CN204610372U - A kind of centrifugal impeller of blade trailing edge band winglet - Google Patents

Abstract

The utility model discloses a centrifugal impeller with winglets on the trailing edge of blades. Due to the existence of the secondary flow in the existing centrifugal fan, the efficiency is reduced and the noise is increased. The airfoil blade pressure surface of the utility model is welded with 3 to 6 small wings; the ratio of the thickness of the small wings to the outlet height of the flow channel is 0.05 to 0.1, and the sum of the thicknesses of all the small wings does not exceed the outlet height of a single flow channel 0.3; the ratio of the length of the winglet to the length of the airfoil blade is 0.3-0.5, and the ratio of the height of the highest point to the width of the outlet of a single channel is 0.05-0.2; the top surface of the winglet is a smooth curved surface, and the top surface and the two Both sides are rounded. The utility model has a row of small wings welded at the trailing edge of the airfoil blade, which can reduce the secondary flow, increase the stability of the airflow in the flow channel, and move the separation point of the gas boundary layer to the trailing edge of the blade, which not only improves the flow efficiency, but also The aerodynamic noise is also well suppressed, which greatly increases the overall aerodynamic performance of the impeller.

Description

Centrifugal impeller with winglets on blade trailing edge

technical field

The utility model belongs to the field of ventilation equipment and relates to a centrifugal fan, in particular to a centrifugal impeller with winglets on the trailing edge of the blade.

Background technique

As a relatively common mechanical equipment, fans have been greatly improved with the development of social science and technology. The development of domestic industry has further stimulated the use of fans, and the use of fans has attracted more and more attention from users. In today's energy shortage in our country, energy saving and consumption reduction is the dream goal of many users, but there is always a lot of waste in the daily use of fans, which increases the economic cost of users. Therefore, it is imperative to improve the efficiency of fans Yes, but if you want to improve the efficiency of the fan, the most important thing is to improve the design level of the impeller. Changing the structure of the impeller is the most effective way.

Centrifugal fans are mainly composed of collectors, impellers, volutes and diffusers. The gas is directed to the impeller through the collector, and the pressure increases under the action of the rotation of the impeller. The gas coming out of the impeller is collected by the volute and guided to the outlet of the volute, and then diffused again by the diffuser, and then transported to the pipeline or discharged into the atmosphere.

Among the many components of the fan, the impeller is the most indispensable for the fan. The quality of the impeller directly affects the performance of the fan. As the heart of the centrifugal fan, the impeller generates power through a reverse pressure process to achieve the purpose of ventilation. When the airflow flows through the flow channel of the fan impeller, it will be subjected to the frictional resistance of the blade surface due to the viscous effect, resulting in flow loss, which will cause a decrease in the total pressure of the fan and affect the performance of the fan. Due to the large pressure difference between the suction surface and the pressure surface of the blade, there is generally a secondary flow of fluid from the pressure surface of the blade to the suction surface in the impeller flow channel. The wheel cover pressure will also form a secondary flow, resulting in a low-velocity zone or even separation between the wheel cover and the suction surface of the blade, forming a jet-wake structure, that is, the relative velocity near the suction surface is low, and the relative velocity near the pressure surface is high. Due to the existence of the jet-wake structure, the efficiency of the centrifugal fan decreases and the noise increases. At the blade inlet, because the airflow is close to a 90° turn, the fluid velocity at the wheel cover is higher than that at the wheel disk, which makes the airflow velocity into the blade uneven and affects the stability of the airflow.

In short, due to the existence of the secondary flow, the thickness of the boundary layer in the same flow channel is different. The boundary layer on the suction surface is obviously much thicker than the boundary layer on the pressure surface, and the boundary layer on the wheel cover is much thicker than the boundary layer on the wheel disk. In this way, not only It will cause the uneven exit velocity of the impeller to form a "jet-wake", which reduces the efficiency of the impeller and increases the noise. Moreover, the thickening of the boundary layer will lead to the separation of the boundary layer, affecting the flow of the mainstream, resulting in a large flow Losses and aerodynamic noise, which are also the main factors affecting efficiency and noise.

Contents of the invention

The purpose of this utility model is to provide a centrifugal impeller with winglets on the trailing edge of the blade, which is welded with a row of winglet structures at the trailing edge of the airfoil blade, which can effectively reduce the secondary flow. , increase the stability of the air flow in the flow channel, and move the gas boundary layer separation point to the trailing edge of the blade, which not only improves the flow efficiency, but also has a good suppression effect on aerodynamic noise, which can greatly increase the overall aerodynamic performance of the impeller.

The utility model comprises an impeller body, an airfoil blade and a small wing; 3 to 6 small wings are welded on the pressure surface of the airfoil blade; the ratio of the thickness of the small wing to the outlet height of a single flow channel is 0.05 to 0.1 , and the sum of the thicknesses of all winglets does not exceed 0.3 of the outlet height of a single channel; the trailing edge line of the winglet is aligned with the trailing edge line of the airfoil blade, and the ratio of the length to the length of the airfoil blade is 0.3 to 0.5, the highest The ratio of the height to the outlet width of a single flow channel is 0.05-0.2; the top surface of the winglet is a smooth curved surface, and the top surface and the two side surfaces are all rounded.

The beneficial effects of the utility model:

The utility model adds a winglet structure to the rear edge of the pressure surface of the blade, which can effectively prevent the secondary flow affecting the mainstream flow, improve the stability of the airflow, slow down the separation of the boundary layer, improve the flow efficiency, and reduce the aerodynamic noise. The overall performance of the fan has been greatly improved.

Description of drawings

Fig. 1 is a partially cut perspective view of the utility model;

Fig. 2 is the welding stereogram of airfoil blade and winglet in the utility model;

Fig. 3 is a sectional view of an airfoil blade and a winglet in the utility model.

In the figure: 1, impeller body, 2, airfoil blade, 3, winglet.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

As shown in Figures 1, 2 and 3, a centrifugal impeller with winglets on the trailing edge of the blades includes an impeller body 1, airfoil blades 2 and winglets 3; a plurality of winglets are welded on the pressure surface of the airfoil blade 2 3. The number of winglets can be selected between 3 and 6, and the ratio of the thickness of the winglet 3 to the height of the outlet of a single channel can be any value between 0.05 and 0.1, and the sum of the thicknesses of all the winglets should not exceed 0.3 of the outlet height of a single runner, otherwise the flow of the main flow will be seriously affected, and the efficiency will be reduced; the trailing edge line of the winglet 3 is aligned with the trailing edge line of the airfoil blade 2, and the ratio of the length to the airfoil blade 2 can It can be any value between 0.3 and 0.5, and the ratio of the height of the highest point to the outlet width of a single flow channel can be any value between 0.05 and 0.2; the top surface of the winglet 3 is a smooth curved surface, and the gap between the top surface and the two side surfaces All rounded corners make it streamlined and reduce the impact on the mainstream.

Due to the existence of the secondary flow, the existing centrifugal fan impeller has different thicknesses of the boundary layer in the same flow channel. The boundary layer on the suction surface is obviously much thicker than the boundary layer on the pressure surface, and the boundary layer on the wheel cover is thicker than the boundary layer on the wheel disk. This will not only lead to the uneven exit velocity of the impeller to form a "jet-wake", reduce the efficiency of the impeller and increase the noise, but also the thickening of the boundary layer will lead to the separation of the boundary layer, affecting the flow of the mainstream, resulting in a large The flow loss and aerodynamic noise are also the main factors affecting efficiency and noise. Especially in the large flow, high pressure centrifugal fan, this secondary flow has a great influence on the performance of the fan.

Since the tail end of the airfoil blade 2 is the part that does the most work in the impeller, the gas flow is also the most unstable section, the part with the largest pressure difference between the suction surface and the pressure surface, and also the part with the most secondary flow. The centrifugal impeller with winglets on the trailing edge of the blade adds winglets 3 to the tail end of the airfoil blade 2, which can prevent the low-velocity fluid on the pressure surface from flowing to the suction surface with low pressure, thereby preventing the secondary flow and preventing the suction surface from being The boundary layer is thickened and separated in advance, forming a separation vortex, which affects the mainstream flow, and the flow efficiency can be improved and the aerodynamic noise can be reduced through the winglet 3 . At the same time, the winglet 3 also has the effect of rectifying the mainstream in a single flow channel, which can reduce the fluctuation of the mainstream in the axial direction, make the velocity of the fluid at the outlet of the impeller more uniform, effectively reduce the "jet-wake" effect, and have a positive impact on the overall performance of the fan. Great improvement.

Claims (1)

1. A centrifugal impeller with winglets at the trailing edge of the blade, comprising an impeller body, airfoil blades and winglets, characterized in that: 3 to 6 winglets are welded on the pressure surface of the airfoil blades; The ratio of the thickness of the wing to the outlet height of a single channel is 0.05 to 0.1, and the sum of the thicknesses of all winglets does not exceed 0.3 of the outlet height of a single channel; the trailing edge line of the winglet is aligned with the trailing edge line of the airfoil blade, The ratio of the length to the length of the airfoil blade is 0.3 to 0.5, and the ratio of the height of the highest point to the width of the outlet of a single flow channel is 0.05 to 0.2; the top surface of the winglet is a smooth curved surface, and the gap between the top surface and the two sides is Round corners.