Speed regulation ratio evaluation method of bladeless fan

Abstract

The invention discloses a speed regulation ratio evaluation method for a bladeless fan. The speed regulation ratio evaluation method comprises the steps that S1, the tested bladeless fan is placed in a test room; s2, arranging a plurality of anemometers in array distribution in front of the air supply outlet of the bladeless fan, wherein the blade planes of all the anemometers are parallel to the air supply outlet plane of the tested bladeless fan; s3, the bladeless fan is started, the bladeless fan runs under the rated voltage and the rated frequency, and if a head shaking mechanism exists, the head shaking mechanism is closed; s4, the bladeless fan speed regulator is arranged at the highest wind speed gear, and the measured wind speed vmh of the highest wind speed gear is obtained through measurement; s5, the bladeless fan speed regulator is arranged at the lowest wind speed gear, and the measured wind speed vml at the lowest wind speed gear is obtained through measurement; and S6, the ratio of the measured wind speed vml at the lowest wind speed gear to the measured wind speed vmh at the highest wind speed gear is calculated, and the speed regulation ratio of the bladeless fan is obtained. According to the method, the performance index evaluation of the speed regulation ratio of the bladeless fan can be scientifically and accurately evaluated.

Description

Technical Field

[0001] The invention belongs to the field of electrical performance evaluation technology, and in particular relates to a method for evaluating the speed ratio of a bladeless fan. Background Art

[0002] In recent years, fans developed with new technologies such as bladeless fans have become the new favorites of the industry and are very popular among users. Due to their unique appearance and comfortable air supply method, they are very popular among consumers, and their sales share in the domestic and foreign markets continues to grow. Unlike the traditional fan, which drives the spiral blades to cut and push out the air through the motor, the bladeless fan drives the wind wheel through a brushless motor to suck air from several air inlets below the base, and compress it at high speed to the annular nozzle above the base, and then eject it from the air outlet. According to the Bernoulli theorem in fluid mechanics, the faster the fluid speed, the lower the pressure. The airflow is ejected at high speed from the narrow air outlet, so a relative negative pressure is formed on the inner surface of the air outlet, driving the air near the nozzle to flow into the ring; in addition, the cross-sectional structure design of the air outlet is similar to that of an aircraft wing, with a certain inclination angle, forming a greater negative pressure through the Coanda effect, driving the air around the air outlet to flow forward, forming continuous air supply, and increasing the total air output of the appliance.

[0003] For comfort fans other than bladeless fans, the speed ratio of the fan speed regulator is the ratio of the maximum speed of the fan at rated voltage and rated frequency to the adjustable minimum speed. In actual test operations, the speed ratio of the corresponding fan can be calculated by aiming the laser at the fan blades, measuring the number of laser pulses per minute, and then converting it into the fan blade speed. However, since bladeless fans use jet airflow to deliver air, and the wind wheel is installed inside the base and does not have exposed rotating blades, the method of measuring the blade speed to obtain the speed ratio is not applicable to bladeless fans.

[0004] At present, regarding the speed ratio measurement method of bladeless fans, the domestic method mainly adopts the bladeless fan speed ratio test method in GB / T43552-2023 "Performance Test Method for Comfort Fans for Household and Similar Purposes" (IEC 60879:2019, IDT). The method is as follows: The bladeless fan operates at rated voltage and rated frequency. If there is a shaking mechanism, turn it off. Set the speed regulator to the highest wind speed gear to measure the wind speed of the bladeless fan. Then set the bladeless fan speed regulator to the lowest wind speed gear to measure the wind speed of the bladeless fan. The speed ratio is the ratio of the wind speed measured at the lowest wind speed gear to the wind speed measured at the highest wind speed gear.

[0005] The above method is currently used in actual test operations, but this method has the following defects:

[0006] ⑴ The existing speed ratio test method of bladeless fans is to measure the wind speed at the outlet of the bladeless fan at the high wind speed gear and the lowest wind speed gear respectively, and calculate the speed ratio through the ratio of the two. On the one hand, the wind speed at the outlet of the bladeless fan cannot truly reflect the characteristics of the air supply wind field during the actual use of the bladeless fan. The bladeless fan drives the wind wheel through a brushless motor to suck air from several air inlets below the base, and compresses it to the annular nozzle above the base at high speed, and ejects it at the outlet. According to the Bernoulli theorem in fluid mechanics, the faster the fluid speed, the lower the pressure. The airflow is ejected at high speed from the narrow outlet, so a relative negative pressure is formed on the inner surface of the outlet, driving the air near the nozzle to flow into the ring; in addition, the cross-sectional structure design of the outlet of the bladeless fan is similar to that of an aircraft wing, with a certain inclination angle, and a greater negative pressure is formed through the Coanda effect, driving the air around the outlet to flow forward, forming a continuous air supply, and increasing the outlet wind speed of the appliance. On the other hand, in actual use, the bladeless fan is at a certain distance from the user, and the wind speed at the air outlet cannot reflect the actual wind speed experienced by the user during actual use. Therefore, the speed ratio measured by this method cannot truly and objectively evaluate the speed ratio of the bladeless fan.

[0007] (2) The wind speed distribution at the air outlet of the bladeless fan is not uniform, and this method does not specify the selection of a specific position of the air outlet for measuring the wind speed, resulting in different testing organizations or different testers selecting different positions of the air outlet for wind speed measurement. The wind speed values ​​obtained vary greatly, affecting the reproducibility of the speed regulation ratio results measured by this method. Summary of the invention

[0008] The object of the present invention is to provide a method for evaluating the speed ratio of a bladeless fan which can accurately evaluate the speed ratio of the bladeless fan.

[0009] The object of the present invention is achieved by the following technical measures: A method for evaluating the speed ratio of a bladeless fan, characterized by comprising the following steps:

[0010] S1. Place the bladeless fan to be tested in the test room;

[0011] S2. A plurality of anemometers distributed in an array are arranged in front of the air outlet of the bladeless fan, and the blade planes of all anemometers are parallel to the air outlet plane of the bladeless fan being tested;

[0012] S3, turn on the bladeless fan, and the bladeless fan runs at the rated voltage and rated frequency. If there is an oscillating mechanism, turn off the oscillating mechanism;

[0013] S4. Set the speed regulator of the bladeless fan to the highest wind speed gear. After the working state of the bladeless fan is stable, measure the wind speed of the bladeless fan. When measuring the wind speed of the bladeless fan, the anemometer measures at the initial position and reaches the set time, then moves to the next position to measure and reaches the set time. Stop moving and measuring when the wind speed of the bladeless fan measured by all anemometers does not exceed 24m / min; select the maximum wind speed from all measured wind speed values ​​as the wind speed v measured at the highest wind speed gear. mh ;

[0014] S5. Set the speed regulator of the bladeless fan to the lowest wind speed gear. After the working state of the bladeless fan is stable, measure the wind speed of the bladeless fan. When measuring the wind speed of the bladeless fan, the anemometer measures at the initial position and reaches the set time, then moves to the next position to measure and reaches the set time. Stop moving and measuring when the wind speed of the bladeless fan measured by all anemometers does not exceed 24m / min; select the maximum wind speed from all measured wind speed values ​​as the wind speed v measured at the lowest wind speed gear. ml ;

[0015] S6. Calculate the wind speed v at the lowest wind speed gear ml Measure wind speed v with the highest wind speed gear mh The ratio of is the speed ratio of the bladeless fan.

[0016] The present invention combines the working principle, application scenarios and air supply wind field characteristics of the bladeless fan, designs the placement of the bladeless fan and the testing instrument, determines the selection scheme of the wind speed test points in the wind field, and realizes the scientific and accurate evaluation of the performance index of the speed regulation ratio of the bladeless fan.

[0017] The anemometers described in the present invention are arranged in one row or more than two rows along the X-axis, and the bracket on which the anemometers are installed is placed at the midpoint of the height of the air outlet of the bladeless fan. In the steps S4 and S5, when measuring the wind speed of the bladeless fan, the anemometers first move upward or downward along the Y-axis, and each movement distance is 40 mm, until the wind speed measured by all anemometers does not exceed 24 m / min; then the anemometers return to the initial position, and then move downward or upward along the Y-axis, and each movement distance is 40 mm, until the wind speed measured by all anemometers does not exceed 24 m / min.

[0018] The anemometers described in the present invention are arranged in one row or more than two rows along the Y-axis, and the bracket on which the anemometers are installed is placed at the midpoint of the width of the fan air outlet. In the steps S4 and S5, when measuring the wind speed of the bladeless fan, the anemometers are first moved left or right along the X-axis, and the distance of each movement is 40 mm, until the wind speed measured by all anemometers does not exceed 24 m / min; then the anemometers return to the initial position, and then move right or left along the X-axis, and the distance of each movement is 40 mm, until the wind speed measured by all anemometers does not exceed 24 m / min.

[0019] The anemometer of the present invention measures at each position for at least 1 minute, and the wind speed value measured by each anemometer is averaged by data obtained by measuring within a period of not less than 60 seconds at a sampling frequency of not less than 2 Hz.

[0020] The laboratory environmental parameters of the present invention meet the following requirements: the ambient temperature is 20°C ± 5°C; the relative humidity is 50% ± 30%; and the atmospheric pressure is 86 kPa-106 kPa.

[0021] The center of the air outlet of the tested bladeless fan of the present invention is at least 1200mm above the ground; the distance between the plane of the air outlet of the tested bladeless fan and the rear wall is at least 1200mm; the distance between the plane of the air outlet of the tested bladeless fan and the front wall is at least 4000mm; the distance between the center of the air outlet of the tested bladeless fan and the wall surfaces on the left and right sides is not less than 1800mm.

[0022] The bladeless fan to be tested in the present invention is a desktop bladeless fan, and the distance between the blade plane of the anemometer and the air outlet plane of the bladeless fan to be tested is 1000mm; or the bladeless fan to be tested is a ground-type bladeless fan, and the distance between the blade plane of the anemometer and the air outlet plane of the bladeless fan to be tested is 2000mm.

[0023] The outer diameter of the anemometer described in the present invention does not exceed 40 mm, and the number of the anemometers is an even number and not less than 4.

[0024] Compared with the prior art, the present invention has the following significant effects:

[0025] ⑴The present invention is used to evaluate one aspect of the speed regulation ratio performance of a bladeless fan, including the requirements of environmental equipment, the placement of a bladeless fan, the layout of a wind speed test table, the operating steps of the test, the selection of valid test values, and the calculation of test results. The present invention combines the working principle, application scenarios, and air supply wind field characteristics of the bladeless fan, designs the placement of the bladeless fan and the test instrument, determines the selection scheme of the wind field wind speed test points, and realizes a scientific and accurate evaluation of the performance index of the speed regulation ratio of the bladeless fan.

[0026] (2) The present invention refers to the characteristics of the air field of the bladeless fan and the actual application scenarios, designs the placement and setting scheme of the bladeless fan and the wind speed test instrument, and simulates the use interval distance between the bladeless fan and the air supply object in the actual application scenario, in order to solve the problem that the wind speed at the air outlet position cannot truly and objectively evaluate the speed ratio, and is more reasonable and practical to test the speed ratio index of the bladeless fan;

[0027] ⑶ The present invention combines the working principle of the bladeless fan and the characteristics of the air supply wind field, designs a more reasonable and effective measurement wind speed value selection scheme for evaluating the actual speed regulation ratio, measures the air supply wind speeds at the lowest wind speed gear and the highest wind speed gear of the bladeless fan respectively, and clearly selects the highest wind speed ratio of the lowest wind speed gear and the highest wind speed gear to calculate the speed ratio, and "dynamically" tracks the center position of the wind speed distribution in the air supply wind field, thereby solving the problem of low reproducibility of the speed regulation ratio test caused by unstable wind speed measurement results.

[0028] ⑷ According to the characteristics of bladeless fan application scenarios, the present invention designs a bladeless fan and wind speed test instrument layout scheme that is more in line with actual working conditions; a global survey on the usage experience of bladeless fans is conducted, and the survey results show that the usage interval of desktop bladeless fans is generally 1 meter, while the interval of ground-type bladeless fans is 2 meters; therefore, in order to better fit the actual application scenarios of bladeless fans and more objectively evaluate their working performance indicators, a bladeless fan and test instrument layout scheme is designed to simulate the usage interval distance between the bladeless fan and the air supply object in the actual application scenario, such as: the distance setting between desktop and ground-type bladeless fans and wind speed test instruments refers to the actual usage interval distance.

[0029] ⑸ The present invention combines the working principle of the bladeless fan and the characteristics of the air supply wind field to design a more effective and reasonable measurement wind speed value selection scheme that reflects its actual speed regulation ratio. According to aerodynamic research and verification of the wind speed distribution of the bladeless fan air supply wind field, the wind speed value measured at the center position of the wind speed distribution of the bladeless fan air supply wind field (at the maximum wind speed) is more stable and has higher reproducibility. Therefore, the present invention "dynamically" tracks the center position of the wind speed distribution of the air supply wind field by measuring the maximum wind speed of the instrument at the lowest wind speed gear and the highest wind speed gear respectively and using the ratio of the two to calculate the speed regulation ratio, thereby solving the speed regulation ratio measurement error problem caused by the poor reproducibility of the wind speed measurement results.

[0030] (6) The test steps of the present invention are clear and highly operable, which solves the problem of poor reproducibility of test results caused by subjective reasons. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Figure 1 It is a front view of the arrangement of the bladeless fan and the testing instrument of the present invention;

[0033] Figure 2 It is a top view of the arrangement of the bladeless fan and the testing instrument of the present invention.

[0034] In the figure: A-bladeless fan to be tested, H-bracket, T-array anemometer, L-laboratory length, W1-laboratory width, W2-distance between the center of the air outlet of the bladeless fan to be tested and the left and right walls, h1-laboratory height, h2-height between the center of the air outlet of the bladeless fan to be tested and the ground, d-distance between the plane of the air outlet of the bladeless fan to be tested and the plane of the anemometer, d1-distance between the plane of the air outlet of the bladeless fan to be tested and the back wall. DETAILED DESCRIPTION

[0035] The present invention is further illustrated below through the description of specific implementation methods, but this is not a limitation of the present invention. Those skilled in the art can make various modifications or improvements based on the basic idea of ​​the present invention, but as long as they do not deviate from the basic idea of ​​the present invention, they are all within the protection scope of the present invention.

[0036] The present invention provides a method for evaluating the speed regulation ratio of a bladeless fan, which specifically comprises the following steps:

[0037] S1. Place the bladeless fan to be tested in the test room;

[0038] The laboratory environmental parameters meet the following requirements: ambient temperature is 20℃±5℃; relative humidity is 50%±30%; atmospheric pressure is 86kPa-106kPa.

[0039] Wind speed test chamber dimensions: chamber length L is 6000mm, chamber width W1 is 4500mm, and chamber height h1 is 3000mm.

[0040] On the side where the fan is delivering air, there should be no obstacles in the test room except for the fan shelf. All tables or shelves used to place electronic instruments should be placed on the other side of the fan and the test plane, with a distance of more than 900mm from the air outlet plane of the bladeless fan.

[0041] During the test, all air conditioning equipment in the test room should not have any impact on the air flow in the test room.

[0042] The bladeless fan to be tested should be placed in the test room and arranged as follows:

[0043] ——The height h2 from the center of the air outlet to the ground should be at least 1200mm;

[0044] ——The distance d1 between the air outlet plane and the rear wall should be at least 1200mm;

[0045] ——The distance between the air outlet plane and the front wall is at least 4000mm;

[0046] ——The distance W2 between the center of the air outlet and the left and right walls should not be less than 1800mm.

[0047] S2. A plurality of anemometers distributed in an array are arranged in front of the air outlet of the bladeless fan, and the blade planes of all anemometers are parallel to the air outlet plane of the bladeless fan being tested;

[0048] The blade plane of the anemometer is parallel to the air outlet plane of the bladeless fan to be tested. The distance d between the air outlet plane of the bladeless fan to be tested and the anemometer plane is:

[0049] ——For desktop bladeless fans: 1000mm;

[0050] ——For ground-mounted bladeless fans, it is 2000mm.

[0051] The measurement should be made using an automatic air volume test device as follows:

[0052] The platform consists of a set of anemometers with an outer diameter not exceeding 40mm. The number of anemometers should be no less than 4, and an even number of anemometers should be used. The size of the anemometer should be such that it can be installed in a space of 40mm between two anemometers;

[0053] Able to clamp the anemometer at intervals of 40mm in vertical or horizontal directions;

[0054] Adjustable in Z axis (automatically or manually) with an accuracy of ±2mm;

[0055] Able to move in X and Y axis under remote control with an accuracy of ±1mm.

[0056] In this embodiment, the anemometers are arranged in a row (or more than two rows) along the X-axis, and the bracket on which the anemometers are mounted is placed at the midpoint of the height of the air outlet of the bladeless fan.

[0057] The above bladeless fans and test instruments are arranged as follows: Figure 1 , Figure 2 shown.

[0058] S3, turn on the bladeless fan, and the bladeless fan runs at the rated voltage and rated frequency. If there is an oscillating mechanism, turn off the oscillating mechanism;

[0059] S4. Set the bladeless fan speed regulator to the highest wind speed gear. After the working state of the bladeless fan is stable, measure the wind speed of the bladeless fan. When measuring the wind speed of the bladeless fan, the anemometer measures at the initial position for 1 minute, then moves 40mm upward along the Y axis to the next position for measurement and for 1 minute, then moves 40mm upward along the Y axis to the next position for measurement and for 1 minute, until the wind speed measured by all anemometers does not exceed 24m / min; then the anemometer returns to the initial position for measurement and for 1 minute, then moves 40mm downward along the Y axis to the next position for measurement and for 1 minute, then moves 40mm downward along the Y axis to the next position for measurement and for 1 minute, until the wind speed measured by all anemometers does not exceed 24m / min, stop moving and measuring; select the maximum wind speed from all measured wind speed values ​​as the wind speed v measured at the highest wind speed gear mh ;

[0060] S5. Set the speed regulator of the bladeless fan to the lowest wind speed gear. After the working state of the bladeless fan is stable, measure the wind speed of the bladeless fan. When measuring the wind speed of the bladeless fan, the anemometer measures at the initial position for 1 minute, then moves 40mm upward along the Y axis to the next position for measurement and 1 minute, then moves 40mm upward along the Y axis to the next position for measurement and 1 minute, until the wind speed measured by all anemometers does not exceed 24m / min; then the anemometer returns to the initial position for measurement and 1 minute, then moves 40mm downward along the Y axis to the next position for measurement and 1 minute, then moves 40mm downward along the Y axis to the next position for measurement and 1 minute, until the wind speed measured by all anemometers does not exceed 24m / min, stop moving and measuring; select the maximum wind speed from all measured wind speed values ​​as the wind speed v measured at the lowest wind speed gear ml ;

[0061] The wind speed value measured by each anemometer should be obtained by averaging the data measured within a period of not less than 60s at a sampling frequency of not less than 2Hz.

[0062] The wind speed of 24m / min is an indicator to distinguish whether it is an effective wind speed. The airflow with a measured wind speed value lower than 24m / min is considered to be a disordered airflow in the environment, and the airflow with a measured wind speed value exceeding 24m / min is considered to be the airflow generated by the measured instrument. In the present invention, the anemometer moves until all measured wind speeds are lower than 24m / min before stopping moving and measuring, to ensure that all effective wind speeds can be tested.

[0063] S6. Calculate the wind speed v at the lowest wind speed gear ml Measure wind speed v with the highest wind speed gear mh The ratio of is the speed ratio of the bladeless fan.

[0064] In other embodiments, the anemometers are arranged in a row (or more than two rows) along the Y axis, and the bracket on which the anemometers are mounted is placed at the midpoint of the width of the fan outlet. The difference between this embodiment and the above embodiment lies in that step S4 and step S5 are different:

[0065] In step S4, the speed regulator of the bladeless fan is set at the highest wind speed gear. After the working state of the bladeless fan is stable, the wind speed of the bladeless fan is measured. When measuring the wind speed of the bladeless fan, the anemometer measures at the initial position and reaches 1 minute. The anemometer first moves 40mm to the left along the X-axis to the next position to measure and reach 1 minute, and then moves 40mm to the left along the X-axis to the next position to measure and reach 1 minute. Until the wind speed measured by all anemometers does not exceed 24m / min, stop moving and measuring; then the anemometer returns to the initial position to measure and reach 1 minute, and then moves 40mm to the right along the X-axis to the next position to measure and reach 1 minute, and then moves 40mm to the right along the X-axis to the next position to measure and reach 1 minute, until the wind speed measured by all anemometers does not exceed 24m / min. The maximum wind speed value is selected from all measured wind speed values ​​as the wind speed v measured at the highest wind speed gear. mh .

[0066] In step S5, the speed regulator of the bladeless fan is set to the lowest wind speed gear. After the working state of the bladeless fan is stable, the wind speed of the bladeless fan is measured. When measuring the wind speed of the bladeless fan, the anemometer measures at the initial position and reaches 1 minute. The anemometer first moves 40mm to the left along the X-axis to the next position to measure and reach 1 minute, and then moves 40mm to the left along the X-axis to the next position to measure and reach 1 minute. Until the wind speed measured by all anemometers does not exceed 24m / min, stop moving and measuring; then the anemometer returns to the initial position to measure and reach 1 minute, and then moves 40mm to the right along the X-axis to the next position to measure and reach 1 minute, and then moves 40mm to the right along the X-axis to the next position to measure and reach 1 minute, until the wind speed measured by all anemometers does not exceed 24m / min. The maximum wind speed value is selected from all measured wind speed values ​​as the wind speed v measured at the lowest wind speed gear. ml .

[0067] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by a person with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for evaluating the speed ratio of a bladeless fan, characterized in that The following steps are involved: S1. Place the bladeless fan to be tested in the test room; S2. A plurality of anemometers distributed in an array are arranged in front of the air outlet of the bladeless fan, and the blade planes of all anemometers are parallel to the air outlet plane of the bladeless fan being tested; S3, turn on the bladeless fan, and the bladeless fan runs at the rated voltage and rated frequency. If there is an oscillating mechanism, turn off the oscillating mechanism; S4. Set the speed regulator of the bladeless fan to the highest wind speed gear. After the working state of the bladeless fan is stable, measure the wind speed of the bladeless fan. When measuring the wind speed of the bladeless fan, the anemometer measures at the initial position and reaches the set time, then moves to the next position to measure and reaches the set time. Stop moving and measuring when the wind speed of the bladeless fan measured by all anemometers does not exceed 24m / min; select the maximum wind speed from all measured wind speed values ​​as the wind speed v measured at the highest wind speed gear. mh ; S5. Set the speed regulator of the bladeless fan to the lowest wind speed gear. After the working state of the bladeless fan is stable, measure the wind speed of the bladeless fan. When measuring the wind speed of the bladeless fan, the anemometer measures at the initial position and reaches the set time, then moves to the next position to measure and reaches the set time. When the wind speed of the bladeless fan measured by all anemometers does not exceed 24m / min, stop moving and measuring; select the maximum wind speed from all measured wind speed values ​​as the wind speed v measured at the lowest wind speed gear. ml ; S6. Calculate the wind speed v at the lowest wind speed gear ml Measure wind speed v with the highest wind speed gear mh The ratio of is the speed ratio of the bladeless fan.

2. The speed ratio evaluation method of a bladeless fan according to claim 1, characterized in that: The anemometers are arranged in one row or more than two rows along the X-axis, and the bracket on which the anemometers are installed is placed at the midpoint of the height of the air outlet of the bladeless fan. In the steps S4 and S5, when measuring the wind speed of the bladeless fan, the anemometers are first moved upward or downward along the Y-axis, with each movement distance being 40 mm, until the wind speeds measured by all anemometers do not exceed 24 m / min; then the anemometers return to their initial positions, and then move downward or upward along the Y-axis, with each movement distance being 40 mm, until the wind speeds measured by all anemometers do not exceed 24 m / min.

3. The speed ratio evaluation method of a bladeless fan according to claim 1, characterized in that: The anemometers are arranged in one row or more than two rows along the Y-axis, and the bracket on which the anemometers are installed is placed at the midpoint of the width of the fan air outlet. In the steps S4 and S5, when measuring the wind speed of the bladeless fan, the anemometers are first moved left or right along the X-axis, with each movement distance being 40 mm, until the wind speeds measured by all anemometers do not exceed 24 m / min; then the anemometers return to the initial position, and then move right or left along the X-axis, with each movement distance being 40 mm, until the wind speeds measured by all anemometers do not exceed 24 m / min.

4. The speed ratio evaluation method of a bladeless fan according to claim 2 or 3, characterized in that: The anemometer measures at each location for at least 1 minute, and the wind speed value measured by each anemometer is obtained by taking the average value of the data measured within a period of not less than 60 seconds at a sampling frequency of not less than 2 Hz.

5. The method for evaluating the speed ratio of a bladeless fan according to claim 4, characterized in that: The laboratory environmental parameters meet the following requirements: ambient temperature is 20°C ± 5°C; relative humidity is 50% ± 30%; atmospheric pressure is 86kPa-106kPa.

6. The speed ratio evaluation method of a bladeless fan according to claim 5, characterized in that: The center of the air outlet of the tested bladeless fan shall be at least 1200mm above the ground; the distance between the plane of the air outlet of the tested bladeless fan and the rear wall shall be at least 1200mm; the distance between the plane of the air outlet of the tested bladeless fan and the front wall shall be at least 4000mm; the distance between the center of the air outlet of the tested bladeless fan and the left and right side walls shall not be less than 1800mm.

7. The speed regulation ratio evaluation method of a bladeless fan according to claim 6, characterized in that: The bladeless fan under test is a desktop bladeless fan, and the distance between the blade plane of the anemometer and the air outlet plane of the bladeless fan under test is 1000 mm.

8. The speed ratio evaluation method of a bladeless fan according to claim 6, characterized in that: The bladeless fan under test is a ground-type bladeless fan, and the distance between the blade plane of the anemometer and the air outlet plane of the bladeless fan under test is 2000 mm.

9. The speed ratio evaluation method of a bladeless fan according to claim 1, characterized in that: The outer diameter of the anemometer does not exceed 40 mm, and the number of the anemometers is an even number and no less than 4.

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