Design and Flow Field Quality Test of First Weather Modification Subsonic Cloud Environment Wind Tunnel in China
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Abstract:
With the development of artificial weather modification efforts, the importance of aircraft for cloud seeding becomes increasingly significant. The effectiveness of aircraft for cloud seeding heavily relies on the stability of onboard detection equipment. To effectively simulate the dynamic operational environment of airborne detection equipment used in artificial weather modification and to enhance the detection capabilities of such equipment, this study presents a design for a recirculating closed-circuit wind tunnel. The primary structure comprises several sections: the test section, diffuser section, corner section, power section, heat exchange section, stabilisation section, contraction section, and reserved section. The interior contains built-in components such as corner guide deflectors, cellular devices, damping screens, heat exchangers, etc. The wind tunnel is arranged horizontally, with a centreline length of 28.09 m and a short axis distance of 5.71 m. The maximum dimensions of the wind tunnel are 31.33 m×10.18 m×5.436 m (length×width×height), while the cross-sectional dimensions of the test segment measure 1.2 m×1.2 m with a stable wind speed range from 30 to 150 m/s. The actual sizes of the airborne detection instruments are taken into account in the design of the test section. Based on a contraction ratio of 12.25, the stable section is designed with a square cross-section of 4.2 m×4.2 m. The diameter of the power section is set at 2.4 m. To prevent damage to the fan blade from test pieces or other objects, a protective net is installed in front of the power section. To verify the rationality of the wind tunnel design, the flow field quality of the wind tunnel is tested according to the “Low-Speed and High-Speed Wind Tunnel Flow Field Quality Requirements” (GJB1179A-2012) and the “Wind Tunnel Control System Design and Checking Guidelines” (GJB 5221-2004). Following flow field calibration tests, various quality indicators-including wind speed range, dynamic pressure stability, drop coefficient, turbulence intensity, airflow temperature variations, axial static pressure gradient as well as directional and dynamic pressure fields are confirmed to meet GJB1179A-2012 standards and adequately fulfil the testing requirements for airborne equipment. Specifically, the dynamic pressure stability is less than 0.5%, and the turbulence intensity is less than 0.2%. When the wind speed is 100 m/s, the temperature rise is 1.31 ℃/h. The aerodynamic and structural design principles applied in this wind tunnel are reasonable and may serve as valuable references for future designs and constructions of similar facilities.
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.