curves and is similar to the geometrical shape of a low-speed wing. By using the novel asymmetric flame stabilizer with the geometrical section, the windward area of the flame stabilizer can be reduced, and pressure losses are effectively reduced. When the novel asymmetric flame stabilizer formed in a planimetry mode is used on a combustion gas turbine, the combustion efficiency can be effectively improved, and the energy utilization rate is improved; by reasonably arranging the position of the flame stabilizer on a ground gas turbine, energy is absorbed, vibration combustion can be avoided, and the working margin is improved.

Description

New Asymmetric Flame Stabilizer

technical field

The invention belongs to the field of gas turbines, and in particular relates to a novel asymmetric flame stabilizer and a ground gas turbine combustion chamber and an aero-engine afterburner comprising the flame stabilizer.

Background technique

If the gas turbine is the crown of the modern industry, then the combustion chamber is a jewel in the crown of the modern industry. It is the existence of the combustion chamber that converts the chemical energy of the fuel into heat energy. For gas turbine combustors, flame stability is one of the most basic requirements. It is required that once the combustion chamber catches fire, the flame can maintain a stable spread under different working conditions. Combustion stability, on the one hand, means that the combustion chamber should work in an appropriate and widest possible range of oil-gas ratio; on the other hand, it means that in the combustion process, under a certain inlet air velocity, the basic conditions for flame stability must be met . Due to the high heat capacity and the high velocity of the inlet airflow, it is difficult to stabilize the flame. Therefore, without exception, flame stabilizers are provided.

Flame holders are generally blunt body obstacles. The oncoming flow flows along the surface of the blunt body to the trailing edge of the blunt body, resulting in the separation of the boundary layer, and the wake vortex is generated due to the viscosity, forming a recirculation zone. Some local flow velocities in the recirculation zone are equal to or lower than the turbulent flame propagation velocity, so that With the necessary conditions for flame stability, once there is an ignition source with sufficient power, the combustible mixture can be ignited. The high-temperature combustion products return upstream through the recirculation zone, forming a stable and continuous ignition source. The recirculation zone acts as a heat reservoir, transferring heat and active substances to the combustible gas mixture in the form of turbulent heat transfer and heat exchange, so that the flame can spread rapidly in the combustion chamber.

In ground-based heavy-duty gas turbines, the combustion area is very large, so it is inevitable that insufficient combustion and low combustion efficiency will occur in some areas. However, the combustion temperature and combustion efficiency are low. The existence of the asymmetric flame stabilizer can solve this problem well, stabilize the flame in this area, strengthen the mixing of fuel and air, and improve the combustion efficiency in this area. The afterburner of an aero-engine has a high flow rate, low total pressure, high total temperature, and because a part of the oxygen in the air has been consumed in the main combustion chamber, the oxygen content is low, which is not good for the chemical reaction of combustion. To solve the combustion stability problem of the afterburner, a flame stabilizer is used. The application of the new asymmetric flame stabilizer, compared with the conventional flame stabilizer, expands the stable working range of the gas turbine, improves the combustion efficiency, has good flame stability, and can adapt to more severe combustion conditions.

Contents of the invention

The technical problem to be solved by the present invention is to propose a new type of asymmetric flame stabilizer that can significantly expand the stable working range of the ground combustion engine and the afterburner of the aero-engine, improve its combustion efficiency, and maintain stable combustion. Compared with the prior art, the present invention has the advantages that compared with other flame stabilizers, the flame stabilizer can effectively stabilize the flame, has higher combustion efficiency under the same total pressure loss, and has a simple structure; it is used on the ground Gas turbines and aero-engine afterburners will make them burn more fully and have higher fuel utilization.

Technical solutions

The object of the present invention is to provide a novel asymmetric flame stabilizer.

The purpose of the present invention is achieved like this:

The novel asymmetric flame stabilizer for improving the performance of the combustion chamber is characterized in that its cross-sectional figure is composed of a straight line and two curved lines, and the cross-sectional curved surface is formed by connecting the three lines end to end.

Above-mentioned novel asymmetrical flame stabilizer, the relation between its characteristic dimension is: the sectional linear length L1 of the asymmetrical flame stabilizer is 8～14 times of the sectional linear height H1, the length L2 of the sectional curve 2 of the asymmetrical flame stabilizer is 1 to 2 times the height H2, and the length L3 of the section curve 3 of the asymmetric flame stabilizer is 2 to 5 times the height H3. L1 and H1 are used to locate the straight line 1; L2 and H2 are used to locate the arc 2, and the radius of the arc varies from 2 to 3H2; L3 and H3 are used to locate the apex of the spline curve, and the positions of the other points can be Obtained randomly under the condition that the spline curve has only one extremum vertex.

The above-mentioned novel asymmetric flame stabilizer is characterized in that: the intersection of the straight line 1 and the arc 2 is connected by an arc, and the radius R of the fillet varies from 0 to 10 mm.

The positional relationship of the above-mentioned new asymmetric flame stabilizer in the ground gas turbine is as follows: the distance H between the new asymmetric flame stabilizer and the outlet of the inner cavity of the flame tube is 5-15mm, and the distance H between the asymmetric flame stabilizer and the outer wall of the flame tube The shortest distance L is 5 to 40 mm. After the position is determined, the asymmetric flame stabilizer is formed by rotating the above-mentioned plane geometry around the central axis of the flame cylinder.

The positional relationship of the above-mentioned novel asymmetric flame stabilizer in the afterburner chamber is as follows: the novel asymmetric flame stabilizer is installed on the section at 150 mm to 350 mm behind the center cone of the afterburner chamber of the aero-engine. According to the actual flow field, 1 to 3 asymmetric annular flame stabilizers are used, and the flame stabilizers are connected to the shockproof heat shield of the afterburner by radial cross-flame grooves.

The biggest advantage of this new type of asymmetrical flame stabilizer is that it uses a cross-section design similar to a low-speed wing. The upper surface has a large curvature and the lower surface has a small curvature. The separation of long air bubbles similar to thin wing separation is achieved, and a vortex is formed behind the stabilizer, that is, the recirculation zone. The rear wall of the stabilizer adopts a single-vertex spline curve to facilitate the formation of the trapped vortex, so that the recirculation zone is stabilized here. Its application can reduce the total pressure loss flowing through the flame stabilizer, improve the combustion efficiency of the gas turbine, and enable the gas turbine to ignite rapidly and improve reliability.

Description of drawings

Figure 1: Ground-based gas turbine flame tube with new asymmetric flame stabilizer

Figure 2: Sectional view of the new asymmetric flame holder

Figure 3: Schematic diagram of the cross-section of the new asymmetric flame stabilizer

Figure 4: Schematic diagram of the circular chamfering of the section of the new asymmetric flame stabilizer

Figure 5: Sectional view of a ground-based gas turbine flame tube with a new type of asymmetric flame stabilizer

Figure 6: Schematic diagram of the relative position of the new asymmetric flame stabilizer

Figure 7: Half-section view of afterburner with new asymmetric flame holder

Figure 8: Left view of afterburner with new asymmetric flame holder

Among the figure 1-new asymmetric flame stabilizer section straight line 1; 2-new asymmetric flame stabilizer section arc 2; 3-new asymmetric flame stabilizer section spline curve 3; 4-new asymmetric flame stabilizer; 5-inner cavity of the flame tube; 6-outer wall of the flame tube; 7-center cone of the afterburner; 8-joint flame groove; 9-new annular asymmetric flame stabilizer;

Detailed ways

The present invention will be further described now in conjunction with accompanying drawing:

With reference to Fig. 2, Fig. 3 and Fig. 4, the present invention provides a novel asymmetric flame stabilizer structure. Fig. 3 is the schematic cross-sectional view of this novel asymmetric flame stabilizer, which is used to illustrate the position constraint relationship of this cross-sectional profile; The fillet position and size of the windward side of the flame stabilizer; the new asymmetric flame stabilizer is formed by rotating the figure shown in Figure 3 or 4 around the central axis of the flame cylinder; Figure 2 is a cross-sectional view of the new asymmetric flame stabilizer. Figure 1 and Figure 5 are used to illustrate the positional relationship of the new asymmetric flame stabilizer in the ground gas turbine flame tube. Fig. 1 is a schematic diagram of a ground gas turbine flame tube equipped with the new asymmetric flame stabilizer; Fig. 5 and Fig. 6 are cross-sectional views of the flame tube used to illustrate the positional relationship between the new asymmetric flame stabilizer and the flame tube. Fig. 7 and Fig. 8 are a half-sectional view and a left side view of the afterburner used to illustrate the positional relationship between the novel asymmetric flame stabilizer and the afterburner of the aero-engine.

Conventional flame stabilizers are simple in structure and rich in use experience. As long as they are used reasonably, they can meet the work requirements, but their total pressure loss is relatively large. The curvature is small, the advantage of this design is

The front stagnation point is located at the front end of the stabilizer, and the streamline flowing through the stagnation point is divided into two parts, one part flows from the stagnation point around the leading edge point through the upper wall of the stabilizer along the wall, and the other part flows from the stagnation point through the lower wall of the stabilizer Flow along the wall. At the upper wall, the particle velocity of the fluid accelerates very fast due to the large change of the wall angle; at the lower wall, the change of the wall angle is small, and the particle acceleration of the fluid is slow. According to the Bernoulli equation, the pressure distribution is such that the pressure is minimum at the point of maximum velocity. Therefore, there is a pressure difference between the upper and lower walls, and they meet each other at the end, thus causing the separation of long air bubbles similar to the separation of thin wings, forming a vortex behind the stabilizer, that is, the recirculation zone. The rear wall of the stabilizer adopts a single-vertex spline curve to facilitate the formation of the trapped vortex, so that the recirculation zone is stabilized here. The vertices and curve form of the spline curve are determined by analyzing the distribution of the velocity field after the flame stabilizer of the gas turbine.

From the analysis of working principle, the new asymmetric flame stabilizer has the following advantages:

(1) The head of the new asymmetric flame stabilizer adopts a wing-like design. Compared with the upper surface of the new asymmetric flame stabilizer, the height of the lower surface is smaller, so the cross-sectional area is smaller relative to the incoming flow direction. Small, thus reducing the total pressure loss across the flame holder.

(2) The formed reflux strengthens the exchange of heat, momentum and mass with the main flow, and increases the residence time of the main flow at the boundary of the recirculation zone, thus improving the combustion efficiency of the gas turbine.

(3) A stable ignition source is established again in the stabilizer, which is protected by the wall of the stabilizer and is not directly affected by the interference of the mainstream. This pioneer flame quickly spreads to the mainstream, so that the gas turbine ignites quickly and the reliability is improved.

The low-frequency oscillating combustion of the combustion chamber is often a self-excited oscillation generated by the mutual coupling of the combustion process in the combustion chamber and the internal sound pressure fluctuation of the system. If the acoustic pressure pulsation is not suppressed, unstable combustion will be caused, which is very dangerous for ground gas turbines. After installing a flame stabilizer behind the inner cavity of the flame tube, due to the With a certain radial distance, the existence of the annular flow field between the flame stabilizer and the outer wall of the flame tube can absorb the oscillating energy of pressure pulsation, suppress the generation of oscillating combustion to a certain extent, and improve the working margin of the ground gas turbine.

The temperature at the outlet of the flame tube cavity of the ground gas turbine is low, and the combustion is not sufficient. Compared with the flame tube cavity, the oxygen and fuel concentrations here are relatively low, and it is not easy to organize stable combustion. Place the flame stabilizer in the This place can significantly improve the combustion efficiency of the ground gas turbine, making the combustion more complete and more stable. Using the flame stabilizer in the afterburner can make the flame more stable, facilitate the organization of combustion, and improve the combustion efficiency.

Claims (5)

1. a Novel asymmetric flameholder, is characterized in that: its sectional view is made up of straight line and two curves, three its transverse surfaces of the end to end formation of line.

2. a kind of Novel asymmetric flameholder according to claim 1, it is characterized in that: the relation between its characteristic size is for the cross section straight length L1 of non symmetric flame stabilizer is 8 ~ 14 times of cross section straight line height H 1, the length L2 of the cross section curve 2 of non symmetric flame stabilizer is 1 ~ 2 times of its height H 2, and the length L3 of the cross section curve 3 of non symmetric flame stabilizer is 2 ~ 5 times of its height H 3.L1 and H1 is used for positioning linear 1; L2 and H2 is for locating circular arc 2, and this arc radius excursion is 2 ~ 3H2; L3 and H3 is for locating the vertex position of SPL, and the position of all the other several points can obtain at random under this SPL of guarantee only has the condition of an extreme vertex.

3. a kind of Novel asymmetric flameholder according to claim 1 and 2, is characterized in that: the point of intersection of straight line 1 and circular arc 2 in addition circular sliding slopes, the radius R excursion of this fillet is 0 ~ 10mm.

4. a kind of Novel asymmetric flameholder according to claim 1 or 2 or 3, it is characterized in that: when it is positioned at ground combustion machine combustion chamber, the distance H of this Novel asymmetric flameholder and burner inner liner chamber exit is 5 ~ 15mm, and the minimum distance L of non symmetric flame stabilizer and burner inner liner outer wall is 5 ~ 40mm.After position is determined, this non symmetric flame stabilizer to be rotated a circle around burner inner liner axis by above-mentioned plane geometry and is formed.

5. a kind of Novel asymmetric flameholder according to claim 1 or 2 or 3, it is characterized in that: when it is positioned at aeroengine thrust augmentation combustion chamber, this Novel asymmetric flameholder is arranged on the cross section at 150mm ~ 350mm place after the center cone of aeroengine thrust augmentation combustion chamber.Determine with 1 ~ 3 this asymmetric annular flame stabilizer according to practical flow field, be connected on the Shockproof heat insulation screen of after-burner with radial connection flame groove between flameholder.