1、 Test background
Conducting atmospheric environment simulation experiments using wind tunnels is an effective method for studying the diffusion of atmospheric pollution. Wind speed profile simulation is one of the key technologies in wind tunnels that simulate atmospheric boundary layer flow. In order to simulate the atmospheric boundary layer wind speed profile in a wind tunnel and generate a wind speed profile that meets the requirements in the wind tunnel test section, it is necessary to quickly generate and quantitatively verify linear and exponential atmospheric boundary layer wind speed profiles in a 0.5 m × 0.5 m low-speed environment wind tunnel for subsequent pollutant diffusion wind tunnel tests. The traditional sharp and rough element scheme can only obtain a single profile at a time, and replacing the profile requires stopping the machine and rearranging the model, which has a long cycle and poor repeatability. CARDC has designed a "nine layer independent adjustment plate" profile simulation device, which requires:
1. Real time measurement of instantaneous wind speed ranging from 0.01 to 5.00 m/s within the height range of 0-400mm;
2. Accuracy better than ± 2%, resolution ≤ 0.01 m/s;
3. Synchronize temperature and humidity recording for air density correction.




2、 Test purpose
1. Verify whether the regulating plate device can form a target linear (α=1) and exponential (α=0.22) wind speed profile at a downstream cross-section of 1700 mm;
2. Quantitatively evaluate the depth of the wake area and the recovery pattern along the flow direction (500-4000 mm);
3. Establish a fast debugging empirical formula for "area ratio speed ratio" to shorten the preparation time for subsequent experiments by more than 50%.



3、 Testing process
Set up a measuring frame downstream of the wind speed profile simulation device test piece, and install a single point wind speed probe on the head of the measuring frame support rod. The probe is 1700mm away from the outlet of the wind speed profile simulation device test piece and can move in the vertical direction perpendicular to the axis of the test section. The wind speed probe used is KANOMAX's intelligent environmental tester, with a probe model of 6533-2G, which can simultaneously measure the speed, temperature, and humidity of the airflow. The wind speed measurement range is 0.01m/s to 5.00m/s, with a measurement accuracy of ± 2% of the reading or 0.02 whichever is greater. The environmental tester 6533 and its installation method are shown in the following figure.



4、 Actual measurement results
Linear wind speed profile simulation
By adjusting the relative positions of the adjustment plates on each layer, the vertical distribution of wind speed can be changed. After initial adjustment, the wind speed trend is basically in line with expectations, and with further fine-tuning, a wind speed profile with high linearity can be obtained. Linear wind speed profiles can be obtained at different speeds, but the higher the speed, the smaller the slope of the wind speed profile.
Exponential wind speed profile simulation
The simulation target is an exponential wind speed profile, and after initial adjustment, the experimental curve is close to the trend of the target curve. After further fine-tuning, the degree of agreement is significantly improved. This device can effectively simulate exponential wind speed profiles.
The influence and development of wake
The wind speed profile has wake effects at different positions downstream of the device, and the wind speed distribution near the device is serrated. As the flow develops, the wake gradually weakens, and the wind speed profile tends to be smooth and uniform.
V. Conclusion
Verified by KANOMAX environmental tester 6533, the device can retrieve linear or exponential wind speed profiles within 10 minutes with an error of less than 3% and a repeatability deviation of less than 1.5%; The wake disappears after 1.7 meters, and the measurement point is set here to stabilize; The change in speed only slightly affects the slope, simply readjust the opening. A set of equipment meets various profile requirements and is economically efficient.


The 65Ser series environmental testing instrument has precise measurement of wind speed and reliable data; The probe has interchangeability and can be adjusted to meet different testing environments and requirements; The probe has a temperature compensation system to cope with temperature differences in different environmental processes and achieve high-precision testing; To meet different testing requirements, the frequency and frequency of data collection can be set, and data retention can also be achieved for convenient real-time reading; One machine has multiple functions, and multiple parameters (wind speed, air volume, air temperature, humidity, differential pressure) are tested simultaneously, making the data more referenceable and improving testing efficiency.
At present, KANOMAX environmental tester 65Ser is widely used in ventilation testing, laboratory control, clean room testing, IAQ evaluation, industrial hygiene, quality control, etc., to ensure process safety and product quality.