KR101746669B1

KR101746669B1 - Pin-fin and cooling apparatus having the same

Info

Publication number: KR101746669B1
Application number: KR1020150154134A
Authority: KR
Inventors: 김광용; 사광진
Original assignee: 인하대학교 산학협력단
Priority date: 2015-11-03
Filing date: 2015-11-03
Publication date: 2017-06-14
Also published as: KR20170052768A

Abstract

The present invention relates to a pin-fin included in a cooling device, wherein the fin-fin is columnar and comprises a gap, the gap being a pillar- And the gap includes a front portion formed such that a cooling flow of the cooling device enters the gap and a rear portion formed to discharge a cooling flow entering the gap.

Description

[0001] The present invention relates to a pin-fin and a cooling apparatus including the pin-

The present invention relates to a fin-fin and a cooling device including the same.

For devices that are exposed to high temperature heat, such as gas turbine blades, electronic devices with complex circuits, cooling is essential to maintain device performance. For example, to improve the efficiency and performance of a gas turbine, a gas turbine engine is designed to operate at 1,500-1700, and the turbine inlet temperature is steadily increased at an annual average of 20 Design trend. However, this results in a heavy load on the turbine blades, which shortens the life of the blades. Therefore, research on various cooling techniques to protect turbine blades has been going on for decades.

The internal cooling techniques include convection cooling, impingement cooling, and film cooling. The internal flow cooling technique uses cooling fluid extracted from the compressor to the cooling channels attached inside the blades Is a technique for cooling the high temperature blades by injecting forced convection. In order to enhance the convective heat transfer through the internal flow path, a device for enhancing heat transfer such as fin-fin, rib, dimple, etc. is installed on the wall surface of the internal flow path. This turbulator disturbs the boundary layer near the wall and promotes the heat transfer by promoting the generation of turbulence. In the case of pin-fins, the cooling performance of the heat transfer surface is improved due to vortex (horseshoe vortex, recirculation vortex, etc.) formed at the contact portion of the heat transfer surface and the pin-fin, It is widely applied to difficult gas turbine blade trailing edges.

The following prior art document 1 discloses that a rectangular fin-fin arrangement allows a 20% increase in heat transfer but produces a 100% pressure loss. Also, referring to the prior art document 2, it can be seen that the total pressure loss is larger for a circular fin-fin arrangement than for an elliptical fin-fin arrangement.

Various studies have been conducted to improve the heat transfer performance of the fin-fin as in the prior art documents 1 and 2. However, it is still required to improve the heat transfer performance and the pressure loss performance of the fin-fin. SUMMARY OF THE INVENTION It is an object of the present invention to provide a new type of fin-fin for improving heat transfer and pressure loss and a cooling device including the same.

Prior Art Document 1: D. E. Metzger, C. S. Fan, S. W. Haley. "Effects of pin shape and array orientation on heat transfer and pressure loss in pin fin arrays." Journal of Engineering for Gas Turbines and Power 106.1 (1984): 252-257 Prior Art Document 2: O. Uzol, C. Camci. "Heat transfer, pressure loss and flow field measurements downstream of staggered two-row circular and elliptical pin fin arrays." Journal of heat transfer 127.5 (2005): 458-471.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fin-fin having improved heat transfer performance or pressure loss performance and a cooling apparatus including the same.

A fin-fin according to an embodiment of the present invention is a pin-fin included in a cooling device, wherein the fin-fin is columnar and includes a gap, And a gap formed between the front portion and the front portion so as to face the direction of the cooling flow of the cooling device so that the cooling flow enters into the gap, And a rear portion formed to discharge the cooling flow entering the gap.

The gap between the front portion and the rear portion may be 180 degrees and the gap may have an I-shape. The rear portion may be formed as two branched portions from the front portion so that the gap may have a Y shape. The angle formed by the two rear portions may be 120 degrees. In addition, the angle formed by the two rear portions at the portion where the rear portion is branched from the front portion is 180 degrees, so that the gap may have a T shape.

In addition, the pin - when the size of the bottom or top side of the fin D, the width of the front portion as G _1, G ₁ / D may be 0.06 or less, the pin - the rear diameter of the bottom or top side of the fin D, When the width of the negative portion is G ₂ , G ₂ / D can be 0.08 or less. In addition, the angle formed by the two rear portions in the portion where the rear portion is branched from the front portion may be 120 to 140 degrees.

A cooling apparatus according to an embodiment of the present invention includes a cooling channel and a fin-fin, wherein the fin-fin is columnar and includes a gap, and the gap is a pillar- Wherein the gap is formed to face the cooling flow direction of the cooling device such that the cooling flow enters the gap and a cooling flow entering the gap And a rear portion formed to be discharged.

The fin-fin and the cooling device comprising it according to embodiments of the present invention have improved heat transfer performance or pressure loss performance. Further, the cooling performance is improved.

Figures 1 (a) - (c) illustrate pin-fins in accordance with an embodiment of the present invention.
Fig. 2 shows a plurality of pin-fin arrangements according to an embodiment of the present invention.
Figure 3 illustrates a cooling channel in which pin-fins are arranged in accordance with an embodiment of the present invention.
Figure 4 illustrates the pin nusel number (Nu _p) and fin nusel experiment number (Nu _p) of the data in accordance with the Reynolds number (Re) for each model.
5 (b) shows a pin-finned ellipse number, and FIG. 5 (c) shows a channel-anomaly number Nu _c . And Fig. 5 (d) shows the pressure coefficient.
6 (a) to 6 (d) show the distribution regions of the particles swirling at a constant intensity according to the fin-fin shape. Through this, it is possible to predict the flow of the fluid through which the vortex is generated through the pin-fin.
Fig. 7 (a) shows the number of the ellipse cell at the lower surface of the channel, and Fig. 7 (b) shows the number of the ellipse at the side of the channel. X is the length of the channel, and D is the diameter of the pin-fin.
8 (a) to 8 (d) show the area-average positive cell number, the fin-finned cell number, the channel cell number and the pressure coefficient according to the width G ₁ of the front portion of the gap and the diameter D of the fin- Respectively. G ₁ is the width of the front part, and D is the diameter of the pin-fin.
9 (a) to 9 (d) show the area-average positive cell number, the fin-fin cell number, the channel positive cell number and the pressure coefficient according to the width G ₂ of the rear portion of the gap and the diameter D of the gap will be.
10 (a) to 10 (d) show the area-average lucer number, the pin-fin lucer number, the channel lucer number and the pressure coefficient according to the angle of the rear part branched from the front part of the gap.
11 shows the area average positive cell number according to the gap and the cooling flow direction.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements. In the drawings, like reference numerals are used throughout the drawings. In addition, "including" an element throughout the specification does not exclude other elements unless specifically stated to the contrary.

Figures 1 (a) - (c) illustrate pin-fins in accordance with an embodiment of the present invention, and Figure 2 illustrates multiple pin-fins arranged in accordance with an embodiment of the present invention.

Referring to Figures 1 and 2, a fin-fin according to an embodiment of the present invention is included in a cooling device, wherein the fin-fin is columnar and includes a gap, And a gap formed between the front portion and the front portion so as to face the cooling flow direction of the cooling device so that the cooling flow enters the gap, And a rear portion formed to discharge the cooling flow into the inside.

The arrows in Figs. 1 and 2 indicate the direction of the cooling flow of the cooling device. 1 (a) to 1 (c), the gap is formed to have a constant width along the height direction of the fin-fin (z direction in FIG. 3). A fin-fin according to an embodiment of the present invention is a pin-fin installed in a cooling channel of a cooling device, wherein the fin-fin is fixedly installed to upper and lower flow paths of the cooling channel. That is, the upper and lower portions of the fin-fin are in contact with the upper flow path and the lower flow path of the cooling channel. In addition, the gap formed in the fin-fin is formed to have a constant width from the top to the bottom of the pin-fin. Further, the gap is formed in a direction facing the direction of the cooling flow of the cooling device. The fin-fin according to an embodiment of the present invention can improve heat transfer performance and pressure loss by including the gap thus formed. The outer surface of the fin-fin and the gap interfere with the cooling flow, thereby improving the cooling performance of the cooling channel of the cooling device.

Unlike the embodiment of the present invention, when the gap is not formed with a constant width along the height direction of the fin-fin, the cooling flow interference due to the gap is expressed in another form. In this case, since the heat transfer performance in the lower flow path and the upper flow path of the cooling channel of the cooling device will be different from each other, heat transfer inconsistency may occur in the entire cooling channel, and cooling performance of the cooling device may be deteriorated. The difference in the cooling flow interference between the cooling channel upper flow path and the lower flow path can further increase the pressure loss.

Further, unlike the embodiment of the present invention, in the case where the gap is not formed in the direction facing the cooling flow of the cooling apparatus, the cooling flow interference due to the gap is not sufficiently generated and the heat transfer performance of the fin-fin is not improved.

Since the fin-fin according to the embodiment of the present invention includes a gap having a constant width over the upper flow path and the lower flow path of the cooling channel, the cooling performance of the cooling device can be improved.

The gap is formed to face the direction of the cooling flow so that the cooling flow can enter into the gap. At this time, a portion formed such that the cooling flow can enter the gap is referred to as a front portion. Further, the cooling flow is discharged to the outside of the pin-fin through the gap, and a portion of the gap through which the cooling flow is discharged is referred to as a rear portion.

Referring to FIG. 1 (a), when the upper surface or the lower surface of the columnar pin-fin is referred to as a reference, the front portion and the rear portion are formed in the same direction so that the gaps can be arranged in an I-shape. Referring to FIG. 1 (b), the gap may include two rear portions branched to the front portion, and the angle of the portion where the rear portion is branched from the front portion may be more than 0 degrees and less than 180 degrees. Thus, the gap may be arranged in a Y-shape. Referring to FIG. 1 (c), the gap may include two rear portions branched into the front portion of the gap, and the angle of the portion where the rear portion is branched from the front portion may be 180 degrees. Thus, the gap may be arranged in a T shape.

As described above, the fin-fin according to the embodiment of the present invention can improve the heat transfer ability because it includes a gap. In addition, the pressure loss can be improved.

1 (a) to 1 (c) illustrate embodiments of the present invention, but the present invention is not limited thereto.

Hereinafter, a pin-fin according to an embodiment of the present invention will be described in detail.

Figure 3 illustrates a cooling channel in which pin-fins are arranged in accordance with an embodiment of the present invention. The cooling channels of Figure 3 are for comparing the heat transfer capability and pressure loss of pin-fins according to an embodiment of the present invention and of pin-fins out of embodiments of the present invention.

3, the cooling channel has a length L, a width W and a height H, in which the cooling flow moves from one direction of the cooling channel in the longitudinal direction (x direction) And pin-fins are arranged in a columnar shape on the lower surface.

In order to compare the heat transfer capacity and pressure loss of the fin-fin with the gap-free fin-fin according to the embodiment of the present invention, numerical analysis on the flow field and the temperature field of the cooling channel was performed. To solve the three-dimensional Reynolds-averaged Navier-Stokes equation, ANSYS CFX-15.0, a commercial computational fluid dynamics code employing an unstructured grid system, was used and numerical analysis was performed by constructing tetrahedral and hexahedral grids. In addition, shear stress transport turbulence model (SST model) was used as a turbulence model to analyze the flow field and temperature field. The working fluid is air (ideal gas, air), the boundary conditions are constant velocity at the inlet, and the outlet is at constant pressure. A constant heat flux condition and a sticking condition were used for the surface of the heat transfer surface and the fin-fin. Figure 4 illustrates the pin nusel number (Nu _p) and fin nusel experiment number (Nu _p) of the data in accordance with the Reynolds number for each model. Referring to FIG. 4, it can be seen that the SIN model substantially agrees with the pin no.

Further, the cooling performance in the heat transfer performance was evaluated by calculating Nusselt number of the area average according to the change of the Reynolds number. The Reynolds number and the Nusselt number are defined as follows.

[Equation 1]

&Quot; (2) "

In the above equation 1 or 2, U is the inlet speed of the internal cooling passage, D _h is the hydraulic diameter of the cooling channel, ρ is the density of the cooling fluid, μ is the viscosity coefficient, q ₀ is the heat flux given the thermal you attach, k _f T _w is the heat insulating wall surface temperature, and T _b is the bulk temperature of each pin-fin.

5 (a) shows an area average mean cell number according to a fin-fin, FIG. 5 (b) shows a pin-finned cell number, FIG. 5 (c) Figure 5 (d) shows the pressure coefficient.

5 (a) to 5 (c), the pin-finned ellipse number indicates the number of the ellipse of the pin-fin, the channel number indicates the number of the ellipse of the pin- The number of the ellipse indicates the number of the pin-fin and the number of the number of the ellipse.

5A, it can be seen that the area average cubic cell number of the I-shaped gap fin-fin, Y-shaped gap fin-fin, and T-shaped gap pin-fin is significantly higher than that of the pin-fin having no gap . This means that the heat transfer performance of the I-gap gap fin-fin, Y-gap gap fin-fin and T-gap gap pin-fin is remarkably higher than that of the gapless fin-fin. The area average cubic cell number of the T-gap pin-fin is the highest because the channel number of the T-gap pin-fin is much higher than that of the pin-fin (see FIG. 5 (c)). It can be seen that the heat transfer performance of the T-gap pin-fin is the best.

Referring to FIG. 5 (d), it can be seen that the pressure coefficient of the I-shaped gap fin-fin and the Y-shaped gap pin-fin is lower than that of the gapless fin-fin. It can be seen that the pressure loss due to the fin-fin in the case of the I-gap gap fin-fin and the Y-gap gap pin-fin can be greatly improved as compared with the gap without the pin-fin. On the other hand, The fins have a high pressure coefficient. Referring to FIGS. 5 (c) and 5 (d), it can be seen that the T-shaped pin-fin has a high heat transfer performance due to a gap instead of having a high pressure coefficient due to the shape of the gap.

6 (a) to 6 (d) show the distribution regions of the particles swirling at a constant intensity according to the fin-fin shape. Through this, it is possible to predict the flow of the fluid through which the vortex is generated through the pin-fin.

5 (a) to 5 (c), the pin-finned ellipse number indicates the number of the ellipse of the pin-fin, the channel number indicates the number of the ellipse of the pin- The number of the ellipse indicates the number of the pin-fin and the number of the number of the channel.

Referring to FIG. 5 (d), it can be seen that the pressure coefficient of the I-shaped gap fin-fin and the Y-shaped gap pin-fin is lower than that of the gapless fin-fin. It can be seen that the pressure loss due to the pin-fin in the case of the I-gap gap fin-fin and Y-gap gap pin-fin can be greatly improved as compared with the gap without the pin-fin. On the other hand, the T-gap pin-fin has a high pressure coefficient. Referring to FIGS. 5 (c) and 5 (d), it can be seen that the T-shaped pin-fin has a high heat transfer performance due to a gap instead of having a high pressure coefficient due to the shape of the gap.

Fig. 7 (a) shows the number of the ellipse cell at the lower surface of the channel, and Fig. 7 (b) shows the number of the ellipse at the side of the channel. X is the length of the channel, and D is the diameter of the pin-fin.

7 (a) and 7 (b), the ellipse number at the lower surface and the side surface of the channel is determined by the I-gap gap fin-fin, the Y-gap gap fin-fin, and the T- Which is larger than that of the pin-fin. Accordingly, it can be seen that the heat transfer performance of the I-shaped gap fin-fin, Y-shaped gap fin-fin and T-shaped gap pin-fin is superior to that of the gapless fin-fin. .

8 (a) to 8 (d) show the area-average positive cell number, the fin-finned cell number, the channel cell number and the pressure coefficient according to the width G ₁ of the front portion of the gap and the diameter D of the fin- Respectively. G ₁ is the width of the front part, and D is the diameter of the pin-fin.

Referring to FIG. 8A, it can be seen that the area average cubic cell number is the highest in the case of the I-shaped gap fin-fin and saturates to a constant value when the G ₁ / D is less than 0.02 in the Y-shaped gap pin-fin. It can be seen that the distribution of the area-average lucer numbers is mainly influenced by the channel number of the lumen (see Fig. 14 (c)). Therefore, it can be seen that the heat transfer performance is improved when G ₁ / D is 0.02 or more in the case of the Y-shaped gap pin-fin.

Referring to FIG. 8 (d), it can be seen that the pressure loss is improved because the pressure coefficient is 0.45 or less when G ₁ / D is 0.06 or less in the case of the Y-shaped gap pin-fin. When G ₁ / D is 0.08 or more, the value is similar to that of the pin-fin without gaps, and the pressure loss is not improved.

9 (a) to 9 (d) show the area-average positive cell number, the fin-fin cell number, the channel positive cell number and the pressure coefficient according to the width G ₂ of the rear portion of the gap and the diameter D of the gap will be.

9A, the area average cubic cell number of the I-shaped gap fin-fin is the largest, and in the case of the Y-shaped gap fin-fin, as the width G ₂ / D of the rear portion of the gap with respect to the diameter of the gap increases It can be seen that the area average positive cell number increases. This tendency was similarly observed in the pin-fin and the channel number numbers. Therefore, it can be seen that the heat transfer performance is improved as the width G ₂ / D of the rear portion of the gap with respect to the diameter of the gap increases in the case of the Y-shaped gap fin-fin.

Referring to FIG. 9 (d), in the case of the Y-shaped pin-fin, when the ratio G ₂ / D is 0.08 or less, the pressure coefficient is 0.45 or less. When G ₂ / D is 0.10 or more, the value is similar to the pressure coefficient of the pin-fin without gaps, and the pressure loss is not improved.

Figs. 10 (a) to 10 (d) show the area-average lucer number, the pin-fin lucer number, the channel lucer number, and the pressure coefficient according to the angle of the rear part diverging from the front part of the gap.

Referring to FIG. 10 (a), in the I-shaped gap fin-fin, the Y-shaped gap fin-fin, and the T-shaped gap pin-fin, the area average austenite number is larger than the gapless pin- . Particularly, when the angle between the rear portions is 120 degrees or more, the heat transfer performance is remarkably improved. 10 (b) and 10 (c), it can be seen that the main factor affecting the heat transfer performance is the channel lumen number.

Referring to FIG. 10 (d), when the angle between the rear portions is 140 degrees or more, the pressure coefficient of the pin-fin without gap is higher than that of the pin-fin.

Therefore, when the angle between the rear portions is 120 degrees or more, the heat transfer performance can be remarkably improved, and the pressure loss can be improved by making the angle between the rear portions 140 degrees or less.

Figure 11 shows the area average cubic numbers along the direction of the cooling flow and gap in I-pin-fin and Y-pin-fins. Referring to FIG. 11, it can be seen that the average positive cell number increases significantly when the gap direction coincides with the cooling flow. This shows that the heat transfer performance is improved due to the variation of the cooling flow by the gap.

A cooling device according to an embodiment of the present invention includes a cooling channel and the pin-fins described above. Specifically, the fin-fin is a columnar shape, and the fin-fin is formed to have a constant width along the height direction of the columnar shape of the pin-fin and includes a gap passing through the pin-fin, The gap includes a front portion formed in a cooling flow direction such that the cooling flow enters the gap, and a rear portion formed to discharge a cooling flow entering the gap. Further, the fin-fin included in the cooling device may include the above-described contents.

The interior of the cooling channel of the cooling device forms a flow path through which the cooling flow can pass. The upper portion of the cooling channel may be referred to as an upper flow path, and the lower portion of the cooling channel may be referred to as a lower flow path, and the fin-fin may be connected to the upper flow path and the lower flow path of the cooling channel.

The pin-fin in the cooling device may be arranged as shown in FIG. 2, but the present invention is not limited thereto. In addition, the cooling device can be used for cooling devices that are continuously exposed to high temperature heat, such as gas turbine blades, electronic devices with complex circuits, etc., and utilize cooling flow for cooling (e.g., air flow). The fin-fin included in the cooling device can improve the cooling efficiency and the pressure loss by forming a gap in the same direction as the flow direction of the cooling flow.

The present invention is not limited to the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

100, 200, 300: Pin-fin
110, 210 and 310:
111, 211, 311:
112, 212, 312:

Claims

In the pin-fin included in the cooling apparatus,
The fin-fin is columnar and comprises a gap,
The gap is formed to have a constant width along a height direction of the columnar shape of the fin-fin,
Wherein the gap includes a front portion formed to allow the cooling flow of the cooling device to enter into the gap and a rear portion configured to discharge a cooling flow entering the gap, and the rear portion is branched from the front portion to two And a pin-fin.

delete

The method according to claim 1,
And an angle formed by the two rear portions at a portion where the rear portion is branched from the front portion is 120 degrees.

The method according to claim 1,
And an angle formed by the two rear portions at a portion where the rear portion is branched from the front portion is 180 degrees.

The method according to claim 1,
Wherein a diameter of a bottom surface or an upper surface of the fin-fin is D, and a width of the front portion is G ₁ , G ₁ / D is 0.06 or less.

The method according to claim 1,
Wherein a diameter of a bottom surface or an upper surface of the fin-fin is D, and a width of the rear portion is G ₂ , G ₂ / D is 0.08 or less.

The method according to claim 1,
And an angle formed by the two rear portions at a portion where the rear portion is branched from the front portion is 120 to 140 degrees.

The method according to claim 1,
And the gap is formed to face the cooling flow direction of the cooling device.

Cooling channel; And
A fin-fin disposed within the cooling channel,
The fin-fin is columnar and comprises a gap,
The gap is formed to have a constant width along a height direction of the columnar shape of the fin-fin,
The gap comprising a front portion formed to face the cooling flow direction of the cooling device and adapted to allow the cooling flow to enter the gap and a rear portion configured to discharge a cooling flow entering the gap, And the cooling device is divided into two from the front part.

11. The method of claim 10,
And the pin-fin connects the lower and upper portions of the cooling channel.