CN110529190B - Method for designing air film holes for inserting and exhausting of cooling flat plate - Google Patents

Abstract

The invention discloses a method for designing a venting membrane hole of a cooling plate. In the present invention, the flat plate is cooled by inserting the exhaust film holes, and the corresponding restrictions are obtained by determining the relationship between the position, the number of holes, the pore diameter of the first exhaust film hole and the length, width and porosity of the flat plate. Condition, under the condition that the opening density of the plate in the area between the first row and the last row is equal, a limited number of feasible cooling schemes can be obtained by adjusting the number of holes flowing to the first exhaust film, and then the plate heat is analyzed by numerical calculation. The temperature distribution of the side wall, the average temperature of the wall and the cooling efficiency can obtain the optimal design scheme. The present invention maximizes the effect of uniform cooling of the entire plate, and simultaneously obtains the optimal design scheme quickly, thereby effectively saving the workload caused by the prior art in designing parameters by trial and error and repeated iterative design methods.

Description

A design method for inserting and exhausting membrane holes of a cooling plate

technical field

The present invention relates to the field of gas turbines, in particular to a method for designing an insert and exhaust membrane hole of a cooling plate.

Background technique

The wide application of gas turbines in aerospace, shipbuilding, power generation, metallurgy, chemical industry, energy and power engineering and other fields is mainly due to the continuous improvement of thermal efficiency. Increasing the temperature of the working fluid is one of the main measures to achieve this improvement. The theoretical combustion temperature of hydrocarbon fuel can reach 2200℃. However, the melting point of gas turbine component materials is much lower than the combustion temperature. Therefore, certain protective measures must be taken to obtain high performance of gas turbines before the development of ideal materials. Film cooling is one of the most widely used cooling and protection technologies for high-temperature components of gas turbines.

The high-temperature components of gas turbines mainly include combustion chambers, turbines, etc., and also include afterburners in military aero-engines. In order to improve the efficiency of steam turbines and enhance the reliability of high temperature components, film cooling technology has been widely used in these components. Air film cooling was originally a two-dimensional slit jet technology derived from jet thawing of airplanes. Since the structure of gas turbine blades is not suitable for the use of slit jets, small-hole jets have become the first choice. Therefore, in the 1960s, as the working fluid temperature of gas turbines increased, the technological prototype of gas film cooling began to appear. At the same time, the efficient cooling effect of gas film cooling has gradually attracted the attention of researchers. Since then, researchers have conducted detailed studies on the effects of its structural properties and flow field parameters. In view of the convenience in processing of the flat plate and the reference between the experimental results of the flat plate and the prototype test of the high temperature wall of the turbomachinery, the basic research on the film cooling is generally carried out by the flat plate. There are various shapes of high-temperature walls that need to be cooled on the inner wall of the gas turbine, and it is not easy to directly design the film cooling scheme. Therefore, the cooling design of the high-temperature wall can be started from the flat plate, and the optimized solution can be applied to the high-temperature wall, and then optimized again according to specific needs.

In order to obtain a more uniform and effective cooling of the high-temperature wall surface with air film cooling, it is necessary to optimize the design of the air film cooling structure, so that the cold air of each air film hole can be fully utilized. At present, there are mainly two types of arrangement of flat film cooling holes in the study: sequential arrangement and insertion arrangement. In most cases, the cooling effect of the plug-in row is significantly better than that of the in-line row. In addition, the structural parameters that affect the cooling effect of the plate are mainly attributed to the diameter of the air film pores, the spacing of the pores, the opening ratio, and the opening angle, etc. The researchers have done a lot of research on the influence of these structural parameters. However, there is no design method that describes how to simplify the uniform cooling of the flat plate by inserting and venting membrane holes.

SUMMARY OF THE INVENTION

Purpose of the invention: The technical problem to be solved by the present invention is to provide a simplified design method for inserting and exhausting membrane holes for uniform cooling of the flat plate. Under the condition that the parameters of the flat plate and the amount of cooling air are determined, that is, the opening rate is constant, it is possible to ensure that the flat plate is in the first row. When the area opening density between the last row is equal, the optimal design scheme can be quickly obtained by this method, which simplifies the design process and saves the workload to the greatest extent.

Technical solution: the method for designing the venting membrane holes of the cooling plate according to the present invention includes the following steps:

(1) The flat plate is cooled by air film holes, the flat plate is square, and there are several air film holes distributed on the flat plate, and the two sides of the flat plate parallel to the flow direction are the first flow direction side and the second flow direction side respectively, The sides of the flat plate that are parallel to the spanwise direction are the first spanwise side and the second spanwise side, respectively, and the air film holes are arranged in a way of inserting and discharging, and the amount of cold air is determined to obtain a determined opening rate;

(2) According to the diameter of the gas film hole and the size of the flat plate, the range of the hole spacing between each row of the gas film hole is obtained;

(3) Ensure that the air film holes of the flat plate have the same opening density in the area between the first row and the last row, and determine the range of the number of the first exhaust film holes;

(4) According to the number of the first exhaust film holes, the numerical value of the hole spacing corresponding to the number of the first exhaust film holes is obtained, and the row spacing of the gas film holes determined by the hole spacing value is obtained through the opening ratio;

(5) According to the determined hole spacing and row spacing, obtain the distance between the first exhaust membrane hole or the last exhaust membrane hole and the side of the flat plate and the number of rows of gas membrane holes, and obtain a feasible gas membrane hole distribution scheme.

其中，d为气膜孔直径，P为气膜孔每列之间的孔间距，S为气膜孔的排间距。In step (1), the opening rate of the plate is φ,

Among them, d is the diameter of the gas film holes, P is the hole spacing between each row of the gas film holes, and S is the row spacing of the gas film holes.

其中，W为平板的宽度。In step (2), the range of the hole spacing is

where W is the width of the plate.

的条件下，a的范围通过W＝(a-1)P+0.25P+0.25P以及

确定，其中，0.25P为第一流向侧边或第二流向侧边距离最近的一列气膜孔的距离。In step (3), the number of holes in the first exhaust film is a, and in the

Under the condition of , the range of a is obtained by W=(a-1)P+0.25P+0.25P and

Determine, wherein, 0.25P is the distance between the first flow direction side or the second flow direction side of the nearest column of air film holes.

In step (4), the hole spacing corresponding to the number a of each first exhaust film hole is obtained by W=(a-1)P+0.5P, and then the corresponding gas film hole is obtained by the obtained hole spacing and the porosity ratio. row spacing.

确定第一排气膜孔与第一展向侧边的距离或最后一排气膜孔与第二展向侧边的距离，以及确定气膜孔的排数，其中，L为平板的长度，H为第一排气膜孔或最后一排气膜孔与侧边的距离，q为气膜孔沿流向的排数。In step (5), by L=S×(q-1)+2H and

Determine the distance between the first vent film hole and the first spanwise side or the distance between the last vent film hole and the second spanwise side, and determine the number of rows of the gas film holes, where L is the length of the flat plate, H is the distance between the first vent film hole or the last vent film hole and the side, and q is the row number of the gas film holes along the flow direction.

For the feasible scheme obtained in step (5), numerical calculation is used to analyze the temperature distribution of the hot sidewall surface of the flat plate, the average temperature of the wall surface and the cooling efficiency, and the optimal design scheme is obtained by screening. By determining the range of the hole spacing and the range of the number a of the openings in the first row, the present invention obtains a determined feasible solution, determines the number q of the air membrane holes in the feasible solution and the distance between the first row or the last exhaust membrane hole from the side edge H value, and finally analyze the cooling effect through numerical calculation to obtain the optimal solution.

Wherein, in the present invention, P is the hole spacing between each column of the gas film holes, the number of columns of the gas film holes refers to the number of gas film hole rows distributed in the spanwise distribution of the gas film holes, and the hole spacing between the gas film holes in each column is also It can be called the spanwise spacing between each row of air film holes; the number of air film hole rows in the present invention refers to the number of rows of air film holes distributed along the flow direction.

The design idea of the present invention is:

(1) On the premise that the arrangement of the air film holes of the flat plate is plug-in, assuming that the length of the flat plate is L, the width is W, the diameter of the air film holes is d, the hole spacing of each column of air film holes is P, and the air film holes are The row spacing of the holes along the flow direction is S, and the opening rate is φ. Calculate the open area of the plate

W＝(a-1)P+0.25P+0.25P，L＝S×(q-1)+2H。(2) The main limiting conditions for the air film holes to cool the flat plate uniformly and to be on the flat plate as a whole are:

W=(a-1)P+0.25P+0.25P, L=S×(q-1)+2H.

一定时，根据需要任选d值，可以在保证平板上从第一排至第q排孔区间的平板开孔密度相等的情况下，得到最小数量的可行设计方案，然后通过数值计算分析得到冷却效果最优的设计方案。(3) Under the above-mentioned limited conditions, when L, W,

When it is certain, the d value can be selected according to the needs, and the minimum number of feasible design schemes can be obtained under the condition that the density of the plate openings from the first row to the qth row of holes on the plate is equal, and then the cooling can be obtained through numerical calculation and analysis. The most effective design.

Beneficial effects: The present invention reasonably designs the arrangement scheme of the vent film holes on the flat plate, and limits the structural parameter range of the air film holes through restrictive conditions, so as to realize the opening between the first row and the last row of holes on the flat plate. The density is equal to maximize the effect of uniform cooling of the entire plate, and at the same time, the optimal design scheme can be obtained quickly, which effectively saves the workload caused by the trial-and-error design methods and repeated iterations in the design.

Description of drawings

Fig. 1 is the structural representation of the flat plate and gas film hole of the present invention;

Figure 2 is a schematic diagram of the calculation of the porosity of the present invention

Figure 3 is a comparison diagram of the average wall temperature and cooling efficiency on the hot side of the plate when the number of holes in the first row of the plate is adjusted;

Figure 4 is a schematic diagram of the temperature distribution of the hot side wall surface of the plate when adjusting the number of holes in the first row of the plate;

Figure 5 is a flow chart of the present invention.

Detailed ways

The technical solutions of the present invention will be further described below with reference to the embodiments.

Example 1: As shown in Figure 1, the X-axis direction in the figure is the flow direction, the Y-axis direction is the spanwise direction, the flat plate 1 is cooled by air film holes, the flat plate is square, and there are several air film holes 10 distributed on the flat plate. The two sides parallel to the flow direction are the first flow side 101 and the second flow side 102 respectively, and the sides of the flat plate parallel to the span direction are the first span side 103 and the second span side 104 respectively , to ensure that the air film holes of the flat plate have the same opening density in the area between the first row and the last row.

(1) The arrangement of the air film holes is plug and row, determine the amount of cold air, and obtain the determined opening rate

(2) The length of the plate is L, the width is W, the diameter of the gas film holes is d, and the hole spacing of each column of the gas film holes is P, that is, the spanwise spacing of the gas film holes is P, and the row of the gas film holes along the flow direction The spacing is S, and the opening rate is

得到

并根据

确定气膜孔的每列之间的孔间距P的范围；(3) According to

get

and according to

Determine the range of the hole spacing P between each column of air film holes;

结合上述步骤(3)，确定第一排气膜孔数量a的范围(a取整)；(4) According to W=(a-1)P+0.25P+0.25P and

In conjunction with the above step (3), determine the range of the number a of the first exhaust membrane holes (a rounded up);

得到由孔间距数值P确定的气膜孔的排间距S，a在取值范围内可取的个数就为该实施例可以得到的方案数。(5) According to the number a of the first exhaust membrane holes and W=(a-1)P+0.5P, the numerical value P of the hole spacing corresponding to the number of the first exhaust membrane holes can be obtained, and through

The row spacing S of the gas film holes determined by the hole spacing value P is obtained, and the number of possible a in the value range is the number of solutions that can be obtained in this embodiment.

得到平板的第一排气膜孔距离第一展向侧边103或最后一排气膜孔与第二展向侧边104的距离H以及气膜孔的排数q，得到可行的气膜孔分布方案。(6) According to the determined hole spacing P and row spacing S, and L=S×(q-1)+2H and

Obtain the distance H between the first exhaust film hole of the flat plate and the first spanwise side 103 or the last exhaust film hole and the second spanwise side 104 and the row number q of the air film holes, and obtain feasible air film holes distribution plan.

For the feasible scheme obtained in step (5), numerical calculation is used to analyze the temperature distribution of the hot sidewall surface of the flat plate, the average temperature of the wall surface and the cooling efficiency, and the optimal design scheme is obtained by screening.

The limiting conditions in the present invention are obtained in the following ways:

As shown in Figure 1, the spanwise spacing of the holes in which the gas film holes are inserted is P, the row spacing of the gas film holes along the flow direction is S, and the pore size of the gas film holes is d, as shown in Figure 2, take a square in the figure The grid is the analysis object, and the opening rate is calculated.

其中，A_h为一个方格内孔的面积，A_S为一个方格的面积。因为

所以

It can be seen from Figure 2 that the number of holes in a block is 0.5, then:

Among them, A _h is the area of the hole in a square, and A _S is the area of a square. because

so

In order to ensure that all the air film holes are on the flat plate, the distance between a row of holes near the first spanwise side 103 or a row of holes near the second spanwise side 104 and the spanwise side boundary should be greater than half of the aperture d; At the same time, in order to ensure uniform cooling, that is, the opening rate remains unchanged, the distance between the two rows of holes on both sides of the span and the boundary on both sides of the span should be 0.25P. therefore,

From W=(a-1)P+0.25P+0.25P, when the plug-in row is used, the number of holes in the first row a≥2, that is, W≥1.5P. therefore

In order to ensure that all the gas film holes are on the flat plate, the length H of the remaining parts at both ends of the first row and the qth row of holes in the upstream and downstream of the hot gas flow direction should be greater than half of the hole diameter d; The effect of the end H value on the uniform cooling of the entire plate air film hole, then

In order to ensure that all the gas film holes do not overlap in the hot gas flow direction, then

Satisfying the above-mentioned qualifications, and utilizing the method of embodiment 1, the specific application mode is:

取孔径d＝2mm。The length of the plate used is L=125mm, the width is W=30mm, and the opening rate determined by the amount of cold air

Take the aperture d=2mm.

得到4mm＜P≤20mm。according to

4mm<P≤20mm is obtained.

得到

得到

according to

get

get

The range of the number a of openings in the first row is 2-7.

From W=(a-1)P+0.5P, PS=64.082mm ² , when a is taken from 2 to 7, six schemes are obtained.

得到6个方案的最终排布方式。According to L=S×(q-1)+2H,

Get the final arrangement of the 6 schemes.

As shown in Figure 3-4, the simulated hot gas temperature is 1200K and the cold air temperature is 600K. After numerical calculation and analysis, it can be seen that when a = 7 takes the maximum value, that is, when the hole spacing P is the minimum, the temperature distribution of the hot sidewall surface of the flat plate is the most uniform, and the wall surface is uniform. The temperature is the lowest and the cooling efficiency is the highest. The simplified design method of the uniform cooling flat plate inserting and exhausting membrane holes of the present invention is applied to the flat plate, and the optimal design scheme is finally selected. As shown in Fig. 5, through the solution of the present invention, the density of openings between the first row and the last row of holes on the plate is equalized, the effect of uniform cooling of the entire plate is maximized, and the optimal design solution is quickly obtained. , which effectively saves the workload caused by the design method of trial and error in the design and repeated iterations in the prior art.

Claims (7)

1. a design method for inserting and venting membrane holes of a cooling flat plate, is characterized in that, comprises the following steps: (1) The flat plate is cooled by air film holes, the flat plate is square, and there are several air film holes distributed on the flat plate. The two sides of the flat plate parallel to the flow direction are the first flow direction side and the second flow direction side respectively. The two sides parallel to the spanwise direction are the first spanwise side and the second spanwise side, respectively, and the air film holes are arranged in the way of inserting and discharging, and the amount of cold air is determined to obtain the determined opening rate; (2) According to the diameter of the gas film hole and the size of the flat plate, the range of the hole spacing between each row of the gas film hole is obtained; (3) Ensure that the air film holes of the flat plate have the same opening density in the area between the first row and the last row, and determine the range of the number of the first exhaust film holes; (4) According to the number of the first exhaust film holes, the numerical value of the hole spacing corresponding to the number of the first exhaust film holes is obtained, and the row spacing of the gas film holes determined by the hole spacing value is obtained through the opening ratio; (5) According to the determined hole spacing and row spacing, obtain the distance between the first exhaust membrane hole or the last exhaust membrane hole and the side of the flat plate and the number of rows of gas membrane holes, and obtain a feasible gas membrane hole distribution scheme. 2. The method for designing the venting membrane holes of the cooling flat plate according to claim 1, wherein in step (1), the porosity of the flat plate is φ,

Among them, d is the diameter of the gas film holes, P is the hole spacing between each row of the gas film holes, and S is the row spacing of the gas film holes. 3. The method for designing the venting membrane holes of a cooling plate according to claim 2, wherein in step (2), the range of the hole spacing is

where W is the width of the plate. 4. The method for designing a venting membrane hole of a cooling plate according to claim 3, wherein in step (3), the number of the first venting membrane holes is a, and in step (3)

Under the condition of , the range of a is obtained by W=(a-1)P+0.25P+0.25P and

Determine, wherein, 0.25P is the distance between the first flow direction side or the second flow direction side of the nearest column of air film holes. 5. The method for designing a venting film hole for a cooling plate according to claim 4, wherein in step (4), each first venting film is obtained by W=(a-1)P+0.5P The hole spacing corresponding to the number of holes a, and then the corresponding air film hole row spacing is obtained through the obtained hole spacing and opening ratio. 6 . The method for designing a venting membrane hole for a cooling plate according to claim 5 , wherein in step (5), L=S×(q-1)+2H and

Determine the distance between the first vent film hole and the first spanwise side or the distance between the last vent film hole and the second spanwise side, and determine the number of rows of the gas film holes, where L is the length of the flat plate, H is the distance between the first vent film hole or the last vent film hole and the side, and q is the row number of the gas film holes along the flow direction. 7. the design method of venting membrane hole of cooling plate according to claim 6, is characterized in that, the feasible scheme that step (5) obtains, utilizes numerical calculation to analyze temperature distribution of plate hot sidewall surface, wall surface average temperature and cooling efficiency , the optimal design scheme is obtained by screening.

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