CN107503801A - A kind of efficiently array jetting cooling structure - Google Patents

Abstract

The invention belongs to the cooling of high-temperature parts of gas turbines and aeroengines and other fields related to array impingement jet cooling, and specifically relates to a high-efficiency array jet cooling structure. Provides three array jet impingement hole structure designs and one tapered rib structure design, including a tapered jet impingement orifice plate arranged in a multi-hole array, an impingement orifice plate with different hole diameter array arrangements, and a An impingement orifice plate with inverted (circular) angles arranged in an array, and a jet target plate with upper tapered ribs arranged in an array. The purpose of this design is to use the least amount of cooling air to maximize the cooling efficiency, and at the same time reduce the overall temperature gradient of the cooling wall to make the heat transfer more uniform and stable.

Description

A high-efficiency array jet cooling structure

Technical field:

The invention belongs to the cooling of high-temperature components of gas turbines and aeroengines and other fields related to array impingement jet cooling, and specifically relates to a high-efficiency array jet cooling structure.

Background technique:

The key technology to improve the thermal efficiency of the gas turbine is to increase the inlet temperature of the turbine rotor. Now the gas temperature of the first-stage moving blade of the gas turbine has reached above 1800K. , transition section, turbine blade, etc.) cannot work at such a high temperature for a long time, and effective cooling technology must be adopted.

At present, the development trend of gas turbines is to increase the temperature rise and reduce the emission of pollutants, both of which require a large increase in the proportion of air used in the combustion chamber of the gas turbine, resulting in a decrease in the proportion of cooling air used for the hot end parts of the gas turbine . In the case of ensuring the thermal efficiency of the gas turbine, how to cool the hot-end parts of the gas turbine more effectively with less cooling air is an urgent problem to be solved at present.

Among all heat transfer enhancement technologies, array jet impingement cooling is the most important and effective method to improve the local heat transfer coefficient, and it is also one of the earliest technical means applied to the cooling of gas turbine blades. The most direct reason for affecting the heat transfer of the wall is that there is a gas boundary layer on the wall, which affects the heat transfer effect of the wall, and impingement cooling can minimize the thickness of the boundary layer in the jet stagnation area to achieve the purpose of enhancing heat transfer.

The existing array jet cooling system has the following limitations:

(1) The experimental cooling system does not take into account that the amount of cooling air is limited in actual working conditions. There is no way to significantly increase the Reynolds number of the impinging jet.

(2) In the existing array jet cooling system, the effective cooling area is within the range of four times the impact hole, and the boundary layer of the jet target plate wall in other areas is thicker, and the heat transfer effect is not good.

(3) After the impinging jet impacts the target plate, a certain amount of cross flow will be generated on the wall of the target plate, and the cross flow will affect the rear jet flow, causing the rear impact jet flow to deviate, resulting in uneven cooling temperature of the target plate as a whole. A large temperature gradient is generated, which affects the service life of the material.

Invention content:

The purpose of this design is to use the least amount of cooling air to maximize the cooling efficiency, and at the same time reduce the overall temperature gradient of the cooling wall to make the heat transfer more uniform and stable. In order to achieve the above purpose, this design provides three impact hole structure designs and a structure design of conical ribs (cooling ribs) on the jet target plate, the scheme is as follows:

A high-efficiency array jet cooling structure, including a jet orifice plate and a jet target plate, the jet orifice plate is provided with a plurality of impact holes arranged in an array; the jet orifice plate is located on the upper part of the jet target plate, the two Between the cavity design.

Further, the flow target plate is provided with a plurality of raised conical ribs.

Further, the impact hole is designed as a tapered hole from top to bottom, the difference between the diameters of the upper and lower port circles of the tapered impact hole is 1.5D, and the inclination angle θ formed by the normal line of the impact hole and the wall surface of the impact hole It is 45°～90°.

Further, the upper part of the impact hole is designed as a chamfer or rounded corner, and the lower part is designed as a cylindrical hole; the chamfer angle α of the chamfered impact hole is 30-45°, and the size of the chamfer is 0.1D-0.3D.

Further, the impact holes are arranged in arrays of three different apertures, and the three apertures are 1D, 1.5D and 2D respectively.

Further, the tapered surface of the tapered rib is a straight surface or a curved surface.

Further, the diameter of the base circle of the tapered rib is 0.5D, and the height of the tapered rib is 0.5D-1D.

Further, the number of the conical ribs and the impingement holes are matched with each other, and the conical ribs are located within the upper vertical projection area of the impingement holes on the jet target plate.

Further, the jet orifice plate is parallel to the jet target plate.

Main advantage of the present invention:

1. Under the condition that the flow rate of cold air is constant, the design of the tapered hole increases the impact Reynolds number to a certain extent and enhances the heat transfer coefficient.

2. The arrangement of different apertures makes the impinging jets of different apertures have different jet Reynolds numbers, and the cooling of the jet target plate is more uniform.

3. The inverted (round) impact hole can increase the flow coefficient of the impact hole, reduce the backflow vortex in the impact chamber, that is, the cavity between the jet orifice plate and the jet target plate, and improve its internal working conditions.

4. For the general impact hole, only the wall boundary layer in the vertical projection area of the impact hole is very thin, so the impact stagnation point area has a strong heat transfer effect. Conical ribs are added to the jet target plate to make the impact The jet reduces the thickness of the boundary layer on the wall of the target plate in a larger range. The so-called boundary layer means that the fluid will produce a laminar flow state near the wall, similar to a thin film, the boundary layer The thicker, the worse the heat transfer effect, achieving the effect of enhancing heat transfer

5. At the same time, the manufacturing process of the hole structure and the tapered rib designed by the present invention is simple and easy to realize.

Description of drawings:

Fig. 1 is a structural representation of the present invention;

Fig. 2 is a schematic view of the structure of a tapered hole type orifice plate;

Fig. 3 is the schematic diagram of the structure of orifice plates arranged with different apertures;

Fig. 4 is a structural schematic diagram of a chamfered orifice;

Fig. 5 is a structural schematic diagram of a rounded orifice plate;

Fig. 6 is a schematic diagram of the target plate structure with tapered ribs facing straight;

Fig. 7 is a schematic diagram of the structure of a target plate with tapered ribs;

Fig. 8 is a schematic diagram of a jet flow field with a tapered rib target plate;

Figure 9 is a comparison diagram of the Nu number distribution of the impact hole shape of the cylindrical hole and the jet target plate of the tapered hole shape;

Figure 10 is a comparison diagram of the Nu number distribution of the jet target plate with or without the tapered rib structure;

detailed description:

The invention will be described in further detail below in conjunction with the accompanying drawings and specific examples, but the present invention is not limited to the following examples.

Referring to Fig. 1, a high-efficiency array jet cooling structure includes a jet orifice 1 and a jet target 3, the jet orifice 1 is provided with a plurality of impact holes 2 arranged in an array; the jet orifice 1 is located at the jet target The upper part of the plate 3 is designed as a cavity between the two.

As an improvement of the scheme, with reference to Figure 2 and Figure 9, the impact hole 2 is designed as a tapered hole from top to bottom, the difference between the diameters of the upper and lower ports of the tapered impact hole is 1.5D, and the distance between the impact holes 2 is 3D, the impact distance (the distance from the impact hole plate to the impact target plate) is 2D, and the inclination angle formed by the normal line of the impact hole 2 and the wall surface of the impact hole 2 is 45°-90°. The results show that: under the same initial cooling air flow rate and pressure, compared with the general cylindrical impact hole, the cooling area of the impingement jet produced by the tapered hole structure is the same, and the cooling efficiency is increased by more than 10%.

As an improvement of the scheme, refer to Figure 4-5, the upper part of the impact hole 2 is designed with chamfered or rounded corners, and the lower part is designed with a cylindrical hole; the distance between adjacent impact holes 2 is 3D, the impact distance is 2D, and the chamfered impact hole 2 The chamfer angle α is 45°, and the length dimension of the chamfer is 0.2D. It was found that: under the same conditions of initial cooling air flow rate and pressure, compared with the ordinary cylindrical impact hole, the reflux vortex in the impact chamber is significantly improved, the flow coefficient of the impact hole 2 is increased, and the heat transfer coefficient is improved. 5.5% or more.

As an improvement of the solution, referring to FIG. 3 , the impact holes 2 are arranged in arrays of three different apertures, the distance between adjacent impact holes 2 is 3D, and the impact distance is 2D. The three hole diameters are 1D, 1.5D and 2D respectively, and the specific distribution is a total of 18 impact holes in 3 rows and 6 columns. Under the condition of the same initial cooling air flow rate and pressure, compared with the ordinary cylindrical impact hole, the cooling efficiency of this design has not been significantly improved, but the overall temperature gradient of the target plate has been significantly reduced, and the overall heat transfer coefficient has been improved. uniform.

As an improvement of the solution, referring to Fig. 6-7 and Fig. 10, a plurality of protruding conical ribs 4 are arranged on the jet target plate 3, and the conical surfaces of the conical ribs 4 are straight or curved. The distance between adjacent impact holes 2 is 3D, and the impact distance is 2D. Compared with the two combined structures of ordinary cylindrical impact holes and conical ribs 4 and tapered hole type impact holes 2 and conical ribs 4, the conical ribs 4 The diameter of the bottom circle is 0.5D, the height of the conical rib is D, and the conical surface is straight and curved. It was found that: under the same conditions of initial cooling air flow rate and pressure, the effective cooling area of the combination of ordinary cylindrical impact hole and conical rib is in the area of 4 times D; the combination of tapered hole and conical rib 4 , the effective cooling area is within the area of 4.5 times D. At the same time, the effective cooling area of the curved conical rib 4 is increased by 25% to 35% compared with the straight conical rib 4 .

As an improvement of the scheme, referring to FIG. 8 , the number of conical ribs 4 and the impact holes 3 are matched with each other, and the conical ribs 4 are located between the upper vertical projection area of the impact holes 2 on the jet target plate 3 Inside.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (8)

1. A kind of 1. efficiently array jetting cooling structure, it is characterised in that：Including jet orifice plate and jet target plate, described jet orifice Plate is provided with the impact opening of multiple arrays arrangement；The jet orifice plate is located at the top of the jet target plate, is therebetween sky Chamber designs.
2. A kind of 2. efficiently array jetting cooling structure as claimed in claim 1, it is characterised in that：Above described jet target plate Provided with multiple raised conical ribs.
3. A kind of 3. efficiently array jetting cooling structure as claimed in claim 1, it is characterised in that：Described impact opening is by up to Designed for tapered hole down, the difference of the gradual shrinkage impact opening upper/lower terminal mouth circular diameter is 1.5D, the normal of impact opening and punching Hit wall surface of the hole institute into tilt angle theta be 45 °~90 °.
4. A kind of 4. efficiently array jetting cooling structure as claimed in claim 1, it is characterised in that：The top of the impact opening is Chamfering or rounding design, bottom is designed for cylindrical hole；The chamfer angle α of the chamfering impact opening is 30~45 °, the chi of chamfering Very little is 0.1D~0.3D.
5. A kind of 5. efficiently array jetting cooling structure as described in claim 1-4 is any, it is characterised in that：Described impact opening For 3 kinds of different pore size array arrangements, three kinds of apertures are respectively 1D, 1.5D and 2D.
6. A kind of 6. efficiently array jetting cooling structure as claimed in claim 2, it is characterised in that：The conical surface of the conical rib is Face directly or be curved surface.
7. A kind of 7. efficiently array jetting cooling structure as claimed in claim 2, it is characterised in that：Described conical rib bottom circle is straight Footpath is 0.5D, and conical rib is highly 0.5D~1D.
8. A kind of 8. efficiently array jetting cooling structure as claimed in claim 2, it is characterised in that：Described conical rib with it is described The quantity of impact opening be mutually matched, the conical rib is located at the impact opening in the upper upright projection region of the jet target plate Within.