SU1719719A1 - Axial fan - Google Patents

Abstract

The invention is intended to improve the aerodynamic characteristics and efficiency of axial fans, to ensure stable operation and reduce the level of acoustic noise due to the fact that the profile of each blade is formed by moving a straight line generatrix, perpendicular to the sleeve, circumferentially in the peripheral section with a radius exceeding the length of the blade 2-4 times, wherein the chord of the profile is inclined to the axis of rotation at an angle of 50-70 ° C. and the case for half the length of the blades is made stepwise with an increase in the diameter at the exit, while the gap between the case and the blades at the exit exceeds the gap at the entrance by 5-40 times. 1 hp f-ly, 2 ill.

Description

The invention relates to a blower fan, in particular, to axial fans used to cool the EC computer hardware.

Axial fans are known, comprising a housing and an impeller mounted therein, the blades of which in the root section have an exit angle of 35-50 °, and in the peripheral one - 0.4-0.6 of the angle in the root section and the ratio of the maximum diameter of the hub to the outer diameter of the wheel is 0.3-0.5.

Fans of this design, due to the loss of kinetic energy due to the swirling of the air flow in the impeller, have insufficiently high aerodynamic characteristics and efficiency.

The installation of special guideways and spreaders makes it possible to raise the aerodynamic characteristics and efficiency of axial fans, but it leads to a significant increase in the level of acoustic noise.

Closest to the present invention is a profile of an axial-flow turbomachine blade, made in the form of a conically expanding curvilinear surface, the generatrix of which intersects the axis of rotation at an angle of 90 °.

However, the use of these blades in axial fans, due to the high profile resistance to the passage of air, will significantly reduce the aerodynamic characteristics and efficiency.

The purpose of the invention is to increase the aerodynamic characteristics and efficiency of axial fans, to ensure stable operation, and to reduce the level of acoustic noise.

This goal is achieved by the fact that the profile of each blade is formed by moving a rectilinear generatrix, perpendicular to the sleeve, circumferentially in a peripheral cross section with radius RKp greater than, the length of the Ucr loam is 2-4 times, while the chord of the profile is inclined to the axis

cl

WITH

Che

4 S

rotation at an angle of 50-70 ° and the body half the length of the blades is stepped with an increase in the diameter at the exit, while the gap between the casing and the blades at the exit of the Dvikh-Drk exceeds the gap at the entrance Dv-Drk 5-40 times.

In contrast to the prototype, in the proposed fan, there is a uniform movement of the air flow with a minimum profile resistance, which leads to an increase in performance and efficiency. ensuring stable operation and reducing the level of acoustic noise. This is facilitated by the reduction in the possibility of direct impact of the escaping air against the walls of the housing.

Fig. 1 schematically shows the proposed fan: in Fig. 2, view A in Fig. 1. The fan consists of a housing 1, inside of which a driving motor 2 is mounted with an external short-circuited rotor and an impeller 3 mounted on the outer surface of it. The profile of each blade is formed by moving a linear generatrix, perpendicular to the sleeve, with a circumference in the peripheral section of radius RKp greater than the length of the blade Wcr 2-4 times, while the chord of the profile is inclined to the axis of rotation at an angle of 50-70 °.

The flow part of the fan for half the length of the working unit is made stepped with an increase in the diameter at the exit, while the gap between the housing 1 and the blades 3 at the exit Dvih-Dr-.k. exceeds the gap at the entrance of the Dx-dr. 5-40 times.

In this design, when the fan is working, the air flow is evenly moved with minimal twisting and profile resistance, which leads to an increase in performance and efficiency, ensuring stable operation and reducing the level of acoustic noise.

In accordance with the theory of Euler-Zhukovsky, the performance and pressure of the blade machines depends on the geometrical dimensions, the shape of the profile and the angles of the impeller blades

“VTV.

where / oo angle of flow in of the average flow velocity;

-productivity ratio;

f - pressure ratio. The invention proposes by increasing the areas and angles of the impeller blades to increase the performance of axial fans in

the central part so that the dynamic pressure of the air flow in any section is the same

$ V const. Naturally, an increase in the coefficient of productivity in the central part should be inversely proportional to a decrease in the size of impeller blades.

ten

R |

where

GWH-G |

- relative value

GW + G

the size of the elements of the blades; GW - the radius of the sleeve of the impeller, m; n is the radius from the sleeve.

points of the blades, m;

g - the radius from the sleeve to the peripheral

blade sections, m. Then, for maximum performance and efficiency. a corner of flow

average speed of a stream of shovels of the worker

wheels should be equal

v (1- |)

or the angle of inclination of the chord in any section arctg -tpr + a.

V (i -f)

where is the value of the angle of attack.

The length of the blades in this section

will make

360 d

n 2 (gv1 + n) ,,, m a

VK COS /, Sin T-

where m is the number of blades of the impeller;

D is the angle on the perpendicular axis of the plane between the beginning and the end.

two adjacent blades.

Thus, in comparison with the known, with the same overall dimensions, bend radii, lengths and tilt angles of external impeller blades, fans with straight lines perpendicular to the sleeve have higher performance, efficiency and stable operation.

In addition, the step expansion

the flow part beyond half the length of the impeller reduces the possibility of a direct impact of the outgoing flow against the walls of the body, which leads to a stable operation mode

fan and lower acoustic noise levels.

The tests carried out showed that the aerodynamic characteristics of the proposed axial fan greatly surpass the best samples of domestic and foreign analogues used for cooling technical equipment in the EC computer. With a lower power consumption of the electric motor up to 25 W, the performance of the fan, as compared with the previously produced impeller - spinning machine, increased from 260 to 360 m3 / h. and the level of acoustic noise was reduced from 65 to 50.5-53.5 dB.

Claims (2)

Claims. 1. An axial fan, comprising a housing and an impeller with blades installed in it, characterized in that, in order to increase productivity, efficiency and reduce the level of acoustic noise, to ensure a steady mode of operation, the profile of each blade is formed by moving a straight line generator, perpendicular a circumferential bushing, circumferentially circumferential in section with a radius exceeding the length of the blade 2-4 times, with the profile chord inclined to the axis of rotation at an angle of 50-70 °. 2. Fan pop. 1. from the lude of the th y so that the body is made stepwise in the zone of the middle of the blades with an increase in the diameter at the exit, and the gap between the body and the blades at the exit exceeds input clearance 5-40 times. Rig. Editor Y. Sereda Tehred M. Morgenthal Order 755; Circulation. Subscription I VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, 4/5 Raushsk nab. Vidl Phases. 2 Proofreader E. Lonchakova