CN110425157B - Efficient gas mixing centrifugal fan - Google Patents

Abstract

The invention discloses a high-efficiency gas mixing centrifugal fan which comprises a cover plate, a volute and a centrifugal impeller. The centrifugal impeller is arranged in the volute; the volute has a spiral flow path part surrounding the centrifugal impeller, and a throat part communicated with the spiral flow path part; the cross section of the spiral flow passage part along the air flow direction gradually becomes larger, and the air outlet passage of the throat part has a divergence angle. The invention adopts the special spiral flow passage part and the throat part design, has the advantages of simple structure and low processing difficulty, optimizes the flow of air flow in the impeller channel, improves the overall pneumatic stability and efficiency of the centrifugal fan, and ensures that the centrifugal fan has higher reliability and economy.

Description

A high-efficiency mixed air centrifugal fan

Technical field

The invention relates to the field of centrifugal fans, specifically a high-efficiency air-mixed centrifugal fan.

Background technique

The gas-mixed centrifugal fan has the advantages of compact structure, large gas-mixing flow coefficient, and high pressure rise coefficient, and is widely used in industrial boilers and household wall-mounted boilers. With the improvement of people's quality of life and the improvement of industry requirements for home appliance standards and equipment standards, efficient , stability and compactness have become the main development direction and pursuit goals of centrifugal fans.

Most current centrifugal fans adopt a backward-facing wind wheel design. The function of the centrifugal fan wind wheel is to use the blades to transition the air flow from axial air inlet to radial air outlet. Since the centrifugal fan generally has a low pressure ratio, simple structure, convenient processing, and high throughput, the blades of the centrifugal fan are generally made of The backward-facing wind wheel is designed with backward-curving blades in the centrifugal section. Although this design scheme is easy to develop, process and manufacture, and improves the overall efficiency of the fan, the problem is that the air flow turns from axial to radial flow, and the air flow does not mix inside the blades, which can easily lead to flammable gas and The air cannot be completely mixed, so that the gas provided by the fan to the boiler cannot be fully burned, which affects the stability of the centrifugal fan's air mixing. In addition, the density of the gas sent out by the fan after mixing is uneven, which reduces the efficiency of the centrifugal fan.

In addition to the impeller, the main components of the centrifugal fan also include the volute part. The function of the volute is to collect the airflow at the impeller inlet and provide mixed airflow and a certain pressure rise at the outlet. There are four types of conventional volute tongue designs: long tongue, flat tongue, pointed tongue and short tongue. Long tongue, short tongue and pointed tongue are collectively referred to as having tongues. When there are tongues, the efficiency of the centrifugal fan is greatly improved and the pressure is increased. As the specific speed increases, the influence of the volute tongue on the performance of the centrifugal fan gradually decreases. The disadvantage is that the noise is louder. The flat tongue is also called tongueless. The advantage of the centrifugal fan without tongue is that the noise is lower. The disadvantage is that the power consumption is large and the efficiency is low. Low. In addition, the increase in the outlet cross section of the volute increases the static pressure of the centrifugal fan, but in most cases the outlet speed is still too large, and airflow backflow will occur at the outlet of the centrifugal fan near the volute tongue, causing the overall performance of the fan to decline.

Contents of the invention

The technical problem to be solved by the present invention is to provide a high-efficiency air-mixed design centrifugal fan in view of the above-mentioned current state of the art. Its purpose is to use a simple structure to achieve smooth guidance of the airflow at the outlet of the centrifugal fan, so that the centrifugal fan can The fan has higher efficiency, more stable operating characteristics and a more compact appearance, making this centrifugal fan more advantageous than similar products.

The technical solution adopted by the present invention to solve the above technical problems is: a high-efficiency air-mixed centrifugal fan, including a cover plate, a volute, and a centrifugal impeller. The centrifugal impeller is installed inside the volute; the volute has a spiral flow channel part surrounding the centrifugal impeller, and a mouthpiece part connected with the spiral flow channel part; the cross section of the spiral flow channel part gradually becomes larger along the airflow direction, and the mouthpiece part The air outlet channel has an expansion angle.

In order to optimize the above technical solutions, the present invention also includes the following improved technical solutions.

The above-mentioned centrifugal impeller is a forward impeller, which is arranged equidistantly along the bending direction of the blades. The number is 9 to 23, the thickness of the blades is 1.1mm to 1.3mm, and the ratio of the height of the air inlet blade to the height of the air outlet blade is 1.3 to 1.3. 1.4.

Both ends of the above-mentioned spiral flow channel part have a cross-section FP and an outlet cross-section BA; a cross-sectional gradient section FA is formed from the cross-section FP to the outlet section BA, and the area R2 of any section in the section gradient section FA is equal to the area R1 of the cross-section BA. The ratio is 0.86 to 1.

The line connecting the center of the smallest section FP in the above section gradient section FA and the center of the axis is the straight line OF, and the line connecting the center of the section AB and the center of the axis is the straight line OA; the straight line OF and the straight line OA form an included angle FOA, and the angle of the included angle FOA is 50 ° to 95°.

The connection point between the above-mentioned mouthpiece part and the spiral flow channel part has a cross-section HE and a cross-section FG. The intersection point I and O between the cross-section HE and the cross-section FG constitute a connecting line OI. The straight line OF and the connecting line OI constitute an included angle FOI. The included angle FOI is The angle is 8° to 15°.

The above-mentioned expansion angle is the angle formed by the EI extension line and the CA extension line, and the expansion angle ranges from 2.2° to 3.4°.

The above-mentioned cover plate has an air inlet, and the area ratio of the cross section of the air inlet to the cross section of the air outlet of the mouthpiece is 1.1 to 1.9.

Compared with the prior art, the present invention has the following advantages:

1. The volute adopts a unique spiral flow channel and mouthpiece design, which has the advantages of simple structure and low processing difficulty. It optimizes the flow of airflow in the impeller channel and improves the overall aerodynamic stability and efficiency of the centrifugal fan. Fans are more reliable and economical;

2. The overall structural size of the centrifugal fan is optimized, making it more compact and increasing the application range of the centrifugal fan.

Description of drawings

Figure 1 is a schematic cross-sectional structural diagram of a centrifugal fan according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1 .

Figure 3 is a schematic cross-sectional structural diagram of the air inlet.

Figure 4 is a schematic cross-sectional structural diagram of the air outlet.

Figure 5 is a schematic diagram of the volute structure.

Detailed ways

The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

The high-efficiency air-mixing tongue fan of the present invention mainly includes a cover plate 1, a volute 2, a spiral flow channel part 2a, a mouthpiece part 2b, a centrifugal impeller 3, an air inlet section 4, and an air outlet section 5.

The high-efficiency air-mixed centrifugal fan of the present invention includes a cover plate 1, a volute 2, and a centrifugal impeller 3. The centrifugal impeller 3 is installed inside the volute 2. The volute 2 has a spiral flow path portion 2a surrounding the centrifugal impeller 3, and a mouthpiece portion 2b communicating with the spiral flow path portion 2a. The cross section of the spiral flow channel portion 2a gradually becomes larger along the air flow direction, and the air outlet channel of the mouthpiece portion 2b has an expansion angle.

The centrifugal impeller 3 is a forward impeller, equidistantly arranged along the bending direction of the blades, the number is 9 to 23, the thickness of the blades is 1.1mm to 1.3mm, and the ratio of the air inlet blade height to the air outlet blade height is 1.3 to 1.4 . In this embodiment, the number of blades is preferably 18, the thickness of the blades is 1.2 mm, and the ratio of the air inlet blade height to the air outlet blade height is 1.35. The number of blades can also be 16, 17, or 19, and the thickness of the blades can also be 1.1mm or 1.3mm.

Existing impellers usually adopt a straight blade design. The leading edge line of the straight blade is parallel to the axial direction. Since the total pressure of each meridional streamline at the inlet is basically equal, for the centrifugal fan inlet, the meridional velocity of the airflow at the blade root is compared with the blade tip. Because their linear speed of rotation is the same under the same radius, the design of straight blades will inevitably lead to the inability of the straight blade angle and the airflow angle to fully match along the blade height direction. The airflow along the blade height direction will mix with each other, causing energy loss. By adopting the forward blade shape and the design of the mouthpiece 2b of the volute 2, the present invention can mix gas more effectively on the windward side, prevent the airflow from flowing back in the radial direction, and improve the flow state at the outlet of the volute 2.

Both ends of the spiral flow path portion 2a have a cross section FP and an outlet cross section BA. The section gradient section FA is formed from the section FP to the outlet section BA. The ratio of the area R2 of any section in the section gradient section FA to the area R1 of the section BA is 0.86 to 1. Among them, the area value of section FP is the smallest, and the ratio of section FP to section BA is 0.86. The area R2 of any section in the section gradient section FA gradually becomes larger along the wind outlet direction.

The line connecting the center of the smallest section FP and the axis center in the section gradient section FA is the straight line OF, and the line connecting the center of the section AB and the axis center is the straight line OA. The straight line OF and the straight line OA form an included angle FOA, and the included angle FOA ranges from 50° to 95°. The preferred angle of the included angle FOA is between 55° and 80°, and the angle in this embodiment is about 60°.

Existing conventional centrifugal fans mostly use short tongue and deep tongue designs. Short tongues are mostly used for centrifugal fans with high specific speeds. When short tongues are used, the efficiency curve is flat, the reasonable working area is large, and the noise is high. Deep tongues are mostly used for low specific speeds. For centrifugal fans, the deeper the tongue, the smaller the gap between it and the outlet of the impeller, and the smaller the leakage between the spiral part of the volute and the outlet of the volute, which is beneficial to improving the efficiency and pressure of the fan, but the noise increases. And the efficiency curve becomes steeper, making the reasonable working interval smaller. In view of the shortcomings of the two existing volutes, the volute 2 of the present invention is equipped with a mouthpiece 2b. The mouthpiece 2b includes a volute FG and an arc HG, which can improve the efficiency and pressure of the fan, reduce noise, and have a wider reasonable working range. big.

The connection point between the mouthpiece part 2b and the spiral flow channel part 2a has a cross-section HE and a cross-section FG, and the intersection point I and O between the cross-section HE and the cross-section FG forms a connecting line OI, and the straight line OF and the connecting line OI form an included angle FOI, the included angle The angle of FOI is 8° to 15°.

The expansion angle is the angle formed by the EI extension line and the CA extension line, and the expansion angle ranges from 2.2° to 3.4°.

As shown in Figure 3, the cover 1 has an air inlet, and the area ratio of the air inlet section 4 to the air outlet section 5 of the mouthpiece 2b is 1.1 to 1.9. As shown in Figure 4 and Figure 5, the centrifugal gradient section LK of the air outlet smoothly transitions to the arc-shaped LNMJ, and the expansion angle of the outlet is 2.2 degrees to 3.4 degrees. The inner wall of the expander is tilted toward the direction of impeller rotation, which can make part of the dynamic pressure Convert to static pressure, thereby improving the static pressure and static pressure efficiency of the ventilator equipment.

The preferred embodiments of the present invention have been clarified, and various changes or modifications may be made by those of ordinary skill in the art without departing from the scope of the present invention.

Claims (3)

1. A high-efficiency air-mixed centrifugal fan, including a cover plate (1), a volute (2), and a centrifugal impeller (3). The characteristic is: the centrifugal impeller (3) is installed on the volute (2). Inside; the volute (2) has a spiral flow channel portion (2a) surrounding the centrifugal impeller (3), and a mouthpiece portion (2b) communicating with the spiral flow channel portion (2a); the spiral The cross section of the flow channel part (2a) gradually becomes larger along the direction of air flow, and the air outlet channel of the mouthpiece part (2b) has an expansion angle; the centrifugal impeller (3) is a forward impeller, arranged equidistantly along the bending direction of the blades , the number is 9 to 23, the blade thickness is 1.1mm to 1.3mm, the ratio of the air inlet blade height to the air outlet blade height is 1.3 to 1.4; both ends of the spiral flow channel part (2a) have cross-sections FP and the outlet section BA; the section gradient section FA is formed from the section FP to the outlet section BA, and the ratio of the area R2 of any section in the section gradient section FA to the area R1 of the section BA is 0.86 to 1; the mouthpiece part ( 2b) The connection with the spiral flow channel part (2a) has a cross-section HE and a cross-section FG. The intersection point I and O between the cross-section HE and the cross-section FG constitute a connection line OI, and the straight line OF and the connection line OI form an included angle FOI , the angle of the included angle FOI is 8° to 15°; the cover plate (1) has an air inlet, and the area ratio of the air inlet section (4) to the air outlet section (5) of the mouthpiece (2b) is 1.1 to 1.9; The centrifugal gradient section LK of the air outlet transitions smoothly to the arc-shaped LNMJ, and the expansion angle of the outlet is 2.2 to 3.4 degrees. The inner wall of the expander is inclined toward the direction of impeller rotation. 2. The high-efficiency air-mixed centrifugal fan according to claim 1, characterized in that: the line connecting the center of the smallest cross-section FP in the gradual cross-section section FA and the axis center is a straight line OF, and the line connecting the center of the cross-section AB and the axis center is is the straight line OA; the straight line OF and the straight line OA form an included angle FOA, and the included angle FOA ranges from 50° to 95°. 3. The high-efficiency air-mixed centrifugal fan according to claim 1, characterized in that: the expansion angle is the angle formed by the EI extension line and the CA extension line, and the expansion angle ranges from 2.2° to 3.4°. .