Centrifugal movable impeller and centrifugal axial flow combined fan comprising same

Abstract

The utility model provides a centrifugal type movable impeller and a centrifugal axial flow combined fan including the same, the centrifugal type movable impeller is arranged between an impeller front cover plate and an impeller rear cover plate, the centrifugal type movable impeller comprises a plurality of blades, outlets of the blades are provided with first trailing edge points close to the impeller front cover plate, and the first trailing edge points are provided with second trailing edge points close to the impeller rear cover plate. A second trailing edge point is arranged at the position, close to the impeller rear cover plate, of an outlet of the blade, a third trailing edge point is arranged at the position, located at the outlet of the blade, between the first trailing edge point and the second trailing edge point, the radius of the third trailing edge point is the average number of the sum of the radius of the first trailing edge point and the radius of the second trailing edge point, and the radius of the third trailing edge point is equal to the sum of the radius of the first trailing edge point and the radius of the second trailing edge point. And in the meridian plane direction of the blade, the third trailing edge point is located below the connecting line of the first trailing edge point and the second trailing edge point, and the first trailing edge point, the third trailing edge point and the second trailing edge point are sequentially connected through an arc-shaped molded line to form an outlet trailing edge of the blade.

Description

TECHNICAL FIELD

[0001] The utility model relates to centrifugal impeller technical field, especially centrifugal impeller and centrifugal axial flow combined fan containing it. BACKGROUND

[0002] The centrifugal-axial flow combined fan is widely used in the current range hood industry. The centrifugal-axial flow fan, i.e. the fan using the centrifugal impeller to increase pressure and the axial flow static blade grid to recover kinetic energy, has much smaller volume than the conventional forward multi-wing fan, and the airflow direction is axial in and axial out. This brings three benefits: it is convenient to install thicker sound-absorbing and sound-insulating structure in the fan box, it is also convenient to flexibly arrange in the entire air duct, and it is convenient to use with low-resistance sound-absorbing air duct.

[0003] However, the disadvantages of the centrifugal impeller are also highlighted here: under normal working conditions, the flow rate near one side of the rear cover plate is always higher than that near the front cover plate, and flow separation is prone to occur near the front cover plate. This can cause a large area of separation at the impeller outlet, forming a clear staggered structure of wake-main flow. When the outflow in this form enters the static blade, it can form strong pressure pulsations at the static blade inlet, and further cause strong blade frequency noise.

[0004] In the prior art, the blade outlet is designed as a bevel or the length or number of blades is increased, but designing the blade outlet as a bevel can cause the front side of the blade to have a relatively strong suction effect, resulting in a clear tendency of the airflow at the impeller outlet to shift from the rear cover plate side to the front cover plate side. This can increase the separation vortex at the hub, and increasing the length or number of blades can narrow the flow passage and reduce the work efficiency; or reducing the blade curvature can require a higher rotational speed to achieve the same performance indicators, increasing noise. SUMMARY

[0005] The utility model solves the technical problem of overcoming the defects of flow separation easily occurring at the front cover plate of the impeller and a large separation vortex at the hub between the centrifugal impeller and the axial flow static blade grid in the prior art, and provides a centrifugal impeller and a centrifugal axial flow combined fan containing the same.

[0006] The utility model solves the above technical problems by the following technical solutions:

[0007] A centrifugal impeller is arranged between a front shroud and a rear shroud of the impeller, and comprises a plurality of blades. An outlet of each blade has a first trailing edge point close to the front shroud, a second trailing edge point close to the rear shroud, and a third trailing edge point between the outlet and the first and second trailing edge points. The third trailing edge point has a radius that is an average of a radius of the first trailing edge point and a radius of the second trailing edge point. In a meridian direction of the blade, the third trailing edge point is below a line connecting the first and second trailing edge points. The first, third and second trailing edge points are connected in sequence by an arc-shaped profile to form an outlet trailing edge of the blade.

[0008] In the present application, the outlet trailing edge of the blade is concave towards the blade axis by arranging the third trailing edge point at the outlet of the blade and connecting the first, third and second trailing edge points in sequence by the arc-shaped profile. Compared with the outlet trailing edge of the blade being beveled, the size of the outlet trailing edge close to the front shroud is ensured, the flow separation at the front shroud of the blade is reduced, the flow separation at the outlet of the impeller is reduced, the staggered structure of the wake-main flow is reduced, the strong pressure pulsation at the inlet of the stationary blade caused by the outflow is avoided, and the blade frequency noise is reduced. In addition, the concave outlet of the blade can overcome the suction of the flow close to the rear shroud at the front shroud, and the separation vortex at the hub between the centrifugal impeller and the axial stationary blade is reduced. The cost is low, the noise is not increased, the flow passage is not narrowed, and the working efficiency of the impeller is ensured.

[0009] Preferably, a ratio of a difference between the radius of the first trailing edge point and the radius of the third trailing edge point to a difference between the radius of the first trailing edge point and the radius of the second trailing edge point is greater than 0.6.

[0010] In the present application, the position of the third trailing edge point is obtained by the above arrangement.

[0011] Preferably, in the meridian direction of the blade, the axis of the blade is a Z axis, and the radial direction of the blade is an R axis. A curvature expression of the arc-shaped profile between the first trailing edge point and the third trailing edge point is dR / dZ, and dR / dZ<0.

[0012] In the present application, by the above arrangement, the curvature of the arc-shaped profile between the first trailing edge point and the third trailing edge point changes monotonously in the meridian direction, that is, the arc-shaped profile decreases from the first trailing edge point to the third trailing edge point along the line connecting the first and second trailing edge points.

[0013] Preferably, the curvature of the arcuate profile near the first trailing edge point is equal to 0.

[0014] In this aspect, by the above arrangement, the curvature of the arcuate profile near the first trailing edge point is increased, so that the size of the blade near the front shroud of the impeller is ensured, and the flow is smoother near the front shroud of the impeller, and the flow separation is reduced.

[0015] Preferably, the arcuate profile between the first trailing edge point and the third trailing edge point comprises a first curvature and a second curvature, wherein the curvature of the arcuate profile near the first trailing edge point is the first curvature, the curvature of the arcuate profile near the third trailing edge point is the second curvature, the expression of the first curvature is d(dR / dZ) / dZ, and d(dR / dZ) / dZ≤0, and the expression of the second curvature is d(dR / dZ) / dZ, and d(dR / dZ) / dZ≥0.

[0016] In this aspect, by the above arrangement, the first curvature and the second curvature are expressed in a segmented manner, so that the shape of the arcuate profile between the first trailing edge point and the third trailing edge point is limited, the first curvature is sequentially decreased and has a smaller slope, and the second curvature is sequentially decreased and has a larger slope, compared with the arcuate profile with the same curvature, the size of the blade near the first trailing edge point, i.e. near the front shroud of the impeller, is ensured, and the size of the blade near the third trailing edge point can reduce the separation vortex at the hub between the centrifugal moving blade and the axial static blade.

[0017] Preferably, the curvature of the arcuate profile between the third trailing edge point and the second trailing edge point is expressed as dR / dZ, and dR / dZ<0.

[0018] In this aspect, by the above arrangement, the curvature of the arcuate profile between the third trailing edge point and the second trailing edge point changes monotonously along the meridian direction, i.e. the arcuate profile below the line connecting the first trailing edge point and the second trailing edge point decreases sequentially from the third trailing edge point to the second trailing edge point.

[0019] Preferably, the curvature of the arcuate profile near the second trailing edge point is equal to 0.

[0020] In this aspect, by the above arrangement, the curvature of the arcuate profile near the second trailing edge point is increased, so that the size of the blade near the exit trailing edge is increased, thereby ensuring the centrifugal force at the rear shroud of the impeller, and reducing the flow separation at the rear shroud of the impeller.

[0021] Preferably, the curvature of the arcuate profile between the third trailing edge point and the second trailing edge point gradually increases from the third trailing edge point to the second trailing edge point, and is d(dR / dZ) / dZ≥0.

[0022] In the present scheme, by the above setting, the curvature of the arc-shaped line between the third trailing edge point and the second trailing edge point is sequentially increased, thereby ensuring the size of the blade near the impeller back cover plate.

[0023] Preferably, the ratio of the radius of the first trailing edge point to the radius of the second trailing edge point is greater than or equal to 1 and less than or equal to 1.1.

[0024] In the present scheme, by the above setting, the size of the blade is limited.

[0025] A centrifugal-axial combined fan includes the centrifugal moving blade as described above, and further includes an axial static blade row, and the centrifugal moving blade is coaxially arranged with the axial static blade row.

[0026] In the present scheme, the centrifugal-axial combined fan includes the centrifugal moving blade as described above, so that the flow separation and separation vortex are improved by the blade structure, the cost is low, the flow separation and separation vortex can be overcome at the same time, the working efficiency of the impeller is improved, and the noise is low, so that the centrifugal-axial combined fan can meet the user demand.

[0027] The positive progress effect of the centrifugal-axial combined fan is that: the third trailing edge point is arranged at the blade outlet, the first trailing edge point, the third trailing edge point and the second trailing edge point are sequentially connected through the arc-shaped line, the outlet trailing edge is recessed towards the blade axis, compared with the way that the outlet trailing edge of the blade is beveled, the size of the outlet trailing edge near the impeller front cover plate is ensured, the flow separation at the front cover plate of the blade is reduced, the flow separation at the outlet of the impeller is further reduced, the staggered structure of the wake-main flow is reduced, the outflowing airflow can not form strong pressure pulsation at the inlet of the static blade when entering the downstream static blade, and the blade frequency abnormal sound is reduced. In addition, the recessed blade outlet can overcome the suction of the airflow near the impeller front cover plate to the airflow near the impeller back cover plate, so that the separation vortex at the hub between the centrifugal moving blade and the axial static blade row is reduced. Not only the cost is low, but also the noise is not increased, the flow passage is not narrowed, and the working efficiency of the impeller is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 FIG. 1 is a structural schematic view of a centrifugal-axial combined fan according to a preferred embodiment of the present application.

[0029] Figure 2 FIG. 4 is a blade meridian view of a centrifugal moving blade according to a preferred embodiment of the present application.

[0030] Figure 3 FIG. 6 is an outlet airflow angle cloud chart of an impeller according to a preferred embodiment of the present application.

[0031] Figure 4The impeller outlet separation vortex comparison chart of the preferable embodiment of the utility model.

[0032] Mark explanation:

[0033] Impeller front cover plate 10

[0034] Impeller rear cover plate 20

[0035] Blade 30

[0036] Outlet 31

[0037] First trailing edge point 1

[0038] Second trailing edge point 2

[0039] Third trailing edge point 3 Specific implementation

[0040] The utility model discloses a preferable embodiment is shown below, and the more clear and complete explanation of the utility model is combined with the drawings.

[0041] The embodiment provides a centrifugal impeller, and the specific structure is as shown in Figure 1 And Figure 2 The centrifugal impeller is arranged between the impeller front cover plate 10 and the impeller rear cover plate 20, and the centrifugal impeller includes a plurality of blades 30, the first trailing edge point 1 is arranged at the outlet 31 of the blade 30 and close to the impeller front cover plate 10, the second trailing edge point 2 is arranged at the outlet 31 of the blade 30 and close to the impeller rear cover plate 20, and the third trailing edge point 3 is arranged between the first trailing edge point 1 and the second trailing edge point 2 at the outlet 31 of the blade 30, wherein the radius of the third trailing edge point 3 is the average of the sum of the radius of the first trailing edge point 1 and the radius of the second trailing edge point 2, and along the meridian direction of the blade 30, the third trailing edge point 3 is arranged below the line connecting the first trailing edge point 1 and the second trailing edge point 2, and the first trailing edge point 1, the third trailing edge point 3 and the second trailing edge point 2 are sequentially connected by an arc-shaped profile to form the outlet trailing edge of the blade 30.

[0042] Specifically, along the meridian direction of the blade 30, the first trailing edge point 1 and the second trailing edge point 2 are arranged at the outlet 31 of the blade 30, the radius of the first trailing edge point 1 is greater than the radius of the second trailing edge point 2, the region between the first trailing edge point 1 and the second trailing edge point 2 is the outlet 31 region of the blade 30, the first trailing edge point 1 and the second trailing edge point 2 are connected by a line, the line is a straight line, and the line is indicated by a dashed line to form the blade 30 with the outlet 31 as the oblique side, and the third trailing edge point 3 is arranged below the line, i.e. close to the region of the axis of the blade 30, and the first trailing edge point 1, the third trailing edge point 3 and the second trailing edge point 2 are sequentially connected by an arc-shaped profile to form the outlet trailing edge of the blade 30.

[0043] The radius of the third trailing edge point 3 is the sum of the radii of the first trailing edge point 1 and the second trailing edge point 2, divided by 2. This means that the exit trailing edge of the blade 30 formed by the arc-shaped profile is recessed towards the axis of the blade 30 compared to the blade 30 with an inclined exit 31. Limiting the radius of the third trailing edge point 3 ensures the size of the exit trailing edge near the impeller front cover plate 10, enhancing the work capacity of the blade 30 near the impeller front cover plate 10, reducing flow separation at the blade front cover plate 10, and thus reducing flow separation at the impeller exit. It also reduces the staggered structure of the wake and main stream, preventing strong pressure pulsations at the inlet of the downstream stationary blade when the outflow enters, thereby reducing blade frequency noise.

[0044] In addition, such as Figure 3 and Figure 4 As shown, the recessed blade 30 outlet 31, compared to the blade 30 with an inclined outlet 31, can overcome the suction of airflow near the impeller front cover plate 10 to the impeller rear cover plate 20. This is because the radius of the blade 30 with an inclined outlet 31 near the impeller front cover plate 10 is larger. To ensure that the blade 30 can weaken the original flow separation at the impeller front cover plate 10, the radius of the blade 30 at that location must be 5-10% larger than the radius near the impeller rear cover plate 20. The recessed blade 30 outlet 31 can overcome the above problem while reducing flow separation, that is, simultaneously reducing the separation vortex at the hub between the centrifugal impeller and the axial flow stationary blade grating. In this embodiment, the blade 30 is not only inexpensive, but also does not increase noise and avoids narrowing the flow channel, thus ensuring the working efficiency of the impeller.

[0045] In this embodiment, the ratio of the difference between the radius of the first trailing edge point 1 and the radius of the third trailing edge point 3 to the difference between the radius of the first trailing edge point 1 and the radius of the second trailing edge point 2 is greater than 0.6. By substituting the radii of the first trailing edge point 1 and the second trailing edge point 2, the position of the third trailing edge point 3 is obtained, thereby ensuring that the outlet 31 of the blade 30 is recessed towards the axis of the blade 30.

[0046] In another preferred embodiment, the ratio of the difference between the radius of the first trailing edge point 1 and the radius of the third trailing edge point 3 to the difference between the radius of the first trailing edge point 1 and the radius of the second trailing edge point 2 is greater than 0.75. By incorporating the radii of the first trailing edge point 1 and the second trailing edge point 2, compared to a ratio greater than 0.6, a ratio of 0.75 results in a smaller indentation depth of the blade 30, leading to more uniform and smoother airflow as it passes over the blade 30.

[0047] In this embodiment, along the meridional plane direction of the blade 30, the axis of the blade 30 is the Z-axis, and the radial direction of the blade 30 is the R-axis. The curvature expression of the arc-shaped profile between the first trailing edge point 1 and the third trailing edge point 3 is dR / dZ, and dR / dZ < 0.

[0048] Specifically, the curvature of the arcuate profile between the first trailing edge point 1 and the third trailing edge point 3, also referred to as the slope, is described by the derivative, and on the basis of determining the value range of the third trailing edge point 3, the values of the third trailing edge point 3 and the first trailing edge point 1 are substituted into dR / dZ, and dR / dZ < 0. It can be understood that the arcuate profile between the first trailing edge point 1 and the third trailing edge point 3 is monotonically decreasing, that is, the arcuate profile along the lower side of the line connecting the first trailing edge point 1 and the second trailing edge point 2 decreases from the first trailing edge point 1 to the third trailing edge point 3 in turn, so as to form a concave part of the outlet trailing edge. From the front shroud 10 to the middle region of the outlet 31 of the blade 30, the radius of the outlet 31 of the blade 30 is monotonically decreasing, and the radius of the outlet 31 of the blade 30 is the largest near the front shroud 10. Therefore, the working capacity of this place is the strongest, and the fluid can be more adsorbed on the side of the front shroud 10, and the separation is inhibited.

[0049] Preferably, in the present embodiment, the curvature of the arcuate profile near the first trailing edge point 1 is equal to 0.

[0050] Specifically, the arcuate profile decreases from the first trailing edge point 1 to the third trailing edge point 3, and the curvature of the arcuate profile near the first trailing edge point 1 is equal to 0, that is, by increasing the curvature of the arcuate profile near the first trailing edge point 1, the radius of the blade 30 at this place is increased, and the size of the outlet trailing edge at this place is increased accordingly, thereby ensuring the working efficiency of the impeller, and the airflow near the front shroud 10 is more smooth, and the flow separation is reduced.

[0051] In addition, near the side of the front shroud 10, the change of the radius of the outlet 31 of the blade 30 is smaller than that of the outlet 31 of the blade 30 with an oblique side, so as to avoid that the radius of the outlet 31 of the blade 30 near the side of the front shroud 10 is too large, which leads to an increase in the wheel resistance loss.

[0052] In the present embodiment, the arcuate profile between the first trailing edge point 1 and the third trailing edge point 3 includes a first curvature and a second curvature, wherein the curvature of the arcuate profile near the first trailing edge point 1 is the first curvature, the curvature of the arcuate profile near the third trailing edge point 3 is the second curvature, the expression of the first curvature is d(dR / dZ) / dZ, and d(dR / dZ) / dZ≤0, and the expression of the second curvature is d(dR / dZ) / dZ, and d(dR / dZ) / dZ≥0.

[0053] Specifically, the curvature of the arc-shaped profile between the first trailing edge point 1 and the third trailing edge point 3 is divided into a first curvature and a second curvature, the first curvature is the curvature of the arc-shaped profile close to the first trailing edge point 1, and the second curvature is the curvature of the arc-shaped profile close to the third trailing edge point 3, the curvatures of which are different, which is described by the second derivative, wherein the first curvature decreases in turn and has a small slope, and the second curvature decreases in turn and has a large slope, and the slope of the outlet trailing edge corresponding to the blade 30 presents a trend of first small and then large from the first trailing edge point 1 to the third trailing edge point 3. That is, the first curvature and the second curvature are expressed in a segmented manner, which limits the shape of the arc-shaped profile between the first trailing edge point 1 and the third trailing edge point 3, that is, the specific shape of the arc-shaped profile is obtained, and compared with the arc-shaped profile with the same curvature, the size of the blade 30 close to the first trailing edge point 1, that is, close to the front cover plate 10 of the impeller, is guaranteed, and the size of the blade close to the third trailing edge point 3 can reduce the separation vortex at the hub between the centrifugal moving blade and the axial static blade.

[0054] In the embodiment, the curvature expression of the arc-shaped profile between the third trailing edge point 3 and the second trailing edge point 2 is dR / dZ, and dR / dZ<0.

[0055] Specifically, in the meridian direction, the curvature of the arc-shaped profile between the third trailing edge point 3 and the second trailing edge point 2 changes monotonously, and the numerical values of the third trailing edge point 3 and the second trailing edge point 2 are substituted into dR / dZ and dR / dZ<0 on the basis of determining the value range of the third trailing edge point 3. That is, the arc-shaped profile below the line connecting the first trailing edge point 1 and the second trailing edge point 2 decreases in turn from the third trailing edge point 3 to the second trailing edge point 2 to form another part of the concave outlet trailing edge, and the other part of the concave outlet trailing edge is connected with the part of the outlet trailing edge decreasing in turn from the first trailing edge point 1 to the third trailing edge point 3 to form a complete outlet trailing edge. At the same time, from the middle region of the outlet 31 of the blade 30 to the rear cover plate 20 of the impeller, the radius of the outlet 31 of the blade 30 monotonously decreases and has a small order of magnitude, so that the flow of the fluid close to the rear cover plate 20 of the impeller is basically not sucked and disturbed, and the separation vortex at the hub corner is not increased.

[0056] Preferably, in the embodiment, the curvature of the arc-shaped profile close to the second trailing edge point 2 is equal to 0.

[0057] Specifically, the arc-shaped profile decreases in turn from the third trailing edge point 3 to the second trailing edge point 2, and the curvature of the arc-shaped profile close to the second trailing edge point 2 is equal to 0, that is, by increasing the curvature of the arc-shaped profile close to the second trailing edge point 2, the radius of the blade 30 at this position is increased, and the size of the outlet trailing edge at this position is increased, thereby guaranteeing the centrifugal force at the rear cover plate of the impeller and reducing the flow separation at this position.

[0058] In the embodiment, the curvature of the arc-shaped profile between the third trailing edge point 3 and the second trailing edge point 2 gradually increases from the third trailing edge point 3 to the second trailing edge point 2, and d(dR / dZ) / dZ≥0.

[0059] Specifically, the curvature of the arc-shaped profile between the third trailing edge point 3 and the second trailing edge point 2 monotonously changes, and the slope of the outlet trailing edge corresponding to the blade 30 has a tendency of gradually increasing from the third trailing edge point 3 to the second trailing edge point 2. The arc-shaped profile between the third trailing edge point 3 and the second trailing edge point 2 is limited by the second derivative, that is, the specific shape of the arc-shaped profile is obtained, and the size of the blade 30 near the second trailing edge point 2, that is, near the impeller back plate 20 is ensured compared with the arc-shaped profile with the same curvature.

[0060] In the embodiment, the ratio of the radius of the first trailing edge point 1 to the radius of the second trailing edge point 2 is greater than or equal to 1 and less than or equal to 1.1. By introducing the radius of the first trailing edge point 1 and the second trailing edge point 2, the size of the blade is limited.

[0061] In another preferred embodiment, the ratio of the radius of the first trailing edge point 1 to the radius of the second trailing edge point 2 is greater than or equal to 1.05 and less than or equal to 1.08. By introducing the radius of the first trailing edge point 1 and the second trailing edge point 2, compared with the ratio greater than or equal to 1 and less than or equal to 1.1, the airflow flowing through the blade 30 is more uniform and smooth.

[0062] The embodiment also provides a centrifugal-axial combined fan, which comprises the centrifugal moving impeller described above and further comprises an axial static blade row, and the centrifugal moving impeller is coaxially arranged with the axial static blade row.

[0063] Specifically, the centrifugal-axial combined fan comprises the centrifugal impeller described above, and the centrifugal impeller is coaxially arranged with the axial static blade row in the air inlet direction. The centrifugal impeller improves flow separation and separation vortex through the blade structure, has low cost, improves the working efficiency of the impeller, and has low noise, so that the centrifugal-axial combined fan can meet the user demand.

[0064] Although the specific embodiments of the utility model are described above, those skilled in the art should understand that this is only an example, and the protection scope of the utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the utility model, and these changes and modifications all fall within the protection scope of the utility model.

Claims

1. A centrifugal impeller disposed between an impeller front shroud and an impeller rear shroud, the centrifugal impeller including a plurality of blades, wherein, The first tail edge point, the third tail edge point and the second tail edge point are connected by an arc-shaped profile in sequence to form an outlet tail edge of the blade.

2. The centrifugal impeller of claim 1, wherein The ratio of the radius of the first tail edge point to the radius of the third tail edge point minus the ratio of the radius of the first tail edge point to the radius of the second tail edge point is greater than 0.

6.

3. The centrifugal impeller of claim 1 wherein, In the meridian direction of the blade, the axis of the blade is Z axis and the radial direction of the blade is R axis, wherein the curvature expression of the arc-shaped profile between the first tail edge point and the third tail edge point is dR / dZ, and dR / dZ<0.

4. The centrifugal impeller of claim 3 wherein, The curvature of the arc-shaped profile close to the first tail edge point is equal to 0.

5. The centrifugal impeller of claim 4 wherein, The arc-shaped profile between the first tail edge point and the third tail edge point comprises a first curvature and a second curvature, wherein the curvature of the arc-shaped profile close to the first tail edge point is the first curvature, the curvature of the arc-shaped profile close to the third tail edge point is the second curvature, the expression of the first curvature is d(dR / dZ) / dZ, and d(dR / dZ) / dZ≤0, and the expression of the second curvature is d(dR / dZ) / dZ, and d(dR / dZ) / dZ≥0.

6. The centrifugal impeller of claim 5 wherein, The curvature expression of the arc-shaped profile between the third tail edge point and the second tail edge point is dR / dZ, and dR / dZ<0.

7. The centrifugal impeller of claim 6 wherein, The curvature of the arc-shaped profile close to the second tail edge point is equal to 0.

8. The centrifugal impeller of claim 7, wherein The curvature of the arc-shaped profile between the third tail edge point and the second tail edge point gradually increases from the third tail edge point to the second tail edge point and is d(dR / dZ) / dZ≥0.

9. The centrifugal impeller of claim 1 wherein, The ratio of the radius of the first tail edge point to the radius of the second tail edge point is greater than or equal to 1 and less than or equal to 1.

1.

10. A centrifugal mixed flow fan characterized by The centrifugal-axial combined fan comprises the centrifugal moving impeller according to any one of claims 1-9, and further comprises an axial static blade row, wherein the centrifugal moving impeller is coaxially arranged with the axial static blade row.

Images