This standard specifies the basic types, dimensional parameters and performance curves of fans. This standard applies to centrifugal and axial flow fans for general use. It can also be used as a reference for fans for other purposes (mixed flow fans). Special technical or other requirements can be specified in product standards or contract agreements. This standard does not apply to cross-flow fans or fan equipment for household or similar purposes. GB/T 3235-1999 Basic types, dimensional parameters and performance curves of fans GB/T3235-1999 Standard download decompression password: www.bzxz.net

GB/T3235—1999
This standard has some changes from GB/T3235-1982 in the following important technical contents: 1) Table 2 in the original standard has been cancelled, and the machine number and impeller diameter of the fan have been changed to "according to the provisions of GB/T17774-1999", which is equivalent to the ISO13351:1996 standard;
2) The flange connection structure and size of the fan in the original standard have been cancelled and changed to "according to the provisions of GB/T17774-1999", which is equivalent to the ISO13351:1996 standard;
3) The number of blades of the general fan in the original standard has been changed to the recommended value; 4) One transmission mode has been reduced from four to three; 5) The structural type of axial flow fan has been added; 6) The sound power level has been added to the noise measurement.
This standard is used in conjunction with GB/T 17774~-1999. This standard shall replace GB/T3235-1982 from the date of implementation. This standard is proposed by the State Machinery Industry Bureau. This standard is under the jurisdiction of the National Technical Committee for Standardization of Fans. The drafting unit of this standard is Shenyang Blower Research Institute. The main drafters of this standard are Kong Guilan and Miao Liping. 175
1 Scope
National Standard of the People's Republic of China
Basic types sizes parameters and characteristics of fans
and performance curves
Basic types sizes parameters and characteristics of fans This standard specifies the basic types, size parameters and performance curves of fans. GB/T3235--1999
Replaces GB/T3235-1982
This standard applies to centrifugal and axial flow fans for general purposes. It can also be used as a reference for fans (mixed flow fans) for other purposes. Special requirements in technology or other aspects may be specified in product standards or contract agreements. This standard does not apply to cross-flow fans or fan equipment for household or similar purposes. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T321-1980 Priority number and priority number system GB/T1236--1985 Test method for aerodynamic performance of fans GB/T2888-1991 Noise measurement method for fans and Roots blowers GB/T17774-1999 Dimensions of industrial fans JB/T2977-1992 Terminology of fans and Roots blowers 3 Basic types
3.1 Fans can be divided into centrifugal and axial flow fans according to the direction of air flow movement. The definitions are shown in JB/T2977. 3.2 Fans can be divided into low, medium and high pressure according to pressure Fan: a) Centrifugal fans can be divided into low, medium and commercial pressure centrifugal fans according to the size of the total pressure, and their definitions are shown in JB/T2977; b) Axial flow fans can be divided into low and high pressure axial flow fans according to the size of the total pressure, and their definitions are shown in JB/T2977. 3.3 Centrifugal fans can be divided into single suction and double suction according to the air intake method, and their definitions are shown in JB/T2977. 3.4 Fans can be divided into clockwise and counterclockwise according to the direction of rotation, and their definitions are shown in JB/T2977. 3.5 The transmission type of the fan can be divided into direct motor connection, pulley coupling and other types. 3.5.1 The representative symbols and structural descriptions of each transmission type of centrifugal fan are shown in Table 1 and Figure 1. Approved by the State Administration of Quality and Technical Supervision on June 14, 1999176
Implementation on November 1, 1999
Transmission type
Direct connection with motor
Pulley
Coupling
GB/T 3235 1999
Structural description
The fan impeller is directly mounted on the motor shaft. The impeller is cantilevered, and the pulley is between the two bearings. The pulley is cantilevered at one end of the shaft, and the impeller is cantilevered at the other end of the shaft. The pulley is cantilevered, and the impeller is installed between the two bearings (including double intake and two bearings supported on the casing or air inlet). Structural type
Impeller cantilevered
Impeller installed between the two bearings
3.5.2 The connection and structural type of the axial flow fan and the transmission device are shown in Figure 2. a
Basic dimensions and parameters
GB/T3235—1999
Figure 2 (end)
4.1 The machine number of the fan is the fan impeller diameter (mm)/100 and is indicated by the symbol \No\. 4.2 The machine number and impeller diameter of the fan shall comply with the provisions of GB/T17774. 4.3 The flange connection structure and dimensions of the fan shall comply with the provisions of GB/T17774. 4.3.1 The hub ratio and hub diameter of the equal hub ratio axial flow fan shall comply with the provisions of Table 2. 178
Hub diameter
Impeller diameter
GB/T 3235—-1999
.0.350
Hub diameter
Impeller diameter
GB/T 3235—1999
Table 2 (continued)
Hub diameter
Impeller diameter
GB/T 3235 - 1999
Table 2 (continued)
Hub diameter
Impeller diameter
A1 250
Note: Numbers with “” are preferred.
GB/T3235--1999
Table 2 (end)
GB/T 32351999
4.4 The representation method of the inlet and outlet geometric angles (β1A, β2A) of the impeller blades of centrifugal fans is shown in Figure 3. G
β2A90—Backward impeller
Direction of rotation
β24 — 90°—Radial impeller
Direction of rotation
β2a>90°—Forward impeller
4.5 The installation angle of the guide vane (the guide vane in front of the impeller) of the centrifugal fan is zero degree when the blade is fully open, as shown in Figures 4 and 5.
4.6 The position of the air inlet box of the centrifugal fan is specified in five basic positions (from the prime mover side) according to the direction of rotation of the impeller and the different installation angles, as shown in Figure 6.
Clockwise impeller
Clockwise 909
Polyester 135
Clockwise 180°
Counterclockwise 135
Counterclockwise 180°
Counterclockwise impellerbzxz.net
Counterclockwise 90°
GB/T3235—1999
The installation position of the centrifugal fan outlet is based on the impeller rotation direction and the different installation angles. Eight basic positions are specified (from the prime mover side), as shown in Figure 7. When the use requirements cannot be met, the supplementary angles listed in Table 3 are allowed. Table 3
Supplementary angle
Forward 315°
Forward 270°
Bottle 135°
Forward 225°
Reverse 135°
80°180°
Reverse 225
Reverse 909
Reverse 270°
Single 451
Reverse 315
4.8 The installation angle of the impeller blade, guide vane (guide vane in front of the impeller) and the rectifying blade of the axial flow fan is shown in Figure 8. The installation angle refers to the value at the mean radius rm, and its calculation formula is: rm
Where; α=
Impeller ratio;
D Impeller diameter;
Hub diameter.
gp—guide blade installation angle t8-impeller blade installation angle; -rectifier blade installation angle Figure 8
4.9 The inlet diameter D (see Figures 4 and 9) of the fan collector, the cylinder inlet diameter D. (see Figure 10), the outlet diameter D (see Figure 9) of the axial flow fan diffuser and the diameter of the air outlet with a circular cross section shall comply with the provisions of Table 4. 184
The number with "A\" is the preferred number (R20 series); 2n is a positive integer greater than 1.
GB/T3235-—1999
Table 4 (the numbers in the table are multiplied by 10\)
The recommended number of blades for the fan impeller is shown in Table 5. Table 5
Note: The number of blades 40.48 and 64 are only applicable to centrifugal fans. A4.00
4.11 The ratio of the dynamic pressure coefficient p to the total pressure coefficient of the centrifugal fan at the highest total pressure efficiency (the mine fan is the highest static pressure efficiency) shall not be greater than the value calculated by the following formula:
For the series of fans, the highest total pressure efficiency of each specification shall be greater than or equal to 70%. 4.12
5 Performance curve
5.1 The performance of the fan is evaluated by the aerodynamic characteristics and noise characteristics of the fan, and is generally expressed by a performance curve. Unless otherwise specified in the contract, general-purpose fans are drawn with air under standard conditions. 5.2 The performance curve consists of the relationship between the following parameters and the flow rate: a) the total pressure of the fan, the total pressure internal efficiency (or total pressure efficiency); b) the static pressure of the fan, the static pressure internal efficiency (or static pressure efficiency); c) the dynamic pressure of the fan;
d) the shaft power of the fan (or shaft internal power); e) the noise of the fan (A sound level or sound power level). Note: According to the specific situation, one of a) and b) and b) and c) can be drawn. 5.3 Performance curve of fan
GB/T3235-1999
a) The factory test of finalized products should be based on the flow range specified in the sample, which is slightly wider than the sample; b) The flow rate of the test of new products (models, prototypes) should be the entire performance curve from the point close to the surge point (from close to zero flow when there is no obvious surge) to the maximum flow rate. When the axial flow fan uses the change of the impeller blades and guide vanes and the centrifugal fan uses the change of the installation angle of the guide vanes to adjust the performance, the performance curve of the blades or guide vanes at different installation angles should be drawn; when the fan is adjustable in speed, the performance curves at various speeds should be drawn according to the use needs of the fan. 5.4 The economic working area of ​​the fan is determined by the flow value range of the two working conditions corresponding to 90% of the highest full pressure efficiency of the fan. 5.5 The aerodynamic performance test of the fan should be carried out in accordance with GB/T1236. 6 The noise test of the fan shall be carried out in accordance with GB/T2888. 5.6
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