Wind Load And Vibration Response Of Steel Frame Of A Large Solar Energy Dish System

Solar thermal power generation is a coupling system which consists of light field of the sun`s radiation, mechanical field of the frame and thermal field of the receiver.Among the system the frame could keep the dish and the receiver in right place. The wind load may cause the steel frame vibration and then influence the condenser performance, make the mirror broken and even the system cannot work. So the research of wind load and vibration response of the solar dish system is very important. Based on the 25 kw dish system, the influence of wind load and flow around characteristic of a single dish frame and two dish frame is analyzed. The research of typical condition wind vibration response of the frame which liner filtering method and FAE technology is carried out. The concrete research content includes:At first, Based on Fluent 6.3 software, the Reynolds mean Navier-Stokes equations were selected to simulate 3D steady wind field of complex dish frame.Computational domain model which conform to unrestraint flow field and grid independent solutions was built by applying multi-angle wind modeling methods with inner domain subarea on cylindrical. And, 45 group results of total wind load, wind pressure distribution and flow around characteristic were acquired by simulation.Change regulations of wind load with different working condition were analyzed, and,the reasonableness of simulation results were verified by qualitative comparative analysis between load curve and parabolic radar antenna wind tunnel test. The ratio of condenser mirror load on total wind load of frame was explored by adopting dimensionless method. Condenser shape factor distribution and extremes of each subarea load were acquired under typical working conditions. And, load generating mechanism was revealed by further analysis of the flow around characteristics.The second, according to a single frame of wind load research, three kinds of the most unfavorable load conditions in single rack situation were selected. Based on software Fluent 6.3, then the interference effects of two racks basic layout form(serial,parallel and inclined column) and distance were simulated. The static wind load interference factors of each arrangement interfered frames were obtained, then thechange rule of interference factors coincided with the arrangement of the layout form and distance were analyzed and the causes of wind load disturbance on frame were explored through the flow field flow chart. The results showed that static wind load factor of tandem downstream disturbed frame was below 1.0, which demonstrated a "shielding effect", whereas the wind load of the upper frame tended to monomer case.Moreover, the interference effects of inclined column layout were also showed a "shielding effect", but weaker than the serial interference. The interference effects between two parallel frames formed a "slit effect", but the effects were not significant.Then, the simplify and building method of the complex dish frame finite element model was giving in the paper, based on Ansys 12.0 plot the model of the frame which suitable for the transient dynamic analysis was built and through the analysis of static load and transmission angle, pointed out the elevation angle driving mechanism deficiencies and to be improved, then comparative analysis of the vibration characteristics of multi-rack elevation angle of the frame before and after improvement which provide a basic for the frame wind vibration response of dish photo-thermal solar energy.Finally, based on the linear filtering method of AR scored 25 groups of conditions of fluctuating wind load(average wind speed 16.0 m/s),carry out the wind vibration time domain solution improved frame. Analysis of the frame of key nodes displacement response characteristics of root mean square and peak distribution,and analyzes the frame of typical working condition of displacement response spectrum analyses, the problem of modal parameter and contribution in frame wind load vibration response,given the displacement wind vibration coefficient of various operating conditions of each rack key nodes, to provide the reference for wind fram structure design. The results show that the displacement response of frame structure in the forced vibration of pulsating load mainly, accompanied by multi-stage resonant response modal participation.the vibration of frame mainly for the frame depending on the day part revolve around elevation angle axis.The peak displacement and root-mean-square distribution of the rack control point is similar,and along the focal axis response components are dominant.Through the research of this paper, the wind load distribution and the role mechanism of dish frame was make sure, the design points of the frame structure was understand. which can provide a basic for frame structure optimize, vibration research and the dish unit layout of the power station.