Research On Effect Of Wind Load And Wind-parameters Of The Air-cooled Structure

The bracket structure of air-cooled steam condenser is new style cooling water device adopted in the large steam-power plant of our country. It is new style structural system occurring with the development of cooling water technology of air-cooled steam condenser. The bracket structure of air-cooled steam condenser is the life blood project of the country, and is the important facility of the electric power plant. The safety of the bracket structure has directive relationship with the normal running of the electric power plant, and is necessary segment of the normal running of large steam-power plant. Most large steam-power plants of our country locate in the north part which is windy area, so the effect of wind load should be taken into consideration in the structural design of air-cooled steam condenser.The lower part of the air-cooled steam condenser is large-diameter reinforced concrete hollow limb, the upper part is 'A' type bracket and wind-break wall, and the top is large-diameter evacuation line. The stiffness of the upper steel truss of the bracket structure is far bigger than that provided by the large-diameter reinforced concrete hollow limb of the lower part; and the equipment of the upper part is the main source of the load of the bracket structure, making the mass centralized in the upper part of the structure. Thus, the bracket structure of air-cooled steam condenser is a typical vertical stiffness and mass distribution severely non-uniform high-rise flexible structure; the lower part of the structure is empty; and the wind load plays a major role in the wind-break wall and has a greater effect on the lower part of the structure. For the specialty and complexity of the bracket structure, many parameters for wind resisting design of the structure, such as the load shape coefficient, wind-induced dynamic property, and wind-induced dynamic coefficient, are still unobvious by now. Thus, it is necessary to do research on wind resisting analysis of the bracket structure of air-cooled steam condenser, including research on the property of wind load distribution and wind-induced vibration, to obtain the load shape coefficient and wind-induced dynamic coefficient of the structure, providing reference to the wind resisting design of the structure.The bracket structure of an air-cooled steam condenser is chosen as the prototype in this paper; wind resisting analysis is studied by means of wind tunnel test method. The property of wind load distribution of the structure is obtained firstly, based on the wind pressure measurements on a rigid model and CFD numerical simulation. The wind-induced dynamic vibration property of the bracket structure is obtained and analyzed based on aero-elastic model wind tunnel test. The wind-induced dynamic coefficient of the bracket structure of air-cooled steam condenser is calculated and studied, based on the displacement response measured in the aero-elastic model wind tunnel test. Finally, based on the wind tunnel test study on the bracket structure of air-cooled steam condenser, combining with the wind load code, the wind resisting design suggestion is presented. The research of this paper is mainly focused on the following aspects:1. Wind pressure measurement on a rigid model of the bracket structure of air-cooled steam condenser is done. Based on the wind tunnel test, the distribution of wind load on the bracket structure is amply studied. Through analysis on the wind tunnel test results, the integrated distribution of wind load on the structure is obtained, and the regularities of spatial distribution are generalized.2. CFD numerical simulation on the bracket structure of air-cooled steam condenser is done. Compared with the rigid model wind pressure measurement test, the simulated resulted is verified, and the applicability of CFD numerical simulation method on the bracket structure is discussed. Based on the numerical simulation, the effect on wind distribution on the bracket structure, which can not be considered in rigid model wind tunnel test, such as the effect of rotation of the fan of the bracket structure, is studied additionally, and the reason for the property of wind pressure distribution is explained by means of flow visualization by CFD numerical simulation.3. The aero-elastic model wind tunnel test on the bracket structure of air-cooled steam condenser is done. The manufacture of the aero-elastic model of the bracket structure is discussed, and the displacement response property of the bracket structure is obtained. By analyzing on the root variance, the mean value and the response spectrum of the displacement response, the wind-induced dynamic vibration of the bracket structure of air-cooled steam condenser is basically recognized. 4. The wind-induced dynamic coefficient of the bracket structure of air-cooled steam condenser is calculated and studied, against the deficiency of the calculation method of the wind load code, adopting the displacement response of the structure obtained in the aero-elastic model wind tunnel test.5. Based on the wind load distribution property, wind-induced dynamic vibration and wind-induced dynamic coefficient of the bracket structure of air-cooled steam condenser obtained by the wind tunnel test, combining with the wind load code, the wind resisting design method is discussed, and suggestion that is easy to apply in engineering design is presented.