Centrifugal fan and range hood

Abstract

The invention relates to a centrifugal fan and a range hood. The centrifugal fan comprises a first disc and a second disc which are oppositely arranged in the front-back direction; each blade is further provided with a front edge corresponding to the air inlet side and a tail edge corresponding to the air outlet side; and the length size of the waveform section in the axial direction of the impeller is marked as H, and H meets the following conditions: 0.8 Dn < = D1 < = Dn, 0.5 < = Hz / Hq < = 2, and 0.05 < = H3 < = 0.3 HZ. The method has the advantages that the problems that a trailing edge structure destroys flowing of a main flow area, the falling vortex frequency is not improved well, and the vortex intensity is intensified can be effectively solved.

Description

Technical Field

[0001] This invention relates to the field of range hood technology, and more particularly to a centrifugal fan and a range hood. Background Technology

[0002] A range hood is a kitchen appliance used to purify the kitchen environment. The centrifugal fan is a key component of a range hood. A centrifugal fan generally consists of a volute, an impeller rotating within the volute, and a motor that drives the impeller. Existing centrifugal fan impellers typically have blades that are straight, single-arc sheet metal structures, meaning their planar unfolded shape is basically rectangular. Due to the characteristics of centrifugal fans, the airflow undergoes multiple bends and changes of direction during its flow, resulting in vortex phenomena caused by flow separation at both ends of the impeller, and also dynamic and static interference with the volute. Existing patents include those that use airfoil designs on blades to reduce flow separation, but these airfoil blades are generally thicker, which reduces the impeller's work capacity. For example, patent application CN202220333700.2 discloses a similar method for impellers, centrifugal fans, and range hoods. Other patents disclose methods for breaking eddies and reducing noise by independently setting equidistant or proportionally varying waves on the leading or trailing edge of the blades. For example, patent application CN202010739577.X discloses a similar method for blades used in centrifugal fans, centrifugal fans, and range hoods.

[0003] However, in existing centrifugal fan technology, the trailing edge of the impeller blades employs toothed or wave-shaped noise reduction designs, primarily for improving wake vortices and modulating acoustic coherence. Typically, toothed or wave-shaped structures are incorporated throughout the entire impeller section. Even in some existing designs that utilize localized wave designs, the structural dimensions / distribution are only related to the blade shape or size. However, in actual fan design, blades are not entirely independent design elements; their aerodynamic performance is strongly correlated with inlet conditions. If the inlet conditions do not match the blade configuration, it can lead to unsatisfactory wake vortex reduction and even disrupt the original stable flow region. This is the main reason why existing impeller blade trailing edge noise reduction structures are not truly effective. Therefore, existing centrifugal fans require further improvement. Summary of the Invention

[0004] The first technical problem to be solved by the present invention is to provide a centrifugal fan that can effectively avoid the problem of trailing edge structure disrupting the flow in the mainstream area, and that the improvement of the shedding vortex frequency is not good, but rather aggravates the problem of vortex intensity.

[0005] The second technical problem to be solved by the present invention is to provide a range hood that uses the above-mentioned centrifugal fan, in view of the current state of the prior art.

[0006] The technical solution adopted by this invention to solve the first technical problem is: a centrifugal fan, comprising:

[0007] volute and impeller;

[0008] A collector is provided at the air inlet of the volute.

[0009] The impeller includes a first disk and a second disk arranged opposite to each other in the front-to-back direction, with the first disk located at the air inlet of the fan.

[0010] Multiple blades are connected between the first and second discs and distributed circumferentially. Each blade also has a leading edge on the air inlet side and a trailing edge on the air outlet side.

[0011] The trailing edge of at least one blade is provided with a straight segment away from the first disk and a wave-shaped segment connected to the straight segment and close to the first disk. The length of the wave-shaped segment in the axial direction of the impeller is denoted as H, and H satisfies the following condition:

[0012] And 0.8D n ≤D1≤D n 0.5≤H z / H q ≤2, 0.05H Z ≤H3≤0.3H Z ;

[0013] Where D1 is the maximum diameter of the collector inlet. The maximum diameter of the collector inlet can be understood as follows: if the collector inlet is a non-circular, irregularly shaped inlet, the maximum diameter of the collector inlet should be the maximum distance between two points on the collector's perimeter that pass through the center of the collector; if the collector inlet is circular, then it is the inlet diameter. n H is the minimum inner diameter of the impeller, that is, the minimum diameter formed by the leading edge of the blade in the radial direction; z Let H be the axial depth of the impeller. For a single-inlet fan, the first disc is the front disc, and the second disc is the rear disc. z This refers to the distance between the front and rear discs of the impeller. For a dual-inlet centrifugal fan, the first disc can be either the front or rear disc, and the second disc is the middle disc. The H mentioned... z This refers to the axial depth on one side, that is, the distance from the front or rear disc of the impeller to the middle disc; H q D1 is the depth of the air inlet space located at the front or rear of the centrifugal fan within the casing, measured as the distance from the outer wall of the corresponding air inlet side of the volute to the inner wall of the front casing. H3 is the length of the straight segment of the blade trailing edge along the impeller axis. The length of the trailing edge wavy segment is affected by the length of the recirculation zone, while the length of the leading edge recirculation zone is affected by two dimensions: the ratio of the collector to the impeller inner diameter and the ratio of the air inlet space in front of the fan to the depth of the corresponding side impeller. If only one dimension is considered, the noise reduction effect and aerodynamic performance cannot achieve a good balance. Therefore, D1 is limited to 0.8D.n ≤D1≤D n This is because the collector diameter is less than 0.8D. n If the fan inlet size is too small, it will affect the air intake volume, while if it is larger than D... n When this happens, the airflow at the inlet edge directly enters the blade passage, affecting aerodynamic performance; for the aforementioned H q If there are other components such as sound-absorbing boxes on the inner wall of the casing, then it is the distance from the outer surface of the volute to the surface of other components on the inner wall of the front casing. When H q When the thickness is not uniform, the arithmetic mean distance H is used. qc , Area element A is generally taken as the effective ventilation area enclosed by the air inlet of the collector; range hoods are limited by installation conditions such as cabinet depth, therefore, H q It should not be too large, generally not exceeding H z Twice as much, H q The length of the straight section should not be too small, as this would result in insufficient space on the air intake side of the first disc, hindering airflow. Considering that the increased blade length in the main flow area of ​​the impeller in this straight section can enhance work capacity to some extent, it will weaken noise reduction. Therefore, the length of the straight section should not be too long. Furthermore, the length of the straight section should meet installation requirements; specifically, the length of the straight section along the impeller axis must meet the requirement of 0.05H. z ≤H3≤0.3H z .

[0014] Centrifugal fans are divided into single-inlet fans and double-inlet fans. For a single-inlet fan, the axial length of the blades refers to the length of the blades between the front disc and the middle disc. For a double-inlet fan, the blades are divided into two segments, front and rear, with the middle disc as the boundary. At least one of the two blade segments includes the wave-shaped segment at its leading edge. The axial length of the blades refers to the length of the blades on one side, that is, the length of the blades between the front or rear disc and the middle disc.

[0015] In some alternative embodiments, the waveform segment includes a first waveform segment positioned relatively adjacent to the first disc and a second waveform segment positioned relatively far from the first disc, wherein the length H1 of the first waveform segment is the corresponding length of the blade recirculation zone, i.e. The remaining portion after removing the first waveform segment is the second waveform segment, and the length H2 of the second waveform segment satisfies H2 = H - H1; the maximum wavelength of the first waveform segment is less than or equal to the minimum wavelength of the second waveform segment.

[0016] The wavelength of the first waveform segment increases sequentially along the axial direction of the blades away from the first disk.

[0017] The wavelength of the second waveform segment increases sequentially along the axial direction of the blades away from the first disc.

[0018] Since the airflow in a multi-blade centrifugal fan is not uniformly distributed along the impeller axis, the wavelength and wave height are preferably gradually distributed. For cases with high turbulence intensity, it is generally required that the waveform segment has a short wavelength and a large wave height. As the vortex situation weakens as it goes deeper into the mainstream area along the axis, the uniform design effect will be weakened. Therefore, the wavelengths of the first and second waveform segments gradually increase from the end closer to the first disc to the end farther away from the first disc, and the wave heights of the first and second waveform segments gradually increase from the end closer to the first disc to the end farther away from the first disc.

[0019] The region where the first waveform segment is located is the blade recirculation zone. A short-wavelength waveform design is preferable for the corresponding trailing edge of the blade to reduce the intensity of secondary recirculation in the reverse direction to the vortex core region. Therefore, the wavelength S1 and wave height N1 of the first waveform segment are defined as follows: The wavelength of the first waveform segment is denoted as S1, and S1 satisfies the following condition:

[0020] β is the impeller outlet angle, and the value range of β is: 150°≤β≤180°;

[0021] The wave height of the first waveform segment is denoted as N1, and it satisfies the following condition:

[0022] 0.01sinβL≤N1≤0.15sinβL; where L is the width of the blade after it is flattened.

[0023] The second waveform segment is located in the main flow area of ​​the impeller. It is advisable to set a wide wavelength waveform to change the trailing edge vortex shedding frequency and improve the pressure pulsation on the blade surface, thereby reducing the aerodynamic noise of the impeller during operation and improving its aerodynamic efficiency. Specifically, the wavelength of the second waveform segment is denoted as S2, and S2 satisfies the condition: S1<S2≤5S1.

[0024] The wave height of the second waveform segment is denoted as N2, and N2 satisfies the condition: 0.05L≤N2≤0.2L.

[0025] As an improvement, both the first and second waveform segments are constructed as waveform curves with concave and convex portions arranged in sequence, wherein the concave or convex portions of the waveform curves are configured as tooth-shaped, arc-shaped, or airfoil-shaped structures.

[0026] As an improvement, the wavelengths of any two adjacent bands in the first waveform segment are denoted as S1. i and S1 i+1 The wave heights are denoted as N1. i and N1 i+1 ;

[0027] The wavelength and wave height of any two adjacent bands in the first waveform segment satisfy the following condition:

[0028] S1i <S1 i+1 ≤1.3S1 i ;

[0029] 0.8N1 i ≤N1 i+1 <N1 i ;

[0030] The wavelengths of any two adjacent bands in the second waveform segment are denoted as S2. i and S2 i+1 The wave height is denoted as N2. i and N2 i+1 ;

[0031] The wavelength and wave height of any two adjacent wavebands in the second waveform segment satisfy the following condition:

[0032] S2 i <S2 i+1 ≤1.3S2 i ;

[0033] 0.8N2 i ≤N2 i+1 <N2 i .

[0034] The technical solution adopted by the present invention to solve the second technical problem is: a range hood, including a housing and a centrifugal fan disposed in the housing, wherein the centrifugal fan is the centrifugal fan described above.

[0035] Compared with the prior art, the advantages of the present invention are as follows: The impeller blade of the present invention has a waveform segment at the trailing edge, and the wavelength segment length is specifically designed based on the actual air intake conditions (inlet size of the collector and air intake space), thereby ensuring that the length of the trailing edge waveform segment can balance the aerodynamic noise and aerodynamic performance of the impeller under different air intake conditions. In a further improved scheme, the waveform segment is segmented. The first waveform segment corresponds to the recirculation zone at the blade tip, and the blade trailing edge adopts a short wavelength waveform design to reduce the intensity of secondary recirculation in the reverse vortex core area. The second waveform segment corresponds to the main flow zone of the impeller and is set with a wide wavelength waveform structure, which can change the trailing edge vortex shedding frequency and improve the pressure pulsation on the blade surface. That is, the blade trailing edge of the present invention controls the vortex breaking in the tip recirculation zone through segmented design, weakens the impact of blade size reduction on the impeller's work capacity, improves the wake vortex shedding frequency, enhances aerodynamic capability, and strengthens noise reduction effect. Attached Figure Description

[0036] Figure 1 This is a three-dimensional structural diagram of a range hood according to an embodiment of the present invention;

[0037] Figure 2This is a vertical sectional view of the range hood of the present invention, cut along the front-to-back direction. The centrifugal fan is a dual-inlet fan.

[0038] Figure 3 This is a three-dimensional structural diagram of a centrifugal fan according to an embodiment of the present invention. The centrifugal fan is a dual-inlet fan.

[0039] Figure 4 This is a vertical sectional view of a centrifugal fan according to an embodiment of the present invention, which is a dual-inlet fan.

[0040] Figure 5 This is a three-dimensional structural diagram of the impeller of a centrifugal fan according to an embodiment of the present invention. The centrifugal fan is a double-inlet fan.

[0041] Figure 6 This is a front view of the impeller blades in an embodiment of the present invention; the centrifugal fan is a dual-inlet fan.

[0042] Figure 7 The image shows a vertical sectional view of the range hood in an embodiment of the present invention, with a sound-absorbing box provided on the side wall opposite to the main air inlet of the centrifugal fan.

[0043] Figure 8 This is a vertical sectional view of the range hood of the present invention, cut along the axial direction. The centrifugal fan is a single-inlet fan.

[0044] Figure 9 This is a vertical sectional view of a centrifugal fan according to an embodiment of the present invention, cut along the front-to-back direction. The centrifugal fan is a single-inlet fan.

[0045] Figure 10 This is a front view of the impeller blades in an embodiment of the present invention. The centrifugal fan is a single-inlet fan.

[0046] Figure 11 This is a vertical sectional view of a range hood according to an embodiment of the present invention, cut along the front-to-back direction. The range hood is a different model, and the front side of the range hood of this model has a non-smooth air intake.

[0047] Figure 12 Comparison of simulated pressure cloud diagrams between the centrifugal fan of this embodiment and the prototype (bladeless trailing edge segmented waveform structure) of this invention;

[0048] Figure 13 This is a comparison diagram of the turbulent kinetic energy distribution on the volute tongue surface of the centrifugal fan in this embodiment of the invention and the prototype (bladeless trailing edge segmented waveform structure). Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0050] The specification and claims of this invention use terms indicating direction, such as "front," "rear," "upper," "lower," "left," "right," "side," "top," and "bottom," to describe various exemplary structural parts and elements of the invention. However, these terms are used herein merely for ease of explanation and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this invention can be arranged in different orientations, these terms indicating direction are for illustrative purposes only and should not be considered as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0051] Figures 1-11 A preferred embodiment of the centrifugal fan and range hood of the present invention is shown. The range hood includes a housing 10 and a centrifugal fan 13 disposed within the housing 10. The housing 10 generally includes a fan frame 11 and a smoke collection hood 12 disposed at the bottom of the fan frame 11, with the inner cavity of the fan frame 11 communicating with the inner cavity of the smoke collection hood 12. An air inlet is provided on the front side wall of the smoke collection hood 12, through which external smoke can enter the smoke collection hood 12. The centrifugal fan 13 is disposed within the fan frame 11. When the centrifugal fan 13 operates, it generates negative pressure, allowing external oil fumes to be drawn into the smoke collection hood 12 through the air inlet. An oil screen is also provided at the air inlet of the smoke collection hood 12 for filtering oil fumes. An oil cup is provided at the bottom of the smoke collection hood 12, which is a long strip extending laterally to collect oil stains flowing down from the smoke collection hood 12. The front of the smoke hood 12 is also provided with a smoke baffle that can deflect back and forth relative to the smoke hood 12. The smoke baffle is connected to the main body of the smoke hood 12 via a hinge mechanism. Specifically, it can deflect forward to open the air inlet and deflect backward to block and close the air inlet. The hinge mechanism used to drive the deflection of the smoke baffle can be a conventional hinge mechanism in the prior art, which will not be described in detail here.

[0052] The centrifugal fan 13 is a key component of the range hood, comprising a volute 20, an impeller 30 rotating within the volute 20, and a motor 35 driving the impeller 30. The volute 20 includes a front cover plate 21 and a rear cover plate 22 facing each other, and an annular wall between the front and rear cover plates 21 and 22. The front cover plate 21 typically has a main air inlet 210, and the rear cover plate 22 has a secondary air inlet 220. Both the main air inlet 210 and the secondary air inlet 220 are equipped with collectors 211. The motor 35 is fixed to the secondary air inlet of the volute 20 via a motor 35 bracket, thus affecting the airflow at that side of the inlet to some extent. Generally, the airflow at the main air inlet 210 is greater than that at the secondary air inlet 220.

[0053] The centrifugal fan of this invention can be either a single-inlet centrifugal fan or a double-inlet centrifugal fan. The difference lies in that the impeller of the single-inlet centrifugal fan has no central disc, while the impeller of the double-inlet centrifugal fan contains a central disc. Figures 1-7 A dual-inlet centrifugal fan and a range hood using the dual-inlet centrifugal fan are shown. Figures 8-10 A single-inlet centrifugal fan and a range hood using this single-inlet centrifugal fan are illustrated. It should be further explained that the impeller of a dual-inlet fan is divided into two blade segments, with the central disc as the boundary. At least one blade segment of the blades in this invention includes a straight segment away from the first disc and a wave-shaped segment connected to the straight segment and close to the first disc. The second disc corresponds to the central disc, and the first disc corresponds to either the front or rear disc. The corresponding impeller design is applicable to either side of the blade segment. Since dual-inlet centrifugal fans currently have a wider range of applications, especially in the field of range hoods, this invention mainly uses a dual-inlet centrifugal fan as an example for explanation.

[0054] For a dual-inlet centrifugal fan, the impeller 30 includes two opposing end rings, a central disc 33 located between the two end rings, and multiple blades 34. The two end discs are divided into a front disc 31 and a rear disc 32. The multiple blades 34 are connected between the front disc 31 and the rear disc 32 and are distributed circumferentially. Each blade 34 also has a leading edge 3401 corresponding to the air inlet side and a trailing edge 3402 corresponding to the air outlet side. Each blade 34 is divided into two blade segments, front and rear, with the central disc 33 as the boundary. The blade segment corresponding to the front disc 31 is the front blade segment, and the blade segment corresponding to the rear disc 32 is the rear blade segment. Generally, the central disc 33 is positioned relatively close to the rear disc 32, meaning that the length of the front blade segment is usually greater than the length of the rear blade segment.

[0055] Most range hoods employ a top-mounted fan structure, with the centrifugal fan 13 housed within the fan frame 11. The air inlet of the centrifugal fan 13 is not open, and the airflow flows smoothly from bottom to top into the front of the fan inlet before turning at an angle to enter the centrifugal fan 13. In this case, it is necessary to construct a segmented impeller 30 noise reduction structure in relation to the dimensions of the collector 211 and the fan inlet housing. In this embodiment, smooth airflow from bottom to top means that there are no structural protrusions obstructing airflow within a certain distance Hs below the centrifugal fan 13, where Hs ≥ 0.5Hq, and Hq is the depth of the air inlet space in the fan frame 11 of the housing 10, either on the front or rear side of the centrifugal fan 13. Figure 7 As shown in the diagram; otherwise, it will cause the airflow to change direction multiple times, resulting in airflow turbulence. Figure 11 This shows a model of a traditional range hood that uses an unconventional top-mounted fan to control the airflow.

[0056] This embodiment mainly focuses on noise reduction design for the trailing edges of the two blade segments. Specifically, the trailing edges of both blade segments include a straight segment 363 away from the front disc 31 and a wave segment 360 connected to the straight segment and close to the front disc 31. The wave segment 360 includes two wave segments: a first wave segment 361 and a second wave segment 362. The one closer to the first disc is designated as the first wave segment 361, and the one farther from the first disc is designated as the second wave segment 362. The extension direction of the straight segment 363 is parallel to or at an angle to the axis of the impeller. The wavelength of the first wave segment 361 is smaller than the wavelength of the second wave segment 362. The first wave segment 361, the second wave segment 362, and the straight segment 363 are sequentially connected or spaced apart along the length of the blade. The first waveform segment 361 mentioned above is not limited to starting at the end of the blade. For example, a short straight segment (not shown) can be added at the end. The first waveform segment 361, the second waveform segment 362 and the straight segment 363 can also be discontinuous. That is, other corresponding transition segments, such as straight segments or other structural designs, can be added between any two segments.

[0057] The length of the waveform segment 360 along the axis of the impeller 30 is denoted as H, and H satisfies the following condition:

[0058] And 0.8D n ≤D1≤D n 0.5≤H z / H q ≤2, 0.05H Z ≤H3≤0.3H Z ;

[0059] Where D1 is the maximum diameter of the inlet of collector 211. The maximum diameter is relative to the irregular inlet of collector 211. If the inlet of collector 211 is perfectly circular, then it is the inlet diameter; D n H represents the minimum inner diameter of the impeller (30), which is the minimum diameter formed by the leading edge of the blade in the radial direction; z H represents the axial depth of impeller 30, i.e., the distance from the front or rear disc of impeller 30 to the middle disc 33; q H3 is the depth of the air inlet space within the casing 10 located in front of or behind the centrifugal fan 13, measured as the distance from the outer surface of one side perpendicular to the volute 20 to the inner wall of the front casing 10; H3 is the length of the straight segment 363 at the trailing edge. However, considering that the increase in the length of the blades 34 in the main flow area of ​​the impeller 30 due to this straight segment 363 can enhance the work capacity to some extent, it will weaken the noise reduction effect. Therefore, the length of the straight segment 363 should not be too long. At the same time, the length of the straight segment 363 should meet the installation requirements. Specifically, the length of the straight segment 363 in the axial direction of the impeller 30 should meet 0.05H. z ≤H3≤0.3H zThe length of the trailing edge waveform segment 360 is affected by the length of the recirculation zone, which in turn is affected by two dimensions: the ratio of the inner diameter of the collector 211 to that of the impeller 30, and the ratio of the inlet space in front of the centrifugal fan 13 to the depth of the corresponding side impeller 30. If only one dimension is considered, the noise reduction effect and aerodynamic performance cannot achieve a good balance. Therefore, limiting D1 to 0.8D... n ≤D1≤D n This is because the diameter of collector 211 is less than 0.8D. n If the inlet size of centrifugal fan 13 is too small, it will affect the air intake volume; if it is larger than D, it will affect the air intake volume. n If the airflow at the inlet edge directly enters the blade passage, it will affect aerodynamic performance; if there are other components such as sound-absorbing boxes on the inner wall of the casing 10, H q This is the distance from the outer surface of the volute 20 to the surface of other components on the inner wall of the front housing 10. When H q When the thickness is not uniform, the arithmetic mean distance H is used. qc , Area element A is generally taken as the effective ventilation area enclosed by the air inlet of the collector 211; range hoods are limited by installation conditions such as cabinet depth, therefore, H q It should not be too large, generally not exceeding H z Twice as much, H q It should not be too small, otherwise the air intake space on the front disc 31 or rear disc 32 will be too small, resulting in poor air intake.

[0060] The length of the first wave segment 361 of the trailing edge of the blade along the axis of the impeller is denoted as H1, where H1 satisfies the following condition:

[0061]

[0062] The length of waveform segment 360 minus the length of the first waveform segment 361 is the remaining part of the second waveform segment 362. The length H2 of the second waveform segment 362 satisfies H2 = H - H1.

[0063] The maximum wavelength of the first waveform segment 361 is less than or equal to the minimum wavelength of the second waveform segment 362.

[0064] The region where the first waveform segment 361 is located is the recirculation region of blade 34. The trailing edge of blade 34 should preferably adopt a short-wavelength waveform design to reduce the intensity of secondary recirculation in the reverse direction to the vortex core region. Therefore, the wavelength S1 and wave height N1 of the first waveform segment 361 are defined as follows: The wavelength of the first waveform segment 361 is denoted as S1, and S1 satisfies the following condition:

[0065] β is the impeller outlet angle of 30°, and the value range of β is: 150°≤β≤180°;

[0066] The wave height of the first waveform segment 361 is denoted as N1, and it satisfies the following condition:

[0067] 0.01sinβL≤N1≤0.15sinβL; where L is the width dimension of the blade after it is flattened.

[0068] The second waveform segment 362 is located in the main flow area of ​​the impeller 30. It is advisable to set a wide wavelength waveform to change the trailing edge vortex shedding frequency and improve the pressure pulsation on the surface of the blade 34, thereby reducing the aerodynamic noise of the impeller 30 during operation and improving its aerodynamic efficiency. Specifically, the wavelength of the second waveform segment 362 is denoted as S2, and S2 satisfies the condition: S1<S2≤5S1.

[0069] The wave height of the second waveform segment 362 is denoted as N2, and N2 satisfies the condition: 0.05L≤N2≤0.2L.

[0070] As an improvement, both the first waveform segment 361 and the second waveform segment 362 are constructed as waveform curves with concave and convex portions arranged in sequence, wherein the concave or convex portions of the waveform curves are configured as tooth-shaped, arc-shaped or airfoil-shaped structures.

[0071] Since the airflow in the multi-blade centrifugal fan 13 is not uniformly distributed in the axial direction of the impeller 30, the wavelength and wave height are preferably gradually distributed. For cases with high turbulence intensity, it is generally required that the waveform segment has a short wavelength and a large wave height. As the axial direction extends closer to the mainstream area, the vortex situation will weaken, and the uniform design effect will be weakened. Therefore, the wavelengths of the first waveform segment 361 and the second waveform segment 362 gradually increase from the end near the front plate 31 to the end away from the front plate 31, or gradually increase from the end near the rear plate 32 to the end away from the rear plate 32. The wave heights of the first waveform segment and the second waveform segment gradually increase from the end near the first plate to the end away from the first plate.

[0072] Specifically, as an improvement, the wavelengths of any two adjacent bands in the first waveform segment 361 are denoted as S1. i and S1 i+1 The wave heights are denoted as N1. i and N1 i+1 ;

[0073] The wavelengths and wave heights of any two adjacent bands in the first waveform segment 361 satisfy the following conditions:

[0074] S1 i <S1 i+1 ≤1.3S1 i ;

[0075] 0.8N1 i ≤N1 i+1 <N1i ;

[0076] The wavelengths of any two adjacent bands in the second waveform segment 362 are denoted as S2. i and S2 i+1 The wave height is denoted as N2. i and N2 i+1 ;

[0077] The wavelengths and heights of any two adjacent bands in the second waveform segment 362 satisfy the following conditions:

[0078] S2 i <S2 i+1 ≤1.3S2 i ;

[0079] 0.8N2 i ≤N2 i+1 <N2 i .

[0080] The impeller blade trailing edge structure of this embodiment adopts a segmented design. The trailing edges of both the front and rear blade segments include a straight segment 363 adjacent to the central disk and two wave segments away from the central disk. The one of the two wave segments away from the central disk is denoted as the first wave segment 361, and the one closer to the central disk is denoted as the second wave segment 362. The extension direction of the straight segment 363 is parallel to or at an angle to the axis of the impeller. The wavelength of the first wave segment 361 is smaller than the wavelength of the second wave segment 362. The straight segment 363 corresponding to the middle of the blade can easily fix each blade. The first wave segment 361 corresponds to the recirculation area at the tip of the blade. The trailing edge of the blade adopts a short-wavelength waveform design, which reduces the secondary recirculation intensity of the reverse vortex core area. The second wave segment 362 corresponds to the main flow area of ​​the impeller. It is set with a wide-wavelength waveform structure, which can change the trailing edge vortex shedding frequency and improve the pressure pulsation on the blade surface, thereby reducing the aerodynamic noise of the impeller during operation and improving its aerodynamic efficiency. The blade trailing edge of this invention uses a segmented design to control vortex breaking in the tip recirculation zone, thereby reducing the impact of blade size reduction on the impeller's work capacity, improving the wake vortex frequency, enhancing aerodynamic capability, and increasing noise reduction effect.

[0081] Figure 12 The simulation comparison of pressure cloud maps between the centrifugal fan of this embodiment and a prototype with a segmented waveform structure without a blade trailing edge (i.e., using a conventional rectangular blade structure) is shown. It can be seen that the area of ​​the high-pressure, low-speed zone at the impeller outlet in the volute region of the prototype is larger than that of the waveform structure with a trailing edge in this embodiment. High pressure indicates a larger low-speed vortex region, meaning that the noise reduction structure design of the blade trailing edge in this embodiment can reduce wake vortices within the blade passage. Simultaneously, from... Figure 13As shown in the diagram, the turbulent kinetic energy distribution on the surface of the volute tongue can also improve the turbulent kinetic energy distribution on the surface of the volute tongue, and the areas with strong turbulent kinetic energy are also weakened.

[0082] In this embodiment, the centrifugal fan is designed for a situation where the centrifugal fan is located inside the fan frame and the air inlet is not open. The noise reduction structure of the blade trailing edge is designed in conjunction with the overall dimensions of the collector 211 and the fan frame, and the design is weighted. Through segmented design, the vortex-breaking control of the tip recirculation zone is implemented, which reduces the impact of the blade size on the impeller's work capacity, improves the wake vortex frequency, enhances aerodynamic capability, and effectively enhances the noise reduction effect.

Claims

1. A centrifugal fan, comprising: The first and second discs are arranged opposite to each other in the front-back direction; A collector is installed at the air inlet of the volute; Multiple blades are connected between the first and second discs and distributed circumferentially. Each blade also has a leading edge on the air inlet side and a trailing edge on the air outlet side. The trailing edge of the blade includes a straight segment away from the first disk and a wavy segment connected to the straight segment and close to the first disk. The length of the wavy segment along the axis of the impeller is denoted as H, and H satisfies the following condition: And 0.8D n ≤D1≤D n 0.5≤H z / H q ≤2, 0.05H Z ≤H3≤0.3H Z ; Where D1 is the maximum diameter of the collector inlet; D n H is the minimum inner diameter of the impeller. z H represents the axial depth of the impeller. q H3 is the depth of the air intake space inside the range hood housing located in front of or behind the centrifugal fan, and is the distance from the outer wall of the side where the air inlet of the volute is located to the inner wall of the front housing; H3 is the length of the straight segment of the blade trailing edge along the axis of the impeller.

2. The centrifugal fan according to claim 1, characterized in that: The waveform segment includes a first waveform segment positioned relatively adjacent to the first disk and a second waveform segment positioned relatively far from the first disk, wherein the length H1 of the first waveform segment satisfies... The length H2 of the second waveform segment satisfies H2 = H - H1.

3. The centrifugal fan according to claim 2, characterized in that: The maximum wavelength of the first waveform segment is less than or equal to the minimum wavelength of the second waveform segment.

4. The centrifugal fan according to claim 2, characterized in that: The wavelength of the first waveform segment increases sequentially along the axial direction of the blades away from the first disk.

5. The centrifugal fan according to claim 2, characterized in that: The wavelength of the second waveform segment increases sequentially along the axial direction of the blades away from the first disc.

6. The centrifugal fan according to any one of claims 2-4, characterized in that: The wavelength of the first waveform segment is denoted as S1, and S1 satisfies the following condition: β is the impeller outlet angle, and the value of β ranges from 150° to 180°.

7. The centrifugal fan according to any one of claims 2-4, characterized in that: The wave height of the first waveform segment is denoted as N1, and satisfies the condition: 0.01sinβL≤N1≤0.15sinβL; where L is the width dimension of the blade after it is flattened.

8. The centrifugal fan according to any one of claims 2, 3, or 5, characterized in that: The wavelength of the second waveform segment is denoted as S2, and S2 satisfies the condition: S1<S2≤5S1.

9. The centrifugal fan according to any one of claims 2, 3, or 5, characterized in that: The wave height of the second waveform segment is denoted as N2, and N2 satisfies the condition: 0.05L≤N2≤0.2L.

10. The centrifugal fan according to any one of claims 2-4, characterized in that: The wavelengths of any two adjacent bands in the first waveform segment are denoted as S1. i and S1 i+1 The wave heights are denoted as N1. i and N1 i+1 The wavelength and wave height of any two adjacent bands in the first waveform segment satisfy the condition: S1 i <S1 i+1 ≤1.3S1 i ;0.8N1 i ≤N1 i+1 <N1 i .

11. The centrifugal fan according to any one of claims 2, 3, or 5, characterized in that: The wavelengths of any two adjacent bands in the second waveform segment are denoted as S2. i and S2 i+1 The wave height is denoted as N2. i and N2 i+1 The wavelength and wave height of any two adjacent bands in the second waveform segment satisfy the condition: S2 i <S2 i+1 ≤1.3S2 i ; 0.8N2 i ≤N2 i+1 <N2 i .

12. A range hood, comprising a housing and a centrifugal fan disposed within the housing, characterized in that: The centrifugal fan is the centrifugal fan according to any one of claims 1-11.

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