CN219934770U - Wavy curve micro-channel and precooler - Google Patents

Abstract

The utility model belongs to the field of precooler heat transfer channels, and particularly relates to a wavy curve micro-channel, wherein the micro-channel comprises a plurality of amplitude-variable wave crest-wave trough structures, and the cross section configuration of the micro-channel meets a configuration equation under a polar coordinate system. Compared with the conventional flat channel, the micro-channel provided by the utility model has the advantages that the thickness of a thermal boundary layer can be reduced, the flow mixing effect of a wall surface and a main flow area can be enhanced, and the heat transfer performance can be improved. Meanwhile, the variable amplitude wave crest-wave trough structure is also overlapped on the basis of the integral curve channel configuration, so that the defect that the curvature of a conventional curve channel is easy to gradually decrease along with the flowing direction is avoided, and the problem that the equal amplitude wave crest-wave trough structure is easy to interfere at the axis of a micro-channel is avoided. Finally, the micro-channel configuration with good flow mixing effect and strong heat transfer capability is obtained.

Description

Wavy curve micro-channel and precooler

Technical Field

The utility model belongs to the field of heat transfer channels of precoolers, and particularly relates to a wavy curve microchannel and a precooler.

Background

Precooler is the core component of precooling type combined cycle engine, and the intensive heat transfer demand is one of the biggest challenges of precooler structural design. Currently, the heat transfer capability of conventional scale channels has failed to meet the heat transfer requirements of the heat transfer channels in the precooler. Heat transfer studies of electronic circuits using microchannels with water as coolant were first performed by Tuckerman and Pease, indicating that the microchannels have extremely high heat transfer capacity. Through experiments on a heat transfer unit JMHX (SABRE precooler capability test module) formed by micro channels, REL company verifies that the surface area volume ratio and the heat transfer capability can be greatly improved by using the micro channels in the structural design of the precooler, and reveals the application prospect of the micro channels in the design of small-volume light-weight high-efficiency precooler.

Conventional microchannel heat exchangers are typically straight channels of a single cross-section, such as some rectangular, triangular, circular, trapezoidal cross-sections. Although they all have good heat transfer characteristics, there are some disadvantages: for example: the streamlines of the coolant within the channels are nearly straight, resulting in uneven fluid mixing and most likely in heat transfer degradation as the thermal boundary layer increases in the flow direction. It is found that the grooves, fins or ribs, porous medium, rough surface, etc. are formed in the micro channel to break and develop the thermal boundary layer, promote the generation of vortex and the mixing of fluid, and thus the heat transfer performance of the micro channel is improved.

To further achieve enhanced heat transfer from the microchannels, researchers have proposed a curvilinear microchannel configuration scheme that finds that curvilinear channels tend to have a larger heat transfer area and higher heat transfer rates in a compact space than flat microchannels. It is considered that the secondary flow caused by centrifugal force in the curved channel enhances the flow mixing near the wall surface and the main flow area, and enhances the heat exchange capability. The Sui and the like explain the reason that the sinusoidal micro-channel has good heat transfer performance based on experimental and numerical simulation calculation results in detail, the bending of the flow channel causes the generation of transverse vortex on the section vertical to the flowing direction, and the size and the number of the transverse vortex are closely related to the Reynolds number. It is also possible to vary the convection current that grows chaotic along the flow direction. After that, the scholars further propose that the sinusoidal heat exchange performance is better when the amplitude is larger.

For curved microchannels, the introduction of centrifugal force results in thinning of the flow and thermal boundary layers, achieving enhanced heat exchange. And as the curvature of the channels decreases, centrifugal force and secondary flow will weaken, resulting in thicker thermal boundary layers and deteriorated heat exchange. In practice, however, a decrease in curvature of the curved channel is often unavoidable. For example, the most common spiral-type curvilinear channels, the curvature of which decreases progressively with the direction of main flow, result in a great weakening of the heat transfer capacity. Therefore, how to utilize the heat transfer advantage of a good curve channel relative to a straight channel, and simultaneously avoid secondary flow weakening and thickening of a thermal boundary layer caused by curvature change, and the heat transfer advantage is an important and extremely promising problem of curve micro-channel configuration design.

Disclosure of Invention

The utility model aims to solve the technical problem of providing a wavy curve micro-channel and a precooler which still have good heat transfer capacity on the premise of reducing the overall curvature of the curve channel.

The utility model provides a wavy curve micro-channel, which comprises a plurality of variable amplitude crest-trough structures, wherein the cross-sectional configuration of the micro-channel satisfies a configuration equation under a polar coordinate system:

wherein R is the polar diameter of the wavy curve micro-channel, and θ is the polar angle;

a. b is archimedes spiral, namely a smooth curve channel equation parameter without a superimposed wave crest-wave trough structure, and a and b are positive values;

n is the number of variable amplitude peak-trough structures;

a is the maximum amplitude in the n peak-trough structures, A is not equal to 0;

θ ₁ is a maximum angle of 1/2.

Still further, the cross section of the microchannel is rectangular.

Still further, the cross-section of the microchannel satisfies the channel cross-section equation:

wherein L is _in Is rectangular in runner length, W _in Is rectangular in flow channel width, D _h The equivalent diameter of a channel, i.e. the size of a rectangular channel, is indicated.

Still further, the microchannel comprises 5 peak-trough structures.

Further, interfaces are arranged at two ends of the micro-channel.

Still further, the micro-channels are integrally formed by 3D printing.

The utility model also provides a precooler comprising the wavy curve micro-channel.

The utility model has the beneficial effects that on the basis of the compact microchannel precooler, the smooth curve microchannel in which the coolant flows is optimally designed, and the wave-shaped structure with variable amplitude is added on the rectangular equal-section channel with a certain hydraulic diameter, so as to obtain the wave-shaped structure configuration with variable amplitude wave crest-wave trough, wherein the amplitude of the wave crest-shaped structure is changed along with the polar angle.

Compared with the conventional flat channel, the micro-channel provided by the utility model has the advantages that the thickness of a thermal boundary layer can be reduced, the flow mixing effect of a wall surface and a main flow area can be enhanced, and the heat transfer performance can be improved. Meanwhile, the variable amplitude wave crest-wave trough structure is also overlapped on the basis of the integral curve channel configuration, so that the defect that the curvature of a conventional curve channel is easy to gradually decrease along with the flowing direction is avoided, and the problem that the equal amplitude wave crest-wave trough structure is easy to interfere at the axis of a micro-channel is avoided. Finally, the micro-channel configuration with good flow mixing effect and strong heat transfer capability is obtained.

Drawings

FIG. 1 is a schematic illustration of a prior art smooth curve microchannel configuration;

FIG. 2 is a schematic view of a wavy curved microchannel configuration according to an embodiment of the utility model;

FIG. 3 is a schematic longitudinal section view of FIG. 2 at A;

FIG. 4 is a schematic diagram of a second configuration of a second wavy curve microchannel according to an embodiment of the utility model;

FIG. 5 is a schematic view of a three-configuration of a three-contoured curve microchannel in accordance with an embodiment of the present utility model;

FIG. 6 is a schematic diagram of a four-configuration of a four-contoured micro-channel in accordance with an embodiment of the present utility model;

FIG. 7 is a schematic view of the structure of the mounting interface of FIG. 2;

FIG. 8 is a schematic diagram of the change rule of the curvature radius along the flow direction in a smooth curve microchannel;

FIG. 9 is a schematic diagram showing the change rule of the curvature radius along the flow direction in the maximum amplitude wavy curve micro-channel in the n wave crest-trough structures in one embodiment;

FIG. 10 is a schematic diagram showing the change rule of the curvature radius along the flow direction in the maximum amplitude wavy curve micro-channel in the n wave crest-trough structure in one embodiment;

FIG. 11 is a schematic diagram of the instantaneous local heat transfer coefficient variation of single-phase flow heat transfer;

FIG. 12 is a graph of the average heat transfer coefficient profile in a smooth curve microchannel;

FIG. 13 is a graph of the average heat transfer coefficient profile in a wavy curve microchannel with maximum amplitude (2 mm) in an n-wave crest-trough structure in one embodiment;

FIG. 14 is a graph of the average heat transfer coefficient profile in a wavy curve microchannel of maximum amplitude (3 mm) in an n-wave crest-trough structure in one embodiment.

In the figure, 1-microchannel; 2-interface.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present utility model are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.

Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present utility model, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; the device can be mechanically connected, electrically connected, physically connected or wirelessly connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In addition, the technical solutions of the embodiments of the present utility model may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present utility model.

As shown in fig. 2-14, the present utility model provides a wavy curve microchannel, wherein the microchannel 1 comprises a plurality of variable amplitude peak-valley structures, and the cross-sectional configuration of the microchannel 1 satisfies the configuration equation under the polar coordinate system:

wherein R is the polar diameter of the wavy curve micro-channel, and θ is the polar angle;

a. b is archimedes spiral, namely a smooth curve channel equation parameter without a superimposed wave crest-wave trough structure, and a and b are positive values;

n is the number of peak-to-valley structures of varying amplitude, wherein varying amplitude means that the amplitude of each two peak-to-valley structures is not uniform, and the amplitude of a single peak-to-valley structure, i.e., the maximum distance from the equilibrium location, is related to the channel polar angle, and is not a constant value;

a is the maximum amplitude in the n peak-trough structures, A is not equal to 0;

θ ₁ is a maximum angle of 1/2.

Wherein, archimedes spiral a, b, the number n of variable amplitude wave crest-wave trough structures, the maximum amplitude A in the n wave crest-wave trough structures is a set parameter determined according to the actual size requirement, the polar diameter R, the polar angle theta and the 1/2 maximum polar angle theta ₁ According to the configuration equation and the obtained parameters obtained by the set parameters, the utility model can finally obtain the microchannel configuration only by inputting the set parameters into the configuration equation according to the actual size requirement.

Referring to fig. 1, when a=0 mm, it means that the micro-channel does not overlap the peak-trough structure, only a smooth curve channel controlled by archimedes' spiral equation;

when A is equal to 0mm, the curve channel with the wave crest-wave trough structure is shown in fig. 2, and the schematic diagram of one of the wave-shaped curve micro-channel structures is obtained according to the requirements of a configuration equation.

On the basis of a compact microchannel precooler, the utility model optimally designs a smooth curve microchannel in which a coolant flows, and adds an amplitude-variable wave structure on a rectangular equal-section channel with a certain hydraulic diameter to obtain a wave-crest-trough structure configuration with amplitude changing along with polar angle.

Compared with the conventional flat channel, the micro-channel provided by the utility model has the advantages that the thickness of a thermal boundary layer can be reduced, the flow mixing effect of a wall surface and a main flow area can be enhanced, and the heat transfer performance can be improved. Meanwhile, the variable amplitude wave crest-wave trough structure is also overlapped on the basis of the integral curve channel configuration, so that the defect that the curvature of a conventional curve channel is easy to gradually decrease along with the flowing direction is avoided, and the problem that the equal amplitude wave crest-wave trough structure is easy to interfere at the axis of a micro-channel is avoided. Finally, the configuration of the micro-channel 1 with good flow mixing effect and strong heat transfer capability is obtained.

In one embodiment, referring to fig. 3, the cross section of the micro-channel 1 is rectangular, and the cross section of the micro-channel 1 is rectangular, so as to facilitate production and processing.

In one embodiment, referring to fig. 3, when the cross section of the micro channel 1 is rectangular, the following channel cross section equation is satisfied:

wherein L is _in Is rectangular in runner length, W _in Is rectangular in flow channel width, D _h The equivalent diameter of a channel, i.e. the size of a rectangular channel, is indicated.

Referring to fig. 7, in one embodiment, two ends of the micro-channel 1 are provided with interfaces 2, so as to facilitate the micro-channel 1 to communicate with other pipelines of the precooler.

In one embodiment, the microchannel 1 is integrally formed by 3D printing, preferably made of GH3536 superalloy material, which meets the design requirements of the precooler microchannel unit in terms of both processing and heat transfer performance.

In one embodiment, the microchannel 1 comprises a 5 peak-valley structure, with particular reference to the configuration diagrams provided in fig. 3-5.

The utility model also provides a precooler, which comprises the wavy curve micro-channel

The utility model also provides a specific embodiment for comparison and test, which comprises the following steps:

fig. 1 is a graph of a smooth curve microchannel configuration under a rectangular cross section, and fig. 4-6 are graphs of wavy curve microchannel configurations with three different dimensional parameters, and experimental section configuration parameters corresponding to the four microchannel configurations are shown in table 1:

TABLE 1 microchannel configuration parameters

Microchannel	Corresponding figures	a/mm	b/mm	W in /mm	L in /mm	D h /mm	A/mm	d w /mm	n	θ/°
											Microchannel one	FIG. 1	80	40	0.8	2	1.14	0	0.5	0	106
Microchannel II	FIG. 4	80	40	0.8	2	1.14	2	0.5	5	106
											Microchannel III	FIG. 5	80	40	0.8	2	1.14	3	0.5	5	106
Microchannel IV	FIG. 6	80	40	0.8	4	1.33	2	0.5	5	106

Experiments and verification are carried out on four microchannel configurations provided in the table 1, and the spiral curve microchannel with the variable amplitude wave crest-wave trough structure is found to have better heat transfer performance compared with a smooth curve channel, so that the spiral curve microchannel is a practical design configuration scheme of a precooler heat transfer unit, and the result is as follows:

(1) Variation of microchannel configuration along the radius of curvature

Fig. 8 is a schematic view of a change in radius of curvature in the flow direction in a smooth curve microchannel (microchannel one), fig. 9 is a schematic view of a change in radius of curvature in the flow direction in a wavy curve microchannel (microchannel two and microchannel three) having a maximum amplitude of 2mm in a peak-trough structure, and fig. 10 is a schematic view of a change in radius of curvature in the flow direction in a wavy curve microchannel (microchannel four) having a maximum amplitude of 3mm in a peak-trough structure.

As can be seen from fig. 8-10, for a smooth curve microchannel (microchannel one), the rate of decrease of the radius of curvature moves downstream with the arc position is gradual. The wavy curve microchannel (microchannel two, microchannel three and microchannel four) with the superimposed peak-trough structure relative to the smooth curve keeps the radius of curvature along most of the area low, which is much smaller than that of the basic smooth curve microchannel configuration. Since the local dean number increases with decreasing radius of curvature, the introduction of the peak-trough structure increases the dean number along the path as a whole, enhancing flow mixing, and the secondary flow of the main flow in both the local and the whole channels is significantly enhanced by centrifugal force.

(2) Local heat transfer characteristics

Fig. 11 is a schematic diagram of a transient local heat transfer coefficient variation of single-phase flow heat transfer.

As can be seen from fig. 11, the change in configuration results in a significant change in the local heat transfer characteristics. Conventional straight channels (not shown) have a constant decrease in convective heat transfer coefficient along the path as the flow progresses downstream to a thicker thermal boundary layer. The smooth curve channel is characterized in that the curvature radius is continuously reduced along with the increase of the radian position, the Dien number of the local position is continuously increased along the way, so that the disturbance of secondary flow induced by centrifugal force to the main flow is enhanced, the Dien vortex influence corresponding to the local position is enhanced, the mixing of near-wall fluid and the main flow is enhanced, the thermal boundary layer is destroyed, the local heat transfer coefficient keeps always increasing trend in a larger radian range, the thickness of the thermal boundary layer is obviously increased along with the further downstream development of the flow, and meanwhile, the decreasing trend of the curvature radius of the smooth curve channel is slowed down, namely the increasing amplitude of the local Dien number is gradually weakened, the disturbance range of the secondary flow to the flow cross section cannot be further improved, the disturbance degree of the thermal boundary layer is reduced, and the local heat transfer coefficient is slowly reduced.

For the wavy curve channel, the curvature of the amplitude structure is superposed on the original configuration curvature by introducing the wavy structure, so that the curvature radius of the wave crest and the wave trough is obviously reduced, the local dean number is greatly increased, the local heat transfer characteristic is obviously changed under the same working condition as that of the smooth curve channel, the wall surface temperature fluctuates, the local heat transfer coefficient at the wave crest and the wave trough oscillates, the basic configuration curvature of the smooth curve channel is weakened by the additional curvature of the wave trough, the basic configuration curvature is strengthened by the additional curvature of the wave crest, the secondary flow disturbance at the wave trough is weakened, the influence range of the vortex is reduced, the local heat transfer coefficient is reduced by a small margin, the local dean number is greatly increased due to superposition of the amplitude and the basic curvature at the wave crest, and the heat transfer coefficient is greatly improved. Meanwhile, the disturbance caused by the amplitude has a larger influence degree, and the vortex generated by the flow by the upstream amplitude is further transferred and amplified along with the downstream amplitude, so that the trend of increasing the local heat transfer coefficient is maintained.

(3) Average heat transfer characteristics

Fig. 12 is a graph showing the average heat transfer coefficient distribution in a smooth curve microchannel, fig. 12 is a graph showing the average heat transfer coefficient distribution in a wavy curve microchannel (microchannel two and microchannel three) having a maximum amplitude of 2mm in a peak-trough structure, and fig. 13 is a graph showing the average heat transfer coefficient distribution in a wavy curve microchannel (microchannel four) having a maximum amplitude of 3mm in a peak-trough structure.

As can be seen from the graph, the average heat transfer coefficient of the 2mm amplitude wavy curve microchannel is improved by 1.5% and the average heat transfer coefficient of the 3mm amplitude wavy curve microchannel is improved by 3.5% at a similar Reynolds number Re approximately 35 compared with the basic configuration smooth curve microchannel. When the Reynolds number is increased to Re approximately 101, the corresponding average heat transfer enhancement amplitude can reach 19% and 23% respectively, which shows that the introduction of the wavy structure to change the local curvature radius enhances the secondary flow, has an effect of promoting the average heat transfer capacity of the micro-channel, and the amplitude of the heat transfer enhancement is obviously improved along with the acceleration of the flow speed.

What is not described in detail in this specification is prior art known to those skilled in the art.

Claims (7)

1. A wavy curve microchannel, characterized in that the microchannel (1) comprises a plurality of variable amplitude peak-trough structures, the cross-sectional configuration of the microchannel (1) satisfying the configuration equation in a polar coordinate system:

wherein R is the polar diameter of the wavy curve micro-channel, and θ is the polar angle;

a. b is archimedes spiral, namely a smooth curve channel equation parameter without a superimposed wave crest-wave trough structure, and a and b are positive values;

n is the number of variable amplitude peak-trough structures;

a is the maximum amplitude in the n peak-trough structures, A is not equal to 0;

θ ₁ is a maximum angle of 1/2.

2. The wavy curvilinear microchannel according to claim 1, characterized in that the microchannel (1) has a rectangular cross section.

3. The wavy curvilinear microchannel according to claim 2, characterized in that the cross section of the microchannel (1) satisfies the channel cross section equation:

wherein L is _in Is rectangular in runner length, W _in Is rectangular in flow channel width, D _h Indicating the equivalent diameter of the channel.

4. A wavy curve microchannel according to any one of claims 1 to 3, wherein the microchannel (1) comprises 5 peak-to-valley structures.

5. A wavy curve microchannel according to any one of claims 1 to 3, characterized in that the microchannel (1) is provided with interfaces (2) at both ends.

6. A wavy curve microchannel according to any one of claims 1 to 3, wherein the microchannel (1) is integrally formed by 3D printing.

7. A precooler comprising the contoured microchannel of any one of claims 1-6.