Grid design method

Abstract

The invention provides a grid design method, which comprises the following steps of: selecting linear spokes and / or arc-shaped spokes according to the distribution condition of an incoming flow velocity field; matching design is conducted on the two-dimensional spoke section, the installation angle of the spoke and the incoming flow angle of the airflow, the resistance coefficient and the airflow deflection angle serve as evaluation indexes, and then the obtained spoke section is recarved to a three-dimensional model; according to the distribution condition of a flow field in the air duct, the distance between the spokes is designed, the distribution condition of the flow field in the air duct is judged, when the airflow speeds of the upper side and the lower side in the air duct are different, the transverse spokes are densely arranged, and when the airflow speeds of the left side and the right side in the air duct are different, the longitudinal spokes are densely arranged; the spokes are arranged in the three-dimensional model according to the designed spoke spacing, and the optimization design of the shape of the whole grating is completed. According to the invention, the technical problem in the prior art that the rectification effect of the grating is poor when the incoming flow velocity of the airflow is not uniformly distributed can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of air conditioners, and in particular relates to a grille design method. Background Art

[0002] With the progress of society and the improvement of living standards, consumers not only pay attention to the economy when choosing air conditioners, but also have higher and higher requirements for comfort. Comfort not only includes the perceived temperature but also the sound quality. For cabinet units (vertical air conditioners), the unique "upper air outlet for cooling, lower air outlet for heating" mode of upper and lower air outlet technology is more in line with the natural convection characteristics of air, the vertical temperature difference in the room is smaller, and consumers feel better. However, the cabinet units developed on the existing mature upper and lower air outlet fan platform encountered an abnormal sound quality problem of discontinuous air outlet during the development process. Analysis showed that this was caused by the turbulence of the flow field in the air duct.

[0003] The related technology proposes to add a rectifier grid on the inner wall of the wind cavity to reduce the number and size of eddies, reduce eddy current noise, and improve the stability of fan operation. The rectifier idea of ​​the grid in this technology is only to improve the rectifier effect by reducing the spacing of the rectifier grid. Directly using the rectifier grid in this application or the rectifier grid manufactured using the rectifier grid design idea of ​​this application to solve the existing problem will face two problems:

[0004] 1) The rectification challenge is more difficult. The above technology is used in the air inlet of the fresh air module. The incoming flow velocity faced by the rectification grille is relatively smaller and more uniform. The rectification grille placed in the air duct faces a greater air flow impact, and the incoming flow velocity distribution is generally uneven, which greatly reduces the rectification effect.

[0005] 2) It is a problem of air volume attenuation and air volume distribution. If the rectifier grille manufactured by the rectifier grille design idea mentioned above is adopted, the grille spacing needs to be adjusted to a very small size to ensure the rectification effect. This will cause a sharp increase in air duct resistance and produce a large air volume attenuation. At the same time, excessive grille flow resistance will also cause the proportion of upper air outlet air volume to decrease sharply in the upper and lower air outlet modes, causing the fan operation to deviate from the design conditions, which may lead to other abnormal problems.

[0006] Due to technical problems in the prior art such as uneven distribution of incoming airflow velocity, excessive attenuation of air volume in the air duct caused by grille flow, and poor rectification effect of the grille, the present invention studies and designs a grille design method. Summary of the invention

[0007] Therefore, the present invention provides a grille design method, which can solve the technical problem of the grille's rectifying effect when the incoming flow velocity of the airflow is unevenly distributed in the prior art.

[0008] In order to solve the above problems, the present invention provides a grid design method, which comprises the following steps:

[0009] Step 1: Select and use straight spokes and / or curved spokes according to the distribution of the incoming flow velocity field;

[0010] Step 2: Design the two-dimensional spoke cross section, the spoke installation angle and the incoming flow angle to match the design, use the drag coefficient and the airflow deflection angle as evaluation indicators, obtain the spoke cross section and installation angle that best matches the incoming flow, and then replicate the obtained spoke cross section to the three-dimensional model;

[0011] Step 3: Design the spoke spacing according to the distribution of the flow field in the air duct, and determine the distribution of the flow field in the air duct. When there is a difference in the air flow velocity between the upper and lower sides of the air duct, the horizontal spokes are densely arranged; when there is a difference in the air flow velocity between the left and right sides of the air duct, the longitudinal spokes are densely arranged; arrange the spokes according to the designed spacing in the 3D model to complete the optimization design of the entire grille shape.

[0012] In some embodiments, in step 1, when the incoming flow velocity field is regularly distributed front, back, left, and right, straight spokes are selected; when the incoming flow velocity field is irregularly distributed, arc-shaped spokes are selected.

[0013] In some embodiments, when the flow velocity field is irregularly distributed, the bending direction of the arc-shaped spokes matches the direction from the high-speed region to the low-speed region of the incoming flow velocity field.

[0014] In some embodiments, in step 2, the two-dimensional spoke cross section is designed to match the incoming angle of the airflow, specifically in the following manner: the thickness of the spoke cross section is t, the heights of the upper and lower ends of the spoke cross section are h1 and h2, and the widths of the upper and lower ends of the spoke cross section are l1 and l2, which satisfy: h1:h2>1, l1<t, l2<t.

[0015] In some embodiments, in step 2, the installation angle of the two-dimensional spokes is designed to match the incoming angle of the airflow, specifically in the following manner: a line connecting the midpoints of the two ends of the spoke cross section is defined as the median line of the spoke cross section, a direction perpendicular to the cross section of the air duct is defined as the vertical direction, and an angle β exists between the median line of the spoke cross section and the vertical direction, which satisfies -30°≤β≤30°.

[0016] In some embodiments, in step one, when the irregular area of ​​the incoming flow velocity field is not larger than 5% of the total area of ​​the incoming flow velocity field, straight spokes are selected; when the irregular area of ​​the incoming flow velocity field is larger than 5% of the total area of ​​the incoming flow velocity field and the irregular area of ​​the incoming flow velocity field is not larger than 15% of the total area of ​​the incoming flow velocity field, multi-segment spokes are used as spokes; when the irregular area of ​​the incoming flow velocity field is larger than 15% of the total area of ​​the incoming flow velocity field, twisted spokes are used as spokes.

[0017] In some embodiments, in step three, the spacing of the spokes is designed according to the distribution of the flow field in the air duct, and the spokes are distributed with equal spacing or unequal spacing.

[0018] In some embodiments, when the spokes are distributed at equal intervals, the interval between two adjacent upper and lower spokes is bs, and the interval between two adjacent left and right spokes is bz, which satisfies 7mm≤bs≤20mm, and 30mm≤bz≤60mm.

[0019] In some embodiments, when the spokes need to be densely arranged, bi (i = 1 ~ n) is the distance between the i-th and i+1-th spokes, and the value range of bi (i = 1 ~ n) is 5 ~ 20 mm. When the spokes need to be sparsely arranged, bj (j = 1 ~ n) is the distance between the j-th and j+1-th spokes in the sparse arrangement, and the value range of bj (j = 1 ~ n) is 20 ~ 60 mm.

[0020] In some embodiments, a minimum distance D between the central axis of the fan and the grille is also included, which satisfies 400≤D≤700mm.

[0021] The grid design method provided by the present invention has the following beneficial effects:

[0022] According to the incoming flow velocity field, choose to arrange the grilles in different directions densely or sparsely to optimize the rectification effect and improve the sound quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0024] Figure 1 is a flow chart of the grid design method of the present invention;

[0025] Figure 2 is a schematic diagram of the installation angle in the grille design method of the present invention;

[0026] Figure 3 is a schematic diagram of a double-trapezoidal spoke cross section in the grille design method of the present invention;

[0027] Figure 4 is a schematic diagram of the olive-shaped spoke cross section in the grille design method of the present invention;

[0028] Figure 5is a three-dimensional diagram of the straight spokes in the grille design method of the present invention;

[0029] Figure 6 is a schematic cross-sectional view of a straight spoke of the grille design method of the present invention;

[0030] Figure 7 is a three-dimensional diagram of multiple spokes of the grille design method of the present invention;

[0031] Figure 8 is a schematic cross-sectional view of multiple spokes of the grille design method of the present invention;

[0032] Fig. 9 is a perspective view of a twisted spoke of the grille design method of the present invention;

[0033] Fig.10 is a schematic cross-sectional view of a twisted spoke of the grille design method of the present invention;

[0034] Fig.11 It is a flow field comparison diagram of a fan with a grille prepared by the grille design method of the present invention installed in the air duct and without the grille installed;

[0035] Fig.12 The velocity distribution cloud diagram when the air duct of the fan is not equipped with the grille prepared by the grille design method of the present invention;

[0036] Fig.13 A velocity distribution cloud diagram when a grille prepared by the grille design method of the present invention is installed in an air duct of a fan;

[0037] Fig.14 is a schematic diagram of a grid with straight spokes in the grid design method of the present invention;

[0038] Fig.15 is a schematic diagram of a grille with arc-shaped spokes in the grille design method of the present invention;

[0039] Fig.16 It is a schematic diagram of the installation position of the grille prepared by the grille design method of the present invention in the fan;

[0040] Fig.17 is a top view of the grille in Example 2 of the grille design method of the present invention;

[0041] Fig.18 is a 3D view of the grid in Example 2 of the grid design method of the present invention;

[0042] Fig.19 It is an assembly diagram of the grille in Example 2 of the grille design method of the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0045] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0046] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0047] See also Figure 1-16 As shown, according to an embodiment of the present invention, a method for designing a grid is provided, the method comprising the following steps:

[0048] Step 1: Select and use straight spokes and / or curved spokes according to the distribution of the incoming flow velocity field;

[0049] The grid layout is determined by the incoming flow velocity field. For the case where the incoming flow velocity field is regularly distributed front, back, left, and right, refer to Fig.14 , a grid with straight spokes can be used; for the case where the incoming flow velocity field is irregularly distributed, refer to Fig.15 , a grid with curved spokes can be used. The bending direction of the spokes is not limited to upward bending. Its bending direction matches the direction from the high-speed area to the low-speed area of ​​the incoming flow velocity field, maintaining a lower flow resistance while ensuring the rectification effect.

[0050] Step 2: Design the two-dimensional spoke cross section, the spoke installation angle and the incoming flow angle to match the design, use the drag coefficient and the airflow deflection angle as evaluation indicators, obtain the spoke cross section and installation angle that best matches the incoming flow, and then replicate the obtained spoke cross section to the three-dimensional model;

[0051] For the selection of spoke cross-sectional shape and installation angle, two important indicators are the airflow deflection angle θ and the drag coefficient C. D The resistance of an object includes the tangential stress (friction resistance) and pressure difference (pressure resistance) caused by the flow of fluid around the object. The friction resistance is affected by the viscosity of the fluid and the roughness of the surface of the object. The size of the pressure resistance is closely related to the shape of the object, so it is also called shape resistance. The resistance coefficient of the object is C D It can be determined by the following formula:

[0052]

[0053] Among them, F D is the resistance of the object, which is in the same direction as the flow velocity; ρ is the fluid density, which refers to the air density in this case; V ∞ is the incoming flow velocity, A is the cross-sectional projection area of ​​the object perpendicular to the direction of the incoming flow velocity, and a plane is made to coincide with the spoke section here. The direction of the incoming flow velocity is the velocity direction of the airflow impacting the section.

[0054] The airflow deflection angle θ is the angle between the incoming flow velocity and the airflow velocity after passing through the grille. Its size affects the flow resistance and rectification effect of the grille. If the airflow deflection angle θ is too small, there will be no rectification effect. If the airflow deflection angle θ is too large, the flow resistance of the grille will increase significantly.

[0055] Therefore, for the selection of spoke cross-sectional shape and installation angle, it is required that the airflow deflection angle θ in the incoming flow velocity field meets the design requirements, and its drag coefficient C D As small as possible.

[0056] Step 3: Design the spoke spacing according to the distribution of the flow field in the air duct, arrange the spokes according to the designed spoke spacing in the 3D model, and complete the optimization design of the entire grille shape.

[0057] The design method of the grille of the present invention is an optimized design for the grille in the air duct of the fan, and the grille is located in the air inlet or outlet of the fan.

[0058] In some embodiments, in step one, when the incoming flow velocity field is distributed regularly in front, back, left and right, straight spokes are selected, and when the flow velocity field is distributed irregularly, arc-shaped spokes are selected. Specifically, when the flow velocity field is distributed irregularly, the bending direction of the arc-shaped spokes matches the direction from the high-speed area to the low-speed area of ​​the incoming flow velocity field. Optimizing the grille layout according to the characteristics of the incoming flow velocity field can improve the sound quality and reduce the duct noise. Based on the flow-equalizing and noise-reducing layout method of the incoming flow velocity field, the grille layout is optimized and adjusted in combination with the flow field of the entire machine and the incoming flow velocity field to improve the flow-equalizing and vortex-breaking effect and improve the sound quality problem.

[0059] In the design method of the grille of the present invention, the basis for judging whether the flow velocity field is distributed irregularly is that if the incoming flow velocity field is roughly symmetrical front to back or left to right, it can be considered to be distributed regularly, otherwise it is considered to be irregular; the velocity directions are not consistent in the strict sense, but the velocity component in the vertical direction is dominant and has the same direction, so the airflow does not generate backflow along the mainstream direction (no obvious vortex area), and the velocity direction is considered to be consistent.

[0060] In some embodiments, in step 2, the two-dimensional spoke cross section is matched with the incoming flow angle of the airflow, specifically in the following manner, in combination with reference to Figure 3 and Figure 4 As shown, the thickness of the spoke cross section is t, the heights of the upper and lower ends of the spoke cross section are h1 and h2, and the widths of the upper and lower ends of the spoke cross section are l1 and l2, which satisfy: h1:h2>1, l1<t, l2<t.

[0061] In the design method of the grille of the present invention, the upper and lower ends of the spoke cross section refer to the two ends of the spoke cross section along the airflow direction, and the spoke cross section is set in the shape of a low-resistance spoke cross section. In order to further reduce the flow resistance, the spoke cross-section shape is based on the characteristics of the aerodynamic performance of airfoil blades, and the spoke cross-section adopts a quasi-double trapezoid and an olive shape. The quasi-double trapezoid means that the bottom surfaces of two trapezoids are connected to form a hexagonal form, and the olive shape means that it is formed by splicing two semi-elliptical curves, which is similar to the airfoil cross-section. The thickness of the quasi-double trapezoid spoke cross-section is t, and the heights of the upper and lower ends of the spoke cross-section are h1 and h2. If t is too large, the flow cross-sectional area will be reduced and the resistance will increase. If t is too small, the strength will be insufficient and other abnormal sound quality problems will be caused by the impact of airflow. Preferably, t=3mm, and further, the value range of t is 2-5mm. The height affects the rectification effect. If it is too short, the rectification effect is poor, and if it is too long, the flow resistance will increase. Preferably, the value range of h1+h2 is 4-10mm. h1:h2 affects the cross-sectional shape and thus affects its aerodynamic performance. The widths of the upper and lower ends of the spoke cross-section are l1 and l2, which must meet the following requirements: h1:h2>1, l1<t, l2<t. See also Figure 3 As shown, the draft angles α1 and α2 of the side edges and the upper and lower chamfers r1 and r2 are set according to production needs. Figure 4 As shown in the figure, for the olive-shaped cross section, its shape is composed of two elliptical curves. The design parameters include thickness t and upper and lower end heights h1 and h2. Thickness t is the maximum distance between the two sides. The parameter value range is the same as that of the double-trapezoidal spoke cross section. The double-trapezoidal cross section is easy to manufacture, while the olive-shaped cross section has better aerodynamic performance but is more difficult to manufacture. According to the incoming flow velocity field, the cross-sectional shape of the grille is finely optimized to reduce the grille resistance coefficient and reduce the air volume attenuation.

[0062] Since the effects of the transverse and longitudinal spokes are not necessarily the same, some mainly play a rectifying role, while others also play a supporting role and have certain requirements for their structural strength. Therefore, the cross-sectional shapes of the transverse and longitudinal spokes are not necessarily consistent.

[0063] In some embodiments, in step 2, the installation angle of the two-dimensional spokes is designed to match the incoming flow angle of the airflow, specifically in the following manner: the line between the midpoints of the two ends of the spoke cross section is defined as the median line of the spoke cross section, the direction perpendicular to the cross section of the air duct is the vertical direction, and there is an angle β between the median line of the spoke cross section and the vertical direction, which satisfies -30°≤β≤30°. According to the incoming flow velocity field, the installation angles of different spoke cross sections are optimized and adjusted to avoid a significant increase in flow resistance caused by excessive airflow deflection angles, further reduce the drag coefficient of the grille, and reduce air volume attenuation. The airflow deflection angle affects the flow resistance of the grille, but the airflow deflection angle is uncertain during design, and the installation angle β is an adjustable design parameter, and the airflow deflection angle needs to be indirectly affected by adjusting the installation angle.

[0064] See also Figure 2 and Fig.16 As shown, the fan is placed vertically, and its air duct is vertical, that is, the direction perpendicular to the cross section of the air duct is vertical, and the installation angle is designed to match the incoming flow velocity field. The installation angle β is the angle between the median line of the spoke section and the vertical direction, which is an important parameter in the grille design. Drawing on the aerodynamic characteristics of the airfoil structure, the drag coefficient of the DU97-W-300 airfoil increases sharply when the angle of attack exceeds 12° under Re=2×106. The angle of attack is the angle between the median line and the airflow direction, which has a greater impact on the airflow deflection. The range of the installation angle β is (-30°, 30°), and within this range, its drag coefficient can be guaranteed to be in a smaller range.

[0065] In some embodiments, in step one, when the irregular area of ​​the incoming flow velocity field is not larger than 5% of the total area of ​​the incoming flow velocity field, straight spokes are selected; when the irregular area of ​​the incoming flow velocity field is larger than 5% of the total area of ​​the incoming flow velocity field and the irregular area of ​​the incoming flow velocity field is not larger than 15% of the total area of ​​the incoming flow velocity field, multi-segment spokes are used as spokes; when the irregular area of ​​the incoming flow velocity field is larger than 15% of the total area of ​​the incoming flow velocity field, twisted spokes are used as spokes.

[0066] See also Figures 5 to 10 As shown, the installation angles of the sections at different positions of the same spoke can be kept the same or different. The spoke type is selected according to the characteristics of the incoming flow, combined with reference to Figure 5 and Figure 6 As shown, taking the cross section of the air duct as the projection surface, when the irregular area of ​​the incoming flow velocity field is not greater than 5% of the total area of ​​the incoming flow velocity field, the incoming flow velocity distribution is simple, and straight spokes can be selected. The total area of ​​the incoming flow velocity field is the cross-sectional area of ​​the air duct, and the area of ​​the irregular area of ​​the incoming flow velocity field is the projection area of ​​the irregular area of ​​the incoming flow velocity field on the projection surface. Figure 7 and Figure 8 When the irregular area of ​​the incoming flow velocity field is greater than 5% of the total area of ​​the incoming flow velocity field, and the irregular area of ​​the incoming flow velocity field is not greater than 15% of the total area of ​​the incoming flow velocity field, the incoming flow velocity is relatively complex, and multi-segment spokes can be selected. Multi-segment spokes are spokes that are connected in sequence and twisted between adjacent segments, that is, there is an angle between the median lines of the cross sections of two adjacent spokes. Fig. 9 and Fig.10 When the irregular area of ​​the incoming flow velocity field is greater than 15% of the total area of ​​the incoming flow velocity field, the incoming flow velocity is particularly complex, and a twisted spoke can be selected. The twisted spoke is a continuously twisted spoke. This design can reduce the overall resistance coefficient of the grille by matching the installation angle with the velocity field.

[0067] In some embodiments, in step three, the spacing of the spokes is designed according to the distribution of the flow field in the air duct, and the spokes are distributed with equal spacing and unequal spacing. Specifically, when the spokes are distributed with equal spacing, the spacing between the upper and lower adjacent spokes is bs, and the spacing between the left and right adjacent spokes is bz, which satisfies 7mm≤bs≤20mm, 30mm≤bz≤60mm. When the spokes are distributed with unequal spacing, it is specifically implemented in the following manner to determine the distribution of the flow field in the air duct. When there is a difference in the air flow velocity on the upper and lower sides of the air duct, the transverse spokes are densely arranged. When there is a difference in the air flow velocity on the left and right sides of the air duct, the longitudinal spokes are densely arranged. According to the incoming flow velocity field, choose to arrange the grilles in different directions densely or sparsely, optimize the rectification effect, and improve the sound quality problem.

[0068] The turbulent flow field in the air duct of the air conditioner can cause a series of abnormal sound quality problems. The present invention solves the abnormal sound quality problem during the operation of the air conditioner by adding a rectifier grille inside the air duct, adjusting the layout of the rectifier grille, the spoke spacing, and the installation position, thereby optimizing the internal flow field.

[0069] The structural parameters of the rectifying grid, such as cross-sectional shape, angle of attack, position, spacing, etc., have a significant impact on its rectifying effect and flow resistance. An unreasonable structural design may even worsen the flow field inside the air duct. The present invention optimizes these structural parameters to match the incoming flow velocity field, further improves the rectifying effect, and solves the problem of excessive air volume attenuation.

[0070] When the spokes need to be arranged densely, bi (i = 1 ~ n) is the distance between the i-th and i+1-th spokes, and the value range of bi (i = 1 ~ n) is 5 ~ 20 mm. When the spokes need to be arranged sparsely, bj (j = 1 ~ n) is the distance between the j-th and j+1-th spokes in the sparse arrangement, and the value range of bj (j = 1 ~ n) is 20 ~ 60 mm.

[0071] In some embodiments, a minimum distance D between the central axis of the fan and the grille is also included, which satisfies 400≤D≤700mm.

[0072] The installation position of the rectifier grid also has a great influence on the rectification effect. If the installation position is located at the rear of the diffuser section, the rectifier grid will not have a rectification effect. If the installation position is too close to the fan, the air duct at the rear of the grid is long, and there is still a high probability of generating a large-scale vortex area. For this reason, the installation position of the grid is adjusted. D represents the distance between the bottom of the grid and the center of the fan axis. Fig.16 As shown, the value range of D is 400~700mm.

[0073] For the selection of the optimal grid design parameters, an orthogonal experiment can be designed, with the spoke spacing b and the installation position design parameter D as variables, the vortex volume V and the grid resistance coefficient CD as the optimization targets, and the optimal grid design parameters can be selected when the vortex volume V≤Vup Under these conditions, we can obtain C D The parameter combination in the minimum case is the design parameter of the optimized grid. The vortex volume V is calculated through simulation, and the vortex area can be seen from the simulation cloud map, which is used to guide the area where the vortex appears, so as to facilitate the vortex breaking design.

[0074] See also Figures 11 to 13 As shown, when a grille designed by the grille design method of the present invention is added to the air outlet duct of the centrifugal fan, the air volume attenuation in the air duct is greatly reduced and obviously regular.

[0075] Example 1

[0076] This case is a cabinet unit that uses a double-suction centrifugal fan platform with upper and lower air outlets. Before installing the rectifier grille, it has a problem of discontinuous air outlet. Figure 1 According to the design idea of ​​the rectifier grid, the velocity field of the flow in front of the grid is obtained through the whole machine flow field simulation, which shows a velocity distribution of high at the bottom and low at the top, high at the right and low at the left. Therefore, the following method is adopted Fig.15 The rectifier grid shown (the horizontal spokes are bent upwards, and the longitudinal spokes are bent to the left). In order to ensure that a single spoke has a smaller flow resistance, the spoke cross section adopts a double trapezoidal shape, where t = 3mm, the upper side height of the horizontal spoke cross section h1 = 3.7mm, the lower side height h2 = 2.3mm, the upper side height of the longitudinal spoke cross section h1 = 5.5mm, the lower side height h2 = 3.5mm, and the other design parameters remain the same, specifically the top width l1 = 0.8561mm, the bottom width l2 = 0.6255mm, the upper chamfer r1 = 0.4mm, the lower chamfer r2 = 0.5mm, the upper draft angle α1 = 10°, the lower draft angle α2 = 30°, and the maximum thickness t = 3mm. For the spoke spacing b, the radial spacing bs = 17.9mm, the circumferential spacing b z Take the value (42,50)mm, and the grille installation design parameter D=400mm.

[0077] After applying this grille to the air conditioner, the flow field changes as follows Figure 1 As shown, it can be seen that the vortex area is significantly reduced, and the experience shows that the sound quality has been significantly improved. Through the wind volume noise test, it is shown in the following table

[0078]

[0079]

[0080] After adding the rectifier grille, the air volume in both the upper and lower air outlet and single upper air outlet modes is increased at the same noise level.

[0081] Example 2

[0082] This embodiment is a cabinet unit that uses a double-suction centrifugal fan platform with upper and lower air outlets. Before installing the rectifier grille, it has a problem of discontinuous air outlet. According to the design idea of ​​the grille of the present invention, the velocity field of the flow in front of the grille is obtained by simulating the flow field of the whole machine, which presents a velocity distribution of high at the bottom and low at the top, high at the right and low at the left. Therefore, the following is adopted: Figures 17 to 19 The rectifying grid shown has the horizontal spokes bent upward and the vertical spokes bent to the left.

[0083] The grille and the air outlet frame are fixed by screws, and the distance between the side of the grille and the wall of the air outlet frame is 700mm. In order to avoid other abnormal sound quality problems caused by the airflow impacting the gap between the lower rectifier grille and the air outlet frame, the lower part of the grille is extended to the inner wall of the air outlet frame to block the gap. In order to ensure that a single spoke has a small flow resistance, the spoke cross section adopts a double trapezoidal shape, where t = 3mm, the upper side height of the horizontal spoke cross section h1 = 3.7mm, the lower side height h2 = 2.3mm, the upper side height of the longitudinal spoke cross section h1 = 5.5mm, the lower side height h2 = 3.5mm, and the other design parameters remain the same, specifically the top width l1 = 0.8561mm, the bottom width l2 = 0.6255mm, the upper side fillet r1 = 0.4mm, the lower side fillet r2 = 0.5mm, the upper side draft angle α1 = 10°, the lower side draft angle α2 = 30°, and the maximum thickness t = 3mm. For the spoke installation angle β, in actual application, the transverse spoke installation angle β1 = 0°, and the longitudinal spoke installation angle β2 = 20°. For the spoke spacing b, the transverse spoke spacing bs = 17.9 mm, the longitudinal spoke spacing bz takes the value of (42,50) mm, and the grille installation design parameter D = 516 mm.

[0084] After applying this grille to the air conditioner, the test data is shown in the following table:

[0085]

[0086] It can be seen that after the whole machine grille, the air volume decreases by about 10m at the same noise level. 3 / h. Taking into account the test error of the test bench, it is judged that the air volume can remain basically unchanged after the rectifier grille, but through personal experience, it is found that the sound quality has been significantly improved.

[0087] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A method for designing a grille, characterized in that: The method comprises the following steps: Step 1: Select and use straight spokes and / or curved spokes according to the distribution of the incoming flow velocity field; Step 2: Design the two-dimensional spoke cross section, the spoke installation angle and the incoming flow angle to match the design, use the drag coefficient and the airflow deflection angle as evaluation indicators, obtain the spoke cross section and installation angle that best matches the incoming flow, and then replicate the obtained spoke cross section to the three-dimensional model; Step 3: Design the spoke spacing according to the distribution of the flow field in the air duct, and determine the distribution of the flow field in the air duct. When there is a difference in the air flow velocity between the upper and lower sides of the air duct, the horizontal spokes are densely arranged; when there is a difference in the air flow velocity between the left and right sides of the air duct, the longitudinal spokes are densely arranged; arrange the spokes according to the designed spacing in the 3D model to complete the optimization design of the entire grille shape.

2. A method for designing a grid according to claim 1, characterized in that: In the step 1, when the incoming flow velocity field is distributed regularly in front, back, left and right directions, straight spokes are selected; when the incoming flow velocity field is distributed irregularly, arc spokes are selected.

3. A method for designing a grid according to claim 2, characterized in that: When the flow velocity field is distributed irregularly, the bending direction of the arc-shaped spokes matches the direction from the high-speed area to the low-speed area of ​​the incoming flow velocity field.

4. The method for designing a grid according to claim 1, characterized in that: In step 2, the two-dimensional spoke cross section is designed to match the incoming angle of the airflow, specifically in the following manner: the thickness of the spoke cross section is t, the heights of the upper and lower ends of the spoke cross section are h1 and h2, and the widths of the upper and lower ends of the spoke cross section are l1 and l2, which satisfy: h1:h2>1, l1<t, l2<t.

5. The method for designing a grid according to claim 1, characterized in that: In the step 2, the installation angle of the two-dimensional spokes is designed to match the incoming angle of the airflow, specifically in the following manner: the line connecting the midpoints of the two ends of the spoke cross section is defined as the median line of the spoke cross section, the direction perpendicular to the cross section of the air duct is defined as the vertical direction, and there is an angle β between the median line of the spoke cross section and the vertical direction, which satisfies -30°≤β≤30°.

6. The method for designing a grid according to claim 1, characterized in that: In step one, when the irregular area of ​​the incoming flow velocity field is not greater than 5% of the total area of ​​the incoming flow velocity field, straight spokes are selected; when the irregular area of ​​the incoming flow velocity field is greater than 5% of the total area of ​​the incoming flow velocity field and the irregular area of ​​the incoming flow velocity field is not greater than 15% of the total area of ​​the incoming flow velocity field, multi-segment spokes are used as spokes; when the irregular area of ​​the incoming flow velocity field is greater than 15% of the total area of ​​the incoming flow velocity field, twisted spokes are used as spokes.

7. The method for designing a grille according to claim 1, characterized in that: In step three, the spacing of the spokes is designed according to the distribution of the flow field in the air duct, and the spokes are distributed with equal spacing and unequal spacing.

8. The method for designing a grille according to claim 7, characterized in that: When the spokes are distributed with equal spacing, the spacing between two adjacent upper and lower spokes is bs, and the spacing between two adjacent left and right spokes is bz, which satisfies 7mm≤bs≤20mm, and 30mm≤bz≤60mm.

9. The method for designing a grille according to claim 7, characterized in that: When the spokes need to be arranged densely, bi (i = 1 ~ n) is the distance between the i-th and i+1-th spokes, and the value range of bi (i = 1 ~ n) is 5 ~ 20 mm. When the spokes need to be arranged sparsely, bj (j = 1 ~ n) is the distance between the j-th and j+1-th spokes in the sparse arrangement, and the value range of bj (j = 1 ~ n) is 20 ~ 60 mm.

10. The method for designing a grid according to claim 1, characterized in that: It also includes a minimum distance D between the central axis of the fan and the grille, which satisfies 400≤D≤700mm.

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