CN103422913A - Turbine with honeycomb inner-wall casing - Google Patents

Abstract

The invention aims at providing a turbine with a honeycomb inner-wall casing. The turbine comprises a casing and a hub. Moving blades are uniformly installed along the circumferential direction of the hub. The hub and the moving blades are installed in the casing. A honeycomb depressed part is arranged at a position corresponding to the moving blades on the inner wall of the casing. The turbine with the honeycomb inner-wall casing has the advantages that the leakage amount of gaps among blade tops of the turbine can be effectively reduced, the off-design performance of a gas turbine is improved and the heat transfer and the ablation caused by high-temperature gas mediums to the casing can be reduced; and moreover, since the honeycomb structure has better grindability, honeycombs instead of the blade tops of the moving blades are ground out once the blade tops rub the casing, and the operation reliability of the gas turbine is improved.

Description

A turbine with a honeycomb-shaped inner wall casing

technical field

The invention relates to a turbine, in particular to a turbine of a large axial-flow impeller machine such as a steam turbine, a gas turbine and an aeroengine.

Background technique

The top clearance loss of the turbomachinery blade is the main source of the rotor blade and turbine stage loss. In the unshrouded turbine, it can account for up to 45% of the rotor blade loss and 30% of the stage loss. In impeller machinery, in order to make the rotor rotate normally, it is necessary to ensure that there is a certain gap between the rotor and the casing. Under the action of the pressure difference on both sides of the blade, the gap will generate a flow from the pressure side to the suction side, that is, the gap leak flow. The loss caused by the leakage flow in the gap is mainly reflected in the following aspects: first, the working fluid in the gap does not have the same deflection degree as the working fluid in the mainstream, so that the working fluid in the gap does not contribute to the work of the turbine; secondly, the working fluid in the gap The jet vortex of the jet, the friction and mixing of the working fluid at the blade tip and the end wall make the entropy of the working fluid increase, resulting in a decrease in the working ability of the working fluid; finally, the fluid in the gap enters the channel of the moving blade, forming a leakage vortex, and The mainstream fluid in the channel is mixed, and this part of loss has the same magnitude as the entropy increase loss in the gap. It can be seen that the existence of the blade tip gap causes the reduction of work ability and the increase of flow loss; and, at high pressure In the turbine, when the high-temperature gas flows through the gap, the jet effect caused by the rapid increase of the airflow velocity will not only increase the complexity of heat transfer on the tip of the blade, but also cause a thermal load impact on the casing, making the turbine casing prone to ablation , affecting the reliability of gas turbine operation.

In order to reduce the negative impact of gas leakage from the blade tip clearance, most turbines currently use methods such as crowning the blade tip and modifying the blade tip to suppress the generation of gap leakage flow. Although these methods can reduce the Small gap leakage loss improves the internal flow of the turbine channel, but its effect varies with specific application turbine blades, such as high and low pressure turbine blades, sub- and transonic gap flow, long and short blades, etc., and operates under variable conditions Under these conditions, these methods are not effective in controlling gap leakage. In addition, the existing technology mainly considers the aerodynamic impact caused by the leakage of the turbine blade tip clearance, and fails to consider the heat transfer impact of the turbine clearance area working at high temperature.

Contents of the invention

The purpose of the present invention is to provide a turbine with a honeycomb-shaped inner wall casing that can effectively reduce the gap leakage flow, improve the performance of the gas turbine under variable working conditions, and reduce the heat transfer and ablation of the high-temperature gas working medium to the casing. .

The purpose of the present invention is achieved like this:

The invention is a turbine with a honeycomb-shaped inner wall casing, which includes a casing and a hub, and the hub is evenly equipped with moving blades along its circumferential direction, and the hub and the moving blades are all installed in the casing, and is characterized in that: the inner wall of the casing and the The corresponding part of the moving blade is provided with a honeycomb structure depression.

The present invention may also include:

1. The honeycomb structure is a radial honeycomb structure or a composite inclined honeycomb structure or a radial-composite inclined hybrid honeycomb structure; the radial honeycomb structure is the center line of the honeycomb structure depression and the The axes of the moving blades are parallel; in the composite inclined honeycomb structure, the angles between the center line of the honeycomb structure depression and the axis of the moving blade below it in the tangential direction and the flow direction are greater than zero.

2. In the vertical direction, the distance between the left end of the honeycomb structure depression and the left end of the upper end of the moving blade is d ₁ , the distance between the right end of the honeycomb structure depression and the right end of the upper end of the moving blade is d ₂ , and neither d ₁ nor d ₂ is larger than the moving blade 10% of the axial chord length at the upper end.

3. The distance between the left end of the radial honeycomb structure or the composite inclined honeycomb structure and the left end of the upper end of the moving blade is _d1 , and the distance between the right end of the radial honeycomb structure or the composite inclined honeycomb structure and the right end of the upper end of the moving blade is _d2 . d ₁ is not greater than -30% of the axial chord length of the upper end of the moving blade, and d ₂ is not greater than 10% of the axial chord length of the upper end of the moving blade.

4. The tangential inclination angle of the depressions of the composite inclined honeycomb structure is 30°-75°, and the inclination angle of the flow direction is 30°-60°.

5. The ratio of the cell size of the concave honeycomb structure to the maximum thickness of the blade tip is 0.7-1.4, the ratio of the honeycomb depth to the maximum thickness of the blade tip is 0.7-1.4, and the cell depth is not less than the cell size.

The advantages of the present invention are that: the present invention can effectively reduce the leakage of the turbine blade tip clearance, improve the performance of the variable working condition of the gas turbine, and reduce the heat transfer and ablation of the casing by the high-temperature gas working medium. Moreover, another advantage of adopting the present invention is that the honeycomb structure has better grindability. Once the tip of the blade and the casing are ground together, the honeycomb will be worn away, not the tip of the moving blade, thereby improving the reliability of the gas turbine operation.

Description of drawings

Fig. 1 is a meridional view of the present invention;

Fig. 2 is a meridional view of an unshrouded turbine with a radial honeycomb inner wall;

Fig. 3 is the A direction view in Fig. 2;

Fig. 4 is a meridional view of a crown-free turbine with a composite inclined honeycomb inner wall;

Fig. 5 is the B direction view among Fig. 4;

Fig. 6 is a C-C sectional view among Fig. 5;

Fig. 7 is a meridian view of a crown-free turbine with a radial-compound inclined hybrid honeycomb inner wall;

Fig. 8 is another arrangement position diagram of the radial honeycomb structure in Fig. 2;

Fig. 9 is another arrangement position diagram of the composite inclined honeycomb structure in Fig. 4 . ;

Detailed ways

The present invention is described in more detail below in conjunction with accompanying drawing example:

Implementation mode 1:

As shown in Figure 1-3, the turbomachinery rotor is composed of a hub 1, a casing 2 and a moving blade 3, and a gap is formed between the casing 2 and the top end surface of the moving blade 3. A recess of honeycomb structure is provided at the corresponding position between the inner wall of the casing 2 and the moving blade 3 .

The technical idea of the present invention is to arrange a series of honeycomb structures on the inner wall of the conventional unshrouded turbine rotor blade case (the side that is mated with the rotor blades) to suppress the leakage of the tip clearance, reduce the leakage of the clearance and improve the efficiency of the turbine. . The purpose of reducing the heat transfer of the casing.

For the leakage flow in the turbine blade tip clearance under variable working conditions, only the leakage flow in the leading edge of the blade is sensitive to the change of the angle of attack, while in the rear half of the blade, the change in the angle of attack has little effect on the gap flow field. This embodiment is in the form of a radial honeycomb structure shown in Figures 2 and 3, which can reduce gap leakage flow.

In the vertical direction, the distance between the left end of the honeycomb structure depression and the left end of the upper end of the moving blade is d ₁ , the distance between the right end of the honeycomb structure depression and the right end of the upper end of the moving blade is d ₂ , neither d ₁ nor d ₂ is greater than the upper end of the moving blade 10% of the axial chord length.

Implementation mode 2:

As shown in Figure 4-6, the honeycomb structure is a composite inclined honeycomb structure, and the honeycomb structure is arranged in the direction of the local leakage flow under the design working condition. Using this technical solution can further improve the effect of gap leakage control;

In the vertical direction, the distance between the left end of the honeycomb structure depression and the left end of the upper end of the moving blade is d ₁ , the distance between the right end of the honeycomb structure depression and the right end of the upper end of the moving blade is d ₂ , neither d ₁ nor d ₂ is greater than the upper end of the moving blade 10% of the axial chord length.

The tangential inclination angle of the composite inclined honeycomb structure depression is 30°-75°, and the flow direction inclination angle is 30°-60°.

Implementation mode 3:

As shown in Figure 7, the honeycomb structure is a radial-composite inclined hybrid honeycomb structure, that is, the honeycomb structure is radially arranged in the leading edge of the blade, and the honeycomb structure is arranged toward the design in the most part of the rear area of the blade. The direction of local leakage flow is arranged under working conditions, and the technical scheme can realize effective control of turbine clearance leakage under variable working conditions.

In the vertical direction, the distance between the left end of the honeycomb structure depression and the left end of the upper end of the moving blade is d ₁ , the distance between the right end of the honeycomb structure depression and the right end of the upper end of the moving blade is d ₂ , neither d ₁ nor d ₂ is greater than the upper end of the moving blade 10% of the axial chord length.

Implementation mode 4:

Considering that the leakage flow of the turbine blade tip clearance mainly occurs in the middle and rear parts, and in order to reduce the loss of the end wall of the casing, as shown in Fig. 8, only the radial honeycomb structure is arranged in the middle and rear part of the blade.

The distance between the left end of the radial honeycomb structure depression and the left end of the upper end of the moving blade is d ₁ , the distance between the right end of the radial honeycomb structure depression and the right end of the upper end of the moving blade is d ₂ , and d ₁ is not greater than the axial chord length of the upper end of the moving blade - 30%, d ₂ is not greater than 10% of the axial chord length of the upper end of the moving blade.

Implementation mode 5:

As shown in Fig. 9, only the compound inclined honeycomb structure is arranged in the rear part of the blade.

The distance between the left end of the composite inclined honeycomb structure depression and the left end of the upper end of the moving blade is d ₁ , the distance between the right end of the composite inclined honeycomb structure depression and the right end of the upper end of the moving blade is d ₂ , and d ₁ is not greater than the axial chord length of the upper end of the moving blade - 30%, d ₂ is not greater than 10% of the axial chord length of the upper end of the moving blade.

It is worth noting that Embodiments 1 to 5 can all reduce the gas turbine blade tip clearance leakage and reduce the leakage airflow velocity, thereby reducing the impact and ablation of the leakage airflow on the casing and blade tip.

Various embodiments of the present invention can be applied in axial flow turbines for different specific applications. The specific structural parameters of the honeycomb (honeycomb cell size d _cell , honeycomb depth h, honeycomb tangential inclination angle α _t and flow direction inclination angle α _s ) can be obtained by means of 3D computational fluid dynamics software simulation or experiment. Wherein, the ratio of the cell size of the honeycomb structure depression to the maximum thickness of the blade tip is 0.7-1.4, the ratio of the honeycomb depth to the maximum thickness of the blade tip is 0.7-1.4, and the cell depth is not less than the cell size.

It is worth noting that the present invention can also be combined with other gap control measures to further control gap leakage, and active gap control or passive gap control can be adopted according to gap design requirements.

Claims (10)

1. the turbine with cellular inwall casing, comprise casing, wheel hub, wheel hub evenly is equipped with moving vane along its circumferencial direction, and wheel hub and moving vane are installed in casing, it is characterized in that: the corresponding part of casing inwall and moving vane is provided with the depression of cellular structure.

2. a kind of turbine with cellular inwall casing according to claim 1 is characterized in that: cellular structure is radially cellular structure or composite inclined cellular structure or the hybrid cellular structure of radially-composite inclined; The center line that described radially cellular structure is the cellular structure depression is parallel with the axis of moving vane in the bottom; The center line that described composite inclined cellular structure is the cellular structure depression all is greater than zero degree with the tangential direction of the axis of moving vane in the bottom with the angle that flows to direction.

3. a kind of turbine with cellular inwall casing according to claim 1 and 2 is characterized in that: in the vertical direction, cellular structure depression left end and moving vane upper end portion left end are apart from being d ₁, cellular structure depression right-hand member and moving vane upper end portion right-hand member distance are d ₂, d ₁And d ₂All be not more than 10% of the axial chord length in moving vane upper end portion.

4. a kind of turbine with cellular inwall casing according to claim 2 is characterized in that: radially cellular structure or composite inclined cellular structure depression left end are d with moving vane upper end portion left end distance ₁, radially cellular structure or composite inclined cellular structure depression right-hand member and moving vane upper end portion right-hand member distance are d ₂, d ₁Be not more than-30% of the axial chord length in moving vane upper end portion, d ₂Be not more than 10% of the axial chord length in moving vane upper end portion.

5. according to the described a kind of turbine with cellular inwall casing of claim 2 or 4, it is characterized in that: the tangential tilt angle of described composite inclined cellular structure depression is 30 °～75 °, and flowing to tilt angle is 30 °～60 °.

6. a kind of turbine with cellular inwall casing according to claim 3 is characterized in that: the tangential tilt angle of described composite inclined cellular structure depression is 30 °～75 °, and flowing to tilt angle is 30 °～60 °.

7. according to claim 1,2,4 arbitrary described a kind of turbines with cellular inwall casing, it is characterized in that: the core lattice size of described cellular structure depression and the ratio of leaf top maximum ga(u)ge are 0.7～1.4, the ratio of the honeycomb degree of depth and leaf top maximum ga(u)ge is 0.7～1.4, and the honeycomb degree of depth is not less than core lattice size.

8. according to the arbitrary described a kind of turbine with cellular inwall casing of claim 3, it is characterized in that: the core lattice size of described cellular structure depression and the ratio of leaf top maximum ga(u)ge are 0.7～1.4, the ratio of the honeycomb degree of depth and leaf top maximum ga(u)ge is 0.7～1.4, and the honeycomb degree of depth is not less than core lattice size.

9. a kind of turbine with cellular inwall casing according to claim 5, it is characterized in that: the core lattice size of described cellular structure depression and the ratio of leaf top maximum ga(u)ge are 0.7～1.4, the ratio of the honeycomb degree of depth and leaf top maximum ga(u)ge is 0.7～1.4, and the honeycomb degree of depth is not less than core lattice size.

10. according to the arbitrary described a kind of turbine with cellular inwall casing of claim 6, it is characterized in that: the core lattice size of described cellular structure depression and the ratio of leaf top maximum ga(u)ge are 0.7～1.4, the ratio of the honeycomb degree of depth and leaf top maximum ga(u)ge is 0.7～1.4, and the honeycomb degree of depth is not less than core lattice size.

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