CN112049817B - Cross-flow fan blade based on bionics - Google Patents

Abstract

The invention discloses a cross-flow fan blade based on bionics. The blade includes a plurality of blade units arranged along the axial direction of the impeller. The leading edge of the blade unit is convex and the trailing edge is concave. The middle portion near the front edge side of the surface is higher than the two sides, and the middle portion near the trailing edge side is lower than the two sides, and the middle portion near the front edge side is higher than the middle portion near the trailing edge side. By adopting the cross-flow fan blade based on bionics of the present invention, the air flow at the front and rear edges of the blade can be improved, the eccentric vortex can be moved down, the efficiency of the cross-flow fan can be improved, and the energy consumption can be reduced.

Description

A bionic-based cross-flow fan blade

technical field

The invention belongs to the technical field of air-conditioning blades, and in particular relates to a cross-flow fan blade based on bionics.

Background technique

With the development of society, energy conservation and emission reduction has become the consensus of the whole society. In building energy consumption, the energy consumption of HVAC system accounts for about 65% of the whole, and the total energy consumption of air conditioners in my country is huge. Under normal circumstances, in order to apply energy-saving engineering design in HVAC systems, the prior art has always been to invent and optimize the design of cross-flow fan blades widely used in air-conditioning systems, so that the fan can achieve the effect of reducing drag and consumption, which is of great practical importance value and social significance.

However, there are still some defects in this design. For example, the surface of the existing blade is flat and smooth, and the airflow is easy to flow laterally; at the same time, the front and rear edges of the existing blade are both long and straight structures, and a large eddy current is easily formed when the airflow passes through, causing the pressure to flow. The differential resistance is large; there is an eccentric vortex on the outlet side of the impeller of the cross-flow fan, which will affect the fan efficiency and reduce the flow instability. Therefore, there is an urgent need for cross-flow fan blades that can reduce the vortex area, reduce the pressure differential resistance, reduce the energy consumption of the fan and improve the efficiency of the fan.

SUMMARY OF THE INVENTION

Aiming at the above shortcomings, the present invention provides a cross-flow fan blade based on bionics, which can overcome the problems of high energy consumption and low efficiency in the prior art, and achieve the effect of reducing drag and consumption.

In order to solve the above-mentioned technical problems, the embodiment of the present invention adopts the following technical solutions:

A cross-flow fan blade based on bionics, the blade comprises several blade units arranged along the axial direction of the impeller, the leading edge of the blade unit is convex, the trailing edge is concave, and the upper surface of the blade unit is close to the leading edge The side middle portion is higher than the two sides, the middle portion near the trailing edge side is lower than the two sides, and the middle portion near the leading edge side is higher than the middle portion near the trailing edge side.

Preferably, on the windward surface of the leading edge, the section profile of the blade unit intersects the first arc, the first straight line, the second straight line, the second arc, the third straight line and the fourth straight line in sequence; The fourth arc, the fifth straight line, the sixth straight line, the fifth arc line, the seventh straight line and the eighth straight line intersect in turn; the middle section is the third arc line, the eleventh arc line, the sixth arc line and the tenth line The two arcs intersect in turn; the left side is the first arc, the seventh arc, the fourth arc and the eighth arc in turn; the right side is the second arc, the ninth arc, and the fifth arc It intersects the tenth arc in turn.

Preferably, the distance between the vertices of the protruding structures of the leading edges of two adjacent blade units of the blade is 4-80 mm.

Preferably, the vertical distance from the vertex of the protruding structure of the leading edge of the blade unit to the straight line where the two ends of the leading edge are located is 1-20 mm.

Preferably, the vertical distance from the vertex of the concave structure of the trailing edge of the blade unit to the straight line where the two ends of the trailing edge are located is 0.5-15 mm.

Preferably, the chord length of the two sides of the blade unit is 8-120 mm, the height of the middle part of the two sides is 1/10 of the chord length, and the height of the ends of the two sides is 1/12 of the chord length.

Preferably, the chord length of the middle section of the blade unit is 9-130 mm, the height of the middle section of the middle section is 1/13 of the chord length, and the height of the end of the middle section is 1/20 of the chord length.

Preferably, the total width of the blades is 50-800 mm.

Compared with the prior art, the bionic-based cross-flow fan blade of the present invention can ensure to improve the airflow at the front and rear edges of the blade, move the eccentric vortex downward, reduce the energy consumption of the fan, and improve the efficiency of the fan. A cross-flow fan blade based on bionics in this embodiment, the blade includes a plurality of blade units arranged along the axial direction of the impeller, the leading edge of the blade unit is convex, the trailing edge is concave, and the blade unit is on the The middle portion near the front edge side of the surface is higher than the two sides, and the middle portion near the trailing edge side is lower than the two sides, and the middle portion near the front edge side is higher than the middle portion near the trailing edge side. By setting the protruding leading edge structure, the vortex area can be reduced and the shape resistance can be reduced; the setting of the concave trailing edge structure can maintain the fluid adhesion, move the separation point backward, and reduce the pressure difference resistance; use the upper surface structural features to suppress the lateral airflow The impeller structure formed by the rotating arrangement of the blades can make the eccentric vortex move down, reduce the energy consumption of the fan and improve the efficiency of the fan.

Description of drawings

1 is a schematic structural diagram of a blade in an embodiment of the present invention;

Fig. 2 is the front view of the blade unit in the embodiment of the present invention;

Fig. 3 is the rear view of the blade unit in the embodiment of the present invention;

Fig. 4 is the middle section sectional view of the blade unit in the embodiment of the present invention;

5 is a dimension drawing of the blade unit in the embodiment of the present invention;

Fig. 6 is the top view of the blade in the embodiment of the present invention;

Fig. 7 is the structural representation of a section of impeller in the embodiment of the present invention;

Fig. 8 is the structural representation of the existing blade;

Fig. 9 is the streamline distribution cloud map of the existing blade;

Fig. 10 is the streamline distribution cloud diagram of the blade in the embodiment of the present invention;

11 is a structural diagram of an experimental volute model in an embodiment of the present invention;

Fig. 12 is the streamline distribution cloud map of the existing cross-flow fan;

FIG. 13 is a cloud diagram of the streamline distribution of the cross-flow fan in the embodiment of the present invention.

In the figure: blade unit 1, leading edge windward surface 2, trailing edge leeward surface 3, left side 4, right side 5, middle section 6, first arc 7, first straight line 8, second straight line 9 , the second arc 10, the third straight line 11, the fourth straight line 12, the third arc 13, the fourth arc 14, the fifth straight line 15, the sixth straight line 16, the fifth arc 17, the seventh straight line 18, Eighth straight line 19, sixth arc 20, seventh arc 21, eighth arc 22, ninth arc 23, tenth arc 24, eleventh arc 25, twelfth arc 26, blade 27, impeller 28, existing blades 29.

Detailed ways

The following description is merely exemplary in nature and is not intended to limit the disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

As shown in FIG. 1 , in the cross-flow fan blade based on bionics according to the embodiment of the present invention, the blade 27 includes a plurality of blade units 1 arranged axially along the impeller 28 , and the leading edge 2 of the blade unit 1 protrudes , the trailing edge 3 is concave, the upper surface of the blade unit 1 is higher than the middle part of the side near the front edge 2 and is higher than the two sides, the middle part of the side near the trailing edge 3 is lower than the two sides, and the middle part of the side near the front edge 2 is higher than the side near the front edge 2 The middle part of the trailing edge 3 sides.

Among them, the upper surface of a cross-flow fan blade based on bionics of the present invention imitates the surface features of shark shield scales, the upper surface of the blade unit 1 is closer to the front edge 2 The middle part is higher than the two sides, and the middle part of the 3 side close to the trailing edge is higher than the two sides. Below the two sides, the middle portion on the side near the leading edge 2 is higher than the middle portion on the side near the trailing edge 3 . The surface features can improve the fluid structure and flow state of the turbidity boundary layer flowing through, and have better drag reduction effect. The fluid in the middle of the side surface near the trailing edge 3 is calmer than the outer fluid, and the fluctuating velocity and turbidity kinetic energy of the fluid are relatively small. The momentum loss of the fluid in the turbidity boundary layer reduces the frictional resistance of the surface.

As shown in FIG. 2 , FIG. 3 and FIG. 4 , in the bionics-based cross-flow fan blade of the above embodiment, preferably, the section profile of the blade unit 1 is the first arc 7 on the windward surface of the leading edge 2 , the first straight line 8, the second straight line 9, the second arc line 10, the third straight line 11 and the fourth straight line 12 intersect in turn; the leeward side of the trailing edge 3 is the fourth arc line 14, the fifth straight line 15, and the sixth straight line 16. The fifth arc 17, the seventh straight line 18 and the eighth straight line 19 intersect in sequence; the middle section 6 is the third arc 13, the eleventh arc 25, the sixth arc 20 and the twelfth arc 26 in sequence intersect; the left side 4 is the first arc 7, the seventh arc 21, the fourth arc 14 and the eighth arc 19 intersect in turn; the right side 5 is the second arc 10, the ninth arc 23, The fifth arc 17 and the tenth arc 24 intersect in sequence. Through the combination of straight lines and arcs, the protruding structure of the leading edge 2 is formed, so that the airflow flows in the direction of the streamline. When the position is moved back, the vortex area is significantly reduced, thereby reducing the shape resistance; at the same time, the trailing edge 3 forms a concave structure, and the tip points to the direction of the fluid. This concave structure can generate strong turbidity to maintain the adhesion of the fluid and prevent the fluid from separating. , thereby reducing the differential pressure resistance.

Preferably, the distance between the vertices of the protruding structures of the leading edges 2 of the blades 27 adjacent to two blade units 1 is 4-80 mm.

Preferably, the vertical distance from the vertex of the protruding structure of the leading edge 2 of the blade unit 1 to the straight line where the two ends of the leading edge 2 are located is 1-20 mm.

Preferably, the vertical distance from the vertex of the concave structure of the trailing edge 3 of the blade unit 1 to the straight line where the two ends of the trailing edge 3 are located is 0.5-15 mm.

Preferably, the chord length of the two sides of the blade unit 1 is 8-120 mm, the height of the middle part of the two sides is 1/10 of the chord length, and the height of the end parts of the two sides is 1/12 of the chord length.

Preferably, the chord length of the middle section 6 of the blade unit 1 is 9-130 mm, the height of the middle section 6 is 1/13 of the chord length, and the end height of the middle section 6 is 1/20 of the chord length.

Preferably, the total width of the blades 27 is 50-800 mm.

The blade performance of the embodiment of the present invention is tested by simulation experiments below:

The size of the blade unit 1 used in this experiment is shown in Figure 5, and the vertical distance B from the vertex c of the protruding structure of the leading edge 2 of the blade unit 1 to the two end points a (a') is 1.5 mm. The vertical distance C from the end point d of the concave structure of the trailing edge 3 of the blade unit 1 to the two vertexes b(b') is 1 mm. The chord length A of the sections 4 and 5 on both sides of the blade unit 1 is 10mm, the chord height D of the ninth arc 23 taking the straight line where the endpoints a and d are as the chord is 1mm, the middle height E is 1mm, and the end height G is 1mm. 0.8mm. The chord length I of the middle section 6 of the blade unit 1 is 10.5 mm, the middle height J is 0.8 mm, and the end height F is 0.6 mm.

As shown in FIG. 6 , the total width of the blades 27 formed by the arrangement of the blade units 1 is 60 mm. The distance H between the vertices of the protruding structures of the two adjacent blade units 1 of the blades 27 is 6 mm.

As shown in FIG. 7 , the blades 27 can be combined into an impeller 28 in a circular array, wherein a section of the impeller 28 includes 36 blades 27 . The rotating arrangement of the impeller 28 can make the eccentric vortex move down and get closer to the volute tongue, thereby improving the efficiency of the fan.

In the present invention, the bionics-based cross-flow fan blade of the above-mentioned embodiment has been simulated and tested with a single blade 27 structure and a full three-dimensional structure of the cross-flow fan, and compared with the data of the cross-flow fan blade in the prior art. , using FLUENT19.0 software for three-dimensional numerical simulation calculation.

(1) 3D numerical simulation of single blade structure

The blade 27 in the above embodiment is modeled. The basic structure of the blade 27 is shown in FIG. 1 , and the dimensions are shown in FIGS. 5 and 6 . Using FLUENT19.0 software to carry out three-dimensional numerical simulation of the blade 27 in the embodiment, the control equation adopts the Reynolds-averaged NS equation, the turbulence model adopts the standard k-ε model, the standard wall function is adopted near the wall, the pressure-velocity coupling adopts the SIMPLE algorithm, and the momentum The equations, turbulent kinetic energy, and turbulent dissipation rate are all discretized by the second-order upwind style. The boundary conditions are velocity inlet and pressure outlet, the inlet velocity is 10m/s, and the outlet pressure is atmospheric pressure 0Pa. When all the residuals are less than 10 ^-5 , the calculation of the current condition is considered to have converged.

Use the same steps to model the existing blade 29. The basic structure of the existing blade 29 is shown in FIG. 8. The front and rear edges of the existing blade 29 are all long and straight structures, and the cross-sectional chord length of the two sides of the existing blade 29 is 10mm, the string height is 1mm, the middle height is 1mm, and the end height is 1mm. The existing blade 29 has a total width of 60mm.

Result analysis:

As shown in FIG. 9 , when the airflow passes through the existing blade 29, a large vortex void area is formed on the lower surface through the leading edge structure, and the airflow leaves the blade surface before reaching the trailing edge of the blade on the upper surface.

As shown in FIG. 10 , in the cross-flow fan blade based on bionics according to the embodiment of the present invention, the leading edge 2 forms a protruding structure, so that the airflow flows in the direction of the streamline. The fluid particles obtain more kinetic energy to supplement, so the position of the separation point is moved backward, the vortex void area is significantly reduced, the airflow is better attached to the surface of the blade 27, the rear edge 3 of the blade 27 forms a concave structure, and the tip points in the direction of the fluid , This concave structure can generate strong turbidity current to maintain fluid adhesion and prevent fluid separation.

According to the above three-dimensional numerical simulation test, the front and rear piezoresistance values of the blade 27 of the present invention compared with the existing blade 29 are obtained, and the results are shown in Table 1.

Table 1 Piezoresistance values before and after the blade

As shown in Table 1, according to the calculation and analysis of the numerical simulation results, the blade 27 of the present invention can achieve the result of reducing resistance compared with the existing blade 29, and the piezoresistance is reduced by about 7Pa, a relative reduction of 12.5%.

(2) Three-dimensional numerical simulation of the cross-flow fan structure

The cross-flow fan model in this experiment is mainly composed of two parts in terms of structure: the impeller and the volute. Therefore, the model is divided into two parts to be processed separately. After the two models are built separately, they are assembled. The volute model is shown in FIG. 11 , and the structure of the impeller of the cross-flow fan of the present invention is shown in FIG. 7 . The main design parameters are: the outer diameter of the impeller is 95.7mm; the diameter ratio is 0.8114; the height of the middle part of the blade is 1.0mm; the height of the blade end is 0.8mm; the effective width of the blade is 60mm;

The three-dimensional numerical simulation of the cross-flow fan composed of the existing blades and the cross-flow fan composed of the blades of the present invention is carried out by using the FLUENT19.0 software. The impeller area is defined as a rotating area, a rotating coordinate system is used, and the fluid is given a rotational speed, and the rest of the area is a static area, and a static coordinate system is used. The calculation solver selects the pressure-based solver, enables the unsteady option, the time discrete format is the first-order implicit format, selects the Realizable k-ε turbulence model, selects the Coupled format for the pressure-velocity coupling, and activates the options Warped-Face Gradient Correction and High Order Term Relaxation. The pressure is discretized by the second-order upwind style, and the momentum, turbulent kinetic energy, and turbulent dissipation rate are all discretized by the first-order upwind style. The density of air in the flow field was set to 1.225 kg/m ³ and the viscosity was set to 1.8×10 ⁻⁵ kg (m@s). The rotational speed of the impeller of the cross-flow fan is 1000r/min, and the unsteady time step is 0.0002s. In the boundary conditions, the inlet is set as the velocity inlet, the velocity is 1m/s, the pressure outlet boundary condition, the pressure value is the ambient atmospheric pressure, the other boundaries are the wall boundary conditions, and the rest of the settings in the calculation are the default settings.

Using the same procedure to model the prior art, the existing cross-flow fan impeller structure consists of the existing circumferential array of blades 29 .

Result analysis:

As shown in Fig. 12 and Fig. 13 , compared with the prior art, the eccentric vortex at the bottom of the cross-flow fan impeller of the present invention is significantly reduced, and it is closer to the volute tongue, and the turbulent backflow near the volute tongue is reduced, and the flow field optimization effect is obvious, which can effectively Reduce gas flow resistance.

According to the above three-dimensional numerical simulation test, the piezoresistance value of the inlet and outlet of the cross-flow fan compared with the blade 27 of the present invention and the existing blade 29 is obtained, and the results are shown in Table 2.

Table 2 The piezoresistance value of the inlet and outlet of the cross-flow fan

As shown in Table 2, according to the calculation and analysis of the numerical simulation results, the blade 27 of the embodiment of the present invention can achieve the result of reducing the resistance, and the piezoresistance is reduced by about 4.08Pa, a relative reduction of 39%.

Compared with the prior art, with the bionics-based cross-flow fan blade of the present invention, the vortex area can be reduced and the shape resistance can be reduced by setting the protruding leading edge structure; the concave trailing edge structure can maintain the fluid adhesion, The separation point is moved back to reduce the differential pressure resistance; the structural features of the upper surface can inhibit the lateral flow of the airflow; the impeller structure formed by the rotating arrangement of the blades can move the eccentric vortex down, reduce the energy consumption of the fan and improve the efficiency of the fan.

The specific implementation cases described in the present invention are only preferred implementation cases of the present invention, and are not intended to limit the implementation scope of the present invention. That is, all equivalent changes and modifications made according to the content of the patented scope of the present invention shall be regarded as the technical scope of the present invention.

Claims (7)

1. A cross-flow fan blade based on bionics is characterized in that the blade (27) comprises a plurality of blade units (1) which are axially arranged along an impeller (28), the front edges (2) of the blade units (1) are protruded, the rear edges (3) are recessed, the middle parts of the upper surfaces of the blade units (1) close to the front edges (2) are higher than two sides, the middle parts of the upper surfaces of the blade units close to the rear edges (3) are lower than two sides, and the middle parts of the upper surfaces of the blade units close to the front edges (2) are higher than the middle parts of the upper surfaces of the blade units close to the rear edges (3);

the section-shaped lines of the blade unit (1) are a first arc line (7), a first straight line (8), a second straight line (9), a second arc line (10), a third straight line (11) and a fourth straight line (12) which are sequentially intersected on the windward side of the front edge (2); the leeward side of the rear edge (3) is formed by sequentially intersecting a fourth arc line (14), a fifth straight line (15), a sixth straight line (16), a fifth arc line (17), a seventh straight line (18) and an eighth straight line (19); the middle section (6) is formed by sequentially intersecting a third arc line (13), an eleventh arc line (25), a sixth arc line (20) and a twelfth arc line (26); the left side surface (4) is formed by sequentially intersecting a first arc line (7), a seventh arc line (21), a fourth arc line (14) and an eighth arc line (22); the right side surface (5) is formed by sequentially intersecting a second arc line (10), a ninth arc line (23), a fifth arc line (17) and a tenth arc line (24).

2. The cross-flow fan blade based on bionics of claim 1, characterized in that, the distance between the vertexes of the protruding structures of the leading edges (2) of two adjacent blade units (1) of the blades (27) is 4-80 mm.

3. The cross-flow fan blade based on the bionics of claim 1, characterized in that, the vertical distance from the top point of the protruding structure of the leading edge (2) of the blade unit (1) to the straight line of the two end points of the leading edge (2) is 1-20 mm.

4. The cross-flow fan blade based on the bionics as claimed in claim 1, wherein a vertical distance from a vertex of the concave structure of the trailing edge (3) of the blade unit (1) to a straight line at two end points of the trailing edge (3) is 0.5-15 mm.

5. The cross-flow fan blade based on bionics of claim 1, characterized in that, the chord length of the cross section of the blade unit (1) is 8-120 mm, the height of the middle part of the cross section is 1/10 of the chord length, and the height of the end part of the cross section is 1/12 of the chord length.

6. The cross-flow fan blade based on bionics of claim 1, characterized in that, the chord length of the middle section (6) of the blade unit (1) is 9-130 mm, the height of the middle section (6) is 1/13 of the chord length, and the height of the end of the middle section (6) is 1/20 of the chord length.

7. The bionic-based crossflow blower blade according to claim 1, wherein the total width of the blade (27) is 50-800 mm.

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