Investigation Of Wind Field Characteristics In Complex Micro-terrain

With the wind flows through complex terrain,the characteristics of incoming wind speed and turbulence degree will be significantly changed by complex terrain characteristics,which makes the wind speed and wind pressure distribution in hilly terrain wind field very uneven,which is obviously different from the flat wind field.However,specifications for regular mountain are usually difficult to apply to actual terrain,so accurate predictions for the wind characteristics of actual complex terrain,including the distribution law of wind speed near various special micro-terrain,are very important for micro-site selection of wind farms,transmission towers other buildings on complex terrain in the future.In this paper,the wind field near the actual complex terrain is simulated by numerical simulation and wind tunnel test to study the wind speed and wind speed ratio distribution at different positions near different micro-terrain,and the research results are compared with national standards.For the validation analysis,wind farms along the constructed Transmission tower-line system lines are also discussed.The main research results are as follows:A CFD-based numerical simulation method is used to study the wind field in a region of eastern China with actual terrain.The wind speed distribution of the whole terrain under different wind directions is analyzed,Including the wind speed distribution at the top,foot and waist of the hill near the actual single mountain terrain,windward and downwind pass terrain,and the interaction between the mountains are focused on.The results show that there will be obvious wind speed-up effect near the mountain top and the pass,and the wind speed will increase locally and then flow back,this wind speed-up phenomenon will be weakened by the shielding effect of the mountain in front.On the contrary,there will be obvious wind speed-down effect at the front and rear foothills,and this wind speed-down effect will be enhanced by the sheltering effect of the front mountain.Based on the numerical simulation results,a terrain model was established in the 8km range near an actual transmission line selected in the area of numerical simulation for wind tunnel test.In this study,the wind characteristics distribution near the positions of maximum wind speed ratio and highest elevation in the range was compared and analyzed with the numerical simulation results,and the research results were compared with the specification of each country.The wind tunnel experimental results are in good agreement with the numerical simulations.For the mountain with small slope,the research results are the closest to the recommended values of American codes and less than those of other codes.For mountains with steep slopes,the research results are much smaller than the national codes.For the pass terrain,near the mountain surface,the research results are larger than the range recommended by the Chinese code,which is conservative.In order to verify the results of the study,a constructed tower line was selected to analyze the wind field in its vicinity.The analysis shows that when the transmission tower-line system passed through the hilly terrain,its unfavorable wind direction angle should be paid attention to.