A 3D Gradient Boundary Transition Device Applied to Wind Tunnel Tests of Terrain Model Wind Field Characteristics

Abstract

The invention discloses a three-dimensional gradually changing boundary transition device applied to wind tunnel tests of wind field characteristics of terrain models. The boundary transition device is mainly composed of a plurality of segments spliced ​​in series, and each segment includes two side panels and a surface layer; each side panel has a vertical edge, a bottom edge and a curved edge; the curved edge of the two side panels The surface layer is fixedly laid on top; the height of the vertical edge of the side plate is equal to the height at the corresponding position of the boundary of the terrain model; the length of the bottom edge of the side plate is 5% to 8% of the width of the wind tunnel, and the side plate The slope formed by the vertical edge and the bottom edge of the side plate is 20°~40°; the curve shape of the side plate is determined by the equation y - r 2 y + r 2 x 2 y 3 - r 2 x 4 y 5 + r 2 x 6 y 7 - r 2 x 8 y 9 - m = 0 Determine, where x represents the radial position of the curved edge, y represents the vertical position of the curved edge, and the parameters r and m are determined by the equation m + m 2 + 4 r 2 2 - m + m 2 + 2.692 r 2 2 = h 0 1.285 ( m 2 + 4 r 2 - m 2 + 2.692 r 2 m + m 2 + 2.692 r 2 ) = k 0 Determine, where h0 is the height of the vertical side, and k0 is the ratio of the height of the vertical side to the length of the bottom side. The invention can meet the requirements of the wind field characteristics after the airflow transition, has low requirements on the space of the wind tunnel, and has strong applicability.

Description

technical field [0001] The invention relates to a three-dimensional gradually changing boundary transition device applied to wind tunnel tests of wind field characteristics of terrain models. Background technique [0002] To build a bridge in a mountainous area with complex terrain, it is necessary to obtain the wind characteristic parameters such as the average wind speed and fluctuating wind speed in the bridge site area through the wind tunnel test of the bridge site area model, so as to provide a scientific basis for the wind resistance design and construction of the bridge. In addition, when the macro and micro sites of wind farms are selected in complex mountainous terrain, the wind field parameters at the wind farm site must also be clarified, so as to provide guarantee for the efficient and safe operation of wind turbines. In the wind tunnel test of the wind field characteristics of the terrain model, due to the limitation of the size of the wind tunnel test section,...

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Problems solved by technology

[0003] The existing transition device is mainly composed of multiple straight 30o slope plates spliced ​​at the boundary of the terrain model. When the incoming flow flows to the slope plate, the air velocity will increase along the slope and the pressure will increase due to the pressure of the slope. As it decreases, a forward pressure gradient will be generated. When the airflow reaches the intersection of the slope and the boundary of the terrain model, the velocity will reach the maximum, and the corresponding pressure will reach the minimum at this time, so the terrain model after the intersection will produce The reverse pressure gradient, when the reverse pressure gradient is too large, the flow will separate, which will cause a large change in the wind field characteristics here and the wind field characteristics of the incoming flow, and make the wind field characteristics of the incoming flow in the test lose Reference significance, and ultimately make the test results inaccurate

Although the method of reducing the slope (such as reducing the slope to about 5°) and extending the length of the slope plate can be used to reduce the influence of the reverse pressure gradient on the incoming wind speed of the test, this method will cause the transition section to be too long, which is harmful to the wind tunnel. The space requirements are high, and it is difficult to apply to the needs of conventional wind tunnel tests

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